2009 Pontiac G8 GXP with 6.2L LS3 engine and 6 speed transmission. Made 346rwhp and 345rwtq on first dyno pull bone stock. Second run was 333rwhp and 332rwtq due to heat soaked MAF pulling timing (very common with E38 ECM vehicles).

Added American Racing Headers in 1 7/8" size with dual catalytics, Vararam cold air intake and tune with EFI Live. The resultant power was 403rwhp and 394rwtq. A gain of 57rwhp and 59rwtq. On G8s, we typically see a 32-34rwhp gain from the ARH 1 7/8" headers and around 10rwhp gain from the Vararam. The tune made a big difference as the electronic throttle body was closing to 50% between 3800 rpm and 5400 rpm due to the max torque threshold being exceeded (from all the airflow gains). The torque gains were tremendous. The car feels like it has 50 more cubic inches.

 

One word WOOOOW...

Awesome results thanks for sharing Patrick any cam plans??

 

Maybe. This GXP would gain another 30-40rwhp with a baby 218/226 cam.

 

Daaaaannnng. Man I love those cars. I wish I had the funds to buy one as my daily driver. Very nice gains!

 

Great gains!

Is that the same thing that happens with the G8 GT's with the torque management? I know they usually gain big at the track with an tune and I know that mine seems to "ramp up" the power as the rpm climbs rather than giving you a big kick down low like a big CI motor usually does.

 

Thanks for posting the info Pat G !! Those things are selling like hot cakes partially because they look nice, but also the huge gains a set of headers, cai, and tune yield. Very mod friendly. Is part of the reason they gain so much due to the highly restrictive factory tune? I ask because I remember when my car first hit the rollers bone stock, it put down 300/300 LOL, what a turd. SAE corrected DJ too.

 

Was it a GT or GXP? GT are putting +-300rwhp.

 

I don't have a g8, I wish I did. I was referring to my stock ls1 that was in my 2000 FRC when I bought it new.

 

Factory tune is very conservative (100k warranty), but the biggest reason for the gains is because the heads are so good and the exhaust is so bad. Headers gain way more than they did on LS1s. Interestingly, the factory air boxes are pretty decent, leaving only small power gains on the table. But when you can gain 34rwhp with headers and stock mufflers, it's truly an accomplishment.

GXP with 6 speed manual.

 

Nice Gains!

 

That's damn impressive.

 

As always....nice gains and details...
Great job!

 

Nice gains!

 

Sounds like it was worth the money. all that new found torque will help get that heavy car moveing

 

The final numbers are average with LS3 Camaros. It must of been pulling some serious timing to dyno that low stock.

 

Question - Pat, how do you feel about those 1 7/8 headers as opposed to 1 3/4, I admit I don't know the specs on the LS3 as compared to the LS1, but are they beneficial for an LS1 with the larger primaries?

 

On an LS3, the 1 7/8" header are about 10rwhp better than the 1 3/4" headers. This number has been confirmed by many sources including American Racing Headers.

 

Think they would gain any over 1-3/4 headers on a smaller displacement heads/cam LS1?

 

Every test I've seen for over 8 years on LS1 Tech shows the 1 7/8" headers making the same low rpm torque as 1 3/4" headers, but slightly more at higher rpm. Sadly, no good 1 7/8" header systems were available for the 4th Gen F-Bodies until recently. All the ones before had really poor y-pipe setups that negated the power gains of the larger headers. The G-8s are like the new 2010 Camaros in that they are blessed with 3" dual pipes coming off the headers into a dual 3" x-pipe. Much better than the 4th gen y-pipes that slam two 3" pipes into a single 3" pipe and call it a performance exhaust.

 

Well Pat, that 4 inch merge you had on your TA certainly was nice. Is anyone making them or was it a one off that you did yourself?