Best M42 Mods

[InNeedOfBoost]

^^ That's basically what I want to do...just need to find one, and for a good price.

[Balleristic31]

I've got the single mass non ac fw lightened to 18 pounds with a stock clutch and it's great

[InNeedOfBoost]

Yea, sorry...I was referring to the single mass M42 flywheel. From what I read in a few places, the M42 SINGLE mass + clutch + pressure plate weighs the same as the M20 setup.

Of course, it goes back to the M20 setup requiring modifications and the M42 SM being ridiculously hard to find.

[decay]

yeah, i was unclear, sorry.

single-mass flywheel was an expensive bit. ask shops that have BMWNA connections.

[Dj Buttchug]

i think he is referring to a single mass M42 flywheel OEM???

also If it hasnt been said yet, mustang injectors for m42 are a pretty sweet cheap mod. You gain no power its just a updated 4 pintle spray injector as opposed to the single pintle oem ones

[irish44j]

Yea, I actually found another thread on M42club about weights.

The clutch and flywheel assemblies together on both the single mass M42 and M20 end up weighing in at the exact same and the M42 doesn't require modification to fit.

EDIT: the below applies to the M42 DUAL-MASS....I didn't notice that he was referring to the M42 single-mass above. But those are damn near impossible to find around here....and M20's there are plenty of em :)

In case anyone wants to know:

The M42 dual-mass flywheel+clutch+pressure plate is 35 lbs. (flywheel is 26lbs).
M20 single-mass fw+clutch+pp is 30lbs. (flywheel is 16lbs)

Basically, the M20 setup is lighter by about 5lbs AND it has more surface area for the clutch, for those running more power....

M20 full assembly


M42 full assembly

[InNeedOfBoost]

Yea, I actually found another thread on M42club about weights.

The clutch and flywheel assemblies together on both the single mass M42 and M20 end up weighing in at the exact same and the M42 doesn't require modification to fit.

Where did you find your M42 single mass?

[decay]

m20 flywheel is lighter; the clutch that goes with it is heavier. polar moment of inertia may be better with that setup, but weight is the same. just so you know what you're getting for the effort.

[InNeedOfBoost]

^^ That's what I was thinking of finding but I'm having trouble tracking one down. Then after reading, the M20 one is lighter then the M42 single mass. I might try this out.

[decay]

i wanted OEM peace of mind, so i got the single-mass flywheel from a non-AC EDM M42 car.

[InNeedOfBoost]

My M42 OE clutch is fairly new, so I'll stick with that for now. The flywheel is the original so I wouldn't mind getting a lighter one.

Any suggestions on weights or brands?

[bmwman91]

OEM M20 clutch and flywheel parts are fine. There is some variance in which throw out bearing to use, but I am running all M20 parts with no issues.

You will need to do a little grinding on the upper oil pan to get the M20 flywheel to clear it, or have it lightened to remove the interfering part.

[InNeedOfBoost]

Just been browsing through here for ideas...sorry to bring this back from the dead but its been giving me ideas.

Whats everyone's opinions on the M20 clutch and flywheel kits as far as brands? Or do you normally just run the OE M20 ones?

Are they direct bolt on to the M42's or do they require any kind of modification.

Not looking to make a bunch of extra power, just want the car to feel a bit more responsive.

[bmwman91]

You will not hit 200BHP unless you bore, stroke and cam it. It could use some head work to breathe better too. You will also have to "work hard" for that 200BHP when driving as it will be sort of a peaky power curve. ITBs will only exacerbate this. It is a fun setup no doubt, but it would get old on the street.

How high you can rev it depends on your desired longevity. With stock internals, I think that you can rev it to 7200RPM all day long. The MM Rally engine I have is software limited to 7700RPM since I told them that I want to drive this thing for another 20 years. The engine has substantially lighter (everything) in the crank and valve trains. I believe that they said that the setup can withstand brief 9000RPM mis-shifts. The main limitation with the M42 is the hydraulic lifters. You'll get valve float if you go much above 7200RPM with the stock ones and stock springs. MM said that they can go over 10k RPM with solid lifters on some race engines, but I don't know how long-lived those are.

[future rs]

So lets say a MSII setup with ITB's and supporting mods. I would like to make close to 200hp. And no I don't want to swap the engine. I like the idea of keeping it high rev 4 cyl.

Also with tuning what can these motors be rev'ed to?