compression ratio
Turbo Mini Forums

did a compression test today and it read 10:5 on the gauge on all cylinders thought that was a bit high for a metro turbo engine being its only std apart from dump valve and only running on 6 psi boost not sure if thats normal i had a mg metro engine in before this one and that read 11:0 ive had no problems with the engine in 2 years it has been in my mini just wanted to know to laeve it or do somethin about it.

cheers dave

10:5 whats??

psi? kPa? bar? pints? milky ways?

10:5 as a figure is useless until you tell us the units!

Yes be handy to know what 10:5?? Im guessing 10.5 bar (150 odd psi) which seems fine providing your planning on keeping with 6psi boost.

-MINI CLUBMAN 1380 TURBO-

I've found that Compression gauges seem to vary quite a bit between makes, and depending how much they've been knocked around in your toolbox.
A better name is 'comparison gauge' as that's the best use for them. LOL!

Sorry to steal thread here but what would be an ideal compression ratio for a turbo pushing 10 psi???

Opinions vary greatly.

I'll assume it's not intercooled. I'll also assume you're running 97/98RON fuel. I'll assume you are about to get it set up on a Rolling Road.
I'm going to say something on the lines of 8.8 thru 9:1 as an absolute maximum.

You will always find plenty of folks who say how they were able to run a lot more, well aren't they clever. They've realised (often without realising) that if you just keep pulling your advance away, you can run whatever boost you want.
This is not the right way to do things however.