Which m20 motor is this??

[slo325i]

Hey guys, so sorry for the noobish question. I've searched for a while to no success.

I recently bought another e30 a '87 325i sedan to be exact :mrgreen::mrgreen:, but the PO told me that the motor is from a '86. Now, I think that this motor is a 2.7l eta??? Well my question is that this motor doesn't have an oil cooler setup at all. Which motor do I have? Is this an ETA motor??

[kronus]

B25 motors did not necessarily have oil coolers.

Does your motor have a cold start valve heading into the backside of the intake box?

[Erick]

I have yet to see a B25 without an oil cooler.

Where's the redline at?

[slo325i]

I'm not near my car at the moment so I couldn't tell ya about the cold start valve. However, my '89 m20 had an oil cooler. The block looks different from a '89 and a '86 because the '86 one doesn't have the fitment for a oil cooler whereas the '89 one does.

[slo325i]

I have yet to see a B25 without an oil cooler.

Where's the redline at?

I think the redlines around 6000.... I'm not sure... But like the PO told me, the motor's been swapped to an earlier model m20.

[Erick]

Well, if you have an earlier model motor, and you're revving it past 4500 rpms, then that motor wouldnt last you a thing.

It's almost impossible to tell though. I could ask you for a picture of the motor, but if the PO installed i manifolds to an e motor, we'd be back at step one again.

Around 6000rpm would sound like you have the tach off a super eta, which is an '88 motor.

[slo325i]

Basically the car is an '87 and the motor is from a '86. The tach on the car goes to 7k. If this was an eta motor, the tach wouldn't go past 4800 right??

[kronus]

Basically the car is an '87 and the motor is from a '86. The tach on the car goes to 7k. If this was an eta motor, the tach wouldn't go past 4800 right??

If it was a motor with eta electronics, it would not rev past 4800. You can use i electronics on an eta and it will go to 7k.*













* and explode shortly thereafter.

[slo325i]

Last stupid question. They had non-eta motors back in '86 right?? I mean the regular b25 motor

[Erick]

Nope, not in the US they didnt.

[slo325i]

WOw, that raises some questions then.... How could I check if my electronics are for this particular motor?

[slo325i]

Could the tach be reading wrong?? Using a B25 tach and eta motor?

[Stephen]

Snap a pic, what does your ICV look like, etc wtc

[jlevie]

The M20B25 became available for the US market with production that began in 9/86. So an 86 motor could be the i variant rather than an ETA. If the engine will rev above 4500rpm, it is either an M20B25, a stroker built from an M20B27, or the cluster is from a 318.

Examination of the intake, CPS, and valve springs should help narrow down what you have.

[Erick]

Any car that's 9/86 is already considered an '87 though.

And the intake will not say anything. If it was an i and he swapped an eta motor, chances are that he opted to use the i intake manifold.