I was racing a friend on Route 1, and put my (automatic) transmission into 2nd gear because I knew we would go from a roll. I held 2nd till 88 mph and then heard the woosh woosh sound of the rev-limiter. I've hit it before but not as long as this time... could I have jurt my engine or anything? I'm worried. Thanks Guys!

 

Hopefully it didnt cause too much valve float, just dont do it often.

 

Even if its a automatic I could hurt my car? It definetly didnt hurt it because boy does it pull stronger now with the exhaust on ;)... but I was wondering long term effects, etc.

 

Stock LT1 valve springs aren't the greatest for punishment. You probably didn't hurt anything, but as the springs get weaker and weaker you won't make as much power as you run into valve float sooner.

 

long term it will hurt things, as the springs will get weaker, as Nathan said

but for now it probably did not

 

Can u ever 'upgrade' these springs? To Prevent this stuff from happening?

 

Certainly. Usually people do it when they have some cylinder head work done. The really good springs take some serious force to compress and are a lot easier to do when the heads are off the car. For example I'm not even sure if I can compress the springs I'm running by hand or not. I've done springs on the car, takes some time, not real fun. All day at work I do springs with the heads on a bench, somewhat fun, takes all of 20 minutes depending on the cylinder head.

An LT1 head I could re-spring in 45 minutes or less if the heads were off the car and I had them at work. :cheers:

 

To give you some idea BTW. I think a stock LT1 spring is set up for around 80 pounds of pressure on the seat. Not too bad, 80 pounds of pressure holding the valves closed. My springs are set up at 140 pounds seat pressure.

What does this mean? Well it holds the valve closed tighter, and it's also a lot harder to open. Seems like that would cost HP, but it's a funny thing. Although it may in fact make the motor harder to turn over the higher spring pressures will allow the motor to turn a higher maximum RPM because the springs essentially pull back faster. Add stiffer springs and lighten up the valvetrain and you can raise your RPM's, assuming the bottom end of the motor can handle it.

We've got some Titanium valves that are just plain bad butt. If they weren't so darn expensive I would have them. As it is I'm set as far as the valvetrain goes to spin it to 7000 rpm's or higher, now I don't because the bottom end wouldn't take it, but it just means I've got some overkill to work with. I've got Titanium retainers and 10 degree locks, saves weight and makes it stronger. Even after my springs start to get older and weaker it's gonna take a long time for them to get so weak as to be back to the original LT1 spec. The springs I have are double springs, really cool actually, a spring inside a spring. There are tripple springs as well.

Oh, one more thing springs do for you is allow for higher lift. Depending on how the spring is made it will reach a maximum lift somewhere, or a coil bind height. That's why you have to change springs if you go with higher lift cam. Essentially the spring compresses until the coils actually touch each other, then if you try to compress it further, something has to give. If you're lucky it will just be a bent or broken pushrod.

I set up a pair of heads yesterday for a guy running a solid roller camshaft. His springs put down 240 pounds of closed seat pressure and would handle upwards of .700 inches of lift! Our pneumatic valve spring compressor could barely compress these enough.

 

Don't sweat it.. at 88mph I'm guessing you have 3.07's.
My crummy 2.59's don't kick out of 2nd gear until 98mph... and I do it religiously (great open roads on the way to work).

The stock programming will keep you out of trouble. Run her hard as ya want. But be sure to keep up the regular maintenance of course.

 

I hold my LT1 Formula at the rev limiter when I auto-cross for several seconds sometimes- the thing has 110,000 miles and doesn't even flinch so I doubt you have anything to worry about.

Or you killed your engine....J/K!!


Tim :)


[Modified by t.renz791, 8:17 AM 10/19/2002]

 

Dan your 2.59's pull to 98 MPH? That is insane! I never knew what gears I had until u just told me ;). IT must be cool though holding second that high!

 

And to think, I've been hitting mine for fun in the driveway doing holeshots!:eek::crazy: I'm not too worried, these motors are tough as hell. I just don't wanna stop doing it! :yesnod: :seeya

 

He said hit the rev limiter (fuel cutoff) not float the valves.

I think it is safe to assume that Chevrolet built in a pad between fuel cutoff and actual valve float so nobody actually floats ones valves just hits the fuel cutoff.

I think there is no problem with it. Harder on the engine-sure, but will it get destroyed...no unless there are other problems.

I have 81,000 miles and lots of fuel cutoff time...no worries.

:)

 

when my motor was stock id hit it all the time. No problems. Just make sure the valve springs arent too weak. LT1 springs are good for mild motors but putting in LT4 springs cost me 14rwhp on a stock motor.. too stiff. So just replace with fresh replacements for the LT1. Only scary thing is eventually stretching the timing chain. And maybe taggng a valve in an extreme case ...

 

Well the rev limiter is there for a reason, to prevent your engine from eating itself. I've hit mine a couple times, but it's much easier to hear with the corsa exhaust because the sound radically changes when it goes lean.

Some guys will keep it pegged at the rev limiter when doing burnouts. That can't be good in the long run! :eek:

 

Any concerns about stock LT1 valve spring rates in this thread are ill-directed. The LT1 spring rates are modest precisely because the CAN be and SHOULD be. Lower spring rates reduce wear and tear on the cam, roller lifters, pushrods, rockers, guides and valves. Lighter springs maximize RWHP and maximize engine life. I have watched a few folks put charles atlas spring kits in a bulletproof, stock-ish motor and even after verifying no coil bind, they subsequently damaged valve train components or experienced premature valve guide wearout. The spring rates should only be high enough to prevent float at an RPM about 5% beyond the rev limiter setting, which is factory set to 5800 RPM. The LT1 spring rates are just fine & you can bang on the limiter all day without any ill-effects. Stronger springs will not allow a higher RPM with the factory limiter. "Banging" on the rev limiter is not hard on the motor compared to those who alter or remove the limiter to exceed the factory 5800 RPM ceiling. Rev limiters and their effects are good, not bad.



[Modified by Rick93Z07, 7:53 PM 10/21/2002]