Thinking of 4g52

[barana]

Gray all thinking of a 4g52 head. On my 54 for boosting. How much do they go for?

[Scorpma82]

May I ask what benefits the '52 head gives over the '54??

Seems a bit of any unusual choice

[barana]

I've read on these forums that it has a smaller combustion chamber to raise the compression up to somewhere near 11.5:1

Ah I see the confusion I've said blown instead of direct petrol injection. Apologies. Will edit.

[barana]

Hmm can't edit.

[Scorpma82]

I didnt think the size of the combustion chamber Had a direct effect on the compression...that usually deck height and piston design.......Astron I '54's run dished pistons whereas the Astron II '54 has flat-top pistons, squaring off the deck and increasing compression

[barana]

Heh certainly, otherwise domed pistons would be useless. And diesel engines that have no significant in head combustion chamber couldn't achieve 22:1 as they do.
Its well known in the holden world that if you want a high compression holden 6 you use a 138-161 red head on a 179-202 engine as it uses smaller combustion chambers.
This same concept has been mentioned by people on this forum with 52 head on 54 block.

[Scorpma82]

Personally..for simplicity reasoning...id tickle the original '54 head to increase the compression

[barana]

Fair nuff

I still want to see if anyone knows what they go for...

[Scorpma82]

I doubt they go for more than scrap tbh.....there was never really anything rare, special or limited about them (apart from the handful of DOHC heads that were made in Japan.)

If a mate has a spare head around.....a slab of there fav drink is usually a fair exchange

[barana]

OK, ta m8.