454 LSX Runway Racer

[Moose1963]

Hi guys,

OK, I currently have a brand new 454 LSX in the crate which I am going to drop into a 68 Vette. The motor is currently rated for a naturally aspirating 700HP. I am going to increase the HP to 1200-1300 using twin turbo chargers. (And before anyone gets concerned, comprehensive frame rigidity and drive train measures will be taken to accommodate the extra power)

in order to do this, I will be of course be lowering the compression ratio from 11.45:1 to the 8.5:1 to 9:1 compression ratio range.

Short of band-aid fixes like head gasket thickening or shiming etc., what is the best what to do this? Based on what I've learned, it would simply be to swap out the high compression pistons for lower compression ones - which I will be doing. Is that all I need to do? I don't need to swap out the cam shaft or crank shaft, right?

The only thing that matters is reducing the stroke, right?

Thanks!

[Pro Touring Store]

That's quite a power goal.
You do not need to lower the CR THAT much. 9.5-10:1 no problem.

It would be best in my opinion to run a further dished piston, however, I don't know the pin height of those pistons. So *maybe* a different rod would be required.

I don't think many people have tested the limits of an LSX 454 crate. Long strokes and boost generally isn't the best idea, lots of stress on components.

Personally I think if you keep your goal a little lower, say 1000hp, you'll have a little more reliable combination.

Regarding camshaft, you'll want to put new valve springs in if they're not already dual.. And consider doing a rocker arm upgrade w/shaft type rockers.. A camshaft wouldn't hurt while youre there, as you could gain some efficiency by putting a custom cam in for your goals.

-Dale

[Jk918]

I agree with above recommendations change pistons, have it balanced and blueprinted etc. Rods and crank in that engine are stout. There's stock bottom end ls handling 800+ hp. I do a custom cam to maximize your combination, I'd also have your heads CNC ported to gain some hp.