lower CR
Turbo Mini Forums

hello there, whats the easiest way to lower CR?

i want to turbo a 998 and it has to produce around 90 HP...

thanks

Hi,
In your case use a 295 head.
Or open out the chambers in the one you have ...
Cheers,
Gavin :)

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i'm sorry but i'm from belgium and my english isnt that good to undrstand "open out the chambers"? what do u mean with 295 head... thanks alot Bat

i'm sorry but i'm from belgium and my english isnt that good to undrstand "open out the chambers"? what do u mean with 295 head... thanks alot Bat

double post sorry

i finally bought a metro NA 1275 engine, and i'm going to turbo it, i only need like a 100HP. so do i only have t0 lower CR like 8.0:1 and replace it with turbo pistons and make the chambers from the head bigger? can i keep my original Cam? thanks

You won't need a compression ratio anywhere near as low as 8.0-1 to achieve 100hp. Just to give you an idea, the stock Metro Turbo had 9.4-1, ran 7psi and had 94hp.
The easiest and cheapest way to lower the compression, should you need to, is to enlargen the chambers in the cylinder head.

Phil.

WWW.TURBO-MINI.COM

Basically you remove the beak out of the head

your looking for 28cc in the combustion chamber

while you have it stripped you are better to change the mild cam to say a kent 266 cam or a swift tune SW5 cam

hope this helps!

Oh, you can use the stock cam, if you want, though an uprated one, such as the Avonbar Phase 2 would be much nicer. Stock pistons should be ok in a low boost application.

WWW.TURBO-MINI.COM

thanks alot benross and turbo phil, so i can keep my original pistons and maybe but not nessasary another cam. And what about the gearbox?

uprated diff pin and overhaul the gearbox. should hold up to 100bhp with good standard parts

133.5 bhp 123 lb torque 116mph @6640rpm 9.5psi
Shakespear RWYB 14.995 91.83mph

thanks chinlesswonder

a little question about the brake lines, i'm restoring my mini completly, its almost completely naked now, almost bare cage, and i was wondering where to buy new brake lines, can i buy them from avonbar?

a little question about the brake lines, i'm restoring my mini completly, its almost completely naked now, almost bare cage, and i was wondering where to buy new brake lines, can i buy them from avonbar?

some good deals on ebay for front and rear subby lines. hardest one is the line running from front to back, bit of a bugger to get straight when it comes coiled up, if yours is in good condition, clean it and reuse it

133.5 bhp 123 lb torque 116mph @6640rpm 9.5psi
Shakespear RWYB 14.995 91.83mph

thanks