k-mart

iTrader: (5)

Right now my '98 C5 has Patriot "LS6 Style" 59cc heads and a g5x2 which is 232/240 .595/.608 on a 114 LSA. The tune is still being worked on because it appears that the previous owner's tuner only tuned it on the dyno and didn't worry a bit about the street. I'm getting surging under 1800rpm and fuel mileage isn't what I expected at 24mpg highway with my M6. I've got all supporting mods (LS6 intake, blackwing, LT's, free flowing exhaust, etc) except for a P&P TB. I was really hoping for more area under the curve with this cam and as you can see from the chart, it doesn't really come alive until 4500rpm. I was thinking about changing it out for a F13 highlift or similar custom cam that will move the power band down about 1k rpm or so. Any suggestions?

N4cer

iTrader: (11)

24mpg is darned good for a heads/cam car. I have no idea why you're disappointed there. So port your throttle body and work on the tune, and you should have no problems. Heck, a tuner I know was pulling over 415rwhp from a cam only G5X2. And trapping close to 120mph in the quarter.

k-mart

iTrader: (5)

That 24mpg is the best I can maintain consistently (I.E. Reset mileage calc. after reaching HW speeds.) on the highway and not on par with many of the h/c C5's that I've seen.

I was really expecting more power from it considering the numbers cam-only like you talked about.

zo6racerx

I noticed your dyno sheet states STD numbers. Do you know what the SAE numbers were?
As for results, attached is my dyno sheet. I have the same cam with AFR heads. See sig. I am pretty happy with my set-up. BTW...three runs on the car with this set-up with a best of 11.42 @121.3 DA almost 3,000 ft.

k-mart

iTrader: (5)

Yeah, I'm not sure what SAE numbers would be since that's STD charts are all that came with the car. I assume they'd be down 7-10hp everywhere. Do you think that your AFR's, LG Pros, and UD pulley would be worth 40rwhp over my setup? I've got LG Streets, BTW.

What kind of mileage do you get on the highway?

hyde

My cam only G5X2 vette 98 model with stock heads completely stock heads....All supporting mods as you have but stock 98 heads and my vette made 417 rwhp....I havent seen to many people have the best luck with Patriot heads..I would start with a good tune and maybe looking at those heads...My buddy with same bolt-ons in his Zo6 with stock 243's made 438 rwhp...Loved the cam thought it pulled like a freight train

zo6racerx

I don't want to start a "head" war, however, all I can say is the AFR heads always seem to deliver great results. I went with the AFRs, LG long tubes and G5x2 cam because it has been a proven combo. I don't believe this combo would be worth 40 HP over yours, but, factor in a good tune and correcting your dyno graph to SAE and you could be closer to my results.

As for mileage, it sucked at first until I got the tune dailed in (low 20's highway). My buddy tuned the car first on the street - part throttle and WOT. We then finished dialing it in at the dyno - part and WOT. After the tuning, the mileage went up and on the highway and it is getting between 28 - 31 mpg.

John

k-mart

iTrader: (5)

Yeah, I'm hoping that we can get the tune worked out soon and that's the source of most of my problems. Hopefully I'll see a decent gain with the p&p tb that's on the way too.