Amount to remove from Chamber to drop compression from
Turbo Mini Forums

I am new to the world of turbo charged A series engines.

I am in the process of installing a turbo to my Riley Elf which is running a 1275 MG Metro Engine, which recently benefited from a rebuild, using a 12A SPI Engine block, which had only done about 10k miles before the later oil pipe design failed destroying the main bearings. A crank regrind and new cam bearings has freshened up the block. I have rebuilt the gearbox/transfer gears with new bearings and syncro rings. I have fitted a turbo clutch plate and uprated diff pin. I am using the MG metro cam.

I have got with the exception of the engine and a fuel pump, all the ancillaries from a MG Metro Turbo.

I have an oil cooler and super cool two-core radiator.

I intending to run a low-pressure turbo set up using the ECU from the Metro. This should help maintain the life of the engine and gearbox. I am looking for a car that is not going to be to highly strung for continental touring.

I was going to use a decompression plate but this forum has talked me out of it.

I want to drop my compression from the MG metro compression ration of 10.5:1 to the MG Metro Turbo compression ratio of 9.4:1

What does this equate to in terms of cc's needing to be removed from each chamber?

What is the maximum that can be safey removed from each chamber before you run the risk of hitting coolant ways etc?

What sort of poer and torque can be expected from the standard MG Metro engine once it has been fitted with the turbo with standard levels of boost?

What sort of MPG can be expected? i only have a 5.5 gallon tank!

HOSS

Yes my home made CR calculator says 4cc, but it has yet to be verified.