big bore/short stroke LSx

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Dec 16, 2006 | 02:27 PM

FreeMyndz v.fp

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big bore/short stroke LSx

Ok, here I am an overzealous n3wb trying to cement my place in the hearts of two totally different goups of ppl...

I wanna do this...- take a bare LSx block, install the shortest stroke crank available (which I presume is outta the 4.8 block). Next I wanna bore the bejeesus out of it with the absolute biggest bore safely attainable in an LSx.

You may be able to see what I'm trying to do...here's the wish list...

11:1 compression
Super stiff valve springs
Cam that will support my high-revving wishes

(All attainable really)

The question is, can someone point me in the right direction because I KNOW this isn't the first time someone has come up with the "anti-displacement formula"

Can someone maybe gimme a parts list? Or maybe we can start a discussion on the pros and cons of such a setup...

BTW, this would all be going in a 240SX (that's where the other party to please comes in...lol)

Cliffs:
Basically, I wanna build a trans-am spec LSx that will rev and still have decent torque...

Sorry for the DP, I'm posting from a Sidekick 2 so I never knew the post went through...lol

Last edited by FreeMyndz v.fp; Dec 16, 2006 at 03:00 PM.

Dec 16, 2006 | 02:36 PM

circa

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From: Puyallup, Wa

a 327 mid 60's early 70's would have a bigger bore and same stroke stock.

if you are looking for rpm's i would go this way as people have squeezed 9k out of them.
all for a price though

Dec 16, 2006 | 02:37 PM

circa

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From: Puyallup, Wa

heheh forgot to mention your powerband would be in the gutter untill 4-6k

Dec 16, 2006 | 02:52 PM

Old SStroker

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From: Upstate NY

Quote:

Originally Posted by FreeMyndz v.fp

Start with the LS7 bore size and 4.8 crank. That's about what GM/Katech did for the first CTSV R Caddy race engines.

FWIW, torque output will depend on displacement, not stroke...but that's another can of worms regularly opened around here.

Dec 16, 2006 | 03:14 PM

FreeMyndz v.fp

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Well, I aint lookng to do NASCAR numbers...lol just trying to have a less torquey bottom-half of the powerband but just as much oomph up top...maybe a good rev range with usable power from 3k-7.5k...maybe 8k...

Plus, in a 240, any V8 torque would get that thing moving...I just don't wanna have traction problems below 3k...

Dec 17, 2006 | 12:50 AM

DavidNJ

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You will be looking at a solid roller with shaft rockers. Probably Ti valves if you want 7500-8000 with LS7 sized valves. and a fairly light bottom end. The small rod journals and piston pins, which are dismissed as not necessary for nearly all configuration on this forum, may be desirable.

But the question, that I will let others answer, is why?

Dec 18, 2006 | 06:03 PM

FreeMyndz v.fp

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I really don't have good reason as to why I would wanna do something like this...I just see myself piecing together a swap, so why not build the exact motor I've always dreamed of having...

Plus, why would I want a stump-pulling torque monster in something like a 240sx? It would defeat the purpose of having a decent-handling easy-to-drive everyday car that I would do some track work in occasionally...

I'm in no way saying that I want a race motor. Just something a little more rev-worthy than your average everyday LSx...

Why did you pick the setup you did? Bet it was outta preference, right?