E30 Touring 3.0L M20 Stoker Build

[E30-TourZing]

So I just triple checked and here are the official results... Before I was measuring from the top of the con-rod, but I decided to get my facts straight and just measure directly from the crank to the top of the block.

On the down stroke my measurement was a pretty accurate 223mm

On the upstroke, my tally was 139mm

The difference is 84mm if my math is correct.

This must mean that I have a euro OBD1 M52B28 crank?

Either way, I am pretty excited. Next step is to do the brass hammer test to ensure its a solid candidate. Do most of you folks get your crank tested at your machine shop? Or do you just conduct the same test and call it a day?

Jim Rowe also told me not to polish the crank. While I certainly trust his word with his experience, have other community members spiffed up the journals while at the machine shop?

Thank you for your input!

[AWDBOB]

Just get the right crank IMO, m52 cranks are CHEAP and are all over the place.

[digger]

The shorter stroke won’t take anything meaningful away from hp most likely as that is dictated by the head, intake and exhaust for the most part. The stroke just affects where the rpm peak is and the shape of the power curve and as a result the torque changes slightly. It’s only like a 1.5% change not a big deal so maybe 5ftlb all else equal

Just need to be mindful that the piston will sit 0.6 mm (half the difference in stroke) down the hole so the block would need to be decked (or thinner MLS gasket) to compensate to achieve the correct squish. Having said that the MM pistons probably aren’t setup for squish like the OE style anyway so its more about making sure the compression does drop too low.

[E30-TourZing]

that p/n seems to be a M51 diesel crank 82.8mm stroke

http://www.athousakis.gr/en/product/...-2242898-9144/

Well Digger, you gave me inspiration to double check my numbers with a tad more accuracy. Its adding up more towards the 83mm mark, and causing me to believe the crank the diesel crank like you were suggesting it was.

My question for all you great folks would be... even if its 1mm off the ideal build spec, should I use it?

Pro's
- Small counter weights
- Likely weighs less (no official facts to prove this yet), meaning lower rotational mass.
- Less machine work on block
- I already have it
- My next best option to get a M52B28 crank will cost me a few hundred dollars + time tearing into the motor

Cons
- The MM Sport kit I bought is set up for 84mm crank
- Lower compression
- Lower displacement
- The serious mental condition of 'it-aint-perfect-itous'


I am aware millimetres in engine building have the potential to be a big deal. Do you think it will make enough of a critical difference that I should consider moving into a true 84mm? Does it have the potential to take 10,20,30 HP, lb/ft of torque away from its potential?

Keep in mind, i'm looking for a super fun street car, not a track car.


Any opinions would be greatly appreciated as I plan to send the block to the dentist in the next week or two.


Thank you all for your time! I really appreciate this community!

[E30-325iS]

Seem like that's what it is.

[digger]

I have a 86mm stroke S50B30US crank with the same number.

Could be it’s the forging number that gets machined into a bunch of applications

[MuDuRkKiO]

( ͡⚆ ͜ʖ ͡⚆) ( ͡☉ ͜ʖ ͡☉) Finally some good fuckin food Sent from my LG-H932 using Tapatalk

[E30-325iS]

I have a 86mm stroke S50B30US crank with the same number.

[digger]

that p/n seems to be a M51 diesel crank 82.8mm stroke

http://www.athousakis.gr/en/product/crankshaft-bmw-2242898-9144/

[wworm]

nice update and good call on double checking the crank. And absolutely yes to any m635 content

[E30-TourZing]

Well.... I had some serious trouble getting a M52B28 Crank in my local area. I was an idiot for not checking deeper into my M52 teardown, and realizing I had a 2.5L motor. After I realized I decided to catch up with my local BMW wrecker and a great fella there gave me what he thought to be a M52B28 crank. After reading the serial number (2242898) it seemed to be a S50 M3 crank. I once again started to look for the right crank, although I had a number of other vintage BMW's roll though the last few months and I put my E30 Touring on the back burner. Last night I was inspired to physically check the throw of the supposed M3 crank in my block.

Sure as shit! I was wrong. I happened to behold a seemingly rare OBD1 M52B28 crank with small counter weights. Not only this, but I do not have any clearancing issues with the block, or auxiliary shaft. This means I save money on the machine work for the idler, and this crank weighs less then a standard M52B28 crank. Less rotational mass internally is good in my books. I was literally jumping for joy once I found out these details.

Here is a photo I took shortly after infront of the M635.

Updates of the motor build and cars current state will follow shortly.

Also, I know this site is for E30's, but do people have any interest in seeing a 85' M635 get a full GC suspension install, exhaust, and odds + ends in the next month?


M635 vs M20 by Jan Willem Wilderom, on Flickr

[wworm]

Those seats are amazing. They look so comfy

[E30-TourZing]

So here is another push before I stop working on my car in for the next few weeks.

First thing I did was clean up my M52 Rods. I will need to get them checked for cracks and to see if they are straight. Baised off of bearing wear I am pretty confident they will be good, but I cant be 100% sure until I get the measurements.

P1011526 by Jan Willem Wilderom, on Flickr

Its hard to see in the photo, but they are fracture split.

P1011527 by Jan Willem Wilderom, on Flickr

P1011528 by Jan Willem Wilderom, on Flickr

P1011531 by Jan Willem Wilderom, on Flickr

A solid cleaning begins...

P1011532 by Jan Willem Wilderom, on Flickr


P1011534 by Jan Willem Wilderom, on Flickr


P1011535 by Jan Willem Wilderom, on Flickr


- Pictures from my Fresh 885 Cylinder head. I will be putting the head together in the next month likely. Looking forward to hearing the idle from my schrick 284/272 Cam.

P1011529 by Jan Willem Wilderom, on Flickr

P1011530 by Jan Willem Wilderom, on Flickr


- I removed my brake booster and painted it up. I plan to go ITB's quite soon, so I am unsure if this will booster will fit. I may need a 944 or E21 set up, but for now this will work.

*Can anyone advise me if a RHD ITB setup will work with the stock brake booster? *

P1011571 by Jan Willem Wilderom, on Flickr

P1011572 by Jan Willem Wilderom, on Flickr

P1011575 by Jan Willem Wilderom, on Flickr


P1011577 by Jan Willem Wilderom, on Flickr


P1011580 by Jan Willem Wilderom, on Flickr

P1011581 by Jan Willem Wilderom, on Flickr


P1011582 by Jan Willem Wilderom, on Flickr


P1011583 by Jan Willem Wilderom, on Flickr


P1011584 by Jan Willem Wilderom, on Flickr



- I went and installed a new master Cylinder for the clutch along with new feed line from the reservoir.

P1011578 by Jan Willem Wilderom, on Flickr


P1011579 by Jan Willem Wilderom, on Flickr


- After drilling out the carrage bolts that hold the steering column I was able to lower the wheel 3/4". Just enough that if I am sitting in the seat I can see over the wheel. I am just under 6' tall, but the recaros are super low.

For the first time in ages I can finally button up the dash. Feels like that job can finally be ticked off the list.

P1011585 by Jan Willem Wilderom, on Flickr



- Then came install of likely my favortie part of the car.... My seats.


fullsizeoutput_2fe by Jan Willem Wilderom, on Flickr

P1011587 by Jan Willem Wilderom, on Flickr


P1011588 by Jan Willem Wilderom, on Flickr


- Also finished off this morning with the linkage install.

* Shout out to Bimmer parts in Duncan BC. ANYTHING OEM you likely need for your BMW can be found there. The Guys who own the business and work there are amazing, and I would comfortably say they beat everyones prices. They ship frequently, so US RV3's can perhaps save with the CDN dollar difference.


P1011589 by Jan Willem Wilderom, on Flickr



- Thats all for now. I will fit some brackets next in the engine bay and send it off to the body shop. Hopefully I will save some money in the next two months and then start working on finishing the motor. Thanks for looking!

Jan -

[E30-TourZing]

Thanks man, appreciate it!

On a different note, as I was reading through your thread I noticed that you said you climb...where at? We were just at Mt. Wells this Saturday , was a super nice day.

My lady is more of the climber, but if we go we stay local at comox lake, or in strathcona park at crest creek.

[Mustachio]

Thanks man, appreciate it!

On a different note, as I was reading through your thread I noticed that you said you climb...where at? We were just at Mt. Wells this Saturday , was a super nice day.