Dyno results -- Comptech Headers Only

[cristo555]

I had my Comptech headers installed today on my bone-stock '91.
I left the OEM exhaust and cats on. We did before and after Dynos on a "dynapack" which I was told is a more conservative (and more consistant) Dyno machine.

Stock rwhp = 228.1 torque=170.7

W/headers rwhp = 237.1 torque=174.9

The hp gains kick in around 5500rpm and is most noticed above 7000rpm.
The torque jumps at around 3000rpm - levels at 5000 - and jumps again around 5500rpm and stays up.

I will try to post the actual dyno reading as soon as I figure out how. I had the work done at
J.E. Imports (410-343-2400) www.jeimportperformance.com in Northern Maryland. James is the owner and did a great job. He only charged $260 for the header install and $75 for each for the Dynapack (4 runs each).
I wonder how much difference an exhaust would make--from what I've seen on my searches...it might be better to put the
$ grand or so towards a supercharger instead. By the way..my NSX sounds a little throatier and a little louder with the headers. As far as feel---it is more responsive and seems quicker. I was going to take it to the 1/4 mile track last Friday for some "before" times but I got rained out.

 

[Xcite50]

I had my comptech exhaust installed a few months back, the gain is similar to yours... I have heard that with the headers and exhaust, you should gain about 25 hp at the wheel. So it comes out to be $100/hp

 

[NoClgDeg]

Thank you for posting you dyno results. My stock 91 dyno'ed at 237 RWHP and 186 Torque with just a K&N Filter. One of these days I will dyno it again to see where I stand with my other stuff.

 

[sjs]

Ouch, $75/pull? That's pretty steep. If the total will add up to more that ~$150 you should negotiate an hourly rate. Around here it is $200 or less the first hour and about 1/2 that per additional hour. You can do a lot of pulls in an hour.

...I have heard that with the headers and exhaust, you should gain about 25 hp at the wheel. So it comes out to be $100/hp

I think 25 hp is quite optimistic as his results with the headers suggest. I more often hear 15-20 and I doubt even that is often achieved.

 

[ChopsJazz]

My '91 with CT headers and CT exhaust routinely dynos at 271 rwhp. No other engine mods.

 

[sjs]

My '91 with CT headers and CT exhaust routinely dynos at 271 rwhp. No other engine mods.

I believe you, but without before and after runs on the same car, same dyno, and similar conditions, that doesn't really tell us much.

Variation from car to car alone is significant enough to make more difference than some people see with I/E/H, and together with other factors you can't really prove anything. Of course the vendors love to pick & choose their numbers to sell product, but rarely if ever do controlled tests support the claims. And I’m not just talking about the NSX.

Then there is also the possibility that the stock ECU will adjust over time to the lower backpressure of the system and un-do some of what was gained, or even increase the gains. Hard to say, and never carefully tested.

My point is, don't be surprised if gains are lower than advertised.

 

[NetViper]

So slapping on the ole' SC is the only way to truly make a lot more power!

 

[cristo555]

It seems logical that headers and even an exhaust would make a much larger rwhp gain after a supercharger install. The higher pressure would create more exhaust requiring less restriction. Of course to test that, someone would have to install a SC with stock exhaust--dyno the car -- then install the headers etc.... Anyone seen that done anywhere ? If that is true, then the headers are a good investment for a future SC.

 

[ChopsJazz]

I believe you, but without before and after runs on the same car, same dyno, and similar conditions, that doesn't really tell us much.
My point is, don't be surprised if gains are lower than advertised.

I know these numbers are relatively insignificant without a proper context. But I have dyno'd the car on three different occasions at two different dynos and with four different chips. All, however, were with the headers and exhaust already in place. All dyno runs were within a few rwhp of each other (again, on different days, different dynos) and, oddly, the stock ECU was the clear winner each time!

I agree with your statement about the differences between individual cars. Mine seems to pull on other NSXes with similar mods.

 

[NetViper]

if there is a difference in power between one NSX and another... what can we do to get a lower performing engine up to the levels of the strongest engines?

 

[Hrant]

if there is a difference in power between one NSX and another... what can we do to get a lower performing engine up to the levels of the strongest engines?

One of the unique attributes of the NSX as a sports car classified in the exotic category is that it is hand built.

And therefore there will always be variations among NSXs, and this has been well documented with posts ...... the percentage increases/decreases are perhaps more meaningful than the abolute numbers.

Tuning might help some but as many have said, unless you test on the same Dyno the same day with the same mods, all comparisons are meaningles except for those comparisons of before and after on a particular NSX on a given Dyno/day - and the gains and losses can be a benchmark for that car.

HTH

 

[madfast]

for ChopsJazz

ChopsJazz,
when you dynoed your nsx with different chips, was one of them the Dali racing superchip? I have that in my car since I bought it. I don't know how the stock ecu feels like. If the Dali chip was dynoed can you post how much hp decrease did you see as compared to the stock ecu? What other chips did you test? thanks!

 

[Lud]

if there is a difference in power between one NSX and another... what can we do to get a lower performing engine up to the levels of the strongest engines?

As mentioned, there will always be some difference between cars. But all kinds of basic things can also make a difference.. air filter, spark plugs, fuel filter, ignition coils, valve adjustment, fuel injectors, etc. The general condition of the engine internals matters too.