Budget M42 turbo build

[gearheadE30]

When I was running my M42 on the track, the transmission gave me constant trouble. It was a major weak point of that drivetrain and is the main reason why I finally gave up on it and swapped in an i6 engine & drivetrain.

I miss the lightness of the M42 engine, but the rest of the drivetrain (including rear diff) just didn't seem to hold up to serious track use.

yeah I've been getting this impression as well. I know the e36 M42 uses a slightly different verson of the getrag 240, and perhaps some of the M50 cars did as well? I can't find any concrete evidence aside from word-of-mouth that the e36 ones are any sturdier, or if they will even mate up, though.

My diff will probably be swapped out for a medium case 3.73 or maybe a 4.10, but I kinda want some lower highway revs. The small case LSD I have seems to be doing really well, though; it's even pretty quiet with poly mounts and such.

[gearheadE30]

42lb injectors are in and running, the charcoal canister has been deleted, the IAC has its own air filter now (somehow this fixed a ton of idle issues) and the crank vent is now vented through a cheapo filter while I try to find a catch can...

[Schnitzer318is]

Sweet. Wish I could run an ICV... I really need to upgrade to MS2.

Mine idles steady after a couple of mins of warmup, but if I turn on the AC, it dies. Soooooo I have to balance my throttle when I want to use the AC on idle. :(

[e304me]

Just running a map? that sounds awesome!!!! Yeah the barn door creates quite a bit of lag. I think it is a pretty big restriction with the supercharger plus i have to run a really small air filter because of space. I will be doing this for sure in the future. no rush on the write-up, but dont forget everything by the time you do it!

By the way the e36 tranny has different ratios. They are much shorter and closer spaced. I got a killer deal on a rebuilt 3.46 with 40% lock up (its amazing) and with the e36 tranny my first gear is longer but the rest of the gears are shorter than the stock setup. I think eventually i will get a 6 speed

[gearheadE30]

Schnitzer-before I put the funky second air filter on, mine took a second or two to compensate. now I can hardly even see the RPM change when I switch it on B)

e304me-haha I'll try not to forget; I've got most of it written down though. I suppose if I can find an e36 trans, I may go that route, then. I want a longer (and medium case) diff anyway... I also considered a 6-speed from a 330i or something, but I can't find one for cheap :(

[gearheadE30]

Scored a 140k mile getrag 240 from an e30 318is for $100 with a guarantee :)

[gearheadE30]

Well, I now have the trans and flywheel and need to buy a clutch kit, the 323i TOB, and have the flywheel lightened. I think I have found some starter bits as well. And a little year-and-a-half long project was just finished: getting the Zender spoiler painted! I'll get pics up soon, cuz it's way too dark to take some now.

[e30guydownunder]

I used the 325i TO bearing that came with my 325i single mass clutch kit. Works fine, save your coin ;)

Keep up the good work.

[e30guydownunder]

I used the 325i TO bearing that came with my 325i single mass clutch kit. Works fine, save your coin ;)

Keep up the good work.

[gearheadE30]

haha too late; I was actually able to get the sachs clutch without the TO bearing and substitute in the 323i one at the same cost. It's nice working for a shop haha. So this weekend I will be installing a new 325i clutch, lightended single mass, M20 starter, new TOB, new pilot bearing, new clutch arm, pivots, etc, newish getrag 240, and a new CSB. Should be fun :).

BTW projected date for starting the turbo install is june 12-13, which is conveniently my birthday weekend haha

[e30guydownunder]

BTW projected date for starting the turbo install is june 12-13, which is conveniently my birthday weekend haha

Cool, The week after is when I finish exams, will be getting cracking on mine again after that point!

[gearheadE30]

Awesome! I just got the trans pulled out of my car, and everything involved there is getting a complete overhaul. M20 flywheel lightened to 16lbs, new clutch and PP, M20 starter, all new seals, pilot bearing, TOB, CSB, guibo, clutch release fork. Its gonna be nice :).

As for the turbo, I just purchased some more -10 AN fittings so I can fabricate an oil drain. After trying to figure out how the hell you mesure NPT fittings, I think I finally figured it out, and am getting senders, bugs, distribution blocks, and the like to install a 300 degree oil pressure gauge and an 80 psi oil pressure gauge. Hopefully they will be able to fit in the face of teh forward center console so I can keep my storage area and vents and everything else, but I don't know if there will be enough space between that and the heater core. Otherwise, they may end up horizontal in the rear center console. Impossible to see, I know, but much more practical on a street car. The boost gauge will be in one of the vents, though, so I can keep an eye on boost creep and such in the tuning stage. Otherwise, all I need now is IC brackets, a few silicone intake bits, and relocation of the coils (to the underhood battery tray) and the washer reservoir (e36 tank mounted over the ABS pump). Its getting close.... :)

[Schnitzer318is]

That clutch is not going to hold up for long with boost. :(

Even at 7psi I experienced slipping with the stock clutch. Had to go with a stage 2 kit from Spec. Not sure if the 325i one will hold up better but we'll see.

[gearheadE30]

Well, hopefully it will...228 mm vs 215mm makes a pretty big difference because of the diameter of the friction material. At a glance, the 325i PP looks a bit wider, but I'll measure it later to confirm.

Weight differences:
M42 FW-28.8 lbs
M42 clutch assembly-38.5 lbs

M20 FW-lightened to 16 lbs
M20 assembly-30.4 lbs.

The difference is reasonably large, and all said and done, it only cost me $400 worth of parts, machining included. There also appears to be a lot less mass on the outer edge of the M20 FW than the M42 dual mass, so that's probly going to make a bit of a difference as well. It should all be installed by sunday if all goes well

EDIT: the friction material on both pressure plates is 3.5cm wide

[gearheadE30]

Pics of some of the progress, in no particular order: