Ok guys please forgive me im new, I have searched but found nothing. I have a 350 bored 60 out and Im making it into a 408. So far its pretty bare I was going to buy a 4" stroker kit, but Im not sure about the compression ratio. The 408 is for low end torque and I didnt know how well it would work with a turbo. Im pretty new to this, it will be a blow threw carb set up. All help would be great. Other than why dont hou search or smart *** replies. I may also be able to gst ahold of a bare 400sbc. Im looking in the range of 750rwhp. Its crazy I know but thanks for any help.

 

I wouldnt do it. You will have a piston that is really thin and a pretty crappy rod stroke ratio.
It wouldnt be good for boost. now my buddy had a 408 like this with a 150-175 hp shot and ran very good for few years but that was mid 500's whp. pistons are too thin imo for high hp usage with boost. Most i would do is 3.75" with either 5.7 or 6" rods and standard 1.125" piston.

Compression at around low 9's to 1 with good aluminum heads/cam and 15-17 psi should easily hit 750 thru a locked converter auto or manual trans. A unlocked th350 or th400 trans will have high losses so may be harder to show 750 on a dyno but who cares. See what it runs at the track.

 

I thought this thread was about a 408 IRON block LS engine....

No comment... 383 would be cheaper, easier, no headaches, more reliable..

Giant crank in a .060+ bored block + big boost sounds like a nightmare. Like putting a tank engine in a shopping cart and running it with dynamite.

With that weak block, i'd keep it a 360, stock stroke 6" rods and a good piston. This will put kess stress on the cylinder walls.

Finding another block could be the cheapest part of building it properly. $500? Machjn ik ng a block usually costs more than the block itself.