Just curious to know how high can an LSx engine safely spin if it was built for max RPM's?

 

How high do you want to spin it. The LSX is a small-block chevy, depending on the size of the crank shaft and connection rods and the materials they are made of you can spin them quite fast. My mild cam LS1 spins to 6500. I am sure there are people pushing over 7k. You just need to put the right components in it.

Chris

 

8000rpm with some $$$ and a few changes. I'll be spinning my new motor to 8k

 

It figures that you would be one of those people!

 

 

You can spin them high but if it can't breathe it is a waste it will fall on it's face.

 

http://www.ls1tech.com/forums/showpo...65&postcount=1

It's too bad the video link is currently down (it's an incredible video), but you can see from the engine dyno #'s posted what they spun this one to.

 

Cam is 28x\30x .921"\.880" 114 LSA Try that around town

 

16:1 compression probably doesn't like pump gas either.

 

Daily Driver

 

cam bully

 

Tom, file expired

 

John is right here. the LSx can spin 8000 RPMs for 100 hours, but with the LS6 intake or Fast 90 intake and 243 casting heads peak torque may be limited to 4800 rpms and peek HP to 6300 rpms. Those are the two numbers that the Intake and heads were desisgned to be run at. Above those numbers is almost wasted energy as the motor can not breath.

 

The conventional wisdom seems to be 6200 RPM for a stock LS1, about 6600 for a stock LS6 as it has stiffer valve springs (maybe Titanium intake valves and definately Sodium filled exhaust valves). If stiffer springs are installed, 7000 RPM is safe for the valve train; however, the limiting factor now becomes the bottom end, specifically the connecting rod ends. ARP makes replacement rod bolts that are supposed to hold the caps on better than stock. Next, I'd say that a completely forged and blueprinted bottom end should be able to withstand excursions to 8000 RPM, which is racecar speed and way over the power range of an acceptable street cam. Another however is now the clutch, and I've never seen any RPM limits published by clutch manufacturers. The current problem for C5 owners is the stock Alluminum bell housing that will not contain an exploded clutch. In the last couple years, a few guys reported exploding their clutches at the dragstrip; interesting that 2 of them had large clutch parts go through the dash and front window, when you would think the direction of damage would be random. Dragstrip running is hugely more abusive to the clutch than roadcourse running where shifts are made a lot slower. There is one company that is about to release a steel bell housing, which is supposed to contain an exploded clutch, but it is likely to be expensive. So you have to ask yourself, "How many RPMs am I going to do, how hard am I going to abuse the clutch, and how much are my legs worth?"

 

 

Why is your compression so low???

 

The question was "if the engine is built for maximum RPM"

A built engine can spin past 8000 rpm. Would it be streetable? In my opinion, yes. Too many people fear big cams. With the right tune, big cams are 100% streetable.

A built street engine can spin up to 8k, no worries. I'll post my results later this year.

EG

 

There are TONS of cars out there with LS6, and especially FAST 90's that are hp peaking WAY beyond 6300. There are also much better heads out there than the stock LS6's.

Here's a graph of a G5X4/ AFR 205/ FAST 90 car. HP appears to peak around 6800, and is still holding strong at 7500.



Do you think it's in his best interest to shift at 6300rpm? Is everything above 6300 "wasted energy"? I don't think so.

The question wasn't what a stock engine will do, it was what an engine built for that purpose could do.

 

However, as far as mechanical reliability the biggest factors are piston speed and valvetrain integrity. The relativly long stroke in an LS1 limits max rpm's due to excessive piston speed for a given rpm, and pushrods and rocker arms are no match for OHV when it comes to rpm capability in a street motor.
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If you are building for max effort, then Pro Stock can run 9500+ rpm's with solid lifters and 900lb seat pressure, but you can't get groceries in those. No trunk. Also, look at the short strokes in the F1 cars, that is one reason they can do 25,000rpm. I saw some data on the relative piston speeds between Pro Stock and F1, and they were actually quite close. There is a limit to rpm's due to max piston speed.

 

I'll be running solid rollers and fully tricked out valvetrain