real compression ratios

[crazylegs]

does anyone know the true compression ratio of a standard european spec mk1? various site/manuals give different answers.

[feral4mr2]

all 3 and 7 rib bigport 4age's are spose to be 9.4:1 c/r.

[crazylegs]

thats what i thought but i was on a site the other day that said they were 10:1 or 9:1.i think they meant the small port and supercharger.thought i`d check my facts prior to the skim.

[LimeyMk1]

So how much are you taking off? Not going for a thinner head gasket?

[feral4mr2]

this site here has the best descriptions/info i have found so far when it comes to what engine actualy has what. scroll down the bottom for engine specs.

http://www.users.bigpond.com/vidore/toy ... engine.htm

[crazylegs]

thanks for that link,brilliant.limey yes to both questions.i am aiming at a 0.6mm hks and a light skim.I think an overall change of about 1mm will get me to about 10.5:1.should manage to stay out of the problem detonation area.what do you think? are my calculations about right?
STILL waiting on TED for my bits.GRRR

[LimeyMk1]

Sounds about right, I'd need to sit down with my thinking cap on though! Are you still going for the undershim Yaris buckets? Remember to make sure they don't bottom out with your high lift cams (could be disastrous ).

[crazylegs]

no the yaris buckets are not needed.Richard at TED says the standard shim set up will be ok as long as the shims and buckets are not worn.we shall have to wait and see!!
as for the compression i have come to the conclusion that 0.9mm raises the compression by one point give or take.