m20b25 rebuild then turbo

[ryanferguson]

I plan to swap out my m20b27 from my 86 325e and put in an m20b25. i read up on strictlyeta.net that he used an 87 325i motor and the wiring harness matched up perfectly. does anybody know if itll just work for that year or can i use a newer 325i motor 88+. along the lines b4 i put the motor in i want to go over it and replace all the engine seals and anything else in particular that looks like it may need replacing... ie water pump timing belt fuel lines, that kinda stuff. but getting to the point, what can the stock internals of the motor hold if i were to FI? id upgrade the head gasket but if i were to run 5-8 psi will it work with stock ecu? what about injectors and fuel regulators and fuel pumps? i dont want alot of power but id like to make 200 or little more hp out of the motor. how about the clutch? its in good shape but will 200hp wear it down quickly on WOT? neways, all input and help is appreciated, i just would like an idea to what it would cost and how much work will need to be done

[FuryriderX]

hey!

limitation of the m20 motor is that rods start flexing at around 400bhp. stock internals can hold >300hp with just a good set of head studs, as long as your tune is good.

thats the biggest thing with boosted cars - you MUST be able to tune it properly. the stock ecu can not read boost due to the nature of the air flow meter that is used on the m20. you can mickey-mouse it with a rising rate FPR and larger injectors, combined with a chip that retards timing, but standalone is really the way to go if you want complete control.

upgrading the head gasket is unneccessary - if you put in a MLS or copper or whatever, then the pistons become the breaking point. if you blow the tune, its just the headgasket that goes, which is a $30 part, instead of hundreds of dollars in pistons.

stock fuel pump will do you fine, its been proven to flow >350hp.

200hp is peanuts for a turbo setup, you will get that with 4psi. as to what the stock clutch will hold, in my experience it lets go around 7psi, or 230-40hp. definitely get a stronger clutch if you plan to go more than 5-7psi. or get ahold of a 325iX pressure plate - its a bit stiffer and will hold 10psi.

another thing you have to consider is the exhaust - anything more than 6-7psi i'd say upgrading the exhaust is a neccessity to avoid grenading the motor due to back pressure.

budget between 3 and 3.5k for a decent, well put together turbo setup. or try and find someone selling a partial or complete kit for an m20.

turbo manifolds for e30's are starting to become more common on ebay - check out the obx manifold adapter - it even has a provision for an external wastegate.

[ryanferguson]

Thanks Greg,
lol i dont plan to make close to 400bhp but i would like around 220-250bhp. i do have a dinan chip but that work work for the m20b25 cause i have it in my b27.

how much does a standalone go for and how hard is it to find one? i will be replacing my fuel pump as its weak already, but ill just go with a bosch 300 which will work good. i already have a 2.5" catback i made myself.

i would like to plan for 8ish mayb 9psi, im not looking to destroy everything on the streets and at the track, but i would like a little more pull and smiles =). i will mod the engine slightly with injector upgrades and adj. fuel regulator and head bolts, but nothing greatly outstanding...mayb later down the road.

i would just like to get everything put together and tuned properly and work my way up from there. i think ill be the only 1 in b.c with a turbo e30 unless someone else is sneaking around with one lol

[E30M3]

for 220-250hp, its probably less of a headache just to go m/s50, m50 with m3cams and a chip will be around 220hp, and a s50 with a chip will be around 250hp.. both are proven swaps with no need to go to a standalone, or a custom exhaust.

theres actually a few boosted e30s running around, and theres a touring thats boosted aswell.

[ryanferguson]

Originally Posted by E30M3 for 220-250hp, its probably less of a headache just to go m/s50, m50 with m3cams and a chip will be around 220hp, and a s50 with a chip will be around 250hp.. both are proven swaps with no need to go to a standalone, or a custom exhaust. theres actually a few boosted e30s running around, and theres a touring thats boosted aswell.

yah ive thought about a motor swap, but that would also involve alot of work aswell (engine and tranny mounts, wiring harnesses, relocating parts under hood. the reason im going with a m20b25 turbo is cause it will clip in to my exhisting wiring harness with only needing to change the ecu.

i guess it all depends really, this will be a couple months from now so i have room to change minds if i want, but the turbo setup sounds much more appealing to me than a swapped n/a even if its harder to tune. i dont mind a hard time to get to happiness

[FuryriderX]

Sounds good - you have a lot of reading to do if you plan on turbo'ing.

The F/I section of e30tech has a lot of really really good stickies about turbo'ing - make SURE you read them before you start posting hahha.

in particular - jordan's massive turbo writeup and Turbo E30 FAQ should get you started.

[jenifer.kaif]

The right person who can suggest you will your car dealer.