Compression ratio question

rule of thumb.. 10-1 with no more than .010 deck clearance for 91/93 octane pump gas and iron heads. You won't be able to use a flat top piston for that.

You get much away from those specs, and your going to be building a very detonation sensitive engine.

I am not saying you can't do it, but your going to spend a lot of time fooling around with it, to make it not detonate under all conditions. It's going to be very temperature and fuel sensitive.


JW

 

It’s a lot more the just a good chamber design that has little to no vortex’s in it !
You would be very surprised how the much the falunted full radius valve job contributes to the fuel falling out of suspension and then you get terrible wet flow conditions which then leads to ping and knock when pockets of fuel and air light off at different times.

This condition totally counter acts the power that the air flow gain should provide from a full radius valve job!

 

That's how my brother's old engine was,..very temperature sensitive never had one that acted like it did

 

I assume that’s why the diamond pistons are dished? 19cc? Do you know the specs of those pistons entirely?

is there something unique to the 455 that makes it so temperamental?

thanks for all the replies

 

Right. I was talking with racetec to get a set for a 4.350 bore, 3.95 stroke, 6.8 rod, and a 10.55 deck height, and my irons measured 71cc. For flat tops I needed to be at least .040 in the hole to get to get the 10.6. Obviously, that seemed a bit high for pump gas premium.

I noticed the diamonds many here use are dished. So my question would be what is the approximate cc for the dish to get close to 10:1 and zero deck?

thanks again