2.5i Engine tuning...

Post Thu Sep 07, 2006 2:02 pm

who is into tuning the engines here?
i have done work on my old ford x-flow, had it up to 143bhp at the wheels. it was faster than my bm so im wanting to get some info if i were to do similar sort of thing with the m20 i got now..

in the ford engine, i had 1.3 pistons +90thou oversize, in a 1.6 block. this meant i got the higher compression from the taller pistons, although they were stock design, they still gave higher compression with good reliability, plus they were less than Ãƒ”šÃ‚£30 each brand new ;)

is it possible to do a similar sort of thing with the m20? eg, putting 320 pistions in, machining the tops for valve clearance etc. to be honest i know nothing about the m20. i dont want to go mad, is there anywhere i can go, or look at to get technical info?

cheers :p

Post Thu Sep 07, 2006 2:09 pm

Think you might have a problem sealing the 320 pistons

Definately in the right place for tech info though!

Perhaps have a search for info on a 2.7 conversion, seems popular and cost effective, or there's always forced induction!

Post Thu Sep 07, 2006 2:24 pm

so i take from that the the 2.0 pistons are not as wide as the 2.5s

could the 2.5 be bored out to a 2.7? i suppose you would need forged pistons for this? last time i looked at forged pistons for my mk1 xr2 they were Ãƒ”šÃ‚£120 each. i dont really want to buy 6 for the bm...

i can remember reading that the 2.5s have a compression ration of 9:1
is this right? its propper pants if it is, how could i bump this up a couple? and would stock pistons be able to take the extra heat?
does anyone know how much can be skimmed off the block if any? i have also been told 1mm - 2mm max can be taken off the head.

i would love to bolt a turbo on the side, but ive seen the cost for one.

Post Thu Sep 07, 2006 2:32 pm

The 2.7's a longer stroke conversion, using standard BMW bits... There's various ways of doing it, all discussed in great length on here - try doing a search!

Post Thu Sep 07, 2006 2:38 pm

oh ok, searching ...

cheers

Post Thu Sep 07, 2006 5:09 pm

The early 2.5 has a 9.7:1 CR.

Don't think there are any probs with the heat and the pistons as I'm running the early engine with my TT setup

Post Tue Sep 19, 2006 10:27 am

does anyone have pictures of a 2.0 head and a 2.5 head? if i were to put the 2.0 head on, i expect i would swap cam and injectors over and all that...??

just thinking, ive been told 2.0 head gives higher compression, is this due to the head having smaller bowls? are the valves the same size? i thought they would be smaller on a 2.0 ?

thanks :p