Combination
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Engine Block Turbos Air Filters Intercoolers Heads Intake/Plenum Throttlebodies CamShafts Headers Down Pipes/Exhaust Systems Cold Air/Ram Air Torque Converters Chips Compression Ratio Alcohol Injection Example Combinations
At the sake of being redundant, these cars are all about combination and there are no magic parts-only parts that work well when complemented with other parts that match up well. This includes the engine, transmission, and suspension.
Let me repeat that for any car to perform up to standard, the basic drivetrain must be in good condition. Engines with flat lobes on the cam, excess slack in the timing chain or missing teeth on the cam gear, low compression, burnt valves or weak valve springs, etc. simply won't run as they should. The same can be said about the transmission and differential. If they are not in good shape, the car will not perform well. It's as simple as that. Bolting monster turbos, etc. on a sick car is simply a waste of time.
Likewise, trying to make ones car perform without the proper accessories-scantool, fuel pressure gauge, etc. is a pointless exercise.
For the purpose of this discussion, I am going to stick to the engine block, turbo, torque converter, intercooler, heads/intake, camshaft, and associated items.
Now, let's talk about what one should expect performance-wise from the car. The intent is not to state how the car has to be built, but, to make you think about how the parts should work with one another and to give you some basis for analyzing current performance and planning future mods.
The factory combination was almost ideal. Turbo size, injectors, fuel pump, intercooler, heads, converter, etc. all seemed to match each other to a tee. There was not a great deal to expand on performance-wise without beginning to change things. It's amazing how much power was extracted from base components without changing out everything for specialty items.
A stock drivetrain should approach 110 mph (low 12's) with race gas, race chip, 2.5" exhaust, K&N air filter, and slicks, and, nothing more. It should be around 103 (low 13's) on 93 octane and a good street chip without slicks and may sneak into the upper 12s. Note that the stock turbo is pretty much all in by 21 psi of boost with a stock factory location intercooler.
Take the above car, add a TA49, or a TE44, add race gas, race chip, and increase the injector size, and with no other changes, it should be approaching mid-elevens. Add alky injection and 93 octane with a matching chip, and, it should be in the elevens even on drag radials if you can hook it up. At this point, the stock intercooler has become an impediment.
Take the same car, go to a TE60-62 turbo, better stock location intercooler, matching injectors, some minor head porting, and race gas/chip, and it should be trying to edge into the tens.
Note that mph is a better indication of horsepower than times as mph is less dependent on driving technique. Go Here and look at Joe Lubrant's chart for mph and times. I think his suggestions for injectors are too small, but, the e.t.s and mph can be very useful when analyzing performance.
Yes, I know, the bulletin boards are full of people with every product sold by vendors, including 70 size turbos, that cannot get out of the 12s. Some of them even own a scantool. On the other hand, there are many that perform as I describe above. There must be a reason! If the car does not approach the mph associated with the above times then it is time to discover why not rather than buying more stuff to add on.
Of course, there is more than one way to achieve ones performance goals, and, it would not be much fun if every car was built identically to the next. On the other hand, certain criteria must be met if there is to be the required synergy between the various components and value is to be received for the money spent. Spending a ton of money on go fast parts and the car does not respond as expected is no fun at at all unless one is simply a Drive-In racer.
It is important to understand the basic science involved in order to make intelligent decisions if one is to achieve the desired goals.
When one sets out to improve the performance of his Buick, it is important to establish aspirations for the car. Is it going to be a daily driver that is mostly street driven? Is is going to be a week end street racer where ultimate drivability is not that important, or will it be a race car where drivability is not a real consideration? Now is when you tell me that it will be a low ten second street car, and that is the point where I tell you there is basically no such thing unless you have a very loose definition of a street car, or you have a lot of money for a stage block, etc.
I am not sure how to approach the subject of synergy so I will try to discuss the various common components that make up the drivetrain and attempt to point out what must be considered when upgrading.
What does the block have to do with it? Everything, if you want to crank the horsepower up and keep it in one piece. Typically a stock block is safe to the vicinity of 525 hp assuming that one has assembled the engine according to good practice (that's another topic altogether) and avoids detonation. Beyond that, the wise typically install engine girdles and steel main caps. Yes, there are a few guys that may be pushing 650 hp or so and don't run girdles....Personally, I think those guys probably get dressed in a phone booth. I suspect they don't make a lot of passes every week like some of us do, either.
It is absolutely critical that one uses good parts, good assembly practices, and avoids detonation if one wants to extract maximum life. The faster one wants to go, the more one is going to have to spend to do it reliably. As my friend, Steve Yaklin, says, "Cubic money beats cubic inches".
It is a waste of money to buy the parts to make 600 hp and have them blow the bottom out of the block.
Turbos are normally listed by flow in cfm. Sometimes, potential horsepower is also listed. A general rule of thumb that can be used to compute this theoretical horsepower is: CFM x 0.069 x 10 = maximum horsepower that the turbo can theoretically support.
Now it is important to understand what a turbo can support and what your engine can generate are often two entirely different things. In other words, just because your turbo can flow enough air to theoretically support 600 hp does not mean that your engine is capable of making 600 hp. Unless the engine is a built with all the necessary components required for complete synergy, it is likely that from a practical standpoint, the actual horsepower will be somewhat less than the theoretical prediction.
When selecting a turbo there are two important parts of the drivetrain that must be matched to the turbo. It should be obvious that the fuel injectors must be of sufficient size to provide the required fuel at the maximum boost/airflow that the turbo will run or the engine can generate. See the section on Injector Sizing under Basics.
Once fueling has been covered, a torque converter with a stall that matches the spool up characteristics of the turbo is a necessity. In general, the larger the turbo, the higher the rpm required to get the turbo into the boost domain. In order for a quick transition to boost, the torque converter must provide sufficient stall to allow the turbo to spool. This means that monster turbo which is so much fun to brag about may require so much stall in the converter that the car is not a lot of fun to drive on the street due to slippage in the converter, and, may actually be slower from a roll, or, off the light than your friend's car with a smaller turbo that does not take five seconds to get spooled up.
Most turbo vendors suggest stall converter stall ranges and injector sizes to complement the individual turbo. I often suggest even larger injectors as per the injector sizing link above if the car is going to be pushed to its limits.
Now, the question of synergy arises. How well is your chosen turbo going to work within your combination of parts?
Let's say you have stock heads, cam, and intercooler and you want to go to a large turbo. A suitable high stall converter and matching injectors are no problem as you don't mind the extra slippage and potentially slushy low speed throttle response. Will you get your money's worth when you put on that TE70 turbo? Obviously it has the capability of flowing a lot more air than a stock or TA49 sized turbo. It ought to be a real kick in the pants at wide open throttle. BUT, the stock heads, cam, intercooler become real bottlenecks that prevent the big turbo from living up to its credentials. It may be able to flow a lot of air, but, not with the bottlenecks between it and the cylinder.
The combination does not work well. It may seem obvious, but, it is not that uncommon to come across such a combination running no faster, and sometimes slower, than a near stock set up.
An obvious problem is with the stock cam that is pushing the rev envelope at 5400 rpm. Put a 3600 stall converter on to match the big turbo and more than a 1000 rpm of usable street power band has been lost in order to have that big turbo, and the engine is not capable of turning the rpm required to absorb the flow capability of the turbo anyway.
Same with the heads as the turbo may easily out flow the capability of the ports at any given lift. Think about it. These heads are the same heads as used on low performance naturally aspirated engines. Using a turbo to push more air through the ports works to a certain extent, but, there are limits to what is efficient, and, beyond that, it becomes ridiculous. As an analogy, consider the case where one wants to pour a gallon of Xylene into the fuel tank and uses a funnel with a half inch outlet to pour the Xylene into. It goes fairly well. Now, consider the case where one has a five gallon jug of race gas to pour into the tank. That small funnel becomes a real hinderance in this case and a funnel with an one inch outlet makes the job go a lot faster. That is similar to the problem when one installs a 70 series turbo on an engine with stock heads.
Yep, air filter. If you want the turbo to spool properly, and, deliver advertised performance, the inlet side must not be a restriction. On a ten second, or quicker car, this is probably a 4" inlet pipe and a 12" filter. Below are some guidelines provide by K&N to Chuck Leeper who kindly passed them on to me.
Will the turbo give you what you paid for if you don't address all the weak links in the chain?
Some very general guidelines.
Expanding upon what I stated above-
Stock long block, intercooler, torque converter, 3" downpipe-- TA49/TE44 Near the mid 11s.
Stock long block, intercooler, 3000 rpm stall converter, 3" downpipe--PTE51 1-2 tenths better but the stock intercooler has become a restriction.
Stock long block, improved intercooler, 3000 rpm stall converter, 3" downpipe--TE60-TE61 low elevens
Stock long block, improved intercooler, 3200 rpm stall converter, ported heads, 3" downpipe--TE62 10.9-11.0
Mild cam, ported heads, good intercooler, 3400 rpm stall converter, 3" downpipe--TE63E (LE45)--10.70
Now there is nothing magic about the above...guys often go faster with even less and a set of ported heads will often improve a TA49 car by a couple of tenths at higher boosts. The examples are merely an attempt to show what is required to obtain a reasonable response from a combination as larger turbos are employed so that performance improvements are noted for the money spent. I assume that adequately sized injectors are used in each case to support the horsepower required to turn the mph normally associated with such times and the suspension is working well.
One issue to keep in mind is that small turbos often seem to like higher timing on race gas while larger turbos that produce higher density air charges tend to like less. Trying to crank more boost out of a smaller turbo may be a wasted exercise as the compressor moves out of its better efficiency zone on its compressor map which then causes undue heating of the charge which then creates a less dense charge-in other words, a wasted effort. Turning the timing up in this case is then a better alternative. On a large turbo, 20-22 degrees of timing and cranking the boost up more may be more optimum. If one does not experiment, one will not know.
Intercoolers are an interesting subject because there are so few facts readily available with regard to performance enhancement other than bigger is generally better if one has reached the point of diminishing returns with the current unit. Determining this point is the difficult thing. Unfortunately, vendor hype often does not do much to clarify the issues.
Intercoolers are very difficult to effectively test even when one has a lot of sophisticated equipment. Red Armstrong spent a year testing intercoolers and promising to post the results and it never happened as he could not quantify results in a meaningful manner.
There has been only one scientific comparison test of which I am aware. It was conducted by Bob Dick and posted in The Source. Bob is a mechanical engineer with a Master's Degree from Villanova concentrating on thermodynamics and he made a valiant effort to scientifically compare several intercoolers on a mid 12 second car (stock intercooler) equipped with a PTE-51 running 21# of boost on 100 octane. This may not be representative of the Ricky Racecars amongst us, but, the results provide plenty of food for thought. It's worth reading and understanding the complete write up so go here when you have the time. Please note that a couple of columns are reversed in the temps provided for the stock intercooler in the table included in the article.
Also, here is an article by an unknown author which was posted by Ed Baker on www.turbobuicks.com. This article contains some theory and discussion of intercooler design and performance.
If one reads Corky Bell, or other turbo experts, one learns that the magnitude of the pressure drop across the intercooler is generally more important than the amount of heat transfer capability of the intercooler. To clarify, the LESS the pressure drop across the intercooler, the better. Obviously there has to be some trade off between the two (pressure drop versus heat transfer) as a three inch straight pvc pipe in place of the intercooler would minimize pressure drop to almost zero, but, would not cool the charge at all and we would be back to hot air cars!
Now, why is the magnitude of the pressure drop important? Boost pressure is measured in the plenum. If the stock intercooler has almost 6# of pressure drop across it at 21# measured in the plenum, that means the turbo is actually pumping 27# of pressure at its outlet.
The heat generated by compressing air to 27# at the turbo outlet is considerably greater than it would be if the turbo only had to make 23# at the outlet to have 21# at the plenum. Why is the temperature important? Two reasons, air density and detonation. Remember that it is not the pressure of air going into the cylinder that makes power, but, rather, the density of the air. The denser the air, the more molecules of air, and, that is what counts. Therefore, if we can reduce the boost at the turbo outlet, the air entering the intercooler will be cooler and the air exiting the intercooler will be also cooler which means our 21# of boost in the plenum will actually be denser and we can make more power at the same boost than before. That is what it is all about. Detonation which is the auto-ignition of the end gases in the cylinder occurs more easily as the air temperature rises and colder air is a major asset in avoiding this problem as well.
Now, what did Bob Dick determine when he compared the thermal and track performances of a stock intercooler, a Duttweiller Big Neck conversion of a stock IC, a CAS V4, a Cotton stock location IC, a PTE front mount, a ESP front mount, a CAS V2, and, a Cotton front mount? Remember, this was a low 12 second street car with a stock IC and a small PTE-51 turbo with limited airflow capability.
Stock IC 5.52 psi pressure drop 4.2 Flow Coefficient
Big Neck 3.62 psi pressure drop 2.5 Flow Coefficient
Cotton stock location 3.16 psi pressure drop average 1.8 Flow Coefficient
CAS V4 stock location 3.02 psi pressure drop average 1.69 Flow Coefficient
ESP front mount 4.10 psi pressure drop average 2.1 Flow Coefficient
CAS V2 front mount 3.62 psi pressure drop average 1.53 Flow Coefficient
PTE front mount 1.77 psi pressure drop average 0.93 Flow Coefficient
Cotton front mount 1.64 psi pressure drop average 0.84 Flow Coefficient
Now, it is not so simple as merely looking at pressure drop or we would be using that piece of pvc that I mentioned above. In fact, it is not simple at all. Restriction within the the intercooler slows down the path of the air thru the intercooler which means the thermal efficiency of the intercooler with regard to heat transfer may be greater.
Mass air flow thru the intercooler must also be taken into account and the Flow Coefficient relates pressure loss and flow. Lower is better. This is a more meaningful number than simple pressure drop, and we see the big front mounts are five times better in this category.
An efficient turbo compressor that does not generate as much heat as another may actually perform better with a slightly more restrictive intercooler that removes more heat when the air density entering the cylinder is compared (this is the reason that the temperature at the turbo outlet of a TE44 is lower than that of a stock turbo at 20# as measured in the plenum--more efficient compressor). One has to be very careful in trying to make decisions based simply on one parameter or another, and one has to remember that the above numbers were measured from a PTE-51 turbo with limited volume and not a T-88 that would really stress the smaller units' capabilities.
In a nutshell, it is not the boost that is being run that determines the power that can be made, but, rather, the amount/density of the air that enters the cylinder on each intake stroke.
At the bottom of this section are the numbers for the thermal performance of the various intercoolers comparing air temp measured at the throttlebody to air temp at the turbo outlet. Note that the front mounts average 30-50 degs cooler at the throttlebody. To be fair, one should be aware that the V4 is fairly old technology today and the Cotton's stock location is made from old factory cores. Today's units may be better with regard to flow coefficients. However, a front mount typically offers more surface area to cooler ambient air which indicates that it should perform better if constructed well. This may well be in conflict with some vendors' claims that a stock location, modern intercooler will perform as well as a front mount. We know that some have been into the nines on stock location intercoolers made from old cores. What we don't know is how fast they would have gone on a new tech front mount. Few vendors, if any, provide any scientifically measured data to support performance claims.
Studying the tests performed by Bob Dick, I have come to the conclusion that the factory intercooler was well matched to the boost provided from the factory on the stock turbo and that a Duttweiller Big Neck conversion will work well for the money on a stock, or near stock, turbo. After all, the flow coefficient on the above test clearly shows the poor flow coefficient of the factory unit when the boost is cranked up. If we typically believe that the factory turbo is all done by 21 # of boost, anything we do to reduce the intercooler bottleneck should extend the useful range of the turbo as the reduction of loss in the intercooler will allow the turbo to run at a lower turbo outlet boost to obtain the desired plenum boost at a cooler temperature.
If we go to larger turbos, it is very obvious why we are not getting our money's worth with the factory intercooler.
Now, one could easily come to the conclusion that a good front mount is the best solution by far. There are a couple of caveats, however. First, there could be a potential overheating problem if one lives in a hot climate as air flow to the radiator is restricted by the presence of the front mount. This is at its worst when the AC is running. A good radiator backed up by dual fans, a HD water pump, and an overdrive water pump pulley is usually a big help in this department. Then we have a problem, potentially, with larger turbos and the larger volume of the tract between the turbo and the throttlebody which may cause compressor surge which can make the car more difficult to drive at light throttle in some cases. Finally, we may have a bit more lag before spool up as we have a larger volume of air to get moving in the system.
Practically speaking, a modern, stock location intercooler should perform almost on par with a front mount at least well into the 11s. I am a bit dubious that they will duplicate the performance on a hot day due to the reduction in air flow thru the core with any streetable duct system no matter what various vendors claim, but, I suspect the difference is not much more than a tenth if tuned properly for both.
The main point of all of this is that the stock unit is a serious bottleneck when it comes to larger turbos and/or more boost as evidenced by the provided numbers, and intercooler improvement should be considered along with turbo size increases, etc.
Here are the temperature differences measured in Bob's tests of the various units.
As stated above, the factory heads that came stock on the turbo Regals have the same ports as the naturally aspirated heads and were not designed for high performance. With a small turbo, however, they work quite well. The turbo pushes the additional air thru them without significant resistance and the small ports are not a real bottleneck in the greater scheme of things. Once larger turbos are used, the small ports begin to provide serious hinderance to the flow potential of the turbo. See my analogy above comparing funnel sizes.
Small ports provide good velocity and throttle response when the engine is not under boost and are good for both performance and fuel economy.
Once the boost is cranked up, a bigger turbo capable of flowing more air, a better intercooler, etc. come into play, the stock heads rapidly become an impediment to making power. By the time the car is knocking on the door of the eleven's, better flowing heads will improve virtually any combination. The larger the turbo, the better the intercooler, the quicker the stock heads become a bottleneck.
Daily drivers don't need, or benefit from, significant metal removed from the ports, but they do respond well to pocket porting and cleaning up the short side radii of the intakes entering the pocket. Normal clean up and port matching along with the aforementioned work will deliver 85% of the performance of a $1200 set of commercially done heads-particularly for those trying to run in the 11s while maintaining low speed performance and fuel economy. One has the option of doing his own work, having them done by a professional, or looking for a used set from someone moving up to a set of aluminum heads.
Cast iron factory heads have often run into the nines and a full blown set of fully ported commercial heads are certainly adequate for running into the tens if the rest of the combo matches up well.
Aluminum heads are available for those that are serious about getting everything possible out of the engine. However, they are more susceptible to damage, cracking, and due to the poorer thermal performance of aluminum, more compression may be helpful. I consider the current crop of aluminum offerings to be more suited to the cars that are largely used for the strip.
I consider a set of mild iron heads as very helpful on any engine that has a TA-49 or larger if it typically runs above 20 psi of boost on 93 and alky, or race gas. There is very little downside if the porting was done properly... Properly meaning reasonable sized ports and consistency between cylinders. Lots of performance improvement for a reasonable expenditure of money makes them attractive to me and they are not instantly obsoleted when larger turbos, etc. are added to the combination.
For street cars, a larger camshaft, that holds the valves open longer and higher, tends to kill performance at low speeds and fuel economy. This probably becomes obvious at about 208 degs of duration as measured at 0.050" of valve lift.
The stock intake is fairly well designed and aftermarket units don't provide much, if any, performance gains for stock blocks. Port matching to the heads won't do any harm, but, may not provide measurable performance gains, either.
The weakness in the stock manifold comes in air distribution and the problem probably lies more within the physics of the plenum design. Air entering the throttlebody, and into the plenum, tends to travel to the rear of the intake and is biased toward ports five and six. As a consequence, these two ports tend to run leaner than the other four.
Hemco, PTE, and Kenne-Bell/Accufab have redesigned the plenum in an attempt to better balance the air flow distribution between the cylinders with some improvement.
In addition, RJC Racing has designed the Power Plate that goes between the plenum and the manifold that works extremely well in equalizing flow between cylinders and is in use on many of the nine second stock blocks as well as more normal performers. It allows one to tune A/F's for all six cylinders rather than targeting an adequate mixture for five and six which leaves the other four too rich. Power Plates are available for the stock plenum as well as the PTE and KB/Accufabs. Testing indicates the PTE and PTE Power Plate are probably the best overall combination for even distribution. There is also an unit for the BGC manifold if one is making a 1000 hp or more. Initially there was a lot of controversy over the Power Plate as many "eyeball" engineers looked at it and deemed it a restriction. Dyno tests, six probe egt readings, and, most importantly, track results have demonstrated that it does work as advertised even on nine second cars.
One of the most popular upgrades, and one of the most useless from a performance standpoint is the addition of a larger throttlebody. I have yet to see any convincing numbers that demonstrated that an increase from the stock 58 mm throttlebody to a 62, 65, or 70 mm unit has increased speed on a mid-ten second car or slower. Some offer improved throttle response as evidence of improved performance. A larger unit appears to have better response, but, it is due to the increased area of the throttleblade which has to be opened less to provide the same airflow.
Now, having stated that larger units don't normally add to performance there are a couple of benefits. First, the original units may have worn seals around the shaft and be the source of vacuum leaks which affect idle. Also, the 70 mm units match up well with those intercoolers that offer 3" outlets.
For years, the best bang for the buck was provided by Jay Jackson who provided reworked units with a 62 mm blade. These are excellently done and are a great replacement for a worn oem original. I am providing a link HERE to his site even tho' he states that he "suspended" sales at the end of 2003.
I believe that Steve Monroe also does the conversions to 62 mm and he may be contacted HERE. Might even be a better bang for the buck. Drop him a line and find out.
One of the beauties of a good turbo street car is that it drives very well when not under boost and has good low in torque in normal driving, and is almost seamless in the transition from no boost to wide open throttle/full boost. Much of this is due to the ability to use a mild cam that is good for low rpm street driving with nice bottom end acceleration and then use the turbo to stuff more air thru the system than normal.
The factory cam is an excellent design that allows for nice unboosted performance from a 231 cubic inch engine and yet has run into the tens for some. My own experience/observations lead me to believe that it is a great choice for combinations aimed down to the mid-elevens. At that point some benefit may be obtained from larger cams if the other components in the combination match up.
As noted before, big turbos generally are restricted in performance if the engine cannot turn the rpm required to be able to ingest the amount of air the large turbo can produce. The factory cam is pretty much done (along with the turbo) at 4800 rpm, or so. We may run it out in third gear thru the lights to 5400-5600 rpm at times, but, we are not making much power-just saving a shift.
Going to a cam of of 206-208 degrees on the intake does not hurt the bottom end torque significantly and should extend the usable rpm range to the 5400-5500 rpm area and add more power to the shift point with a bigger turbo. Makes good use of those ported heads as well.
Larger cams can be used, but, may be in conflict with good streetability.
In the above, I am referring to flat tappet cams. Over the years, there have been numerous reports of flat tappet cams with wiped lobes. Experienced engine builders seldom have this problem.
Looking at the engine readily shows a potential problem. Normally, the lifter should be situated to one side of the cam lobe in order that the taper ground across the lobe and the convex base of the lifter combine so that the rotation of the cam causes the lifter to rotate. When one looks down the lifter bores of the Buick engine at the cam, one will see that some bores are almost centered over the cam lobes rather than being offset properly. Number 3 exhaust is particularly bad in this respect. Is it a problem with the block casting, or is the problem with the cam blank? People argue both ways and I have never tried to measure to see which has the problem. It does not really matter. It is a problem that must be dealt with by the user. Those lifters which are not properly offset will not rotate properly and are subject to early wear along with the cam lobe.
Why do experienced builders seem to have a far smaller rate of failure? First they take great care to follow proper break in procedures and secondly, they stay away from excessive spring pressures. The factory springs are rated at 78 lbs +/-4 lbs at an installed height of 1.727". Going to a spring that is significantly stiffer will do little for the rpm range of the cam and nothing for the power band, but, it may shorten the life of your cam considerably as well as contribute to wear on the front cam bearing.
LT1 springs often exert 100-105 lbs of pressure when the valve is closed and are simply too much. They were suggested in the early days when the problem was not well understood, or, recognized. Some still tout them. Today, the Comp Cam spring # 980 is an excellent choice when the cup is omitted. This spring is slightly stiffer and includes a damper that helps eliminate spring harmonics at upper rpm ranges. Similar springs are available from Sealed Power, etc.
Using a spring of the proper range along with good break in procedures goes a long way in avoiding cam problems. Some companies such as Lunati may increase the the taper ground into the lobe in an effort to increase lifter rotation. Whether this helps, or not, when the lifter is centered on the lobe, I don't know. I don't think it can hurt. Dry lubing the lobes certainly helps as does using plenty of moly paste on the lobes and lifter bottoms during installation. Priming the engine so that oil is fully circulated thru the engine definitely helps as well as running the engine at the rpm suggested by the cam manufacturer for at least the minimum time stated is also vital.
An alternative to a conventional flat tappet cam is a roller cam. This largely eliminates the chances of lobe wiping. There are some downsides, however. First and foremost is pricing. The cost can be four times that of a flat tappet cam set up.
Secondly is the stronger spring pressure required. Most seem to require a spring of some 135 lbs which puts more pressure on the cam bearings and on the rocker shafts. Heavy Duty bearings and shaft reinforcements should be used. Billet cams require more rigging to adapt to our engines. I have no experience with the latest non-billet units, but, if they prove to have a long life, they should eliminate some of the installation problems.
I really like the performance of my roller which has 210 degs of duration at 0.050". It has almost the same torque off idle as the stocker and allows much more flow at higher rpm than the flat tappet lobe designs which don't provide nearly as much "area under the curve". Roller cam lobes are much more square (less peaked) than flat tappet lobes and the valves stay open more for a given duration due to the rapid opening and closing of the valve.
Due to the hydraulic roller lifter, spring tension, weight of the lifter, etc., rpm is limited to 5800-6000.
No matter which cam one selects, three things are imperative. 1) degree the cam in properly. 2) Set the lifter pre-load properly. 3) Break in the flat tappet cams carefully.
Match the cam operating power band to the torque converter, heads, turbo, etc. Installing a cam with long duration that does not begin to make power until somewhere past 3000 rpm does not do anything for drivability and insures that a higher stall converter be used to get the car moving off the light.
Remember that a combination that takes seconds to spool won't be too impressive on the street.
The factory headers are the equal of after market units until well into the tens. As long as the originals are not cracked to such an extent that they cannot be repaired, they tend to perform better on slower cars and just as well as aftermarket units for stock block cars.
If one is gung ho, the factory headers can be welded around the tube entry to the flange and then ported out to match the heads.
Hooker headers were available for our cars at a reasonable price, but, they had larger tubes which killed exhaust velocity and often were much weaker at lower speeds than factory headers. They also lacked the turbo brace and sometimes contributed to a very short life for the factory oil return line from the turbo which would crack from the vibration. I would advoid them like the plague.
The ATR or Kenne-Bell headers worked quite well on really fast cars...say tens or faster. The ATR, at least, has been known to frequently crack in the past few years.
All in all, expensive headers provide very little for the money and may not fit with your current down pipe.
Once one has arrived in the twelves, a good 3" down pipe begins to make a difference. A turbo car does not like back pressure. The closer one gets to zero back pressure, the quicker the turbo will spool and the faster it will go on top end.
A good 2 1/2" mandrel bent exhaust system works very well down into the 11's. People run even faster on them, but, a larger diameter system may do even better at that point.
From a cost stand point, it is difficult to beat the cost of the Hooker 2 1/2" aluminized system altho the mufflers that come with it can be improved upon if you are going all out. I prefer the straight thru designed mufflers that flow better such as Ultra-Flos or Maxflows. I don't like Flowmasters which generally don't flow as well and I dislike the sound.
If one wants to spend the money there are some excellent 2 1/2-3" systems available in stainless steel. Larger diameters are generally louder and I don't like the single shot style as they sound like the UPS truck to me. Not much fun to cruise around with and listen to the stereo.
The factory air filter in the cannister is restrictive and becomes worse as the boost is turned up and more power is generated.
There have been at least three different attempts to improve upon the factory implementation.
The first involves the removal of the factory filter and cannister and simply placing a K&N style cone shaped filter at the end of a metal maf pipe situating it above the charcoal cannister and behind the large hole in the radiator support.
The second is to use a Kenne-Bell set up where the filter is located similar to the first, but is enclosed in a cannister that has an outlet attached to a 4" hose that picks up air from behind the air dam beneath the bumper.
The third involves locating the filter in front of the radiator support hanging down behind the bumper.
The Kenne-Bell method is quite restrictive as the cannister fits quite snugly around the filter and most of the air flow comes from the four inch opening to the hose. Tests long ago showed this set up to be slower than an open element in the first 1/8th mile and then picking up some speed as air was rammed in at high speed. Some people cut off much of the cannister leaving enough of it to attach the hose to. Others threw the cannister away and merely left the hose in the radiator support hole so that it directed outside air over the filter when the car is moving. The downside to either is that a lot of dirt, leaves, etc. are blown into the engine compartment.
There are about three products offered that mount the filter in front of the support and behind the bumper where the air should be a bit colder. I think this one is one of the nicer ones. The downsides to this one are possible exposure to the elements-particularly water, and on really fast cars that may run in the nines, more air flow restriction due to the additional bends in the pipe.
I don't think that the air in a moving car is much hotter directly behind the radiator support inside the engine compartment than in front of it. I believe the air going thru the turbo is heated far more than the difference between outside air and the underhood air at this particular location. Driving down the road, the air going into the throttlebody on my car measures ten degrees warmer on average than the outside air temperature in the summer. Remember that the air temperature just above the pavement is often much higher than the actual air temperature measured a few feet off the ground and this is the air being picked up. For serious purposes, one can add a hose when racing to direct outside air across the filter and remove it at other times to avoid trash coming into the engine compartment.
I like this technique combined with a 4" maf pipe for faster cars/bigger turbos. To help keep the underhood temps down, one can remove a section of the hood-firewall rubber seal in front of the driver which will allow the hot air to easily escape as well (makes it easier to place your fuel pressure gauge on the windshield when tuning/racing)
For cars in the tens, or quicker, I like the Pro-Flow filters at the bottom of this page with a 12" length and 4" diameter outlet. For cars slower, a 3" diameter version should do very well. They are a bit expensive, but the additional area always helps. The venturi exit may make the biggest flow improvement, however. As sucking is always less efficient than blowing-on intake systems-I think it helps to maximize improvements on the upstream side of the turbo wherever possible.
As stated under the turbo section, it is very important to match the turbo to the effective torque converter stall speed in order to obtain adequate turbo spool up.
Now, stall speed is a very imprecise matter as it depends not only on the blade angle and diameter of the converter, but, also on the power the engine makes. If a converter stalls against the brake to 3000 rpm, and one improves the horsepower of the engine by another hundred, then the same converter may now stall to 3400 rpm with no other changes.
Altho' one can buy a converter rated at a certain stall, one won't be sure what it actually stalls to until it is in the car. We also have the problem of defining stall. If we use brake stall (what rpm will it go to when you plant your foot on the brake and stand on the gas until the wheels try to turn), then that is probably most common...but, we may find that one car tries to turn the rear wheels at 3# of boost and another can reach 12# of boost before the wheels turn. As that is probably considerably more horsepower, that will push the rpm even higher.....again, the joys of defining and measuring stall.
The factory converter measures 12" in diameter and stalls in the vicinity of 2200-2400 rpm depending upon the power made by the engine and the quality of the rear brakes.
The factory converter that stalls in this range is perfectly adequate for the factory turbo or a TA-49/TE-44. Many have run into the lower 11's on the original converters. Anyone that says that a higher stall converter is required to spool a TA-49 or a TE-44 has a problem somewhere with the car in question. Chips that are not well made for ones set up are often to blame as they are too rich or the timing is not right.
Now, most of the factory style replacement converters don't seem to have the right stall speed for our cars and are often down around 1800 rpm in stall. That will not get the job done very well-certainly not for the slightly larger turbos. For this reason, if one needs to replace his converter due to age, problems, etc., then I suggest one go ahead and buy a 12" converter stalled to 2600-2800 rpm if one has nothing larger than a TE-44 turbo. On a well tuned car, one may have to leave at a slightly lower boost to keep from blowing street tires or drag radials away, but, that just makes it more fun.
I do not recommend 12" converters stalled higher than 2800 rpm. In order to achieve the desired amount of stall, the fins have to be bent so much on a large diameter converter that the converter will then slip excessively on the top end and generate more heat and less top end mph. I know there are cheap 12" converters on the market that are rated at 3000-3200 rpm, but, it goes against the laws of physics and they are simply too inefficient.
If one wants/needs a stall above 2800 rpm, then it is time to go to a smaller diameter converter where the angle of the fins can be less and the converter will have less slip at wide open throttle going thru the lights. There are good 10" converters available for stalls in the 3000-3400 rpm range and 9/9.5" that will cover this range and above. A good converter will allow you to build spool without taking all day and yet be acceptable in everyday driving unless one has gone out of the ball park on turbo size.
I am not going to say much about chips. I have mainly run the MaxEffort chips for a long time now and consider them a better bang for the buck than a FAST system. I suspect we will see someone in the Eight's with one some day. They are strictly open loop and not meant for passing emission's requirements.
I am sure The Extender is an excellent chip as well, but, the problem I see with any programmable chip like the Extender or MaxEffort is that the average user does not have a clue how the various systems work together and never learns how to extract maximum benefit from them with regard to the individual car in question. In fact, more harm than good may be the result of uninformed "Tuning".
I don't like the generic chips from some of the big names, either. I suspect they cause many of the poor spooling, poor performance results we hear about.
If I were to buy a conventional, or semi-conventional chip, for one of my cars, I would go to one of the individuals that do chips and give him enuf information about my car and my intended use so that he could tailor a chip to my needs.
Okay, this is not a part, but it is a vital link in the combination. Long ago, Ricardo demonstrated that lower compression ratios make more horsepower than do higher ones in forced aspirated implementations. People often point this out when the subject arises as a "fact". Too some extent, it is.
What Ricardo did not take into account was effective cylinder pressures and the effect of compression ratio on power "under the curve" as compression, camshaft duration, and size of turbo are all considered. I linked to an article under the Basic section on compression which makes for interesting reading and contemplation.
Peak horsepower is of interest primarily to those guys who like to run their car on a dyno and talk about it. Power under the entire curve is more important to those that are trying to extract the best all around performance from their car, particularly for daily drivers that operate across a wide rpm band.
In essence, the longer the duration of the camshaft, the lower the cylinder pressure and the more compression that can be run without running into detonation. Larger turbos that heat the charge less under boost also improve the situation.
As we increase the cam duration and the cylinder pressure drops, an increase in compression tends to offset the loss and maintain the low end power which is nice on the street for good throttle response and quick spool. This is well understood in building conventional engines, but, is often ignored on our turbo engines by many with the exception of people like Lawrence Conley and Kenny Duttweiller who often build 9-1 engines for the street. If we get much past 9-1 on a stock cam, we may begin to incur some detonation when not under boost due to excessive cylinder pressures.
Even engines with stock cams seem to benefit with a bit more compression on the street even if total boost may be a bit less. Low timing chips seem to like it as well.
The easiest way to approach 9-1 is to use a single shim gasket rather than the thicker composites as used on the 86-87's.
Alcohol Injection works by reducing temperatures in the combustion chamber so that detonation risk is lowered and more boost may consequently be run. The cooler charge is also denser and denser is always better.
A well atomized spray into the up pipe leading to the throttlebody from one, or more, nozzles introduces the alcohol into the engine. The act of vaporization within the combustion chamber removes heat from the mixture thereby lowering temperatures and allowing more boost to be run before detonation occurs.
Depending upon the system, the engine combination, tuning, and so on, one may be able to run 22-26# of boost on 93 octane, and some brave souls have done more. I would say 24# is a good number for the average car. Of course, timing has an effect just as it does on non-alky cars.
There is some debate as to which may be better-straight alcohol, a mixture of alcohol and water, or straight water. The chemistry is somewhat complex and I have mainly used straight alcohol. Some believe that the fuel content of alcohol is important, but, I doubt that it is all that important in the quantities we typically inject. Maybe if the current fuel system is on the edge of being inadequate, it helps?
As there are a number of alcohols available, perhaps some consideration of the chemistry involved might be helpful. As I decided that I had enough chemistry after surviving organic chemistry in school, I am going to rely on discussions by Carl Ijames and John Estill from the past when alcohol injection was in relative infancy as well as my own thoughts/experience. I have been running alky injection for quite a few years. I became seriously interested when I started running Max Effort chips and began talking with Steve Yaklin who developed his own systems and was a pioneer in serious performance from an alky spray. I have spent a lot of time discussing/arguing alcohol with him and, as I have begun to understand some of the chemistry behind the technique, I have learned I should have spent less time arguing, and more time, following his lead.
Narrowing down alcohol to the three major types readily available, we have methanol, denatured, and isopropyl.
Methanol is the form used in alcohol fueled drag cars and certain roundy round racers (Indy cars, for example). It is a non-drinkable, highly poisonous form. It is considered to be a safer form of fuel as it is more difficult to burn than gasoline and does not catch on fire easily from its fumes. It can be difficult to see when burning as it tends to burn wih an almost invisible flame and we often see guys getting sprayed down to put out a fire when we cannot see it on tv.
Ethanol is the drinking form of alcohol made from corn. I recall it by the name of EverClear from years gone by. As it is heavily taxed in this form, we don't normally find it in bulk, and, of course, its sale is regulated just like a bottle of Jack Daniels. Instead, we find Denatured Alcohol which is ethanol with a dash of methanol in it to render it poisonous...extremely poisonous. It is subsidized by the government and used in some areas as Gasohol which is usually about 90% gasoline and 10% ethanol. It may be used to raise the octane slightly, but, due to his lower heat content, it does not make a very satisfactory fuel when one considers the pros and cons.
Isopropyl alcohol is most commonly available diluted with either 30% water, or, about 9% water and sold as Rubbing Alcohol. It's a pretty expensive means of running alky injection.
Looking at the pros and cons of the three types of alcohol when it comes to selecting which to use in our systems, we have several things to consider. Among these, are price, availability, heating value, latent heat of vaporization, vapor pressure, and corrosiveness. Octane is about the same for all three.
In bulk, racing fuel distributors usually sell methanol at a much lower price per gallon than one can find for denatured, and/or rubbing alcohol. As it is primarily available through fuel distributors, one can not simply walk into a paint store, or drug store, and buy it as we can denatured or rubbing alcohol.
Compared to gasoline, alcohols have a much smaller heat content value. Using approximate numbers, Gasoline has approximately 18,000 btu's per pound. Methanol has approximately 8600 btu's and ethanol has about 11,500 btu's per pound. As the alcohols have much less heat content, we must run 40-60% more alcohol than we do gasoline to make equivalent power as gasoline. This means the A/F ratios for making power with alky are probably going to be more like 5 or 6. Note, this is for using alcohol as a primary fuel and not for cylinder cooling with alky injection (unless one is trying to use it for fuel replacement as some do). If we were looking at solely heat content, then ethanol would seem to be a better fuel. It's not necessarily that simple.
Latent Heat of Vaporization is the amount of heat that must be absorbed by a liquid in order to cause it to change from a liquid to a vapor. This absorption of heat comes from the combustion chamber heat and as the liquid is transformed to a vapor, the chamber temperature drops as heat is removed and used by the transformation process. This is the primary principle behind alcohol or water injection. Create steam which lowers the combustion chamber temperature which, in turn, reduces the risk of spontaneous combustion which is what detonation is.
Carl Ijames posted the following long ago.
Alcohols do have much
higher heats of vaporization than hydrocarbons which means they will cool
the intake charge better. For comparison, hydrocarbons are about 70-80,
methanol is 262, ethanol is 204, isopropanol is 159, water is 560, and
nitrous oxide about 40, so methanol absorbs about 3.5 times more heat than
gasoline as it vaporizes.
Now, from the above, it would seem that water is the clear choice for an injection fluid. Again, it is not that simple as vapor pressure comes into it. Vapor pressure is tied closely to the boiling point of a liquid. Alcohol vaporizes (boils) at a lower temperature than does water and this affects the performance of the injection fluid.
Water injection: 0.40 lb/min of water will vaporize, cooling the air down from 150 F to 109 F.
Methanol:
100%: 1.08 lb/min of methanol will vaporize, cooling the air from 150 F to 96 F.
50%: 0.55 lb/min of methanol/water will vaporize, cooling the air from 150 F to
107 F
Ethanol:
100%: 1.26 lb/min of ethanol will vaporize, cooling the air from 150 F to 100 F.
50%: 0.57 lb/min of ethanol/water will vaporize, cooling the air from 150 F to
108 F
Isopropyl:
70%: 0.76 lb/min of alcohol will vaporize, cooling the air from 150 F to 107 F.
91%: 1.14 lb/min of alcohol will vaporize, cooling the air from 150 F to 104 F.
100: 1.50 lb/min of alcohol will vaporize, cooling the air from 150 F to 102 F.
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From the above, I gather that methanol actually works better than water
when it comes to cooling due to its lower vaporization pressure even tho water
when it boils releases more heat. I may be wrong as I am not a chemist.
John may not be a chemist, whereas Carl is, but, John is very competent technically and I believe the above explains why methanol is a superior injection fluid as it seems to back up what we see in practice. Notice that about 2.5 times more methanol is consumed in the process but it reduces the resulting temperature more than water, or combinations of water and the three kinds of alcohol.
When it comes to corrosion, nothing compares to methanol...it eats metal up quickly and some lubricant should be used with it when it is used with a pump or system that contains metallic components in order to attempt to extend component life. The other alcohols are not nearly as corrosive.
With regard to octane, one can find all kinds of alleged octanes for alcohols ranging from 98-160. I suspect alcohol may be difficult to measure properly as octane measurement was developed for gasoline based fuels and the test engine is calibrated specifically for gasolines. Most government and oil company sources seem to show it to be in the 101-103 range. Perhaps, when mixed, it has a greater effect than it does on a stand alone basis? In other words, it is a synergistic reaction?
One of the dangers of methanol, in my opinion, is that it has a high sensitivity. Sensitivity is defined as the difference between research octane and the motor octane. The larger the difference, the more abrupt the transition between no detonation and detonation. This can occur very violently when methanol is used as a primary fuel as those of us that ran alcohol cars may recall. I think one needs to be very careful as one starts to remove gasoline and add methanol so that it starts being a significant part of the overall fueling rather than simply as a combustion chamber process.
I don't know the point at which this may occur, but, I think the average daily driver should be careful as he tries for the last pound of boost. Let someone who does not mind engine rebuilds to the pioneering.
Finally, I often see people touting the benefits of alcohol as an oxygenator. Nitrous is an oxygenator, alcohol, is not. It is an oxygenate and there is a big difference. Alcohol may be described as a pre-burnt hydrocarbon. As evidenced by the BTU content from above, it does not have as much oxygen it as gasoline. This can be noted by anyone that burns oxygenated fuel (gasohol is one) and gets lets gas mileage from it.
Using alky injection, the quickest time I have seen is 10.15 on a stock block car. More typically are mid-elevens from very streetable cars. I like it. Just remember to keep the bottle full! One will not get the amount of power using it as one may from race fuel, but mid-elevens on a daily driver is nothing to sneeze at.
Finally, I want to discuss timing. In theory, an alcohol fueled car requires more timing as the fuel burns more slowly and, therefore, the flame must be lit earlier. This is not necessarily the case with alky injection as gasoline is normally the primary fuel (particularly on 93 octane). As one starts to use more and more alky, one may find a need to have a bit more spark advance in lower gears. I have not found this useful on drag radials as I always have too much "spool" and blow the tires away anyway. On a slick equipped car, using a bit more timing may be beneficial. Again, I would caution the newcomer to go slow and work into tuning that works for his car under given conditions. What reportedly works for someone else could possibly be the ticket for a new engine for another person if caution is not practiced. Remember that our intake manifolds are "dry" manifolds designed for air only...not air/fuel. Using it as a "wet" manifold with alcohol as a significant source of fuel may expose weaknesses in distribution which may lead to problems for those that like to push the boundaries.
When tuning with alcohol, I prefer to leave a little more margin for error than I may with race gas. As noted above, alcohol has a lower heat content than does gasoline. I have found that EGTs are usually a bit lower when alcohol is used safely than I can get by with on a good racing gasoline. I typically tune for a little over 1500 degs F with alcohol and I tune for NO detonation. As noted above, the octane sensitivity of alcohol can lead to extremely violent detonation which the boundary is crossed. Those that try to use it as a substitute for racing gasoline may find themselves changing a lot of head gaskets and other parts if it is pushed too far.
I use the Max Effort chips which allow me to remove/add fuel at wide open throttle by flipping the thumbwheel. This does not affect part throttle operation. As I can change the fueling in very small increments, I can dial in the EGTs very precisely and alter the A/Fs as I require to maintain the EGT and the desired "No Detonation" status as weather, etc. changes. I have never had a problem spooling the turbo on 93/alky so I have not seen a need for changing the timing to accommodate the alcohol. In fact, I have had a problem with too much boost too soon-particularly on drag radials and have had to dampen it with the abilities of the Max Effort to affect fueling at launch.
I have used the SMC kits from the time they were introduced without any problems, Straight denatured alcohol has been the fuel of choice as the pump origininally used tolerated it best. Recently, I decided to upgrade the kit in my GN to the latest one with a progressive digital controller and an external methanol rated pump. SMC was the first to try a progressive controller but did not really see the need for such on Turbo Buicks. The current digital controller has a built in MAP sensor and, due to the digital composition, provides one both the ability to precisely turn on the pump at a specified boost level without any experimentation, and to set the point where the pump has ramped to full pressure/flow with precision.
One of the selling points for the progressive controller by those providing them is the elimination of transitional knock without bogging down the engine with excessive alcohol at low boost levels. Personally, I have never found this to be a real problem and think it is more hype than real problem.
For street cars, alcohol injection works very well as it provides a cheap alternative to race gas which allows high boost and increased performance while keeping the combustion chamber steam cleaned. From my experiences, it does not matter whether one uses home built kits ala Steve Monroe, Steve Hall, Bob Avellar, etc. that cost less than $200.00 build, or the high dollar kits from SMC, PAC, etc. They all work very well. The more expensive ones may be quicker to dial in for the less experienced, but, that seems to be the main benefit.
Just remember that the more horsepower than is wrung out of a given combo, the sooner it will break and the more it will probably cost to fix it. That is simply racing.
Here are some links that might prove interesting.
http://members.cox.net/stevemonroe/AlcoholInjMod.html (Steve Monroe's do it yourself)
http://www.eere.energy.gov/afdc/pdfs/fueltable.pdf
http://www.eere.energy.gov/afdc/pdfs/afv_info.pdf
http://www.geocities.com/rad87gn/tech/alcohol.html
As a side note, some have tried propane injection in recent years. In theory, propane works differently. By the ideal gas law, a gas cools as it expands. This is what happens when propane is released from the bottle. I have not seen any dramatic results from propane as of yet although some may have done better than the results I have seen. Perhaps it is early in the product cycle and it will eventually do better? Maybe the fault is in the users that don't understand how to use it? Maybe it works best in diesels? I don't know.
Just for the heck of it, I will throw out a couple of combinations that I think work well....certainly not the only ones as the possibilities are almost infinite.
Mild--good for the Elevens on drag radials and a great daily driver
Stock short block with stock cam, mildly ported heads, single shim headgaskets, TE-44 turbo, stock to 2800 rpm 12" converter, 3" down pipe, 12" open air filter over the charcoal cannister, 55# injectors, factory headers, extended stock location intercooler, alky injection, PTE Plenum and Power Plate.
Serious Street--good for low Elevens on alky and into the Tens on race gas and slicks
Forged pistons, girdle, mild roller cam, well ported heads, single shim headgaskets, LE-45A turbo (66 wheel) from Limit, 3600 rpm stall 9.5" converter, 3" down pipe, 12" open air filter with 4" maf pipe, 75# injectors, factory headers, front mount intercooler, alky injection, PTE Plenum and Power Plate.
A Walbro 340 will work for both although the second combo will be at the limit if one tries to go quicker than a 10.7 or 10.8. One could get buy with 55# injectors on the second combo if one does not try to go more than a 10.8. We are talking about normal weight cars and not a Miata or such.
Any faster and it is time to seriously upgrade the fuel delivery system. I have said elsewhere that I don't like double pumpers and much prefer a pump made for the volume required and matching fuel lines.