V8ImpSS

does anyone know what the max bore with stock sleeves on an LS4 is (FWD 5.3L)?

I was under the assumption that it would be the same as any other Lxx 5.3L, but some others in the LS4 section of the forum have their doubts.

thanks in advance!

CAMSTER

iTrader: (10)

Put an ls3 in there, let some respect flow for ya....

V8ImpSS

Thanks for your intelligent contribution. Send me a crate motor and a custom bell housing and I will gladly stuff it in there

CAMSTER

iTrader: (10)

What i was thinking about is, to just get you a good use ls3 and put it in there for less than the price of redoing the smaller one, and with out the engine open heart surgery, which will surely ge a lot more work and involvement and very expensive, and instead of running around looking for parts and machine chop, and waiting for people and having a thousand pieces out of your car, just shop around, then pull one out and put the other one in, everything should hook rite up and exterior dimensions are the same, so no one will know,
what's inside, just let them find out the hard way, i bet will cost you less, and be a lot faster, with less down time less work, and the end product will put a smile on your face, trust me.

LS1MCSS

iTrader: (18)

Exterior dimensions aren't the same. There is a big difference in the bellhousing mounting and I think the starter mounting is a lot different also. It would be cheaper to mod the LS4 than change to anything else.

redtan

iTrader: (5)

The engines themselves are the same, it's the accessories and stuff that are different to make the engine fit turned 90*.

CAMSTER

iTrader: (10)

The trannie too, should bolt rite up, the is a small possibility the starter dented ring has a different number of teeth, just swap the rings...

V8ImpSS

The difference is: shorter crank, single belt serpentine system, and bell housing bolt pattern, and the starter bolts to the bell housing, not the block.

A RWD LSx would work, because I'm getting the new 6T75 trans which has the "RWD" bolt pattern.

However, I have free machine shop access, as well as engine assembly...but I don't want to take advantage of them and make them resleeve the block if I don't have to I order to get more cubes

CAMSTER

iTrader: (10)

RWD LSx would work, because I'm getting the new 6T75 trans which has the "RWD" bolt pattern.

However, I have free machine shop access, as well as engine assembly...but I don't want to take advantage of them and make them re sleeve the block if I don't have to I order to get more cubes

Good man, so which block will you be using, the LSX block can net you a 440 Ci with the 4" stroke, and with 11 to 1 comp you could be making 600 whp, but require a lot of drive train beef ups, still think a stock LS3 is a viable solution and will still use your drivetrain.....Remember fwd will have lots "less" power loss thrue the drive train, and minus 120 front end lbs, compare to the LSX block, and you'll be saving a lot of money...just beef up the trannie before it goes in so will live, with the extra power, and use headers, and cam if you desire.

V8ImpSS

I didn't mean the X block, I was just using x as a variable. But I think I'm going to try to find and LS2 block on the cheap and make around 500 easy which is plenty for this car. Thanks for the ideas!

CAMSTER

iTrader: (10)

Cool man, is surely going to be a riot, will be nice if you could have the 3rd gear shift clutches up graded to 6 clutch PAC, before trannie goes in, so you won't have to get back in it later, or just race in drive, instead of over drive, to protect those clutches.
Don't hesitate to PM me if you have any questions, by the way i have a real nice cam for that combo if you need it, will give you a keeler deal..

spy2520

iTrader: (3)

back from the dead....

Is this actually doable? I have a friend that wants a 6.0 or 6.2 in his Impala an I'm trying to figure out what can be done.

G Atsma

It is NOT doable. The LS4 block is a different animal than the other LS blocks. Shorter, different trans mounting bolt pattern, and completely different accessory mounting.
Plus, the fwd trans is very fragile; barely able to handle the stock 5.3, much less anything more powerful.

KCS

iTrader: (20)

I think he's asking if the 6T75 trans with a "RWD block" will work. I'm assuming it's a different transmission to mount the block transverse in the engine bay, but with a normal LS/SBC bolt pattern.

spy2520

iTrader: (3)

Yeah thats what i was getting at.

G Atsma

The FWD/transverse tranny bolt pattern is completely different than the RWD bolt pattern. Unless it's a newer version of the old 6T75 tranny, a RWD block will not bolt to it

spy2520

iTrader: (3)

It looks like the OP was under the assumption the 6T75 has the rwd bolt pattern. I'm not familiar with the transmission but was hoping someone had more info on if this is the case.

G Atsma

I have not heard of ANY FWD tranny with the "traditional" RWD Chevy bolt pattern. If that existed, AND it could live with 4-500HP, it would sell like hotcakes! EVERY kitcar would have it! Hey tranny mfrs., ARE YOU LISTENING???

spy2520

iTrader: (3)

Yeah. Would be nice.

G Atsma

Yep!