524td build, minus the d

[turbodan]

The subject:







A 1985 524td with 89k on the odometer, seems to be in good overall condition. Alpine white like my first e28 dating back to 2003ish.

The motor is pissed off and I'm not interested in becoming a diesel specialist so I will be converting it to gas and installing this M20:



Today I ordered a turbo, a bit larger than the other build. It's a GT2971R with the 90 trim turbine and .86 AR housing on the hot side. It's in between the GT2871R I used at one point in the past and a little shy of the GT35R I ended up with on the old build. Theoretically it should be capable of 400+ RWHP, though the turbine side is about 10% smaller than the 35R that I previously achieved those power levels with.

300 rear wheel would be perfectly fine, and if need be I can push it up from there.

[gadget73]

are you going to name it Ken ?

[turbodan]

I have not seen the Barbie movie, that may be a prerequisite for that joke.

Perhaps I'll substitute Dan for Diesel. Keep the original badging.

[gadget73]

I haven't seen it either but my slightly older cousin was a Barbie fanatic when we were kids, and at some point I became aware that Ken was not exactly anatomically correct.

[turbodan]

The name would be appropriate, this 524td is not going to be anatomically correct for long.





This is the previously mentioned GT2971R fresh off the FedEx truck. This is the absolute largest turbine and compressor combo available in this T25 frame. Very compact with plenty of flow.

[turbodan]

A clutchmasters segmented kevlar clutch. On sale at Bimmerworld, which is a place I have never heard of or bought from. They had it on the shelf for a very good price. I highly recommend giving them a call.

[turbodan]

This project is finally getting some progress. Since the engine that was destined for this swap ended up being needed for the other car, I've been trying to figure out a course of action. The block I have, the original engine that came out of the other one, is substantially scored in multiple cylinders. I did harvest the super ETA pistons, rods and crank. These all should be usable with some cleaning up.

That motor was definitely beat, as the rod bearings show:



All things considered it is a pretty poor candidate for a build, so I eventually sourced a spare M20B25 bottom end. I could either swap the super ETA stuff into this B25 block or just refresh the B25 and use it as is. Displacement really isn't a big factor with forced induction, especially a difference of 200cc's. The B25 actually revs better than a super ETA based stroker too, which is just a matter of engine dynamics when only changing displacement. Same intake, same valves, better breathing at high revs. I tested a B25 back in the old days and it ran very well as far as I can remember. The only thing that gives me pause about making any changes is the amount of effort that went into the current tune and the truly excellent result of that. Some time will be required to adjust the fuel tables but it certainly could be done.

Currently I'm stripping the B25 down for a thorough cleaning, honing and inspection. I still need to pull the M21 out of this diesel but there's no reason not to get the M20 fully situated before proceeding.

[turbodan]

I spent a few hours yesterday moving this car closer to the house, right up behind the garage where I can get started.

Today I pulled the turbo and manifold off. I was somewhat intrigued by this stock turbo, specs have always been hard to come by. Now I know that it is a T3 50 trim compressor mated to a 47mm turbine wheel inside of a very small A/R turbine. Of all of these specs, the turbine A/R is definitely the main issue for anyone considering using one of these on a gas engine. A much larger A/R housing would uncork the hot side and allow this thing to reach the potential of the compressor, which looks like it should be good to at least 250rwhp. Suitable for a low boost system on a 2.7 or smaller engine. 250 rear wheel is nothing to sneeze at, that's almost 300 at the crank.

The external wastegate is interesting as well, being vacuum operated. I actually might try this thing out to improve efficiency during cruising. It would be open at idle and part throttle and close as soon as you put your foot into it, at which point the entire volume of exhaust gas would be routed through the turbine until the main wastegate opens. I'll have to determine exactly what vacuum level this thing opens and closes at. It would be useful if it stays open until about 60 or 70 kpa.

[Punnzzells]

Start of another great build thread.... will be following this one.

[turbodan]

Updates. Not much though.

I recently backed into this thing with a case 280 while doing some dirt work in the yard. This thing then bounced backward and into the west facing wall of my house. Did a number on the master bathroom. Car sustained only a little damage to the front bumper. The house was worse. Sure didn't take much to push that wall in.

I have been working, going to school and remodeling the master bath over the last few months. Garage time has been expended on two wheeled projects. This car needs to get going though. I have two M20B25 short blocks, three heads, a couple of these td manifolds and a couple of turbos laying around. All of the ingredients are on hand, I need to cook.

Next semester will be organic chemistry, which is expected to suck, but I won't be working so I should be able to get some shit done. It would be very nice to at least get the engine and transmission out.

[tig]

Love this!