Raising compression affect tune?

[Dylan]

Hi guys, I'm looking at pulling my 304 down don for a freshen up.
If I was to raise the compression, probably just by zero deck the block would the tune need adjusting at all?
Either to run right again or to make use of the extra compression?

[krusty]

I'm tipping if you are freshening up the engine a new cam would be going in if it doesn't already have a performance cam. If it has or will have one and hasn't been tuned before and considering the bump up in comp you would be wasting your time not to bring it all together with an improved tune imo.....

[Dylan]

Thanks Krusty, Motor already has quite a few mods. Fitted with a Crane 288 solid cam and a Motec twin throtte body manifold.
Still 304 cubes and 10.5 compression. I thought maybe zero deck the block to bring the compression up a bit while its apart.
Ideally i would stroke it but funds are down at the moment.

[Holden202T]

you don't really want to go much higher than 10.5 on pump fuel anyways ....

[Dylan]

Even with the 98 Octane getting around these days?

[Holden202T]

well put it this way, you can go higher in comp maybe to 11-11.5 but you'll need to retard the timing along to stop it knocking on 98

[darcy]

With a 288 installed straight up; 10.8SCR only netts 8.0DCR in a 304 - this should still be plenty ok on pump gas.

[blownvp]

i think that will change with revs.the higher you rev it the higher the dynamic cr will be.

[Bomber Watson]

Not really, at higher revs theres so much going on it shouldnt get any detonation.

I've personally never had detonation at high revs, always low revs/low load when the cylinder pressure is highest and the air/fuel is going relatively slowly.

With a 288 around 11:1 should be fine.

I have a mate who managed to run 12:1 on 98 pump gas in a 202 with [email protected].

Cheers.

[delcowizzid]

you wont hear detonation at high revs a but it can definately still be present and doing the damage