hbomb2k

I use my LT1 car to drift, so safe to say it sees plenty of high rpms.

I have the 6AL MSD rev limiter set at 6000, which seems too high for it to be safe with completely stock internals.

I was thinking 5000 would be safe to bounce off of (if i have to) in a corner , is this realistic? and if not what are the weak links in the motor that could use upgrading. I read somewhere else that as long as you have good oil pressure 6000 is fine for the bottom end, but the valve train doesn't like it.

ChopperDoc

A few considerations here. First is your connecting rods and pins. Those are going to take the most punishment from high rpm. If one fails, the piston just keeps on sailing either up or down.

Second is your cam and valvetrain. If you don't have enough spring pressure to close the valve, then you risk floating one and that can result in piston kisses and bent or broken valves. This will be mostly determined by your ramp rates, spring pressures, total dynamic weight, and total duration. For every gram of weight loss in your valvetrain you can expect another 40 rpm or so.

I'm no expert on the LT1, but 6000 isn't particularly high in my opinion. Just a thought. I'm sure some other guys can weigh in with more experience on those engines.

The final consideration is your piston speed. Speeds over 4000 fpm are probably pushing it for that motor. The absolute maximum, as in on par with F1 and NASCAR is 5200. They're pretty much maxed out on the limits of technology.

To determine piston speed: RPM x stroke / 6 = piston speed.

Hope that helps.

KW Baraka

iTrader: (7)

Bullet proof your valve train and rev limit that bitch at 6500 RPMs.....

KW

hbomb2k

I eventually plan on doing that, but can anyone give me a ball park on what is safe with a totally stock valvetrain?

KW Baraka

iTrader: (7)

Your tach has a 'red line'......yes? That would be your limit with stock(ish) valve springs.

If you have aftermarket springs, the vendor should be able to tell you what would be their safe limit.

KW

350 groundpounder

iTrader: (5)

Stock cam poops out on power after around 5200rpm. I didnt like reving past 5700rpm with stock valvetrain and old stock springs.
With build valvetrain and bigger cam i try to stay under 6200rpm. Seems over 6300rpm increases the chances of spun bearings dramatically.

nomoneyz

iTrader: (15)

If your car is stock, then stock limiter is what you should set it at. Seems simple to me.

fex77k

iTrader: (2)

Springs definitely limit a stock lt1.

ZEN357

I'd go 4700.

ChopperDoc

I'm with the other guys that are saying just use the stock settings. It's a stock engine after all. Unless you're looking for a reason to rebuild it, stick at or near the stock rpm redline. A little over probably won't hurt you, but until you build it for the task, there's no sense in really trying to figure it out. GM already did that for you.

rentedmule

I auto-x mine and frequently (multiple times per run, many runs per season, multiple seasons) run it at the factory red line to avoid shifting between corners. That's not saying it couldn't explode at any moment, just that it's been fine so far...

Chaotic94

hbomb2k

Thanks for all the good advice, generally it seems i shouldn't be too afraid of a little high rpm.

I think ill leave it at 6000 call it good. I don't try to rev the hell out of it, its just that in drift you never know what you might need.

ACE1252

I'm pretty sure you only need 2700.