M20 Turbo Build

[E30ISLIFE]

Hello everyone,

i've been following this forum for quiet a while now and finally decided to join hoping that someone could help me with the correct turbo build for mine m20.
My dream was always to turbo my e30 m20 engine after i would overhaul it and after 3 years of building my car i'm finally done overhauling the engine. I've a garage at my disposal and a lot of experienced mechanics around me, but we've never actually build a m20 turbo engine and so we are not very familiar with the turbo's. So to start off on the right path i could imagine with all the experienced people on this forum FI their engines i would probably find the right help asking around here.
So my question is: Who could point me to the right direction turbo building my M20 on low boost 9-10 psi max. I want to be able keeping it as a daily drive without blowing anything up and ofcourse just keep it as reliable as possible with a turbo. Yes it has to be a turbo, no i do not want to make a N\A swap like a s50 or anything. Engine has been combined with with a 325e 1985 block and a 325i 1987 head. compression is as i remember 8,4 but i could be wrong. It has run 3000 miles since the overhaul and everything is running perfect.
My budget that i had in mind is about 3-4k for parts only. Maybe there's a complete set that i do not know of, hopefully someone can tell me what parts of what brand i could use best.
Any help is much appreciated!

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[E30ISLIFE]

some help would really be appreciated folks, still i am not sure where to look or what to look for building a turbo m20 as a daily drive. hope anyone can help out on this matter

[GazM3]

There is not much love on the FI forum for anything other than the m50 or s52. Maybe that's all people here have experience with perhaps. I've asked a few questions on m60 stuff for similar response. I'm not having a go at this section and probably no advice is better than the wrong advice LOL.

The little m20 engine is a great engine and like all NA BMW engines really love to be boosted.
Im no expert or don't have any experience ever boosting an m20 but like all projects get the fundamentals correct and you will be happy.

Compression at face value would seem good for fi. The key fundamentals for turbo build are firstly the intake manifold. A good tuned length tubular setup with external wastegate would be preferred or if on a budget u can turn the Oem headers upside down and make a connection pipe.
Secondly the turbo choice is key to your power goals and your intended use. Whether u want big hp or good responses. If choosing well u can kinda have both. Others here can suggest the ideal turbo but the little m20 should take 400rwhp easily. If the engine is still apart perhaps some upgrades to rod bolts, head studs and head gasket would be the go.

The other fundamental and probably most important issue is the tuning. Spending money on a quality aftermarket ecu say like the haltech will be money well spent as u can run it off a wideband sensor and dual in the required air/fuel ratios and it will sort the fuel loads for you. Using others well u have to program the fuel loads and injector duties manualy taking time.

It sounds like a nice project. Perhaps forums that seem to cater more for e30 like r3vlimited.com may be the go.

[someguy2800]

here is my old turbo m20. This is a 2.7 bottom end, 2.5 top end combo with an ebay turbo and homemade manifold. I ran it from 17-21 lbs on a home built megasquirt.



You will find alot more info on R3Vlimited or e30tech.com

I would suggest you do a search for "m20 build thread" and spend a few days reading other people's builds to get a sense of what is needed.

One of the members on here makes turbo manifolds for an m20. There are others available if you do some looking.

http://www.rapidspoolindustries.com/...g/m20-manifold

For tuning I recommend getting a megasquirt pnp ecu, or if you are really handy with electronics and wiring you can build a megasquirt system and harness from scratch to save some money.
https://www.diyautotune.com/product/...-bmw-e30-325i/

For a turbo you will be looking for something like a gt3071 or a HX30.

[BMWManiac]

I too built a M20....I would suggest a BW256, GT28r or GT30r....something that will provide excellent boost response, and still have some room. That paired with a 3.73 LSD was a lot of fun

[E30ISLIFE]

little update, it has been a while since i have visited the forums.
first of all thanks for the input and advice!
We've been discussing the matter for a while back home and came to the conclusion that we had our compression ratio all wrong. Using the 85 bottom with the 87 head gave us a high compression making it more suitable for N\A. Combined with the lack of experience in turbo's, the decision has been made to run the engine with a sharper camshaft combined with itb's and a good ecu tune. it's a pity that the turbo project is come to an end, but we're going to make it worth our time building this engine into a nice n\a m20. will post more in the future when the project starts!

[JOutterbridge]

What did the compression end at? I'd still try a small turbo as suggested above on low boost. HX 30 or 35. Gt30 S257 etc. NA may be ok but its really not the same....