How about an M20 build thread

[turbodan]

This is going to be the second bottom up turbo motor build for this project. Starting with a 1982 production M20B27 block. Back in 2008 or so I picked up a set of new old stock Mahle .50 over super eta pistons, so the block was bored. I've been itching to put this thing together ever since.



Heres the pile of parts. The crank and rods came from the motor I just pulled out of the car, which was an M20B27 from an e30. I preferred to use the rotating assembly from that motor since they've been tested under boost and 7k RPM already. The rod and main bearings are Kolbenschmidt standard size.

I started with a furniture dolly from Harbor Freight. Wanted to do this inside. If I had a real garage to work in, I would have mounted it on an engine stand. That comes later. The first thing that goes in are the pistons and rods, through the top of course. I had some extra pistons and rings, so of course everything went well and I didn't need them:



Time to flip the block and put in the rest of the guts:



The bearings fit very well. Just like factory. While it was easy I put a few drops of oil on the wristpin bearings and along the cylinder walls from the bottom. Then the crank goes in:



Slap on some bearing caps and bolts, torque everything and you've got a nice new bottom end. Main cap bolts got ~45 ft-lbs and the rod cap bolts take 15 ft-lbs plus 70 degrees.



For now thats where its at. I was going to button up the front timing case but the Victor Reinz aftermarket garbage seals do not fit correctly. The inner seal lip fits well but the outer seal lip does not make contact with the journal. Same situation for the front main seal and the intermediate and cam seals. Since it would be a damn shame to put this together anyway, I'm going to order some BMW seals and never buy another Victor Reinz product again.

I've got another four weeks before the new owner flies out to pick it up, so while I feel like I have time for delays like this I do feel somewhat concerned at the same time.

[ldsbeaker]

Tell me you're married.

[turbodan]

Yep. Shes too happy that the car is sold to complain about building engines in the spare bedroom.

[ldsbeaker]

Yep. Shes too happy that the car is sold to complain about building engines in the spare bedroom.

My wife would shit a kitten, spare bedroom or not. I have rebuilt halfshafts at the kitchen table (not the "fancy" table)...

Are you upgrading the engine any besides the overbore/pistons?
HP goal?

[turbodan]

This is pretty much the same engine as the last one that made 380rwhp. It will be going together with an MLS head gasket and the combustion chambers have been reshaped a bit to improve resistance to detonation and lower the CR.

Should make just a wee bit more power and be more reliable.

[mooseheadm5]

Here's to wives that let us crazy people build motors in the house!

My last teardown was a motorcycle engine.

[T_C_D]

I like it. Is this going in the shitbox e28 or did you sell that one?

[turbodan]

Call it Shitbox II. Just like the original $500 shitbox but with a genuinely straight body. The block is going to be the only thing in or on the car with paint on it.

[Duke]

Call it Shitbox II. Just like the original $500 shitbox but with a genuinely straight body. The block is going to be the only thing in or on the car with paint on it.

Sounds like you are drifting to the "stance" realm.....be very, very careful not to fall into that pit.

You build site is awesome, a friend and I rebuilt a motorcycle in his apartment living room when I was in college. It was a 70something Honda Hawk. We put down a sheet of plastic when we started. When finish there was a perfect outline of that sheet made in grease and dirt on the carpet. He did not get his deposit back.

[turbodan]

Call it Shitbox II. Just like the original $500 shitbox but with a genuinely straight body. The block is going to be the only thing in or on the car with paint on it.

Sounds like you are drifting to the "stance" realm.....be very, very careful not to fall into that pit.

Riiiiiiight

[T_C_D]

Call it Shitbox II. Just like the original $500 shitbox but with a genuinely straight body. The block is going to be the only thing in or on the car with paint on it.

Sounds like you are drifting to the "stance" realm.....be very, very careful not to fall into that pit.

You build site is awesome, a friend and I rebuilt a motorcycle in his apartment living room when I was in college. It was a 70something Honda Hawk. We put down a sheet of plastic when we started. When finish there was a perfect outline of that sheet made in grease and dirt on the carpet. He did not get his deposit back.

Dan had the only stock spung e28 turbo in existence.

[scarey013]

I can't imagine Dan EVER drifting into the stance realm.

[DangerWillRbnsn]

Cool build Dan... Your wife must have some kinda patience! I have a 3 car garage, with parts spilling into the house now. My better half is not thrilled, but has accepted it. I don't think I could build in the house though, that might be the breaking point.

Lets see the car it's going in!

[Xenocide]

Subscribed.

I've been waiting awhile for Dan to make another m20 scream.

[turbodan]

Got new seals today from BMW. Same gap as the aftermarket seals. Fuck. Threw away $70 on that.

I think the car will be running the weekend of the 17th. I'm trying to decide if I want to sack up and run 1.4 bar right out of the gate or just set it at 1 bar. I like to roll the dice, but not as much as I used to. The car will be running much closer to sea level with its new owner, so I figure the same wastegate springs that get 1 bar up here will yield about 1.2 bar at the lower elevation.

[turbodan]

I think I might get this thing in the car this weekend. Weather is supposed to be crappy Saturday and we're having an open house mid-day Sunday, but maybe Sunday evening. With the days getting longer I could probably bust it off after work too. I'd like to get to drive it a little before it goes away for good.



Just need to throw the head on dunk it back in the car. There really is nothing to rebuilding these things.

The super eta pistons do poke quite a bit over the deck. Makes for an effective quench area I guess.

[T_C_D]

I am confused. What car is this engine going? Something you sold? Will you be left with any e28?

[turbodan]

The original turbo 528 was the '88. That car was dismantled and scrapped about a year ago. Swapped pretty much everything into this straight, rust-free '86 528 chassis. I do have a stock '83 528 collecting dust in the driveway too.

Once this car goes I won't have a turbo e28 anymore. My priorities have changed a bit in the last few years. I would rather spend time with my wife and daughter than wrenching on this thing in the garage. I'm tired of spending time and money on it. I'm also pretty sure if I keep driving this car I will end up in prison and the car will be crushed. I've had my fair share of narrow escapes from the law around here. When we get the house sold and things settle down a bit I'll probably get back into boost with the 540. Bummer is that I know for a fact this build will perform consistently and be dead nuts reliable. Everything is worked out, the tune is solid, there will be no problems. I guess if I'm ever going to be able to sell it, now would be the time.

[turbodan]

Did some stuff, and then some more stuff happened, and the engine is in.



Hate how dirty everything is in there. Old engine had a severe oil leak from the intermediate shaft seal and possibly others. Oil everywhere. I will probably finish off a case of brake cleaner on this job before its all done.

Rest of car:



The dusty but pristine and pliable dash:

[Xenocide]

Foaming engine cleaner goes much further than brake cleaner in my experience. What manifold are you planning on using?

[turbodan]

But you have to introduce water with foamy engine stuff. I dont add water to my engine compartments.

Manifold is this old thing:


Still hanging in there after like five years. Cracks appear from time to time and I weld 'em up. Surprisingly that branch for the wastegate has never cracked. I fully expected it to be a problem.

[turbodan]

Car looks much better with the style 66's on it. They'll be going back on before its delivered to its new owner.

[Kyle in NO]

Dan had the only stock spung e28 turbo in existence.

When you drove my 533i in South Bend it had a completely stock suspension. Bitch rode good too.

[T_C_D]

Dan had the only stock spung e28 turbo in existence.

When you drove my 533i in South Bend it had a completely stock suspension. Bitch rode good too.

That seems like a lifetime ago.

[turbodan]

Car has been running for a few days now. Break in is a real bitch the way this thing runs. I like the idea of running 1200 miles without any boost or high revs, but I have to compromise in order to get the tune dialed in for the new owner. I haven't revved it above 5k, which I feel is reasonably conservative. I don't let it rev or make any boost until the oil is nice and warm.

Boost is set to 1 bar/15 psi. In that configuration it has no problem at all blowing away the 265/40R17 Potenza RE760's on spoolup in third gear. We're not talking about scrubbing them or struggling to hook but absolutely lighting them up. Its stronger than its ever been. I've occasionally seen slight traction loss in third depending on road surface condition but I've never had the rear end just break loose and float on the tires in third like that. Shits ridiculous.

This afternoon was all about going through the engine compartment fixing little stuff. All of the things I wrapped up hastily late at night long ago and never got around to doing right. Repaired some wiring connections, found a few loose hose clamps causing a slight coolant leak. The whole engine is clean and dry. Not a seep to be found. Gives me a chub just thinking about it.

[Xenocide]

Do you think the super eta pistons made much of a difference over your previous build? I suppose it's far to early to tell, but that was the only major difference right?

Sounds like a nice tidy baby six build.

[turbodan]

The original turbo motor used super eta pistons. After a few years I pulled that motor out and put together a M20B25 turbo motor, then I dunked the turbo stuff onto a standard eta block, and now I'm back to the original super eta block with a 2.5 top end combination.

The main functional difference between the standard eta and super eta pistons is the rings. The 82-87 eta motors came with what I presume are low drag piston rings. They work fine up to about 5000 RPM, above which they have a hard time controlling oil. If you run up to 6500 RPM and chop the throttle you'll be laying down a smoke screen as soon as you get back on the throttle. I've seen this with two perfectly good eta bottom ends. The super e has the same rings that were used in the M20B25 and M50B25, which have no problem with high RPM and high vacuum conditions.

[Nebraska_e28]

Pics & video please?

[Shadow]

^ my old m20 with a eta block did that allot.
reved it out to 7k and let it go. Only time I got oil smoke out
the exhaust. I thought it was valve seals or something.

[TheE28Ranch]

"Build it, and they will come."