Dynamometer Results & Comparisons - Mild Pat G Spec Cam results. Low numbers?

Well, I recently had a Pat G spec cam installed and removed all of the DOD components. The cam is 222/226 .597/.605 114+2. I have Kooks 1 7/8 mid length headers w/high flow cats, Vararam intake, MagnaFlow cat-back and the car was street tuned with a wideband after the install. I know I would make a little more with long tubes and getting rid of the cats, but I seem to be pretty far off from other G8s with almost identical cams. I know it is probably pointless to compare dyno results, but I was expecting a bit more. The car made 361hp and 350tq. Not too impressive if you ask me.

http://www.youtube.com/watch?feature=player_detailpage&v=EhMOuJLzzWc

Car is too rich up top to carry the powerband. Mids hurting the top end pull... auto #s will be lower... small cam... with power peak @ 5700 it might even be a tooth off.

From what I've read, the IRS sucks up some power, like on the 04-07 V. I'm running almost the identical cam, and mine pulls hard to 62-6300rpm through a 4L60E and 1 1/2" primary mids with the time in my sig, and I'm not done tuning it yet. Like DietCoke said, pull a little fuel from it and see how she likes it. Mine is @ ~12.9-13.0 if I remember correctly. Don't get too wrapped up in the numbers, but that still looks low, even for that cam. Run it, and report back.

I know the powertrain is sucking some power, but it seems very low in comparison to other G8s with mild cams. I'm trying not to get too caught up in numbers, I just want to be sure I'm making the most out of what I have. As far as running rich, I'm not sure. It was tuned by John Weeks on the street, I'm pretty sure he knows what he's doing. Although, I guess something could have changed in the last few weeks.

Car is too rich up top to carry the powerband. Mids hurting the top end pull... auto #s will be lower... small cam... with power peak @ 5700 it might even be a tooth off.

After taking another look it does look like it is running a little rich up top. I'll have to see what I can do about that.

Mids hurting the top end pull

I would venture to say that the mid length headers are actually helping his top end.

No disrespect to Pat and/or Geoff (both are great knowledgeable guys), but L76 / LS3 engines respond much better to a lot more exhaust duration from my personal experience. Earlier on I tried some 4-6 degree splits on those engines with mediocre results. Once I reformulated and went to a 10-12 degree split the cars were picking up much more power and TQ.

FWIW, you can run a mid 220's intake / mid 230's exhaust on a 114-115 in those engines and still retain excellent driveability. The necessity to go with a "baby" cam in an attempt to keep good driving manners went away with the GEN IV engines and new PCM's.

Good luck.

No disrespect to Pat and/or Geoff (both are great knowledgeable guys), but L76 / LS3 engines respond much better to a lot more exhaust duration from my personal experience. Earlier on I tried some 4-6 degree splits on those engines with mediocre results. Once I reformulated and went to a 10-12 degree split the cars were picking up much more power and TQ.

FWIW, you can run a mid 220's intake / mid 230's exhaust on a 114-115 in those engines and still retain excellent driveability. The necessity to go with a "baby" cam in an attempt to keep good driving manners went away with the GEN IV engines and new PCM's.

Good luck.

Yeah, I realize now that there are other routes I could have gone with. Like I said though, the car does feel a lot stronger, with good drivability. Eventually I may want more. I have had the car for 3 years now, and still haven't taken it to the track. I hope to change that soon. But mostly its used to go to and from work, and maybe a short road trip. I am happy with the way it is performing, I just want to make sure the car running as strong as it can. Thanks for the input.

Just to add, I have no complaints on John's tune. His tune was spot on after just a little bit of tweaking. I would recommend his services to anyone.

Should have gone with long tubes, there is no downside. Good on you for doing the bigger primaries though. Cats won't hold you back much at all. I'm guessing you could have gone bigger but am also guessing you wanted mild lift/lobes since it's a DD. That looks to be why PatG spec'd you such a mild cam, to make it a well-rounded, reliable grind. Yes, the IRS and 6L80e suck down some power. Did you confirm the converter was locked? Do you have the "before" numbers?

Mine made 357/382 with just Kooks 1 7/8" LTs, catless mids, Corsa cat-back, Rotofab, and a dyno tune. DA that night was over 3000' (hot humid night in Ft Worth).

Just ran a 12.96 @ 109 in 2700' DA Saturday night. Get it to the track and see how it runs, then you can figure out if your numbers really are that low, or if it was just a super stingy dyno.

I had a 5.3 with shaved 243's, 224/228 .581/.588 112+2 and a fast 90 made 351/344 through an unlocked auto....

yeah seems low if my 5.3 with similar cam is close to your numbers. mine made 349/352 thru a 4l60e with stock converter, though mine probably has less drivetrain loss.

I didn't have any software hooked up at the time of the runs so I can't verify whether or not the converter was locked. The car feels really strong, and I've made a few changes to the shift points and they seem to be right where they need to be. It feels like more than 361, either way I want to get it on the track and what kind of time I can get. If I can get mid to high 12s I think its making the power it should. Especially on a stock converter.

1 7/8" long tube AR or Kooks headers gain 30rwhp on stock cammed G8s, so I would expect you'd gain way more than that with a 222/226 cam.

1 7/8" long tube AR or Kooks headers gain 30rwhp on stock cammed G8s, so I would expect you'd gain way more than that with a 222/226 cam.

Would it really make that much over the 1 7/8 mid length? I know there would be some gain, but how much realistically? I'm pretty much over the numbers, I just couldn't believe there were intake/header/exhaust cars making more power than my setup.

1 7/8" long tube AR or Kooks headers gain 30rwhp on stock cammed G8s,

Yeah that's going from iron manifolds to LT headers.

He's not going to gain 35+ rwhp going from 1 7/8 mid lengths to 1 7/8 long tubes. Maybe 5-10 mostly under the curve.

Yeah that's going from iron manifolds to LT headers.

He's not going to gain 35+ rwhp going from 1 7/8 mid lengths to 1 7/8 long tubes. Maybe 5-10 mostly under the curve.

Thats what I was thinking. Maybe about 5 to 10hp by switching to long tubes.

It's a dyno....without before and after numbers its hard to say if you are really low on power or the tune is off....

Yeah, my fault for not getting a baseline done. I really don't think there is much room for improvement on the tune. Hopefully I can get out to the track sometime within the next few weeks.

The tune is off. A 12:1 ratio is nearly a full point rich. I run around 12.7-12.8 at WOT and both of my cats are still the ceramic color (not black) after 2 years of driving.

Will you gain 30rwhp by leaning it out, no, but it will be better for the cats, fuel econ and power/tq will go up.

Another thing to keep in mind; my car uses a very short and direct intake. Not sure how the G8 is setup. The VE table is a good 2-3% different between on the road and on the dyno due to a ram air effect. So the road tuning may be spot on but on a dyno it could look off because the engine is getting a little less air.

The motor seems to be peaking a little early too. My cam isn't too far off from yours and peaks almost 1000RPM later

My intake is a Vararam over the radiator, so its pretty much a straight shot into the intake. And the fan they were using was on its 3rd set of last legs. It was barely moving any air. So, yeah definitely a difference in airflow. G8RAM has pretty much the same cam, and peaks right at the same RPM, of course on his he made 408 with landspeed heads and SLP catted longtubes. As far as the AFR, I think around 12.5 is where we wanted to be, which may have been the case when using the wideband on the road. Then again, it could have crept a little since that tune. Seems to happen a bit with the G8s ECM.

Something definitely not right with this result. Who installed the cam - was it degreed correctly?

I would expect at least 390rwhp on one of your dynos over there with that cam in an A6 L98 - even with short 1 3/4" primary 4-1 headers and cats like many run over here.

Good luck with it.

cheers

It was installed by a GM mechanic I met through the G8 forum. Unfortunately I wasn't able to be around during the install. I was having it done while my son was visiting from Virginia. That being said, I can't say for sure everything was 100% correct, but the guy isvery competent and does it for a living, so I will give him the benefit of the doubt that everything is installed correctly. There is really only one way to know for sure though.

Here is a pic of the G8 intake.

http://vararam.com/images_new/G8-in-car.jpg