: AR Headers and Hennessey Intake Results

06-09-09, 09:35 PM
I had the AR Headers and Hennessey Intake with tune done, and the results are pretty much as expected.

521 HP/483 TQ, rear wheels. These numbers are pretty close to the 522/490 obtained by AR Headers when they dynoed their car. The only significant difference was that they got a 50 TQ gain as well (then again, that car started at 440 TQ). I don't know how much time passed between my arrival (after a long highway trip) and when the car was placed on the dyno, but variability in the extent of stock heat-soak levels could theoretically account for some of the differences, IMHO.

The stock numbers on my manual transmission car were 464 HP/457 RW TQ, so the total difference was 57HP/26TQ.

In addition, the post mod, pre tune numbers were 498 HP/479 TQ, and the differences were most apparent after about 3500 RPM, where the TQ curve stayed higher for longer from there to 6000+.

With regard to the SOP feel, it seems a bit quicker, but I drove from Houston (Sealy) back to San Antonio with my 4 year-old in the back, and it was in the high 90's. I'll need to do my routing morning drive to work and back down familiar roads to properly evaluate the difference in feel.

I decided not to go with the Corsas, but instead to leave the stock mufflers on the car. I think I'll end up sticking with that decision; this set-up has a moderate increase in exhaust volume (mostly under load, not so much at idle or highway cruise), but retains the exhaust sound character.

The supercharger sounds changes are significant, and in a good way! The whine is more audible, and the air-rushing sound is cool.

Anyway, I'm pleased with the sound and dyno changes for these conservative mods. At some point, I may do the pulley, but I don't want to be without the car for a whole week (this is my daily driver).

06-09-09, 09:59 PM
This is great detailed reporting. Thanks!

06-09-09, 11:00 PM

Thank you for documenting this for the rest of us.

Notice any drop in boost?

Mike C

06-09-09, 11:24 PM
I'll get back with you on the drop in boost. Per JT, there is a net loss of 1-1.5 psi, and I did intend to try and notice the boost under WOT, but I've been distracted by the driving (and listening). I don't normally look at the boost gauge too much, but if I remember to, I'll post it. Stock, it reached the 3rd line (9psi).

06-10-09, 10:38 AM
Thanks for doing a write up on this setup. I was interested on the AR headers also, and when I talked to them, they said the headers with stock mufflers would be a little loud. Do you mind posting up a video clip of how the car sounds now? Thanks in advance!

06-10-09, 12:02 PM
Bummer--I was so hoping for more from the intake/exhaust. Any chance you had a tune only done to compare these results?

06-10-09, 12:10 PM
What are you using to tune your car?

06-10-09, 09:47 PM
Nice, any videos?

06-10-09, 11:30 PM
To answer a few questions.

I'll have to figure out how to upload a video. I have an analog recorder, but my wife's camera is pretty new, and it can do video clips. It's true, at this point, all I could find on the web was stock and full exhaust (AR Headers and Corsa), but not the setup I have, without the Corsa exhaust. Give me a few days on the video.

As far as boost goes, I am getting 8 psi now (about 2/3 of the way from the 2nd to the 3rd bar on the boost gauge). I was getting up to the 3rd bar before (I'm assuming the scale is linear, and that that signifies 9 psi).

More on the HP/TQ curve (and I may scan that in later): A comparison of the TQ curves shows the least TQ is gained in the midrange, where the TQ peak is. In the lower 1/3 of the curve, there is a 50 to 70 ft-lb increase, so the peak numbers don't quite do the curve justice.

The tuning was done at Hennessey. They have been very professional.