what has more potential?

[E30 Wagen]

In a turbo application, what has the most potential for power gains, an M42, or an M10? I'm also wondering which would be more reliable, and also lighter.

[nando]

I would say M42, because of the much superior 4 valve head/dohc design and more modern electronics and engine management. you will need custom low compression pistons though, and M10 turbos are much more common.

[E30 Wagen]

I would say M42, because of the much superior 4 valve head/dohc design and more modern electronics and engine management. you will need custom low compression pistons though, and M10 turbos are much more common.

So, is it more work to turbo a m42, like does it require more tuning? Is that what makes turbo m10's more common because they are more reliable with stock internals?

[nando]

M42s have 10:1 compression, which is the biggest reason you don't see many turbos on them. I don't think the strength of the internals has much to do with it at all.

[PeaveyBassist]

M10s are just more simple and everyone has done it. M42 would definitely be the way to go if you want the most power though IMO. M42 has more potential with the head design like Nando said.

Will

[SA E30]

Here in SA we got 2 M42 Turbo's running about on is stroked to 2.0lt the other 2.1lt ... they both making over 400whp.

[ehlpitel]

IDK, the e30 M42 lacks a knock detector making it not TOO great for turboing, especially if you're going for HUGE power. On the other hand, the M42 has some forged internals IIRC so it should be decently stout. I would go with an M10 just b/c it's cheaper to replace, weighs less and was supposedly used by BMW for F1 applications using FI.

[SA E30]

[nando]

IDK, the e30 M42 lacks a knock detector making it not TOO great for turboing, especially if you're going for HUGE power. On the other hand, the M42 has some forged internals IIRC so it should be decently stout. I would go with an M10 just b/c it's cheaper to replace, weighs less and was supposedly used by BMW for F1 applications using FI.

how many M10s have knock sensors?

[MikeE30325i]

I would say M42, because of the much superior 4 valve head/dohc design and more modern electronics and engine management. you will need custom low compression pistons though, and M10 turbos are much more common.

yeah my buddy has an M10 and it is turboed. 318 hp to the rear wheels. in a stock 84 318i shell. one helluva car.