Sweet_SS

Run 7 psi no tuning...478 rwhp and 492 ft/bs. However, as you can see the car got way worse on run 13...9psi. The general consensus is saying valve float, bad springs or even cam. I have brand new LS6's that are being tossed in next week. All in all, Im excited. The car still has some left in her ;D

NGK TR6's gaped to .28
A/F: 10.53
Timing/Spark: 9 degrees

Ps- I am racing with altitude LOL 4500ft above sea level. So this is actually decent power on 7psi with no tuning.

boostedlt1

iTrader: (2)

you ran 7, wait 9psi with NO TUNE?!?!

Sweet_SS

The timing was taken down and the a/f was around 10.53. Car wasn't tuned to make power on 9 psi. The car was already tuned on 6psi...kept rich on 7psi. Just wanted to see how the car was going to react when increasing boost. It spiked to 9psi...tuner let off and backed boost back down. Car for some reason when trying to tune on 7psi, didn't want to make any power after 5200. Torque keeps falling off. Thought it was back pressure, but that checked out. Spark and a/f was inline. The only other thing is weak springs or stock cam needs to be swapped. Trying to figure out why the car is acting up...up top.

sho-me speed

iTrader: (55)

9 degrees of timing?? Should have been double that or more. Show your AFR curve. Graph says max was 14.33 where was that at?

Sweet_SS

I will take another shot of the graph. I think the 14.33 a/f was at idle. As far as the timing goes, 9 degrees is way conservative, which is fine. We were just trying to figure out why the car keeps falling off.

XtremeDime

iTrader: (16)

I was told not to go above 8psi on the LS6 springs.

And holy **** only 9* of timing?

Sweet_SS

Crap, I was told different on the LS6 springs. Ya, only 9 degrees of timing LOL. That's going to be fixed here soon

Fbodyjunkie06

iTrader: (10)

I guess the reason his a/f is still at 10.5 with only 9* of timing is him being at alt. he already has less air than most of us and that is going to make his tune richer off the bat right there or am I wrong thinking this?

Sweet_SS

I can still have the car tuned for 11's on the a/f and increase timing. However, I have to run more boost to make the same power as some at sea level. I would actually have to run 10 psi + to make what a sea level car would make on 7-8psi. Basically, if you take a car from sea level and bring it up here, it will loose 1-2 psi, if not more straight off the trailer. That car will run richer too. So your theory is close.

ZL1Killa

iTrader: (17)

dude... 10.53 AFR... seriously...why that goddamned rich?

lean it out to 11.5 at 9psi (even 7psi) maybe you can get away with 12.0 AFR.

take your timing up to ~16~18 degrees
use around 16 degrees at peak torque then nail it with some more timing above peak torque (18)

you are leaving a MESS of power on the table. Stock heads? stock ls1? why are you running it the way you are? I read the thread all the way through.... so you are thinking your boost limit is the springs and/or cam? .... what is your timing above peak torque? usually turbo/boosted cars like more timing after peak torque

Sweet_SS

We really couldn't tune the car anymore. WOT at 7psi...5200 the car suddenly just drops off (pedal still down @ WOT). I'm guessing adding more timing up top will actually keep the torque curve up? When the car falls off, you can hear the exhaust stutter. Everyone is thinking the valve springs aren't doing their job. I could be wrong!!! The motor does have over 140K on the clock. I had the car on two different dyno's/Tuners and both are saying the same thing. No point in leaning it out or adding more timing if Im loosing cylinder pressure...valve float (weak springs). What are your thought?

Nitroused383

iTrader: (10)

SAE dyno correction factor compensates for altitude. If you want your actual power numbers you need to use uncorrected numbers, which is probably around 410-420 actual rwhp. Get a set of PAC 1218 or 1518 springs, they are great. You should also upgrade your pushrods while you're at it.

JRENIGAR

iTrader: (37)

Mine was tuned for 7psi @ 200 ft above seal level in 90 deg heat and made 414/392 @6000rpm through an unlocked auto with no cool down time and 15deg timing on a dynojet. I kept the shifts at 6k and timing increases didnt gain anything so it was left there for safety. The a/f ratio was set for 11.3-11.5. Engine has 180k on it with factory longblock. The #'s arent really what I was hoping for but its runs good on the street. Id suggest changing springs and if that dosent fix it then, IDK... Good luck.

Sweet_SS

I will change out the springs and let everyone know how it goes. Thanks for all the input guys. It's appreciated.

robbyredneck

iTrader: (1)

am i the only one who thinks those are damn good numbers for such a soft tune?

Sweet_SS

As promised, here's the full graph...including a/f.



@ Robbyredneck, thanks. They are good numbers. I was only hoping to make mid 500's.

JRENIGAR

iTrader: (37)

If he had a supercharger that would be correct but his turbo should just spin higher to make up for the difference and keep the boost relatively the same, no???

JRENIGAR

iTrader: (37)

****, Id take those #'s all day long.

Fbodyjunkie06

iTrader: (10)

I dont think so less air is less air. Less air entering the motor on the same tune would result in the tune becoming richer. The turbo has to work harder so its efficiency goes down. I am guessing the reason the psi goes down is because the loss of air makes the backpressure go up on the turbo because it is having to suck harder to actually makes less boost so back pressure city on a small turbo. I think this theory sounds right, at least in theory lol.

Fbodyjunkie06

iTrader: (10)

Yea I think my theory is correct as I have seen and heard of diesel guys getting away with running larger turbo chargers at altitude because the size of the compressor housing makes up for the loss of air at altitude therefor forcing more air into the motor.