Dynamometer Results & Comparisons - American Racing 1 7/8" LT results on G8 GXP M6....

Ok, this is a bit of a long read, but has some great info, so it's worth reading. I apologize for the long post in advance. So I headed down to the dyno this afternoon. I got the longtubes put on earlier this week. I made a thread about it's my initial impressions on fitment, quality, and sound. The only thing that was burning me a little was the price. They weren't cheap! Not that I expected them to be, but they are the same price as the ones on my vette. And us vette guys used to complain about the "vette tax". These were on par with the price of any header for a vette so is there such a thing as G8 tax? LOL...

Anyway. I figured the car was running a lean so I hooked up hptuners and my wideband and proceeded to tune away. Now, the common mistake alot of hometuners(like myself) make is to dial the car in on the street by veryifying a/f with a wideband. After that add timing until the car is either on the threshold of KR(knock retard) and back off a bit so it doesn't ping. I've had fairly decent success after confirming dyno results in the past. So I was reluctant to head down to the dyno this morning at all seeing as I have the car dialed in very nicely with no KR and fueling is dead on at 12.5 across the board. But, wifey is out of town, I'm bored, why not go spend the $75 bucks to confirm the old but dyno right?


Ok, so my first pull on the dyno made some great power. I almost packed it up and went home from here. Why? I can't add any more timing because it will ping on the street. I don't need to add more so it will show more on the dyno only to have to pull the timing back out later. I have the fuel curve dead on and don't want to mess with it. I am using AR's catted 1 7/8" tubes. I lost a little bit of power: 3whp/4wtq from 3700 to 3900rpms. I figured I had to pay the piper for getting the bigger tubes now knowing I am putting a maggie on later. However the car made 20whp/11wtq peak over my previously dyno tuned numbers. See the graph below:
http://pic50.picturetrail.com/VOL431/781229/2971386/377005257.jpg
So being as I can't add any more spark, I wonder if it will make more power with less? I started with 1* here and there and the end result was that I ended up pulling about 3.5* of spark from 2400 to 4400 and 1.5* of spark up to redline. The car made a tremendous amount more tq!!!!! Another 25wtq under the curve and 11wtq peak!!!! It also picked up 6whp peak and up to 18whp under the curve. Needless to say, I am stoked. No loss in power over stock, or over my previously tuned setup. These gains were over tuned numbers so I couldn't be happier. See this graph below:
http://pic50.picturetrail.com/VOL431/781229/2971386/377005256.jpg
Overall, it was the best $75.00 bucks I've spent to spend some time on the rollers today. Of course on the street on the way home not a hint of pinging on HPtuners and the car absolutley rips. It was 102* in the dyno cell, the car never saw IAT's less than 104 with the hood open and fan blowing. LOL.

The car may have made another 5whp leaning it out as well, but I spent alot of time over the last 2 days making sure that the a/f is at 12.5 and being able to pull through 4th gear without it leaning out with the vararam and other mods. The old tuned setup vs the new tuned setup the car is very different on the street. It picked up almost 30wtq under the curve, averaged 23wtq under the curve in gains and 25whp peak and up to 28whp under the curve. The graph below represents my old tuned pulley/vararam setup vs longtubes. These two pulls are about two weeks apart.
http://pic50.picturetrail.com/VOL431/781229/2971386/377004456.jpg

Thanks for American Racing for a kick ass product. Worth every penny :)

fuck yea bro those are some very respectable gains for headers only plus a little tuning!

Very nice numbers so only 1.7/8 Headers / Vararam/ Pulley and tune??

Is the car M6??

lucky! :) nice gains ... what was the timing befre and after?

can somebody explain how less timing without knock to start with give such gains?

The car took a ton of timing down low without knocking. 28.5* to be exact. But It wasn't pinging. I started to remove some timing and got down to 25 to 25.5* and that was the cars sweet spot.

Oh, and the cars only mods are ported tb, pulley, vararam, headers. The car was previously tuned for everything else but the headers.

Doug, Great info and a good read.
It's amazing the HP/TQ that can be found when you have time to play.
Bob

You just learned what alot of tuners already know. More timing never means more power...

You just learned what alot of tuners already know. More timing never means more power...

So you are basically confirming what GTODoug just posted. There isn't a magic number of how much timing these cars like, you have to find the sweet spot, or where the motor is happiest.

Thanks for the info GTO DOUG. I would love to have one of these G8's as a daily driver. Do the headers and tune like you did and be done.

I would love to have one of these G8's as a daily driver. Do the headers and tune like you did and be done.


Lies, you know you would do at least an intake and a sleeper cam, just because it's begging.

Well you never know. I have to get one first.

nice read + informative.

You just learned what alot of tuners already know. More timing never means more power...

I didn't mean to come off as if I've found something out earth shattering. I just learned something is all. It may help the guys who tune themselves. I have had this happen in the past as well, but usually on more intricate setups(stroker,high comp head cam swap etc.) I just wasn't expecting it on a bolt-on car is all.

Thanks for reading guys!

Very interesting read, and great gains!

I didn't mean to come off as if I've found something out earth shattering. I just learned something is all. It may help the guys who tune themselves. I have had this happen in the past as well, but usually on more intricate setups(stroker,high comp head cam swap etc.) I just wasn't expecting it on a bolt-on car is all.

Thanks for reading guys!

I didn't mean it in a bad way.It's good that you took the time to play with timing instead of just running the most timing and saying the headers made little power down low.Just brings out that a dyno is a very usefull tool to get the most out of the car that you would never see on the street fully tuning it.

Thanks slowhawk, I'm happy I took the time as well. Makes me wonder about previous setups I've run. I never quite took that approack. I usuallly run max timing/and 13.0afr and call it a day. This opened my eyes as a DIY tuner.

Dougie

Great results, and very interesting analysis!

Thanks for the tech tips today... Let mr know if you'd like to go try this again on a certain blue Vette for old time's sake!

Wow man, great post. One that I especially appreciate since I just bought HPT to mess with (mess up) my tune, lol