different plans
Turbo Mini Forums

been looking at somthing different for my clubman. At 1st i was just going to put +80 pistons in it. After finding out about how people in the 80's used to fit hilman imp 875 pistons to 1098 engines i decided to go for that.
its 134thou over bore. You usualy have to mill the block by 135thou to bring the pistons crowns to the deck....i had the idea (be it rather stupid or not) to not mill the block down by the 135thou, this is turn is going to lower the compression ratio enough to turbo charge it.

does anyone think this is do-able?
im not sure on a few points tho, like if the imp pistons are going to be strong enough to withstand the pressures, i can probably get a few spare pistons, if i get a cross sectional cut would this show me roughly how strong there going to be? or will i have to get it harness tested and alike?
and other thing im not sure, with not miling the block down and having the space above the piston(yet before the block deck and Cyl. head) to lower the CR rather than opening the head. Does this actualy seem ok to do? or would i be much better off just opening up the head? will be bolting a 12g940 head on it anyway

the engine CC will be about 1215cc iv roughly calculated thinking about GT17, but im unsure if this will be just overkill for the engine. Iv read bats problem with mounting the GT17 to the mirage manifold so ill decide closer to the time weather or not ill make my own or just buy

all things aside, should make for a "unique" turbo engine and i might actualy earn my right to be around here :p

cheers for putting up with for what might seem stupid to alot of people lol...im just not "normal"

David.

I've heard of this done in the past but if I recall correctly the issue was with piston failure - I may be completely wrong though!

I think it is do-able.

A recent Avon winner ran his pistons a long way down the bore I believe.

You still may have to mill some off the top of the block. You will not need all the 0.134".

Why 12G940? You can get good results from a 12G295 and not have to pocket the block. There is a theory that the pockets could create localised hot spots.

The GT17 would be a good choice in my opinion.

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."

i was thinking 12g940 simply because thats what i already have

now for 1 single noob question. Which engines were the '295s on?

as for the piston failure thing, iv asked a few question on the imp club asking there experiences of strength and forced induction use..there fair slow over there, not too much going on

David.

A lot of twin carb small bore engines had the 12G295 head. Coopers, MG1100, 1098 Spridgets etc.

Ebay usually has a few although shows are the best source. You should be able to get a bare head for about £35. Dont spend a lot on a head with springs and valves as you will want to change them anyway.

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."

exelent, going malvern this weekend ill be able to pinch one from there...i hope (if the clubman makes it >_<

David.

nope wont be going malvern. it broke, does mean ill be bale to do this engine sooner now!

out of interest does anyone know the outside diameter of the gudgeon pin?

David.