G295 for NA use
Turbo Mini Forums

As above, anybody that has had a 12g295 head skimmed for naturally aspirated use, if you can remember can you please advise how much you had skimmed off for the desired compression ratio?

I sat the head so the face is level and put what I have calculated to give me around 10.5:1 compression ratio, 24cc, of fluid into the combustion chamber then measured from the face of the head to the fluid level, as advised was the way to check. I measured 90thou but my head guy has told me that seems a little excessive making me doubt me calculations.

I hope you can help me out as I am really starting to lose motivation again...

Thanks

Jack Jones

its a long time ago but I'm pretty sure the one I had had about 80thou taken off.

I would say though that you may find a cheaper head already suitable for your engine and sell the 295 for a premium if its never been skimmed as it will appeal to the turbo use - they are getting harder to find

My notes and measurements from 1984 give a chamber area of 30.2 cm2.

So 0.33mm of skim will remove 1 cm3.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

last one i measured was 28.5 cm3 and was standard as far as i could tell as it even came with the proper D type pistons

Double-Blind experiment, N:
An experiment in which the Chief Researcher believes he is
Fooling both the subject and the lab assistant. Often accompanied by
a belief in the Tooth Fairy.

how about flat tops?
flush/above deck height?

Thank you for the responses guys, rob can you remember what cr you ended up with? Assuming you were also using flat top pistons?

Turbo this, I am going for more or a bolt on 'performance enhancer' rather then a full strip down

Jack Jones

Id try and find one that has already been skimmed. These heads are in limited supply. Having this one on the side allows for you to easily go turbo in the future.

I have a nice ported & polished unleaded 12G295 that is in service on my 1100 at the moment.
I've just had another one prepared for the new engine, so the current one will be available once I've finished the current build programme.

Metric is for people who can't do fractions.

That would be nice Alex thank you but I can't put any more money into this build so I would only be able to do a straight swap for my good original head against a skimmed one

Jack Jones

I'd be up for a part-ex, but unless yours has unleaded inserts already fitted and been crack tested, it wouldn't be a straight swap...

Metric is for people who can't do fractions.

If you message someone like benross you may find he has a head he would swap for both of your benefits

Hasn't been crack tested and not sure about the fitment of unleaded inserts (not really sure how to check), the head came of a running car although has been sitting for a while, the guy I brought it off really is quite a genuine guy though and I will be trusting his word when I fit it if I get it worked.
The head has been sent to my head guy now but he hasn't yet got back to me so I don't know if its been worked yet. If I could find out Alex, I would be very interested in a swap?

Jack Jones