Finkelstein

Hey everyone, I'm starting my LS3 project of which I already have a bare block that needs a hone. My first factor here is the hone. it's at the stock bore which is 4.065". If I have it honed at that it will be about 4.067 or 4.068 I believe. What is a good bore size that is also popular? This engine will be going in an RX7 so it's a really light car and wont need as much hp as other cars to get going. I am at a crossroads on whether to go ahead and stroke it out keeping it naturally aspirated, which I would prefer. Or to use F/I. Now obviously i'll get the hp out of the F/I but I want to keep this thing going without it and having the ache to have it tuned as much.

What I want: Longevity of the engine as well as MAX of about 580 HP(rwhp).
Main question: Is it safe to keep it naturally aspirated by boring it out to 4.07 and using the 4.10 or 4.125 stroker?

Thanks everyone.

427zm

iTrader: (9)

NA always has less problems associated with it, but with a LS3 based motor you're going to have to do a max effort motor to make that number. Going max effort, will lead you to less longevity, and provide you a car most likely you won't like to drive unless you're at the strip all the time.

Being that your car is an RX-7 personally, I'd look to go stroker 416 (4.07x4.00) as opposed to the 4.10 or 4.125. You can get 530 wheel out of it with good heads and cam, and it'll be live able. It'd also be reliable, and streetable. As for the 4.10 or the 4.125 cranks, with stock sleeves, neither will be as reliable as a crank 4" or shorter. When you add stroke length piston speed increases, as does piston rock. The less of both of these situations the better.

Here's an example of a LS3 based RX-7 that moves out. He's gone with the 4.10 crank in his. Not what I'd recommend, but it works dang well here:


If you went FI, again you could have reliability, but there are many things that have to be done right in order for it to run right. The fuel system is impairitive to a good FI setup, and that runs big bucks. You also wouldn't want to go stroker b/c there wouldn't be any advantage really. Boost is awesome, but there are so many things that have to be looked at, and done correctly to make it work well.

Finkelstein

I think I'll take your advice and stick with naturally aspirated. I have a daily driver but I think I may look into something like the setup this guy is running. I'll report back if I can find some solid info on using the regular 4 inch crank or going to 427

BOLO

iTrader: (40)

The only way to get 427cid utilizing a 4.000" stroke, is a bore of 4.125". Like the LS7. Or resleeve an LS1 or an LS2 for that bore size. GL.

MertezWS6

iTrader: (8)

I'm going to disagree with the no advantage stroker comment. The more ci the more power potential. I would not go bigger than a 4" stroke. I have a LS3 418 that just put down 566 rwhp and 546 torque. Through an M6 and 9" rear. I used ported LS3 heads with .660 lift. 11.5 compression ratio on 93 octane. Stock LS3 intake with 92mm tb. 1 7/8 manifolds. And a 230's-240's cam motion custom cam by EPS. And underdrive pulley. I think I can squeeze a few more ponies with some porting on the intake. This was speed density tune too. Oh and my cam is very smooth, 1200 RPM'S in 6th gear no problems. With LS3 heads you do not need a bigger cam than 240's