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First dyno run - 3.2L only SC

13 May 2001
Mesa, AZ
Well, I went out and Dyno'd my NSX today at Technodyne here in Tempe, AZ. The only modification to my car is a Comptech 6.9psi SC - the rest is stock.

RWHP came out to 313.7 at @7400, and 216.8 for the Torque. The guy who did the Dyno (Bradley) said those were good numbers for just a SC on a 3.2L.

Has anyone else ever Dyno'd a stock 3.2L NSX with just a SC?

I am throwing Intake, Exhaust, and Headers on it Thursday, and will dyno it again on Friday.

Now, I'm definitely concerned about the numbers that I've encountered so far - this shows only a 45RWHP increase if I was running stock baseline (for a '00) around 267 at the rear wheels.

Comptech claims 365RWHP with intake, exhaust, headers, and SC. I'm going to be VERY surprised if adding the Intake, Exhaust, and Headers really gives me another 50 horsepower... but we'll see on Friday!

Is anyone here with a 3.2L and Intake, Headers, Exhaust, and SC running around 365RWHP?

David Allen
'00 Silverstone NSX-T
My otherwise stock 3.2L SC NSX-Z coupe came in at 343 RWHP (uncorrected) and 325 RWHP (corrected). Max torque (corrected) was 235, with torque above 200 from 2.5K RPM all the way to redline - almost flat above 3.5K RPM. Ambient conditions - cold morning in Silicon Valley, just slightly higher elevation than sea level.

The RWHP numbers for stock 3.2L (no SC) generally appear to run from 250-260 RWHP (corrected), so your reference number for a stock 3.2L is probably a bit optimistic (or just an outlier). So the SC alone looks good for roughly 60 RWHP improvement.

I'm sure we'll all be interested in seeing the post-intake/header/exhaust runs!


[This message has been edited by Number9 (edited 22 May 2001).]
What's the difference between corrected and uncorrected, and how does one get these numbers converted?

The numbers you provided seem much more on track to what I've heard - I'm wondering how on earth comptech is getting 365RWHP on their dyno with just Intake, Exhaust, Headers, and SC. You can see the dyno chart on their website at http://www.comptechusa.com/images/dyno/2000NSXscPlot3.pdf.

They state their stock NSX ran 268RWHP @7200RPM to start off with...

David Allen
'00 Silverstone NSX-T
The Comptech number is definitely on the high side. Assuming the usual 11% driveline losses (this seems to be the concensus figure - though I can't articulate the basis for this other than a circular argument that assumes that the published crank number is correct) for a late model NSX and the published 290 crank horsepower, you should see about 258 on the dyno, which is roughly what one sees in the runs at my local dyno (dynojet) and consistent with what is shown in the Phoenix dyno day results for the NSXCA-SW group. Also, the appearance of the Comptech plots/tables suggest they're not even using the same brand of dyno, so that's a big variable. So take it all with a grain of salt.

As for corrected #'s, they're supposed to account for variables such as ambient air pressure, temperature and who knows what else and presumably normalize the measured #'s at some standard temp/pressure so that the results can be more readily compared for runs at different times/places, etc. I'm not sure how well this works, but it is the intent.

Originally posted by Requnix:
I'm wondering how on earth comptech is getting 365RWHP on their dyno with just Intake, Exhaust, Headers, and SC.

Tune, tune, tune. I got an extra 20 hp or so with an afternoon on the dyno. Doug H. gets just under 400hp at the wheels on his car by using a better tuning system (and a slightly larger pulley).
The guys at Dynotech recommended I spend an 'afternoon' with Mark Basch and do some tuning as you recommended.

What methods of tuning did you find to be the most effective for an additional 20RWHP?


David Allen
'00 Silverstone NSX-T
Agreed that tuning is a "good thing" (TM). When you do your next run, have them insert the sniffer so that you can check the air/fuel ratio. If there are any oddities, you may be able to improve via tuning. If it's correct throughout the rev range, then further tuning of the extant parts won't help much. In my case, the air/fuel ratio was fine so the car will require more low restriction go-fast parts or more PSI, period.

Again, keep in mind that the Comtech stock baseline RWHP number is highly suspect. Most stock 3.2L won't get 268 correct RWHP. So their car is an abnormally strong specimen or you can scale back ALL their numbers by subtracting a constant 10 HP or by multiplying by a scaling factor, say 258/268. I think the error bars swallow the delta, so don't get hung up on Comptech's numbers.

Originally posted by David Allen:
What methods of tuning did you find to be the most effective for an additional 20RWHP?

Two things:

1) The A/F ratio is key. Don't think about tuning for a specific hp level. This is a foolish approach and will always lead to an unsafe condition, usually too lean. Instead, get the A/F ratio as optimal as possible accross the entire rpm range. The sniffer on the dyno is great for this. Let the hp fall where it will.

2) Keep in mind that, when tuning the CT kit, you are essentially trying to find the best fit between two different curves. The FMU pressure curve and the boost curve are not the same, so you need to manipulate them to get the best match possible. If you do not have the plates/springs to alter the FMU, order them before you put the car on the dyno. The set will usually come with tables showing the different rising rates for the different configurations. I don't remember the FMU brand, but it is probably stamped on it somewhere - if not, ask Shad at CT. As you do each dyno pull, measure the A/F ratio accross the entire rpm range, then think about whether the fuel curve (it is really pretty flat) needs to be steeper or lowered. If you can find a dyno facility that does a lot of blower installations, you are ahead of the game. They are really common on muscle cars and trucks, so try to find a shop that does Kenne Bell kits or some other Whipple-based systems.

If money is not an issue, you could also set up a fuel system similar to the Bell TT kit using a couple of extra injectors and a Rebic or similar fuel controller. It's a bit more money, but a lot more precise.

Good luck.