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Just got back from my dyno tune after installing some ARH headers. My car is a 2009 LS3 M6 with stock engine. I know a lot of people say to go with 1 7/8 on an LS3, but I plan on keeping it pretty close to stock, and I was a lot more interested in low end torque, so I went with 1 3/4. I also got them ceramic coated locally. Install was pretty simple, just followed the instructions. Probably the hardest part was running the wires , and I decided to put heat shield on a lot of wires and hoses. I also put a heat shield on my starter which you can read about here https://www.corvetteforum.com/forums...at-shield.html. They fit really well. After putting them on there was a noticeable increase in power. The car was also quite a bit louder with the npp open, and there was some drone at low rpm under light throttle, and it was a little too raspy for my taste at WOT above 4000rpm. So I installed some little borla resonators, which really tamed down the rasp, but didn't really do anything about the drone. So I put some cable clamps on the npp so that it stays open about 3/8" when closed. Sounds pretty good to me now, and the guys at the dyno place said it sounds good too. Anyway, onto the numbers. I did a baseline pull 2 years ago when I got the car and it put down 380 hp and 358 ftlbs. Then I changed the rear gears to 3.90s. So before putting the headers on I did another baseline and put down 377 hp and 360 ftlbs, which surprised me, I thought I'd lose a lot more. Then I installed the headers, and today, which was a rainy day, I went in to get tuned. The final results were 378 hp and 385 ftlbs, all numbers are corrected. Peak numbers also happened earlier, 4472 vs 4542 for torque, and 5742 vs 6000 for hp. He only ran it to 6000rpm this time, which is where the 2 lines crossed, so I may have lost a little bit above that. I was kind of surprised I didn't gain any hp up top, but I got what I really wanted which was more midrange, so I'm happy with it...for now, lol.
* Update in post #4 *
*Update*
I discovered there was a small manufacturing defect with one of the cats, so I called ARH and they sent me a new x pipe. While that was going on I looked at my air filter, it looked a bit dirty, but not too bad, and it only had 48 000km and GM says it's good for 80 000km, so I thought it should be ok. Wrong. I tapped the filter on the bench and 2 tablespoons of dirt came out. I think this explained why I lost torque so quickly after 5200rpm, it was running out of air. So I put a new air filter in, and got retuned. This time there was a bit of knock in the midrange, so he had to pull a bit of timing in that area. Final results were 391hp and 380 ftlbs. Here's a graph of the 3 runs
As a comparison ... My 2011 GS (A6) dynoed 371 RWHP when bone stock.
Added 1 3/4" headers with cats and a dyno tune .... Using the same dyno, it made 405 RWHP (increase of 34 RWHP)
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Here is the dyno sheet after installing the headers and dyno tune:
EDIT: Why my car stopped making any more power above 5,500 RPM ..... I don't have a clue
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Something started happening at 5500 rpm. Looks like it started pulling timing.
Looks similar to when I had my car dynoed a month ago. Started pulling timing about 5000 rpm. Ended up being a weak coil that started misfiring right at 5000.
Tuned Vararam and gutted cats with secondary cats intact still. I dynoed 394 on mustang dyno and 397 on a dynocom.
thru an m6. Installing longtubes, x pipe, and a airraid and hoping for 430
Curious, why are you removing the vararam for an airaid?
the vararam blocks the radiator and on 100° track days I see 240 water temps. There was a c6z that was stock. He didnt see temps go over the 220s. I was looking for a stock c6z intake but got a deal on the airaid
ARH header install and results
