V8 compression ratio

[MARSHO]

Hi, can someone tell me what the compression ratio would be on a rover 4.6 engine with 4.0 litre pistons and sd1 heads fitted , many thanks David.

[rev-erend]

I think it's 9.3 : 1



It's normally recorded on the block / head face .. you can just see it .. often needs wiping as it get covered in oil and other rubbish.

[AntonyJ]

rev-erend said:

I think it's 9.3 : 1



It's normally recorded on the block / head face .. you can just see it .. often needs wiping as it get covered in oil and other rubbish.

Its 9.35, but the OP question relates to the fact that he is intending using 4.0 pistons which have a shallower dish than the 4.6 ones.

I would be interested in the answer as well as its something I intend building, but sticking with the later 28cc heads instead od Sd1, err ones...

[russell_ram]

David,



4.6 (4551cc) with 4.0 piston bowls, std 36cc SD1 heads and 'tin' gaskets I calc to be 10.10:1 CR, if you change the tins for composites it reduces to 9.5:1.



HTH



Russ

Edited by russell_ram on Wednesday 23 May 13:24

[AntonyJ]

russell_ram said:

David,



4.6 (4551cc) with 4.0 piston bowls, std 36cc SD1 heads and 'tin' gaskets I calc to be 10.10:1 CR, if you change the tins for composites it reduces to 9.5:1.



HTH



Russ

Edited by russell_ram on Wednesday 23 May 13:24

What about with 28cc heads and composite gaskets?

[MARSHO]

Many thanks for the replys regards, David.

[russell_ram]

"What about with 28cc heads and composite gaskets?"

Easy - 10.6:1 - that's the easiest 4.6 performance improvement you can make.

They are only 9.35 as std so the can run on dodgy low RON fuel without having to retard the ignition too far. Remember that early 5 star fuelled RV8s were all >10:1 from the factory.

Russ

[AntonyJ]

russell_ram said:

"What about with 28cc heads and composite gaskets?"

Easy - 10.6:1 - that's the easiest 4.6 performance improvement you can make.

They are only 9.35 as std so the can run on dodgy low RON fuel without having to retard the ignition too far. Remember that early 5 star fuelled RV8s were all >10:1 from the factory.

Russ

So its good for more power then?

[MARSHO]

Hi can some one tell me what the compression is on a standard 4.6 with sd1 heads many thanks David.

[GTWayne]

A bit shameless I know but I have two pairs of heads that I have been hanging on to for a project that has never really gone anywhere ( sound familiar? ) and have decided to move them on because life is to short yada yada yada and a host of other mundane real life crap so if anyone is interested, PM me. I pair are TVR 5.0ltr BV + ported and the other are a bit more mild Real Steel stage II Jobie's, just the ticket for someone out there no doubt.