Bramlok

iTrader: (7)

Fbody car, full bolt ons, with V3 cam and PRC LS6 heads, LS6 intake, 1 7/8" headers with ORY and Corsa. M6 car with stock gearing. Originally tuned in 70* weather with low humidity on a dynojet and made 421hp/389tq. The tune is spot on. Perfect A/F ratio, perfect drivability.

I had the chance to strap in down at another shop and do a few pulls, also on a dynojet. On this day it was hot and humid. 97* and high humidity. The car with same mods put down 446hp/409tq.

The only problem at both shops is it started pulling vacuum as early as 3000rpm all the way to redline at 7000. They both said it was due to a restriction in the intake somewhere. Either the LS6 intake, the throttle body (ported stocker), stock MAF, SLP Lid or a combination of all of the above. I found this odd and I've never heard of this problem before. Both shops said with a better flowing intake system to expect even better numbers, and it would also stop pulling vacuum.

But I guess the bottom line is both shops are well known and it just shows how far off dyno numbers can be on any given dyno and day. If anything, my numbers should have been much lower on the hot and humid day. At this point I could give a **** about dyno numbers as long as the cars drives good and pulls hard, which is does.

And next time your bolt on, cam only car makes numbers like 440hp/410tq, take those readings with a grain of salt.

thunderstruck507

iTrader: (18)

With you setup I think a Fast intake would benefit you, but it's up to you if it's worth it, sounds like the car is running healthy.

You could do a GM 85mm maf with no screen or the wider mesh aftermarket screen for cheap and see if it helps some but you are likely just at the limit of the stock intake, especially in the higher RPM range.

redtan

iTrader: (5)

It's not a problem, it's just how things are with engines and the laws of physics. Unless you have a ridiculous setup like NASCAR, you're always going to be pulling vacuum and have less pressure in your engine than outside.

Of course a better flowing intake system will make even better numbers, especially on a H/C car. A 2 year old could've told you that...

Camaro99SS

iTrader: (4)

Interesting results. My car was tuned on a pretty stingy dynojet, and I've wondered what it'd make on a different one. Dynos are just tools though, and track times are the ultimate barometer.

Jason

Bramlok

iTrader: (7)

Well, in my case it is a problem. I have enough of an intake restriction to where it's throwing MAP sensor codes when driving it hard. At WOT it's pulling 3" Hg which is more than acceptable.

That was unnecessary. I don't know how many 2 year olds you talk tech with, but I have hard evidence and numbers that show that an LS6, ported stock TB and SLP lid are not enough in some cases and even can cause issues with certain setups. So for everyone that says an LS6 is good enough for a H/C cam setup, that may not always be the case. I know that now after getting in a few dyno runs, learning a few things and sharing my experience. I am not just basing my logic on "I could have told you so internet theory".

I'm getting off point here. My main point was to show that different dyno's can read a wide range of numbers when running the same car with same mods, under different temp and humidity conditions.

Bramlok

iTrader: (7)

Very true about track times and how it runs. It never hurts just for fun to throw in on another dyno just to see, if there is any discrepancy between dynos and numbers.

Bramlok

iTrader: (7)

Yes, that's the plan down the line, maybe over the winter or next year. But for now, I just got it back together and want to drive it for the summer.

ctd

iTrader: (1)

You mentioned weather conditions during both dyno runs being different. Were the runs in Std or corrected configuration of the dyno's?.

If they were corrected runs then weather would have been factored & calculated, the runs would be comparable.

I always watch the torque numbers the dyno indicates, if you see inflated numbers that's a pretty good indicator.

BrntWS6

iTrader: (7)

Glad to see you finally got everything done....solid numbers!

thunderstruck507

iTrader: (18)

That seems odd that it's throwing codes with 3". IIRC mine was ~4 before the larger MAF and a bigger inlet air filter and the car ran fine. I haven't even checked it since then.

I might be confused on the measurement though. I compared the MAP reading with key on engine off to the reading at WOT. Started developing a discrepancy around 4k rpm.

Bramlok

iTrader: (7)

Other than throwing the MAP code it runs fine. It will only throw the code if I drive it hard and repeatedly shift at around 6500rpm. If I shift at 6000-6200, it's fine and won't trigger the light.

smahlum_21

I just purchased same setup as you but have a fast 92 TB and ported 92 intake. Ill let you know when I get my car dynoed what the numbers are so maybe we can compare how much that LS6 is holding you back

BrntWS6

iTrader: (7)

~20rwhp....I have that setup too and that's what I gained on the same dyno.