mountainbiker2

I have an 04 Z06 crate motor that I've been revving to 6800. At 50% of my autocrosses (24 in a year) I've needed a few more mph. What happens is, I just sit on the rev limiter for 1-3 seconds. I think raising up to 7100 should take care of it. I know one T1 racer that has his set at 7100. I'm not looking to get 100k miles out of the motor. I also drive on Hoosiers A6's to every race. So I'm not looking for the perfect solution. Just some real race experience. What do you guys think?

thanks,
Steve A.

supersick99z

iTrader: (66)

It's possible, but for how long on stock rod bolts who knows! You may just be carrying your internals home in a trash bag one day, that is if you find them all

ULTIMATEORANGESS

iTrader: (4)

at least upgrade your springs.

got-a-ls1

iTrader: (12)

yes good springs... and it would be better then bouncing off of the rev limiter on purpose like that... but if its a stock motor your making less power up there and may be better off shifting if you need to extra mph... If you cant shift because of the layout you should probably at the least have some katech or arp rod bolts installed if you are gonna be turning 7000 repeatedly.

Damian

iTrader: (89)

No way I'd push the stock valve springs up that high. LS6 springs usually start floating around 67-6800.

Run a good double valve spring, and put ARP rod bolts in the bottom end (easy to install). I would also have the PCM tuned to ensure your fueling is safe at those rpm levels. After that, you should be good for a while.

mountainbiker2

Okay, looks like I might need valve springs. Which ones? Keep in mind I'm keeping everything stock internally. My motor has been dyno tuned. Kooks headers and cold air intake is all it has.

Thanks again.

Steve

SLP4CamaroSS

iTrader: (16)

question you should ask do you make power all the way up to 7100rpm. might not be worth if the hp goes down a hell of alot around that rpm range.

Damian

iTrader: (89)

I'd recommend the PSI, or the PAC 1518s. You need to run the strong single spring possible. Single springs have better harmonics than most dual springs, which play a factor in valvetrain stability at high rpms.

ARP rod bolts are HIGHLY recommended for high rpm applications and if the motor is out of the car they're very easy to install. ARP includes instructions and if you follow them correctly it's a breeze.

IMO, that's a problem that needs to be resolved. You need to find a good reputable tuner that can tune your car on the street for the RPM ranges you'll be racing in. Unless you're tuning on a loaded dyno, a dynojet w/ a 1500lb load is not going to make a PCM accurate for 7000+ rpm operating ranges.

Gary Z

The combination of the lightweight LS6 valves and PAC 1518 springs is good to at least 7000 rpm with the LS6 cam. I have LS6 heads with 1518 springs and a bigger cam and my limiter is at 7200. My WOT 2-1 shifts have hit 7800 without damage. My pistons have -2cc reliefs which gives me some leeway you won't have.

mountainbiker2

Here's a small video on me hitting the rev limiter at 6800. Listen carefully. I can't change the music, it's already in my You Tube videos.

thanks,
http://www.youtube.com/watch?v=MBDONDNKWbE

got-a-ls1

iTrader: (12)

after watching that i think if i were you i would just go to a slightly taller rear gear that will get you 4-5mph higher in that gear... increasing the limiter is not the answer IMO (your losing power reving that high on stock motor anyways) and thats such long stretches on the limiter i dont know is 300 rpms would even be enough. I dont think a taller gear would hurt you at other points on the track and would likely make you faster on those big fast sweeps.

On another note man that looks like fun!!

got-a-ls1

iTrader: (12)

double tap

Damian

iTrader: (89)

Damn dude, you are ALL OVER the rev limiter in that video.

Definitely time for some springs and higher rev limiter. I'd also not skimp on the tune. Make sure a tuner adjusts your fuel to be safe at those rpm levels.

Makes me miss the **** out of my Corvette. Auto-X'ing is so much more fun than drag racing.

nysbadmk8

Katech or Arp Rod bolts, A strong Valve Spring, and a complete tune ( not just on a dyno )

Or go with a taller rear tire or more gear

NC98Z

iTrader: (1)

Shame you can't go to a taller tire.

mountainbiker2

Higher gear or taller tire will not work. There's a lot of 30 mph corners also that I leave in 2nd. gear.

Damian

iTrader: (89)

The solutions to your problem have been discussed and finalized. Now go do them.

HioSSilver

iTrader: (8)

lower gears like 4.10 and us 3rd. I use to have my limiter set at 7000 on my crate ls6 ...it would rev there but it ddid'nt like it. I now have HS roller rockers and it does seem to rev free'r up there but my limiter is still at 6800

00ChevyScott

iTrader: (10)

I rev my 5.3 truck motor up to 6800 almost daily, I don't see how an LS6 couldn't do 7100 safely (with appropriate valve springs of course).

KurtRardin

iTrader: (11)

Quick question: Is it dangerous to upgrade the rod bolts in an engine that's already got mile on it? I feel like disturbing the bearings would be risky, but I've never worked on the bottom end of an engine.