m42 turbo... whats the most potentional?

[Kozworth]

I was wondering since m42s are forged internals, if there are any members on here that have really pushed the m42 to its potentional. I wasnt really a fan of them since I am an m20 guy, but I respect the engineering that was put into the m42.

I am basically looking for the frozensolid of the m42 world. For those who do not know frozensolid, he put a stock m20 bottom end build to 450hp.

Thanks

[willworkfore30s]

I think a few people have run them at 22 psi in a race situation but I think I read that was about the max. I believe they were making around 350-400 rwhp. Someone should chime in and give you more specifics as my answer is only based on what I think I remember from reading different threads on here. There is an m42 turbo fact thread floating around. I am picking up a spare m42 this evening to begin a most likely slow turbo build.

Paging Buttchug

[Kozworth]

Well, I like the idea that its still an e30 engine, but modern in the sense of chain driven/more valves/ etc. What I think is really interesting is how it is forged internals, so I wouldnt understand why you couldnt make some decent power.

I would also assume that under cruising with a low diff, you would still get m42 mileage depending on the tune, which makes it a more practical turbo build, not to mention its lighter and has more space.

[willworkfore30s]

Turbos can often increase efficiency. I have read about people with turbo m42's averaging 35 mpg's.

[Dj Buttchug]

100 hp

[wazzu70]

Im not aware of anyone who is really pushing the stock bottom end to the limits on a turbo M42.

You should be able to put down 300whp without issue though. If you want to reach the full potential of the engine you are going to need a programmable engine management system.

The M42 is a pretty solid engine and is a lot more capable than most give it credit for.

[MF DOOM]

100 hp

^^my car on 9psi.


If i could go back in time I would never have parted my old m42 engine, found an 02 shell for it and fed it as much boost as possible.

m42s are cool engines. Saw some dude using one in his small airplane and it made me think of building a go kart type thing with an m42.

[willworkfore30s]

Im not aware of anyone who is really pushing the stock bottom end to the limits on a turbo M42.

I completely missed the part where he was asking about the stock internals. I HQ autosport is who I was talking about getting close to 400. But I'm sure they are not running a stock bottom end

[wazzu70]

I completely missed the part where he was asking about the stock internals. I HQ autosport is who I was talking about getting close to 400. But I'm sure they are not running a stock bottom end

They were running the diesel crank, aftermarket forged rods, and custom pistons.

[Gerta]

Wouldn't cost of a diesel crank, aftermarket rods, pistons, etc ... cost you as much as a metric mechanic engine? I've got a spare M42 now and I think I might head along this route. Cost estimates on going this route? I assume also that ARP studs and a MLS gasket are required. Seems like it would almost be cost prohibitive (but I like it!)

[MF DOOM]

The cost of building a lower end will be nowhere near the price of a MM engine. And just have the forged factory crank balanced and be done with that. Depending on your goals the oem rods may be fine too. MLS for what? Are you looking to just lower compression or..?

[unevolved]

It's pretty rare to see someone really pushing an M42.

[wazzu70]

You can build an engine with the diesel crank, aftermarket rods and pistons, ect. for significantly less than an MM engine depending on how much of the work you can do yourself.

If you use lower compression pistons, there is really no need for any headgasket besides the OEM unit.

ARP head studs are not required, but are an incredibly smart idea. Why would they be cost prohibitive?


Personally, I wouldn't spend the money on the stroker crank. I would put that money into a good turbo instead. The 1.8L engine can make plenty of power.

[unevolved]

If ARP head studs are cost prohibitive, you have no business playing with turbos. I'd almost put that up there with running without a wideband in the "asking for trouble" category.