Possible M20B28 Turbo build - collecting parts

[Quaser]

Hi All

I have just purchased a 2 door 320i, and want to do a 2.8 stroker turbo conversion on it.

Ive read the Wiki and it advises on:

m52b28 single vanos crank
m20b25 engine of course (pistons)
m20b20 rods

With this, the wiki says that compression ratio is about 9.75:1 - is this low enough for a turbo, or should i get a MLS gasket as well to drop it further.

Which turbo should i be looking at getting for around 400-500bhp and which cam is suggested.

Also, where can i get the spacer for - is there anyone on here that does it?

Q

[maggspower]

PMed

[Lurch320i]

I'm selling my turbo kit
Everything you need

[motormanmick]

Really good book to get, Maximum Boost by Corky Bell, well worth the read, helps you understand what's going on, design/testing/instillation and importantly detonation.
You will need a turbo capable of over 20 psi boost, to give you an idea, a good 2.8 stroker will yield around 210/220 bhp at atmospheric pressure which is 1bar or 14.7 psi. In a perfect world, if you boost by 14.7 psi you will double the volumetric efficiency of the engine and it will produce around 420/440 bhp, but when you compress air it heats up and expands, thus reducing pressure, hence the intercooler, if the intercooler is 90% efficient, then 90% of 14.7 psi is around 13.4 psi. Just to give you an idea, there is a lot going on. Ideal compression ratio for your project is around 8:1 or a tad more, trade off in low compression and big boost is size of turbo required and lag as a result, best get the book, I learnt plenty from it.

[Lurch320i]

Really good book to get, Maximum Boost by Corky Bell, well worth the read, helps you understand what's going on, design/testing/instillation and importantly detonation.
You will need a turbo capable of over 20 psi boost, to give you an idea, a good 2.8 stroker will yield around 210/220 bhp at atmospheric pressure which is 1bar or 14.7 psi. In a perfect world, if you boost by 14.7 psi you will double the volumetric efficiency of the engine and it will produce around 420/440 bhp, but when you compress air it heats up and expands, thus reducing pressure, hence the intercooler, if the intercooler is 90% efficient, then 90% of 14.7 psi is around 13.4 psi. Just to give you an idea, there is a lot going on. Ideal compression ratio for your project is around 8:1 or a tad more, trade off in low compression and big boost is size of turbo required and lag as a result, best get the book, I learnt plenty from it.

Amen that book is good even if it is a bit old
I spent many nights reading that as i was collecting parts

[michael7s]

get M50 as they are more capable of this kind of bhp.

I used to have m20b25, but now changing to m50b25 ith large holset turbo

[Quaser]

I already have an m50b28 turbo project going on in an e36 - the 320 I just got came about at a decent price - (£1800 with full adjustable billies, scorpion exhaust, 83 genuine miles and decent bodywork, a set of white returned bbs, and 17" Brock deep dish alloys)

Rather then have 2 m50/52 turbo projects, I decided to stick to the m20, although I am contemplating a m60b40 conversion instead - how difficult are they to turbo??

[motormanmick]

for anyone that would like that book, Maximum Boost by Corkey Bell, pdf link below

http://www.fusca.net/wp-content/uploads ... _boost.pdf

if your in the planning stages, it's a must read.

[_Dan_]

my clutch is for sale .. have a bid, its in the uk and going to go less than a new one would cost you.

http://www.ebay.co.uk/itm/Spec-Stage-3- ... CA:GB:1123