m20 rebuild cost?

[Guest FrantiC]

Anyone got a rough idea for a full rebubild of an m20?

Looking to rebuild my 2.7i motor, 525e block (m20b27) with 325i head (885) and turbo it.

All oem stock stuff (rod bearings, main bearings, rings, gaskets, valve stem seals etc), only aftermarket / upgrades would be o-ringed block and ARP headstuds.. Which I have gathered from on e30tech to be enough for a decent amount of boost (stock rebuild with o-ringed block + arp headstuds) which should be sweet for 14psi (im only planning around 8-10psi).

[topcat 11]

based in an m30,which i believe isnt much more.

230 bearings

250 rings

240 gasket/seal set.

cam belt ??

120 block decking

80 head plain

head studs 350-400 if you go this way

100 oil fittings

50 drain welding + fittings

+ the cost of turbo,manifold,exhaust/down pipe,wastgate,RRFR,bigger injectors?,ecu or chipping?

+ another couple hundy of miscellanous bits and pieces

think thats about it.prices will vary

m

[Boost Junky 1]

I know this is a different motor but for my M50 i just purchased my MLS headgasket and ARP headstuds. Cost me about $500 for head gasket (thicker 0.140") and my studs were $340, i believe the studs for the M20 were slightly cheaper? I would go about running a thicker headgasket rather than doing the O-rings in the block I was under the impression that its a bit of a finiky way of doing it.

[Guest FrantiC]

I know this is a different motor but for my M50 i just purchased my MLS headgasket and ARP headstuds. Cost me about $500 for head gasket (thicker 0.140") and my studs were $340, i believe the studs for the M20 were slightly cheaper? I would go about running a thicker headgasket rather than doing the O-rings in the block I was under the impression that its a bit of a finiky way of doing it.

Alot of people seem to prefer the o-ringed + OEM headgasket over something like an MLS headgasket for the m20. But I know where I can get some ARP headstuds for the m20 at like 250 USD.. I think at only 10psi it should be fine. Seen higher boosted setups on e30tech (14psi and pushing 400hp at the wheels with the o-ringed block / OEM headgasket).

I figure it'll cost me alot but yeah stroked 2.7 is ftw, boost added will be nutss hehe

So I am thinking around 1000-1500 for just engine work, Just need to work out everything else and what turbo I am going to go with ..

[CamB 48]

o-rings about $20 a bore for machining.

Basically could be from 2k - 10k depending on how much you replace, what you upgrade and how much you can do yourself.

[CamB 48]

The only thing I would add based on the e30tech / Swedish way is:

- big turbo that spools late

- free flowing exhaust

- Megasquirt or some other full engine management

- standard head gasket fine

- arp head bolts required

- standard pistons and US-spec compression ratio fine

The key to the way they do it is that the big turbo isn't producing significant pressure until after the engine's torque peak, so you are less likely to get detonation (and can use a standard head gasket). The free flowing exhaust (and big exhaust side of the turbo) also ensures little backpressure so helps avoid detonation (brought on by exhaust reversion). The tuning is also critical to avoiding detonation - correct fueling, correct ignition advance, etc.

[Guest FrantiC]

Yeah I've already decided I'll definitley be going with a piggyback / aftermarket ECU. Most likely Megasquirt as it's easily self-tuned at home sort of thing and DIY..

Anyone recommend what size turbo I should go with?

[Guest FrantiC]

o-rings about $20 a bore for machining.

Basically could be from 2k - 10k depending on how much you replace, what you upgrade and how much you can do yourself.

Alot would be myself such as enngine assembly, But machine work like honing cylinders, o-ringing, skiming/plaining, having head rebuilt and the cost of new bearings, etc is what I really wanna try figure out to get a rough idea how much this is gonna cost me.

[BM WORLD 1264]

i have a nice M52 2.8L crank(lighter and better than M20 type) for your engine , and maybe bore out the block to make it a 2.9L or 3L with some nice light custom pistons etc .

do it once do it properly

[CamB 48]

If I was doing it I'd try a Gt30 or gt35 size - roughly 55mm inducer and 60mm exducer and ~50 trim. It'd be called a 500hp turbo, or there abouts. That's only my opinion though - haven't tried it.

[Madhatter 0]

if you get into the realms of 400hp id be looking at rods then too, at the very least, decent rod bolts and maybe shot peen your existing ones. Only one company offer rod bolts in a kit for the m20, cant remember who it was though (maybe vacc?), otherwise you have to go to arp with bolt dimensions and see what they can match up.

honestly, if you are doing a rebuild now id be throwing in things like rockers, eccentrics and shafts too, plus maybe another cam more suited to the turbo. Stock one will develop pretty good power with guys running over 300hp using them, but it could be an option too.

[Andre3000 55]

i have a nice M52 2.8L crank(lighter and better than M20 type) for your engine , and maybe bore out the block to make it a 2.9L or 3L with some nice light custom pistons etc .

do it once do it properly

I'm as keen as a pregnant teen!!!

Not a fan of turbos esp on a 200k engine, naturally aspirated all the way.

BPF on this conversion with as little professional hours as poss?

[CamB 48]

BPF on this conversion with as little professional hours as poss?

The answer's probably still $2k (full gasket kit + bearings and rings and some machine work), plus the cost of the crank and getting a special spacer made up. I'll assume you can find M20B20 rods for close to nothing(!) - see the link.

http://www.msportster.co.uk/faq.asp?FAQ=25

The problem as I am finding with "as little professional hours as possible" is that the amount you need is inversely proportional to your own ability. Mine always seems to be lacking.

Any mods or freshen up of the head will cost more again.

Edited March 21, 2009 by CamB

[tibbs.james 1]

As a matter of referene.

I had my M20 cylinder head machined for $400, to get the exhaust manifold machined was $60

New Rod Bolts ( aftermarket replacments ) were $80

Top Gasket Set Was $150, Lower set was $90

By the time i got the Cambelt, Water Pump and tensioner it was close to $800.

For my 300zx Nissan

block Bored, Crank polished, pistons machined painted and new frost plugs for $500.

Mahle Piston rings were $150, Main bearings were $100 Rods were $80

Lower gasket set was $80

This is based on nearly trade prices and all work being completed myself

[Andre3000 55]

The answer's probably still $2k (full gasket kit + bearings and rings), plus the cost of the crank and getting a special spacer made up. I'll assume you can find M20B20 rods for close to nothing(!) - see the link.

http://www.msportster.co.uk/faq.asp?FAQ=25

The problem as I am finding with "as little professional hours as possible" is that the amount you need is inversely proportional to your own ability. Mine always seems to be lacking.

Would i also benefit from getting a higher/lower (watever it is) angle cam? 272??

[CamB 48]

With the bigger capacity, yes definitely. Would then need a remap... so more monies.

[Andre3000 55]

Iv already bin saving for this mod for quite a while but im hoping to buget it to 3 grand. But i dnt wana stinge on parts. Like Brent said "Do it once, do it right"

[Boost Junky 1]

Alot of people seem to prefer the o-ringed + OEM headgasket over something like an MLS headgasket for the m20. But I know where I can get some ARP headstuds for the m20 at like 250 USD.. I think at only 10psi it should be fine. Seen higher boosted setups on e30tech (14psi and pushing 400hp at the wheels with the o-ringed block / OEM headgasket).

I figure it'll cost me alot but yeah stroked 2.7 is ftw, boost added will be nutss hehe

So I am thinking around 1000-1500 for just engine work, Just need to work out everything else and what turbo I am going to go with ..

If you are only running 10psi then you will find it much easier and less of a headache to run a thicker headgasket.. from my understanding there is alot of mucking around to setup an o-ringed type setup. With a thicker headgasket you only need to slap her in along with getting your head decked and cleaning up the block surface. However I just recalled your rebuilding the M20 so it may not be much more work to o-ring it I guess its just down to which is cheaper and easier and more practical?

That $340 for headstuds was in NZD dude, heres some for an M20 for USD$199 here

As for my turbo I read alot of info through bimmerforums in the states where alot of my motors have been turbo'd. Most guys on there recommend max a GT3582R aka GT3540R so I went for that. IMO I would probably stick to something slightly smaller for the M20 as they dont flow as much as the M50.. maybe like a T3/T4 or GT25 - GT30R,

Someone correct me if any of this is wrong sometimes I question my own theorys, could all be wrong lol...

Luke

[CamB 48]

Not a GT25 anything - way too small. If a GT28, at least a GT2871. A GT3071 costs the same as a GT2871 (and same size compressor wheel anyway), so I'd consider that the minimum if buying new.

[*Glenn* 854]

Iv already bin saving for this mod for quite a while but im hoping to buget it to 3 grand. But i dnt wana stinge on parts. Like Brent said "Do it once, do it right"

When bugeting ... always X by 2... and you'll end up with about 3X if your lucky... been there...done that... and doing it again

[Guest FrantiC]

Went down to Quality Auto Machinists today and asked them for a figure on the work I want done.

O-RING the head : $350

Other head work - Replace valve guides, valve seats, head skim, etc etc : $410 (+ Parts)

So looking at over $1000 to have the head rebuilt and o-ringed.

I think bottem end was only like $800ish including the parts. Forgot what he said..

[|ncary 0]

Forgive me but this is all in retarded imperial, only cause garrett measure their turbos in that system. Too bad they make awesome turbos..

At 7000RPM the 2.5 M20 flows through 308CubicFeet of air per minute. (my intended redline)

On 10psi at 85% Volumetric Efficiency (single cam goodness), the turbo must flow 38.2 pounds of air per minute. At the torque peak of 4000RPM, 21 lb's per min. You idealy want boost before 4000 then to actually make 2g on a new garrett worthwhile. Or less if buying used ha.

Spending hours staring at info and turbo graphs, I came to this conclusion for the set-up I'm considering

GT2876 with .64 exhaust housing

Calculating exhaust flow rates see that thing spool before 3, easily, and top out right around 7000RPM for a shitty M20 2.5 with good boost management and the right wastegate size. (link G4 of course, my friend works at link ) And that works at 1 bar (14psi) and 7 psi, because as you increase the boost, the limit on the graph heads diagonally up to the right, staying in the efficiency islands (Around 68-72% depending on boost) Anything less than 60% is bad, and those maps only show 65% and above. So, heaps of room.

The next step is a GT30, it'd be doing less work for the same results, but the response wont be the same as this thing. I've had a nice internet chat to a guy from e30tech with a GT28 (a rare person who doesn't put a big f**koff Holset or GT35 on a whatever-they-could-get-their-hands-on turbo system) and says at anything over 2.5-3000RPM, it's like a beautifully smooth monster of torque.

I'm doing this ^ or S50B32 if one pops up. *DIBS*

Edited April 2, 2009 by Incary

[CamB 48]

Without wishing to push the e30tech way, the concern over a 0.64 GT28 housing is that it will choke off the top end of the engine and you might never reach 7,000rpm. At an absolute minimum you'd want a 0.86 a/r I think.

For that reason, I'd go GT30, with a larger exhaust side.

Edited April 2, 2009 by CamB

[|ncary 0]

Yeah I was concerned about that.. thought a well placed wastegate would solve that though. .84 is too big for my goals. Why is there no .74!?