The LS2 has a 4.00 bore. Can it safely be taken to 4.030? No boost/juice.

 

According to J. Potak's book the listed max bore is 4.020" with a footnote that states that the 4.02 is a Factory Specification but 4.030" is obtainable.

 

Thanks!

I have that book.....

 

This works out nicely. 4.030 with a 4.125 stroke makes 421 inch-a 71 inch bump my my tired high mileage LS1.

Now for some nice heads....

 

I would keep the motor square to reduce potential oil consumption issues.

 

yes, that's something to consider.

 

A 403 (4.005x4) or 404 (4.010x4) would give you a nice boost with a good set of heads. 530rwhp is attainable with the right setup with a 402. 550+ is possibly as well if you're willing to go all out. That's a nice bump over where you are now.

 

Excuse my ignorance. By square do you mean match bore to stroke? How is oil consumption increased? Thanks

 

Yes, see when increasing stroke you bring the piston further down in the cylinder which exposes the bottom of the piston out of sleeve further at BDC. This action allows the piston to rock more and eventually can lead to an increase in oil blow by consumption.
One could resleeve with longer sleeves and that helps if one is set on running bigger than 4.00 stoke.

 

Learn something new everyday

 

like^

 

My goal is to reach 427 inches-or so. The LS7 block is rather costly. With a four inch stroke, it'll have longer sleeves? Are the sleeves in a LS3 block as long as in the LS7 block?

 

Nope.

 

I wouldn't get hung up on the couple of cubes a max bore will buy you. Bore it what it *needs* to clean up, you'll have a more stable bore under power and make more power as well as being more durable.

 

LS3 block + 4.100" stroke would be an okay combination. 4.07" x 4.1" would get you 427 on the nose. Wiseco makes pistons for the 4.100" stroke that reduce some of the oil consumption issues. However, you end up with a thin crown on the piston, so it's pretty much an NA only setup or very mild boost/nitrous. It's only a little bit more expensive than the LS2 and a cheaper alternative to the LS7.

 

An easy way to decide your combo: Divide your rod length by the stroke, if the number is lower than 1.50, try and avoid it. A 6.125"rod length divided by 4.0 =1.53, still reasonable. A 6.125 length divded by 4.250' =1.44, not so much.

 

Lots of good new info for me

 

Hey KCS thanks for that. Could you elaborate? What is the difference in length?

 

YEP. That's why I'm not looking at a 441.

 

I'm looking at rods at 6.125 and a stroke at 4.125. The resultant ratio is 1.48.

The rotating assembly I'm looking at is the new kits from Wiseco with K1 cranks & rods-unless somebody think's it's not a good product/kit.