stroking a m42?

[38927]

Hey guys... BUMP!
M42's own!

[Febi Guibo]

M42 madness

I've got a major case of m42 mental illness.. and, g#d willing, I'll have some substantive news on this subject by the end of the year.

Still percolating, but something to the effect of:

- 2.0L diesel crank (89mm stroke)
- new pistons
- as little reciprocating mass as possible (still working this out)
- 258 degree cam (still working this out)

the above maybe builds to 2100cc or so...

It's going to be expensive, and hella expensive vs. an engine swap. But, I like the dynamics of the car a lot and am learning how to drive it right... we'll see how it comes out. Going to take a long time. madness!!

but, the car will be crazy quick, super light, and if everything works out... rev to (practically) no limit... even more of a fun thing.

(cry for help: Please talk me out of this!)

kidding.... seriously, sometimes, you have to be stubborn in the face of, well, all common sense to get interesting results. I'm due for a rebuild in the next 12 months anyway...

[screamingbmwe30]

why not just use the m42 crank?is .1 liters worth it when you have to buy afermarket pistons?

[Febi Guibo]

well...

well.. the whole plan only nets an additional 300cc or so, so I'll take the 100cc from the diesel cranks (this is still at the kinda theoretical stage, as you may have guessed)...

The basic idea is to get close (stay with me here) to s14 power with having less overall car weight than an e30 m3, with a (slightly) more high-tech valve setup.

[Digitalwave]

well.. the whole plan only nets an additional 300cc or so, so I'll take the 100cc from the diesel cranks (this is still at the kinda theoretical stage, as you may have guessed)...

The basic idea is to get close (stay with me here) to s14 power with having less overall car weight than an e30 m3, with a (slightly) more high-tech valve setup.

You could probably do an S14 swap for the same price, and as a bone stock engine with more power it'd probably be more reliable.

[Febi Guibo]

Yeah, looking into it also... having said that... rebuilt S14 engines are getting really expensive (eg, back to the S50 option everybody is doing)

...getting an S14 engine with 100k of spirited driving gives me maybe 50k more miles before another build?

although, you're right, an S14 is still le$$ than my planned M42 white elephant... obviously, reality is sinking in...

[Rob]

what harmonic balancer are you planning on using?

[38927]

Dont detur this dude. Go for th em42 build. I have yet to see a properly setup m42.

[Digitalwave]

Dont detur this dude. Go for th em42 build. I have yet to see a properly setup m42.

I'd love to see it too, but I really feel bad for people (like Dave Adams) that spend a fortune on motors and are disappointed with the results.

[Rob]

agreed, but that's entirely dependant on the expect (realistic or not) results. If he wants to make a 200hp street M42, well he'll more than likely fail. If he wants to satisfaction of having a warm/hot m42 that not many folks have seen, then I'm all for it. Maybe there's a few tips in the build other folks could use?

[Bavarian3]

...getting an S14 engine with 100k of spirited driving gives me maybe 50k more miles before another build?
-------------------------------------------

Eh... not always fact.....

It would be interesting on doing a M42 build, I agree... but I think you might need a stronger cam...

I am sure with some ITBs, cams, and a piggy back system you can get some HP....

The thing is: is it worth it? Well I am sure if you are pouring money into a M42 motor, when you can get more power for less, then to some it may not be worth it.......

[Jon325i]

I'd love to see it too, but I really feel bad for people (like Dave Adams) that spend a fortune on motors and are disappointed with the results.

This is true. I had talked to Dave on several occassions while he was building up that 3.0L M20....its a shame it didn't pan out as he hoped. I still give him kudos for putting in the time, money, and effort not to mention thoroughly documenting everything. It provided a ton of valuable info for future M20 stroker engine projects as far as what works and what doesn't.

The whole M42 stroker idea seems to ring a similar tone to what Dave attempted. If someone is dead-set on doing this project, they would be venturing into relatively unchartered territory. Documenting the entire process and outcome would serve to substantiate this mod as well as write another chapter into the book of performance BMW engine building.

I applaud the courageous soul who takes on this challenge :-D

Jon

[e9nine]

I'd love to see it too, but I really feel bad for people (like Dave Adams) that spend a fortune on motors and are disappointed with the results.

There is a reason his numbers were low. No one is always lucky to get their desired results first time around when it comes to building "motor-kits." It's in the hands that do the work, not the wallet that funds the project or the tally of the bill. No offense to Dave of course as he obviously had options and chose certain paths.
There are people out there who build potent motors with either a check book and the right hands or with the right brains/know-how and nominal $$ by comparison.


The m42 is the least appealing motor in the e30 chassis. M10s can be built to surpass them in power, we all know the story with eta's and m20b25s. The m42 has been tweaked by few but not many.

Dbilas does make an m42 version of their ITBs with software :)

[cunninglinguist]

The M42 is the most advanced engine that was installed in the E30. it's a shame about the hydraulic tappets though.

kempower.be has some stuff for the M42/S42

[38927]

I wonder if anyone will ever go through with a m42 build.