Teach me BMW M42 + snail

Backstory:

• I am designing the support and structure for relocating the S52 rearward thru the firewall of my race car.
• I run in CM class, which is 3.5L or less and due to stuff I won't bore you with, a 1.8L with a puffer will still fit under that limit.
• An S52 is $$$ to make more than about 270 to the wheels. I'm at 250 and getting my ass handed to me. An S54 is also expensive.
• I can get a 1.8L M42 for free
• It is smaller, lighter and robust
• I hear people say things like 350 to the wheels with a turbo, no problem

So, this is w2wc racing... huge 1980s style turbo lag ain't going to be acceptable to my buttah smooth driving style nor is blowing E36 M3 up every other weekend when I'm paying entry fees going to enamor itself to my wallet. What do I need to learn to add a snail to an M42 in a reliable, responsive way that will give me approx 350 whp and good torque characteristics. For the record, this his has been tried unsuccessfully by smarter, more well equipped people than I so naturally, having heard they failed, I'd like to rub their noses in it.

Go!

M42 with refreshed rods and low comp pistons plus headwork perhaps....... FWIW, I'll be happy with low 200's whp out of mine.

Its an expensive route versus S52......thats for sure. And I doubt you could have your power goals without lag.....

I'm 100% positive he could have his power goals with little enough lag that it won't matter on a track.

GPS, get in contact with Levent at GutenParts. One of his regulars father has a built M42 with over 300whp, he might be able to put you in touch.

But I'd think cams, headwork, nice pistons and rods + E85 should make it attainable

yamaha wrote: M42 with refreshed rods and low comp pistons plus headwork perhaps....... FWIW, I'll be happy with low 200's whp out of mine. Its an expensive route versus S52......thats for sure. And I doubt you could have your power goals without lag.....

I have an S52 w/ cams now - its a 5k DIY rebuild to get the power to where it needs to be. An S54 is a bit more than that by the time I take engine management into account. I can't see how swapping 4 rods, pistons and lowering the compression would be worse than either of those even considering engine management, and all the parts I still don't have because magasquirt can run this setup (S54s, not so much). The gains in balance and lower weight plus boost and higher revs from a 4 cyl (over straight 6) I was hoping would be a competitive edge I could afford. Lag below say 3500 - 4000 RPMs would be fine - I can use gearing to keep the revs up - especially if I can rev to 8500 w/o flinging valve parts all over the place.

Ahh, gotcha. It could be done, but I'll bite with the list of what you'll need. You wouldn't need rods necessarily(stock should be forged), but they're cheap enough to replace, pistons yes, headwork, cams, and you'll have to figure out something with the intake setup. The engine can do it, but thats what you'll run into. IDK if I'd spin it any faster than the I-6's though.

Just remember, the M42 is a relative of the 320i touring car engines they raced in europe.....but those parts are salty. My friend found a 320i itb intake with the 8 injectors, but it was almost $4000.....

My friend has a e30 318is with a TD05-12A from a Starion. It's quick and doesn't have much lag at all.

182hp and 210ft/lbs at 8psi running Megasquirt. He needs bigger injectors and more boost.

I wouldn't recommend it. My suspicion is it'll cost about the same to boost an M42 up to the power levels you want, then it'll be less reliable on track with more heat related issues and stuff that'll blow up...

Can you lighten your car more?

he's claiming 330hp w/turbo m42

In reply to m4ff3w:

Moar info please . . .

docwyte wrote: Can you lighten your car more?

It gets harder and harder... I am very light now, even for a gutted sedan but as part of this winter's "make your own suspension and move the engine" project I'll be removing as much unused metal in-front of the subframe as seems prudent. Some of the steel chassis points will become aluminum. We are talking 10s of lbs though, not hundreds.

I didn't think this would be a magic bullet but there are a lot of smart guys in here - if the consensus was "sure, that will work" I'd start looking harder at snails but I'm not hearing a lot of that. So... I'm probably looking at tried and true NA stuff. Fun food for thought though.

I say it'll work, but it may not be any cheaper in the end. Might be lighter, though.

BMW did take the M42 racing when they created the S42. From what I remember reading on the M42.. a couple of the engineers at BMW mentioned that the head on the M42/44 flows BETTER than that of the S14.

The biggest problem I see with this.. the angle of the engine. You are either going to have the turbo under the head the way the engine is cranked over on it's side.. or going to have to put it up front by the radiator.

Personally, I like the idea.. anytime somebody can build a BMW four that out performs the 6s, I get excited

92CelicaHalfTrac wrote: I say it'll work, but it may not be any cheaper in the end. Might be lighter, though.

I'm in the same boat here......it is possible, will be lighter, but it'll be close to the same money.

It's a tough, tough little engine. BMW got a lot of hp out of one. I suspect you can get 300+hp on a challenge budget and could get reliable power out of it for less than an S motor (challenge version - m42 + t3 + 15psi - no other engine mods, should be close to 300hp - head gasket or pistones might not live long w/10:1 stock pistons). I think the problem is that it's not a well-travelled path so there isn't the easy road map like an S engine or even a hotted up m52.

I think I'm budgeting $4-500 for new forged pistons that will drop it to 9:1.........also, where the hell did that guy get that intake mani from.......

oldtin wrote: It's a tough, tough little engine. BMW got a lot of hp out of one. I suspect you can get 300+hp on a challenge budget and could get reliable power out of it for less than an S motor (challenge version - m42 + t3 + 15psi - no other engine mods, should be close to 300hp - head gasket or pistones might not live long w/10:1 stock pistons). I think the problem is that it's not a well-travelled path so there isn't the easy road map like an S engine or even a hotted up m52.

M42 is alloy block - are you sure you are not thinking of the M10 when you say double-tough?

If I drop the compression to 8:5 or 9:1 and keep the stock everything else... no go boom on 15lbs?

the rotating assembly should be completely forged already.......they're built pretty solid. If you want anything past 200-250rwhp you'll need headwork, cams, and intake mani......I guarentee that.

VAC has a head porting service for M42 engines for reasonable money. I'd buy "Cat" cams(I think thats what the one company is called), and figure out a short runner log style intake manifold with a single throttle body plate(instead of the wonky reverse 2 plate they all have)

It's not 1998 anymore, why are people still dropping compression for boost? At this point the fuel and tuning options make the sky the limit when it comes to power and boost.

Your problems are going to be oiling and heat on a track. Big radiator, an oil cooler and hood venting will be key. Water cooled turbo is a must as well for longevity's sake. For the track you'd probably be happy with anything in the GT2X range. .60 A/R should be pretty snappy.

red5_02 wrote: It's not 1998 anymore, why are people still dropping compression for boost? At this point the fuel and tuning options make the sky the limit when it comes to power and boost. Your problems are going to be oiling and heat on a track. Big radiator, an oil cooler and hood venting will be key. Water cooled turbo is a must as well for longevity's sake. For the track you'd probably be happy with anything in the GT2X range. .60 A/R should be pretty snappy.

Because some motors make more power on lower compression with more timing than with more compression and less timing.

This might not be one of them, but who knows.

He'd probably have to go with the biggest GT2x he could find for 350whp, methinks. I'm thinking more like GT3071 or a small EFR.

you could do an M10 and boost it. There seem to be quite a few options out there and the M10 is said to hold a lot of power under boost without issue.There seem to be a good amount in the 300+hp range. Just a thought. Especially since you can pick up M10's all day for next to nothing.

The spinny parts are forged with lots of support. There's a fair number of street cars running 7-12 psi reliably - supercharged and turbo. Change from bolts to studs and I think it would reliably hold up to 15psi. I think Jakeb on here may have some experience with them. He's done a few bmw engine swaps and m42/2002 swaps.

I think this is the guy you want to talk to since it looks like he's running a turbo m42 on the west coast - 16 psi, stock rods, crank and rebuilt head - JE pistons 8.5:1

Giant Purple Snorklewacker wrote: M42 is alloy block - are you sure you are not thinking of the M10 when you say double-tough?

I'd have been more than a little surprised if this were true and I hadn't noticed, but I just went out and stuck a magnet to the block of the M42 waiting to be rebuilt and go into the 2002...

It was sold to me as an M44, but IIRC I've verified by CAS location and peeking at the valvetrain through the oil filler cap that it's an M42.

EDIT: Very interested in this thread for M42-on-boost info, though since my application is street/autocross, I'm thinking supercharger over turbo...

i thought m42's have a forged rotating assembly, and m44's do not.

it's been a long time, though.

In reply to belteshazzar:

I believe you are correct, but I'm obviously fuzzy on a lot of details. Too much garage building and too much time with that M4x just sitting on a stand, giving me reproachful looks...