smaruska

I'm new here and kicking around the idea of swapping a LS2/LS3 aluminum motor into a 1995 Mustang. Reason being that 351w rollers are not exactly known for their strength and are only 2 bolt mains anyway. DART blocks are good but heavy and an aluminum DART is like $5k just for the block... I can get a whole LS3 stroker with forged rotating assy. for less and have the lightweight block.

So does anyone know off the top of their heads how high you can spin a 4.00-4.100 stroke LS2/3 motor without any issues and how much power you can put to the block before experiencing cap walk or any sort of failure?

I hear he LQ4 iron blocks with the 6 bolt mains are basically indestructible but then there is still the weight issue and I will want this car to be primarily for handling.

Fireball

iTrader: (21)

LS2 data I've seen first hand...

cap walk about 800hp give or take...easily fixed with pinned mains.

I pushed the stock block and mains to ~1700-1800 fwhp. Liners finally let go at that level...mains were still happy...This was an OEM block with hardblok in the waterjackets for more rigidity...

smaruska

So basically for a street car that sees autox and 7k-7.5k RPM at like a 600whp level I would not even be coming close... Pin the mains and a magnacharger/KB would not max it out?

Fireball

iTrader: (21)

yeah...no issues if you have decent internals.

ProductionS14

Oil pumps don't like to spin that high... not even an aftermarket one. Talked to the guys at Melling when my friend was building an LS1 for his S13 drift car, when we mentioned wanting to spin over 7,000rpm they said they didn't really have a solution for the cavitation. I hear about people spinning higher without issue, and I'm sure there are people who would like to argue this.

The LS2/3 pumps might be better at handling the higher RPM, I'm really not sure at all on those. If you're going straight line it may not be as much of an issue because you don't have the g-loads compounding the problem as much as on a drift/grip car.

All I know is that you don't quite need to spin it that high, 7,000rpm is plenty enough. With a superchaged setup you're already looking at around 5,000rpm of usable torque and horsepower. If you want to go higher, and are already building an engine, maybe an ARE dry sump system is in your future? Gets into decent money just to spin an extra thousand, though.

As for the power level, you should be fine. Pin the mains for safety etc.

COPO9560

If you are shooting for 600 rwhp and plan FI, you won't need anywhere near 7000 rpm to get there. Block and rotating parts will probably live longer at 7000+ than your valve train - this is where you need to invest wisely for a high rpm engine.

smaruska

Well I AM thinking of trying to keep the motor making useful power up till about 7k rpm but I'd probably shift before that especially since it would be a street/strip car. I want something that I can drive to the autox (or drag strip), thrash the hell out of and then drive back.

Maybe I'll look at a LS1 based motor for cost savings if it'll take the power just as well. Although it doesn't look like it is very much more for a LS2...

1SLwLS1

iTrader: (6)

The 4.000" + bore opens a lot of doors, I would opt for the LS2 over the LS1, although you can re-sleeve, etc, for $$$.

AES Racing

iTrader: (6)

7500rpm with factory style pump is fine, provided you're not getting any extra windage then normal. At about 8000rpm oil starts to turn white with air cavitation.

pump spins 1:1 with engine speed, SBC oil pump spins 1/2 speed of engine.