I have an M90 that I'm looking at purchasing, currently carbureted. I got some great info from a member here but still have some more questions that someone can hopefully help me with. This was the info I received from the member:
After processing this info, here's my next set of questions:
From the above info I gather that the M90 swap can be done by following a standard M30 swap into an E30, but the only difference might be adapting the particular vintage of motronic to it. I haven't read alot on M30 swaps, but from the above and a little reading elsewhere, can I extrapolate that using an M30B35 would allow me to use the existing engine harness in my 325i, and just swap the ECU and any appropriate engine-side sensors/components? And to have this compatibility in an M90 I'd need to use the balancer from a B35, which might have the incorrect number or pattern of mounting/bolt holes? Anyone know whether the holes match up; I'd much prefer to simply keep my engine harness and altogether keep the swap as simple/drop in/"normal" as possible.
Are there any definitive or respected swap guides that I could lean on in terms of seeing EXACTLY what parts I would need to collect for such a project? Something along the lines of an E30 M30 Swap for Dummies? I know a respectable amount of information about E30s, however engine internals and specifics are definitely a weak area for me and still fairly intimidating. I know one that I'd perused before was this one, and it seemed very thorough.
I had read somewhere on here about people using something from M10 engines in regards to the intake on M90s I think? Is this something worth looking into, or is not applicable to my application, or am I even just misreading things?
The engine I'm looking at comes with a transmission also (seller said either 262 or 265, he's not sure which, but it's the non-dogleg one). The price was started at $1000 for both tranny and engine, although I spoke with him and he seemed willing to negotiate since he's not exactly sure of the value, and I don't want the weber carbs. Is this a fair price? What would be reasonable to try to bargain to?
Lastly, what kind of differentials do M30 swaps require? Is the medium case one used on M20 E30s appropriate? I have a 3.73 LSD sitting in my garage that I bought not too long ago to swap into my E30 and it'd be a nice bonus if it were appropriate for the swap.
Thanks for any answers or help you can provide.
The M90 is just slightly different from your standard M30, and is techincally still an M30. M90s were only offered in Europe (well, basically everywhere but the US) where they were used in the E12 M535i, E23 735i and E24 635CSi.The M90 designation means that it's the "L" block bottom end which is essentially the same as what the M88/3 and S38 motors used. They literally spawned from the M49 racing block used in the 3.0 and 3.5CSL race cars. It's got an 84mm stroke and a 93.355mm bore for a total of 3453cc vs 86mm and 92mm for a standard 3430cc M30. The cylinder head was the same as what the 3.2 and 3.4 used but M90s generally had a slightly hotter cam from the factory. They are more willing to rev than a long stroke M30 and somehow they feel quite a bit more powerful despite being rated at the same 218hp in European trim.
Installing an M90 in an E30 is exactly the same as an other M30, so you will need mounts, a B34 pan and pump, and thats about it. You can run early or late Motronic on an M90 as long as you can source the correct parts from a donor. I think the only issue you MIGHT run in to is if you want to use Motronic 1.3 (same as the 325i or B35 powered E24, E32 and E34) is that the toothed balancer on the front of a B35 might have the wrong number of holes to bolt to an M90. This is not confirmed though... If you want I could go count the bolts on my M90 vs my B35. The Motronic 1.1 like the E28 535i/is and mid-run 635CSi used would be a very simple conversion as long as you use a flywheel with the pins for the reference sensors.
Installing an M90 in an E30 is exactly the same as an other M30, so you will need mounts, a B34 pan and pump, and thats about it. You can run early or late Motronic on an M90 as long as you can source the correct parts from a donor. I think the only issue you MIGHT run in to is if you want to use Motronic 1.3 (same as the 325i or B35 powered E24, E32 and E34) is that the toothed balancer on the front of a B35 might have the wrong number of holes to bolt to an M90. This is not confirmed though... If you want I could go count the bolts on my M90 vs my B35. The Motronic 1.1 like the E28 535i/is and mid-run 635CSi used would be a very simple conversion as long as you use a flywheel with the pins for the reference sensors.
From the above info I gather that the M90 swap can be done by following a standard M30 swap into an E30, but the only difference might be adapting the particular vintage of motronic to it. I haven't read alot on M30 swaps, but from the above and a little reading elsewhere, can I extrapolate that using an M30B35 would allow me to use the existing engine harness in my 325i, and just swap the ECU and any appropriate engine-side sensors/components? And to have this compatibility in an M90 I'd need to use the balancer from a B35, which might have the incorrect number or pattern of mounting/bolt holes? Anyone know whether the holes match up; I'd much prefer to simply keep my engine harness and altogether keep the swap as simple/drop in/"normal" as possible.
Are there any definitive or respected swap guides that I could lean on in terms of seeing EXACTLY what parts I would need to collect for such a project? Something along the lines of an E30 M30 Swap for Dummies? I know a respectable amount of information about E30s, however engine internals and specifics are definitely a weak area for me and still fairly intimidating. I know one that I'd perused before was this one, and it seemed very thorough.
I had read somewhere on here about people using something from M10 engines in regards to the intake on M90s I think? Is this something worth looking into, or is not applicable to my application, or am I even just misreading things?
The engine I'm looking at comes with a transmission also (seller said either 262 or 265, he's not sure which, but it's the non-dogleg one). The price was started at $1000 for both tranny and engine, although I spoke with him and he seemed willing to negotiate since he's not exactly sure of the value, and I don't want the weber carbs. Is this a fair price? What would be reasonable to try to bargain to?
Lastly, what kind of differentials do M30 swaps require? Is the medium case one used on M20 E30s appropriate? I have a 3.73 LSD sitting in my garage that I bought not too long ago to swap into my E30 and it'd be a nice bonus if it were appropriate for the swap.
Thanks for any answers or help you can provide.
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