Learn Me: m20 swapped into a BMW 2002

92dxman wrote: M20 was used in E30's and M42 was used in later 318's correct 90 til 98-99ish?

M42 ended production in 95.. m44 ended in the US with the 318ti in 1999

For blown BMW 2002's, see if you can dig up a copy of the Mongrel Motorsports 2002 challenge car- it was a '76 2002 which had an interesting blower set up.

They won the challenge that year.

NordicSaab wrote: So, I'm already looking ahead to the 2017 Challenge and an m20 is the obvious choice for the $100 BMW 2002. Locally, I have found a complete engine, transmission, harness, and ECM for $400. The only catch is that it's an eta motor, but beggars cant be choosers. Anyone have knowledge of this particular swap. Car is a 1974 FWIW

I would say the M42 is the obvious choice. Just a bit less power than the M20, really, and much lighter engine+trans overall. An M42 will be faster than an ETA motor in most situations, actually (though a B25 motor is faster than an M42). But for handling purposes alone the slightly less power of the M42 is a good tradeoff for much better weight balance on your car - especially for the challenge where autocross comes into play.

Also, I've found both of my M42s (with transmissions and harness and ECM) for $300 or so.....

Thanks for all the input. I think the eta is going to be a buy anyway. The owner is talking about throwing in a set of 2002 doors and a hood (which i desperately need) as part of the package.

Also, from me research there is only a 85lb weight penalty with the M20.

Maybe if my luck continues I can find a "i" head and a set of high compression pistons.

alfadriver wrote: For blown BMW 2002's, see if you can dig up a copy of the Mongrel Motorsports 2002 challenge car- it was a '76 2002 which had an interesting blower set up. They won the challenge that year.

Was it a Downing-Atlanta blower? I remember that had interesting superchargers for smaller BMWs.

My 76 had a mild N/A build and I always wanted to do an S2000 swap.

If it were my money and strictly on trying to win something on a challenge budget though, I would look at a cheap CA18det, Ka24det (ebay turbo kit etc), SR20det (if possible in the budget). 13bt etc. Put about 250whp so the ground in a 2002 in a light inline 4 or turbo rotary setup and you'd be doing pretty darn well.

In reply to crankwalk:

I can't remember- that was 14 years ago! I do remember the car was REALLY well done, and has the carb upstream of the blower.

I also remember the drag race was rained out, and the autocross was very wet. (we finished 10th)

Wife had a '92 318iC. It was an E30 Vert with the M42 motor. Remember that convertibles generally follow a year behind the others on model changes. The M42 was quite perky and would get >30mpg turning 4,000rpm at 80mph. The convertible was heavier than the coupes, so it had a 4.11 final drive. If you can find one of them, it still had V-belts, vs. serpentine belts of the later versions.

In reply to djsilver:

Actually, all the E30 M42 2 and 4 door sedans had a 4.10 final drive from the factory, and the M42 was not sold with an auto in the E30. The vert actually got a 4.27 if I remember right. The G250 used in the E36 generation had a 1:1 5th rather than being overdriven, so those typically had different ratios, but if memory serves, the automatic 318ti and 318ic had a 4.44 ratio. Note that 4 cylinder cars have a small case diff rather than the medium case that the 6 cylinder cars had. They do interchange though; I have a medium case 3.73 in my 318is.

Kind of weird thinking about all this stuff again...I got my E30 where I want it probably 7 years ago and at that point stopped perusing r3v, and it seems like I've forgotten quite a bit.

Another vote for the M42 - it's a fun engine. I did not like the 325e eta engine much. If you do get the eta block, in making a 2.7i stroker, there is a matching "i" head that doesn't suffer a major compression loss, but IIRC it is from the euro 323i (called a "731" head as opposed to the US spec M20B25 head that is colloquially referred to as "885"). I see these for sale occasionally on forums:

r3v: School me on the 731 head

The Mongrel car used a tbird sc iirc

crankwalk wrote:

alfadriver wrote: For blown BMW 2002's, see if you can dig up a copy of the Mongrel Motorsports 2002 challenge car- it was a '76 2002 which had an interesting blower set up. They won the challenge that year.

Was it a Downing-Atlanta blower? I remember that had interesting superchargers for smaller BMWs. My 76 had a mild N/A build and I always wanted to do an S2000 swap. If it were my money and strictly on trying to win something on a challenge budget though, I would look at a cheap CA18det, Ka24det (ebay turbo kit etc), SR20det (if possible in the budget). 13bt etc. Put about 250whp so the ground in a 2002 in a light inline 4 or turbo rotary setup and you'd be doing pretty darn well.

No need for the SR20det unless you score one for cheap.....the m42 outflows them by a fair margin and are dirt cheap. Honestly, i'd probably give the stock m10 a chance first though.....eBay turbo kits for them are sub 600 and you can get EFI setups from e21's all day long for peanuts.

In reply to WOW Really Paul?:

m10 will get a chance this year, but I don't see it being a long term solution. I can easily piece together a turbo kit for under $200, but the FI setup would take time.

If I do any motor other than a BMW engine it will be a 4g63 NA with an ITB setup.

In reply to NordicSaab:

Any early e30 318i will yield efi. ;)

WOW Really Paul? wrote: In reply to NordicSaab: Any early e30 318i will yield efi. ;)

cool! Anyone on here have a m10 318i they can amputate the EFI from for me? :)

z31maniac wrote:

Robbie wrote:

mad_machine wrote: do some research on the very rare S42 and replicate it... which shouldn't be hard to do

???? I thought the s42 was like a 'our motorsport team built three cars and 2 engines for each car' kinda deal. I was under the understanding that replicating it would essentially mean you are a BMW race engineer and have a high quality machine shop and lots of base materials at your disposal. Do you have information otherwise? I am very interested.

You are correct. If you wanted to spend $$$$ M42 with the M44 diesel crank, ITBs, high comp pistons, etc. Send a blank check to the guys at Rebello racing to build you a monster. I suspect you could likely buy a new Mustang GT for what the engine would cost.

Here's a Rebello M42 for sale: Rebello M42 for sale.

226hp...not too shabby for NA 1.8L. :)

In reply to Tyler H:

So... $7500 in engine into a $100 car... I think not

makes me wish my m44 had not gone to the crusher with the car.. but at the time I did not have the inclination to save it. If I had, it would have been yours for the taking

NordicSaab wrote: In reply to Tyler H: So... $7500 in engine into a $100 car... I think not

Me neither, but imagine how much that blank check was made out for? ;)