Compression & Stroke???

[BORY]

i was looking at doing a 426 but they have a 10:1 and a 11:1 whats the diff and also u have a stroker kit i kow that will make the stroke bigger and what size and if its worth to do one?

[bwamos]

Compression of 10:1 or 11:1 is pretty much exactly as it says.

I'm ignoring a bunch of factors to keep it simple.

Lets assume the displacement of the piston is exactly 426cc's and the volume of the head dome is 24cc's to make an even 450cc's for simplicity sake.

10:1 from the bottom of the stroke to the top of the stroke the chamber volume will be compressed from 450cc's to 45cc's

11:1 from 450cc's to 40.9cc's

13.5:1 from 450cc's to 33.3cc's

Remember air pressure is on a steep parabolic curve, so the pressure in the 13.5:1 is much much higher than that of the 10:1. Compressing air also gives off heat, making the gasses even hotter, and that much more prone to pre-detonation. That's why high octane fuels are required for high compression engines.

Here's a link to a very good description of exactly what compression ratios entail.. and the difference between Dynamic, and Static compression.

http://cochise.uia.net/pkelley2/DynamicCR.html