E30 Zone

Hi I've been reading some of the posts on here and would like some insight.

I just purchased an 86 325e and am wondering what I should do with the engine after I am done with fixing the body.

I read that I can make it a 2.7i by switching the heads and ecu from a 325i. I can also change the cam and flywheel, new pistons, and lsd. I was thinking maybe installing a turbo down the road.

Does anyone know how much this will cost me approx? I can do all the work myself, and what kind of HP/Torque figures I would be getting?

Or would it be worth it for me to switch my motor to a quicker 3.0 (m4) or 3.0 tt (n54) engine?

Thanks.

There's something about the old motor and keeping the heritage which is making me lean toward keeping the original motor.
I wont be tracking the car or abusing it much. Just making it for a summer car and something to keep in the family for future generations

i should have mentioned that my target hp is mid 250 to 300

Get6 a 2.8 crank and rebuild the original motor.Looks standard but can do over 200 hp with the correct cam and fuel set up

do you know how much this will cost approx? I found a 330i motor and tranny and all the accessories for $2000, so maybe that will be more worth it?

Would cost more than the other engine you can get but would be rebuilt,look standard and you dont have to mess around fitting it.
Depends what you want as the end result. Some 3.0 engines use oil So how confident are you on the condition of the used engine?

Thanks! I think I'm going to do the rebuild option. Any idea what else I need besides the ecu, harness, 885 head, afm, intake, throttle body valve springs, 325 injectors, performance cam?

Also if I bore to 2.8,what else would I need?

Thanks for all the help

... Also, can I use a performance chip like a dinan or a Jim conforti instead of changing the ecu and wiring loom?

You don't bore it to 2.8 you use an m52 2.8 crank.Search on here and you will find how to do it.If you already have a 2.7 bottom end rebuild that with 325 pistons,head and ancilliaries.Fit a better cam and have a remap. You should end up with over 200 hp and still look standard.Drive it like that for a while and decide if you need more power then

M52 single vanos cranks are getting rare now.

Andyboy wrote:M52 single vanos cranks are getting rare now.

This is true, I think it is simply because there are less early M52s falling over to bore wear issues.

They are however not rare as there is still a lot of early M52B28s about, they just don't seem to come up for sale very often now without buying an M52 to break.

The other option is to get a TU (double vanos) crank and have the counter weights "bobbed", that is machined down a bit to reduce their diameter.

Oh and good luck fitting an M4 engine or an N54, the first you would be lucky to get south of 10K and the latter I do not think has been swapped into anything non CAN yet.

How does machining the balance weights affect the balance of the crank? I have a spare one but I didn't think I could use it . Having said that my 2.8 is smooth even with rods and pistons of different weights the crank was designed for.

The early non TU crank is slightly under balanced and the later crank is over balanced IIRC.

A 6 cylinder does not have the same balance issues as a 4 pot.
6 cylinder inline engines have perfect secondary balance where the forces of the pistons and rods cancel each other out.
The balance webs on the crank are to balance the rotational motion of the crank only.
(yes a bit of a simplification).

It is worth noting that not all cranks are fully balanced, it is not uncommon to find cranks under or over balanced, this is done to alter the way the crank flexes or to offset other forces in the engine, more ink has been spent on the relative merits than there is ink in the BIC factory.

Quite a few people have bobbed the M52TU cranks to the dimensions of the early cranks with no ill effects.

sorry to thread hijack - but I used to have a tuned b27 and got it to 230bhp back in the day (seemed a lot then - lol)

Assuming I used the same mods, would a m20b28 be more or less powerful in bhp and torque?

what is the best setup for the engine - single vanos crank, which pistons, conrods etc and does the block need machining down like the 2.7 did or would it be a perfect fit. (assuming using 325i pistons)

I want to turbo charge this project, so which compression ration should I be looking at (my 2.7 was something like 10.5!)

Quaser wrote:sorry to thread hijack - but I used to have a tuned b27 and got it to 230bhp back in the day (seemed a lot then - lol)

Assuming I used the same mods, would a m20b28 be more or less powerful in bhp and torque?

what is the best setup for the engine - single vanos crank, which pistons, conrods etc and does the block need machining down like the 2.7 did or would it be a perfect fit. (assuming using 325i pistons)

I want to turbo charge this project, so which compression ration should I be looking at (my 2.7 was something like 10.5!)

The 2.8L is M52B28 crank, eta 130mm rod, M20b25 piston, nominally 0.5mm off block (check actual dimensions recommended 0.9-1.0mm piston to head clearance) the 8.8 pistons give about 9.7:1 and the 9.7:1 pistons give 10.7 give or take.

No changes other than engine size most likely you’ll gain some more torque but about same hp, peak hp will be a few hundred rpm lower. If you add breathing mods then you will be better off.