Comptech NSX Supercharger
Comptech offers a supercharger kit for all NSX model years. The basic kit is called their "6.9 PSI" kit. Boost is 2 PSI wide open throttle at 1200 RPM, 3 PSI wide open throttle at 2000 RPM, 6 PSI wide open throttle at 4000 RPM or higher. No boost (cutout) at high manifold vacuum, idle to cruise RPM. Comptech also offers a "9 PSI" kit using a different diameter pulley for a bit more "oomph."
There are 300+ NSX supercharger kits installed and there are no known engine failures related to the supercharger kit. As with any mechanical part, a few of the supercharger units themselves have failed (usually bearing problems in the blower unit), but Comptech has taken care of their customers in all these cases.
The kits for the NSX-T come with a new engine cover (which re-uses a bunch of hardware from the factory cover) and their NSX-T billet aluminum strut tower brace. The factory engine cover and strut tower brace from the NSX-T will not fit with the supercharger installed. All Comptech supercharger kits are 50-state legal and come with the required CARB E.O. emissions sticker. Estimated installation time is 8-12 hours. Some shops may be able to do it faster if they have done the kit before.
The Comptech unit is a Whipple 1600A, a Lysholm positive-displacement twin-screw design with a displacement of 1.6L/REV (0.656 CFM/REV) and an internal lubrication system. Typically, twin-screw superchargers, by design, have the ability to maintain a higher volumetric and adiabatic efficiency than most roots types. This allows the Comptech unit to provide consistent boost and compress the intake charge very efficiently with a minimal increase in air intake temperature. This combination helps provide almost instant boost (unlike centrifugal and roots type superchargers) to increase and broaden the torque curve substantially.
The basic NSX Supercharger Package includes the following major parts: Whipple 6 psi. supercharger with an intake assembly, 3.8" diameter supercharger pulley (applicable to the 3.2 liter engine), 4.2" diameter supercharger pulley (applicable to the 3.0 liter engine), crankshaft pulley (same diameter as stock), in line fuel pump, PROM chip for 1991-1994 models only, and all necessary installation hardware.
Comptech keeps the stock fuel injectors and boosts rail pressure to 100 PSI. The 9PSI kit includes Honda high-flow injectors (Honda part #06164-POF-000). They are not used in any US vehicles but can be ordered from Japan. The fuel pressure regulator is a generic "Super FMU" from Vortech Engineering and is pre-set by Comptech for their kit.
Since the installation requires the alternator to run backwards, the OEM alternator cannot be used. In order to stick with a Honda OEM part, Comptech uses the 1992 Honda Prelude alternator which is the only one Honda ever sold which runs the opposite direction. It is Honda part #31100-PT3-A52RM.
The installation of the kit requires the following modifications to the stock vehicle: The stock crankshaft pulley is removed and replaced by a equal diameter pulley which is modified to accommodate the supercharger drive belt, the MAP sensor wire is modified with an in-line resistor for 1991-1994 models only, an in-line fuel pump is installed next to the fuel filter, the stock 15 amp fuel pump fuse is replaced with a 20 amp fuse, a resistor located on stock fuel pump is removed, and the stock intake manifold is removed and replaced with the combination supercharger and intake manifold configuration.
[From the Comptech web site] "Many NSX owners mention that their car is outstanding in handling and overall performance, but that it lacks that good old fashioned "big-block grunt" After many months of extensive testing and engineering work, Comptech is getting close to making available a bolt-on Comptech NSX Supercharger Kit designed exclusively for the NSX. Their goal with the project is to offer NSX enthusiasts a reliable (OE-quality), cost-effective method of generating maximum horsepower and low-end torque through forced induction.
Boost is 3 psi at 2,000 RPM, with a maximum 6 psi at 4,000 RPM - generating well over 380 horsepower! Substantial power gains are achieved without the necessity and cost of rebuilding the engine. Because superchargers require less space in the engine compartment, the engineering on the project has allowed Comptech to retain the factory engine compartment cover for a complete factory stock look.
The kit Includes Supercharger unit, modified intake intake manifold (exchange), modified supercharger inlet, custom pulley assembly, alternator, special alternator mounts, 6 rib belt, crank pulley (exchange), special fuel system plumbing, high-flow fuel injectors & fuel rail, high-pressure fuel pump, modified electronics (exchange basis). This is an extensive package that offers impressive power gains to the NSX's already potent powerplant. Expected time for installation is 1-2 days shop time."
The CT supercharger uses the following belt: Goodyear Gatorback 4050705 5PK1790. It is a GM 2.0L serpentine belt. You should stick with this belt; other belts may be cheaper but they can slip. Both the 6PSI and 9PSI setups use the same belt. Note: The first few supercharger kits were produced using a different pulley and had a different belt with 6-grooves as opposed to the 5 grooves on this belt. These early kits have round fuel rails instead of square and an intake manifold made of a factory unit with a box section welded to it instead of a cast manifold. If you have one of these early kits, call Comptech for belt information.
Supercharger performance data from a Comptech brochure (engine HP at the crank - car is a 3.0L NSX with Comptech headers and exhaust):
0 to 60, 4.8 seconds
Comment: the torque curve remains very wide, similar to the unboosted engine.
[WSC] After recent modifications to the fuel system and a revamped chip from Comptech I repeated dyno testing on my car today. At the last two track events with the new equipment I felt that the engine had considerably better torque with less abrupt off-throttle decceleration and the dyno confirmed my impression. The specifics are as follows:
date 1/6/99, Vinci Hi-Performance, 407-292-4500, Dynojet Model 248E
3rd gear run from 2000 rpm to 8000 rpm, temp 49 degrees F, pressure 30.27 inches of Mercury, 2 runs
run 1 max torque 258 lb-ft @ 4400 rpm, 339hp @ 7900 rpm
torque curve virtually flat between 3000 and 8000 rpm (range 228lb-ft to 258lb-ft)
The above numbers are not corrected for temperature or barometric pressure...they are raw data collected at the rear wheels (correction factor for air pressure and temp calculated to be .93 which would give max hp at 322).
Currently the car has the following engine mods: Comptech supercharger (revised pulley), Comptech revised fuel pump, injector settings, Comptech airbox, Comptech headers, Comptech competition exhaust, Comptech chip, Technomagnesio 18x10 rears with Michelin MXX3's, 13.5 inch Brembo cross-drilled rotors, (size and mass of rear wheels/brake rotors affects hp numbers as discussed previously)
These numbers are significantly better than the last 2 dyno runs that I made (288 and 305 max hp uncorrected). Comparing curves, the torque curve is a little flatter and higher than on the previous runs. If losses through the power train are in the 15-20 percent range, expected hp at the crankshaft would near the 390hp claimed by Comptech. FINALLY....truth in advertising.
[DB] In spite of seemingly never ending El-Nino related hassles at home, I managed to get a 1-1/2 hour drive on my newly equipped car this week. I went down some quiet side streets and into the mountains. Basically I'm reviewing the supercharger, airbox, and short gears. My other mods are old.
I believe this is what the NSX always should have been. Instantaneous smooth knifelike throttle response. It's as if the accelerator was connected to something that makes the road go faster rather than the car, as if the car was inertialess. Never have I experienced such zero lag power. This engine still has the good wide torque curve of VTEC, and throttle application is just as progressive and smooth as it always was. I need never have worried about jerky throttle response.
Naturally, the handling is unchanged and superb as always.
The strangest thing is a factor I personally would not have predicted to matter at all. The sound, good god, the sound. From inside, the supercharger makes a sound like a symphony of musical gears. It reminds me very much of the sound I heard on TV when they piped a signal from inside a Mercedes CLK racecar. From outside I cannot say, I haven't heard it that way.
In summary, *wow* is all I can think of.
The whole equipment list is as follows:
'92, 5 speed, supercharger, airbox, headers, HKS exhaust, short gears, K&N 'stock' filter, non-compliance bushings, no spare tire, no brake splash shields, 5 point belts both sides, fire extinguisher. Bridgestone RE010's front, S02's rear, 16/17 inch stock wheels. The supercharger has many associated smaller but necessary mods as part of the kit, not the least of which is a new fuel pump and different chip.
I'm doing a new tail lens. It says "NSX SC" instead of "Acura." Next maybe I'll get rid of a little more weight. Got the new lighter battery. Maybe I'll make an aluminum engine cover which still provides sunlight protection for the hoses and belts.
Highway (freeway and backroads) 24 mpg
[DH] I am currently getting about 12-14 mpg, using 50% highway, 50% street over the past two gas tanks. Currently have about 2000 miles on the supercharger.. But I am hammering on it. I mean REALLY hammering on it. Every little opening in traffic it is going to the redline. Just about every stoplight I hit 8000 RPMs in 1st, and if clear, hit it in second.
[WSC] I have been disappointed with the overall performance of the Comptech supercharger. I've had it for year... other than eating mufflers it hasn't lived up to expectations. I will be looking for alternatives (such as Jackson Racing's SC) in the near future.
[DB - 99/3/1] After a year, I'm really very happy with this setup. Cheap it's not, but everybody knows that.
It's now one year, 10,000 miles of street driving and about four hours on the track since I had the Comptech Supercharger installed. For informational purposes, I also had the 'Japanese' gearset, the Comptech airbox, and the Comptech rebuilt-modified-25%-more-clamp-force stock dual plate clutch installed at the same time. Previously, the Comptech headers, HKS exhaust and non-compliance bushings were done.
The most interesting thing that happened was that after a few weeks, while driving to work one day, the engine started to feel like it was seizing: the idle would just stop but could be maintained with an unusual application of moderate throttle. There was a *nasty noise* coming from the engine compartment. I drive very moderately on the street, so I had no clue what might be wrong. I coasted down the hill to a gas station and phoned my mechanic. This is a guy who owns his own NSX and takes care of 15-20 NSX's. He drove over and started it for a few seconds, shut it down and called for a flatbed which took the car to his shop. An hour later he phoned me that one of the supercharger bearings was seized, and it wouldn't cost me a cent.
Comptech provided outstanding first class support; even the tow was paid for, and my insurance would have covered that. Two days later I was back in business.
To my knowledge, this is still the only actual supercharger failure which Comptech has suffered. It's a little amusing, because on one of our subsequent NorCal NSX events, we visited the Comptech facilities and had a free lunch at a dealer in Sacramento. During lunch, one of the Comptech engineers, possibly a consultant, opined that there had been no supercharger failures. I felt it would be bad form to pipe up in front of fifty people, "Oh yeah? There was one!," so I smiled into my salad and kept my counsel for some other occasion such as this. Probably the guy didn't know; that would be par for the course.
The supercharger proper is a Whipple unit, and it was returned to the factory, but Comptech says they never got a failure report back. The internal oil supply was working fine. The bearings supposedly went overseas for analysis. I guess I don't really care.
There were a couple of less traumatic items which were handled with varying degrees of aplomb. One day the mechanic phoned me and said "There's a replacement pulley to put in. They found out the material of the original design was incorrect. Why? Well it's pretty hot there! Duuhhhhh..."
The second item is the so-called Supercharger Improvement Kit. This needs a little explaining. The original setup had a peculiar driveability problem which I called The Herkie-Jerkies. What happens is this: you are going slightly downhill and maintaining speed so the throttle is closed. Then you want to pick it up and you crack open the throttle just the tiniest bit: Whiplash! The Herkie-Jerkies! There was almost no way to transition smoothly from throttle off to slight throttle on when the car was under downhill force. On the level the problem was still there, but not as bad. This was an annoyance for everyday street driving, but not bad enough to cause extreme pain.
My mechanic's car had the problem worse than mine. He influences so many Comptech sales that they cannot afford to ignore him when he complains about something; indeed, I don't think they want to ignore him, he is perhaps the most knowledgable beta tester they'll ever have. Thus, presto-digitalis, the Supercharger Improvement Kit, one thousand dollars, thank you very much.
What is it really?
Let me apologize in advance if I mis-characterize the problem; my knowledge may be faulty.
The basic difficulty with the original system was that there are a limited number of fuel mapping points in software, and the needs of mapping for high power levels made the number of points at low power levels rather too few for smooth operation under all conditions, with the supercharger. For the aftermarket designer to add more points in software is really not reasonable; it involves significant code changes in parts of software which have no available documentation. So they couldn't do that.
They overcame this problem by doing two basic things:
1) Replacing the stock fuel pressure regulator, which in effect had only two output pressures, with a different diaphragm regulated unit, which reacts to manifold pressure in a more smooth and continuous way.
2) A new fuel pump controller replaces the stock controller. The stock unit basically controls the fuel pump to two speeds. The new unit has a semi-continuous pump speed control function.
By these techniques they completely eliminated the problem, and the throttle response is now very smooth at low power levels, regardless of engine loading or manifold pressure, as far as I can tell after a few months of testing. No more Herkie-Jerkies.
A Comptech representative has commented to me that the overall high power operation may also be improved in certain cases. That's possible, but the mechanism by which that may happen is obscure to me.
The Comptech supercharger is now refined enough for the most demanding customer who wants lots of power and completely smooth driveability.
Here is a presumably honest and uninflated data set on the Comptech Supercharger. The numbers are at the rear wheels and corrected to standard temperature and pressure. The car has the supercharger, airbox and "Supercharger Improvement Kit." There are other non-relevant mods like brakes, etc. This was measured with a DynoJet model 248C at Frey Racing in Mountain View, CA.
No dry ice in the intake system, heh, heh.
The engine estimated HP uses 15% estimated losses to calculate; maybe that's too much, I don't know. I'm using Redline oil in the tranny.
The most noteworthy thing here is the truly remarkable flatness of the torque curve. You will not see anything like that flatness on another high powered car. That's VTEC for ya.
Guess what else? That's the same power to weight ratio as an unmodified Viper. Guess what else? I saw the dyno recording of a modified Viper: 450 RWHP! There is always somebody with more horsepower. Well, the Viper certainly wins the less-expensive horsepower race, but it still is not my kind of car.
[MWH - 99/3/3] I was told by Comptech that the total number of superchagers sold by them for the NSX is about 55 units. 15 of these were installed on the 3.2 liter NSX , one of which I just bought. After a test drive and inspection, I was sold. It is of MY OPINION that these units are worth every penny Comptech is asking! YA WHOO!!!
[MBA - 99/11/10] I sell and install CT SC kits, so most will say that my opinion is biased. That said, I think there are allot of reasons to consider the CT kit. First, and VERY important, is that I believe you will have a better network for service after the install. If you have a problem with a CT product, you have basically the whole Acura dealer network, and a few notable independents, to work with. The CT kit is simpler in design for achieving the same results and if this is a car you drive allot, simple equals reliable.
[CA - 99/12/1] My NSX did 322.8HP to the wheels with the stock Comptech SC pulley (6.9psi), stock gears, RM headers, CT exhaust and Uni filter as well as KN filter ( no difference). I did have 18in wheels, but not sure that matters. We did three runs, about 322.x consistently. The smaller pulley (9psi) was said to give about 20 more HP, but you have to swap out the SFMU, some say you have to swap injectors as well, but I not sure. Overall I am very impressed and pleased with the 6psi blower, there is significantly more power in the lower rpm's.
[DB - 99/10/31] Quite a number of units have been dyno'd now. All the numbers I have seen (4) are 320HP +/- a small amount, at the rear wheels, with the standard 6PSI boost. Comptech's numbers from the engine test cell show 385-390 HP. I'm sure these numbers are both accurate, which leaves a bit of mystery loss if the drivetrain is 14%, which I also believe. So what happened to the rest? 385x.86=330. There is 10 to 15 HP which went somewhere. If we could find it, maybe we could get it back. Early this year they (Comptech) began a effort to resolve the issue, but the pressure of other jobs put it on the back burner.
[NS - 99/12/23] I would like to relate my experiences with Mark Basch and the Comptech Supercharger.
Mark Basch installed a CT supercharger on my 96 NSX-T during the past week. I am completely impressed with his NSX knowledge, workmanship, integrity, and especially his customer service. I deal with alot of people, with all of my hobbies, and he is one of the top people I have had the pleasure to meet. He took time to discuss options with me (hours, since I ask alot of questions), before I had even committed to spend any money. We spent alot of time discussing general NSX technical information that has helped me determine a strategy for future upgrades. Mark does all of the NSX technical work himself, and personally stands by it. I have seen him take personal time, (outside of shop hours and weekends) to help myself and other NSX customers with their issues. All of the work he has done for me has been first rate, and I expect to be seeing him in the future other goodies.
Now on the the Comptech supercharger. It is fantastic, period! My '96 was completely stock before this work. I had Mark install a set of short gears (purchased from RM at a fantastic price during his internet sale), and took my car to Technodyne in Tempe, Az. for a dyno run. Chris Cervelli is the owner and was very willing to work with us. He uses a Dynojet 248 dyno. My car came in at corrected:
Max HP = 233.5@ 7250 rpm
After the CT supercharger was installed, using stock exhaust manifolds and stock exhaust the corrected numbers looked like this:
Max HP = 299.8 @ 8000 rpm (I need a .2 hp increase)
Total gain from the supercharger without any other goodies installed was 66.3 HP at the rear wheels. The NSX feels like a new car. No more hole in the 1-2 shift and enough power to give you a big grin. The HP curves showed that the SC started increasing the power from 2000 rpm (~8hp) slowly increasing the gap to 66 hp. In fact the curve was still rising all the way to the rev limiter, (mine kicks in right at 8000 rpm). This was great; no modest gains that you might forget about after a couple of weeks of driving.
Comptech 9 PSI Upgrade
[WSC - 99/8/19] I've had the CT supercharger in my car since early 1998. The 9psi upgrade was installed about 3-4 months ago. I have had no reliability problems with either the original configuration or the revised injectors, modified ECU, or the smaller pulley/belt set-up. The car has been driven hard for about 20K miles in multiple track events including NSXPO98 and 99.
The only minor problem is a wandering idle point especially when the car is first started up.....it goes from just about stalling out to 1800 rpm then back down again......haven't been able to fix this yet but it seems that increasing the idle rpm to about 1100rpm has improved it somewhat. This began with the 9psi upgrade. It did not happen with the original set-up.
Also for all of you who know my muffler stories, I have not had to replace a muffler since the newest design was released late last year. I also ran the stock muffler cross-country for 6400 miles and ran it hard at Laguna Seca with the supercharger....no problems.
[MBA - 99/11/10] I don't recommend the 9 psi kit for a heavily used car either. I think the wear and tear from a constant 9psi is too much. I haven't driven an "M", but have seen Alex's car and its a good looking quality kit. I'll be installing an "M" kit in a few weeks, as well as 2 or 3 more CT kits.
[DB - 99/10/31] With the 9PSI boost kit, you get 420 at the engine, but only time will tell if it blows up too soon. Obviously, they're not pushing to sell that.
[WSC] As some of you know, I am on Comptech muffler #3 in the past 8 months...blown baffles on the first 2 despite supposedly designed to withstand the supercharger. Brought along straight pipes so I could avoid having to order muffler #4 (they've all busted after track events)...then couldn't get the 14mm nuts of the exhaust flange (had 3 guys try)....but lo and behold, the new muffler held up?
[AVE - 00/1/13] So you just finished slapping on an SC on your T. Burying your foot to engage VTEC results in a rattle sound coming from the engine bay. It does it all the time in first, most of the time in second and sometimes in third. Hmmmm, what changes between 1st, 2nd and 3rd? The gear ratio; therefore, the torque to the rear wheels; therefore, the rotational engine deflection in it's mounts; therefore, part A rubbing against part B.
Part A is the bronze vent on the snout of the SC, between the drive pulley and the body of the SC. Part B is the bottom of the passenger-side strut bar. Part B is already machined to clear the SC, but in my case, not enough. Attacking it with a cutter attachment in a Dremel tool solved the problem by creating more clearance between part A and part B.
[MWE - 00/1/16] I really didnt know I had a problem until I got my 94 on the Dyno. With the CT Supercharger, RM Headers, CT High-flow cats, and CT exhaust, I am only getting 290 HP at the wheels. At full boost, the indicated fuel pressure (taken off the service fitting on the fuel filter) jumps up to 95-100 PSI, then comes down slowly as RPMs build to around 75 PSI or so. A 10-12 PSI drop is normal. From discussions with Shad, it appears that the most likely culprit is that my in-tank fuel pump is on the weak side, and not up to snuff for the task - he has had to replace a few in-tank pumps on SC cars in the past.