9 replies to this topic

[ohc_turbo]

hi, bit of a question with the turbo compression, im using a normall asperated morris Ital block which i dont know what the standard CR is? what i do know is the metro N/A 1275 is 10.5 and the turbo edition is 9.5

i was going to look out for a standard set of metro pistons but with a cr of 9.5 is will be too high anyway for what im going to use the engine for.

i have read on here that grinding out the head will lower the compression but how much will this lower it if i still use the standard pistons that came with the n/A lump? i need to do this anyway so does anyone have a good source where to get this done?

i need the engine to be fairly reliable, im going to use an intercooler fairly large front mount and will have adequate fueling to help with the detonation, what do people recommend? do you recommend me boring out the head with getting either a set of turbo pistons or other aftermarket turbo pistons, if so where is the best source to but some good well known fairly cheap pistons that will do the job?

thanks for any repiles

[Turbo Phil]

Is it a 1275 engine ? If so you need to divide 1275 by 4 {no of cylinders} = 318.75. This gives you the swept volume {V}
Then you need to know the volume above the piston {C} This includes pistons dish, head gasket, ring land volume, chambers & pistons crown to block distance.
V+C divided C = compression

The Metro Turbo has a compression ratio of 9.4-1 & has 21.4cc chambers opening out the chambers to 26.5 {for example} will take the compression down to 8.4-1.
The Turbo Metro runs 12cc pistons though.
I can work the head for you if you require.
Phil.

[ohc_turbo]

its a 1275 n/a engine

im going to run at the most 15psi through the engine, if i only have work on the head and use the standard n/a pistons this wont be enough will it?

do you know anone who has a set of standard turbo pistons or have a company who can produce these for fairly cheaply

can you give me more info on the headwork, price etc., its a normal 12g295 head

cheers

[Turbo Phil]

Do you mean 12g940 ? 295 is the 998 cooper & MG 1100 casting. I charge £50 to work the chambers, & postage is £10.
I doubt the standard NA pistons will stand 15psi, Morespeed do some decent cast ones i believe with 13cc dish, this with a 26.5cc head would put the compression down around 8.25-1. This should be spot on for 15+psi.

[mighty_mini]

Once i get round to turbo'ing my engine, i will be running 10.5:1CR high compression turbo is the ultimate cool! Although i will only be aiming for 200hp it should be mega responsive and all round torquey.

[Turbo Phil]

Are we talking A-series here ? On standard forecourt fuel ?

[mighty_mini]

K series, but still standard NA internals on forcourt fuel.yes

[ohc_turbo]

thanks for replies, all turbo bits now got apart from the pistons and the head work so i will look into the morespeed items, ill be in contact with you turbo phil when ive striped the head down etc. it is a 940 head so shouldnt be a prob, my mistake.

thanks for help

[Rosslin Racing]

how can an Ital block fit a Mini? or did I miss something ie its going in an Ital.

[welshdan]

will be running my engine at 9-10 psi, thats got a cr of 9.25...