How to build an m20b27

[budha59]

Hey!

My little race car's m20b20 is starting to get a bit tired and want to build a m20b27 motor by stroking a multivalve m20b25.

Does anybody have any advice or better yet, has someone on the forum built one of these before? I need to know what pistons, rods and crank to use.

 

[UpNcOmiNg!]

M20 or m50? Multivalve motors only came from the e36 onward.

 

[Psymon69]

ive bn through this one... looks to be much cheaper to get a better import engine. the m20s are getting old and expensive. M50 is the way to go. or even 1uz cough couch:fencelook:

 

[hennie]

m50 will be way cheaper than to build a m20 2.7
the pistons for it will cost you R6000 each then you 2/5 need a head block and 325 rods and a 2.7 crank (ultra rare and freaking expensive) from R4000 and up

 

[born2boost]

I would rather refresh your M20B20 and fit a bolt on turbo, keep the compression stock and boost 0.5bar. You will be much happier with the same money invested.

 

[Pfw28]

I would rather refresh your M20B20 and fit a bolt on turbo, keep the compression stock and boost 0.5bar. You will be much happier with the same money invested.

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I would rather refresh your M20B20 and fit a bolt on turbo, keep the compression stock and boost 0.5bar. You will be much happier with the same money invested.

 

[budha59]

Thanks for all the advice so far.

There are however some rules that I need to adhere to, and that is that the car has to have preiod correct modifications done with technology available before 1990.

So I thought my best option would be to build myself a m20b27 with sides on, wild cam, big valves, higher compression.

Is it possible to use my current m20b20 to go 2.7 or is the head too restrictive?

 

[rhett325]

Nah you will need to get an 885 325i head.

Also the 320i runs a smaller bore than a 325 so you will need to rebore it and fit 325i pistons as well.

I would buy a 325i block and head and a complete E36 328i sub assembly (rods, crank, pistons). With these in the motor you get a displacement of 2.8 and quite a rorty M20.

Also as far as my research has highlighted sides DO NOT work well on an M20, it relies on a longish intake.

Racing Snake on this forum is a MAD M20 expert, I have seen a 323i he build walk away from a 2.9 stroker.

Buy a decent M20B25, take the head to Racing Snake for fiddling, deck the block and do electric fans and a few other small things and you will have yourself a chirpy little car I can assure you!

 

[Psymon69]

what he said :thumbs:

for 2.7 its a 2.7 crank, 320 rods. 2.8 I take would be too new as they come out of an E36?

2.7 crank is from 325e, 525e and 325is. The 320 head will need quite a bit of work to get to the 325 one, but not impossible (depends on if you have an engineer in the family). The 320 block is also known for not likeing being bored to that size (water jackets or some jazz), but then again its also been done.

First prize would be a 525e sub and then 325i head. theres a replica alpina cam on gumtree done by APS (the 200sx at the track).

 

[Andrew M325iS]

I would rather refresh your M20B20 and fit a bolt on turbo, keep the compression stock and boost 0.5bar. You will be much happier with the same money invested.

Hi Mr.

Tell me, how much do you recon it would cost me to rebuild my m20b30, a complete rebuild and can you also recommend an electrician for the wiring how and the cost.

If you need more details please let me know.

Sent from my SM-G900H using Tapatalk

 

[ecKARd]

I would rather refresh your M20B20 and fit a bolt on turbo, keep the compression stock and boost 0.5bar. You will be much happier with the same money invested.

Hi Mr.

Tell me, how much do you recon it would cost me to rebuild my m20b30, a complete rebuild and can you also recommend an electrician for the wiring how and the cost.

If you need more details please let me know.

Sent from my SM-G900H using Tapatalk

This is quite an old thread, things might have changed quite a bit since these statements were made.