Guys,

Its a new project, C6Z06, Lsx block, PRC 285 six bolt heads.

Am about to pull the trigger on the upgraded top mount twin turbo kit from UPP, kit seems to be very promising.

Now for the motor... I needed to know the difference in power and reliability between the LSX 427 and the 434ci
Am I risking the motor by going 434? Will it make more power than the 427?

I'll be maxing out the turbos
Planing to hit the max possible.
Your opinion please

 

Do a 427...want to keep as much cylinder wall thickness as possible. Their want be much HP differences between the two anyway. Also if something where to happen to the block with the 427 you still have room to grow.

 

Agreed! i would do the 427 and never look back.

 

I've seen allot of people runing that 434cid and was wondering why! The block is LSX and in order to achieve the 434ci I have to eat the walls up to 4.155
Will that be risky? Am I gonna gain anything?

 

It won't make a bit of difference really for power. 427 for now and save it for later if needed. Done.

 

The max bore on the LSX block is 4.200 can't go any bigger than that I believe. So that leaves you with .045 to play with over 8 cylinders if something happen to the cylinder walls. IMO DON'T do the 434...keep it at 4.125 bore and don't worry about having the bigger dick then someone else . Hell I would do a 418. Its going to make pretty much the same power.

SMEC

 

Lol,
This is what I was thinking.. There shouldn't be any difference but I was curious.. Why people go 434ci

 

434 a little extra cubes. Heads flow better on a bigger bore, still plenty of wall thickness.

 

They started out with 427's lol, 434 is the next go round

 

Pretty much. With an expensive block, might as well leave room for a rebuild. Power difference won't be measureable. Turbos/heads/intake/etc will limit power way before cubes do.