Do i swap a M20b20 into my E30?

[OldE30`]

Hey guys,

So i have a m20b20 laying around and an m10b18 in the car currently ( 1993 bmw e30 318i) which lacks any sort of power, and im pretty sure the compression is low as it doesn't like starting ever especially when it's already warm (I'll test this and post results soon)

But i'm wondering if it's worth swapping the m20b20 into it and maybe putting a b25 head on it? Or just leaving the head and putting a small turbo or something on it to make it a little more powerful. I'm not looking for any big hp numbers but around probably 200hp would be pretty sweet.

Also what costs would i be looking at if i decided to do the swap? (Change engine mounts, driveshaft, any custom fabrication etc.)?

Thanks, sorry if its a noob question at all.

[SkiFree]

But i'm wondering if it's worth swapping the m20b20 into it .

Welcome to r3v. To answer your question, no, no it is not worth it.

[varg]

I don't know about that. Unless I lived in the middle of a bunch of tight twisty roads I'd rather have an extra 20hp than the weight savings of an M10 vs an M20. If the M10 is worn out and has low compression and the M20 is good, even though it's only a B20 it's a significant upgrade bone stock. There is a lot involved in the swap of course, and depending on how much of the M20 setup you have it could be pretty expensive to do since you could have to source hoses, exhaust, transmission, driveshaft, wiring harness and ECU, etc.

[AndrewBird]

If you are going to swap, you would be better off swapping to an M50/52. I know you already have the M20, but an M50 would give you nearly double the HP and be a simple swap. You would already be close to your 200 HP goal without doing anything.

[wworm]

^ this is why I went with an m52 over building an m20. Stock engine with as much power as a built m20. If you don't have AC you can keep the weight pretty similar to an m20, but all will definitely be heavier than your m10.

If you wanna get creative you can build the m20 to a 2.7/2.8 stroker motor. Plenty of info on that around here. IIRC, the m20b20 has a pretty good head/cam for a stroker.

Search around here, theres plenty of inspiration and information to get you going. A turbo m10 would be kinda cool in an e30 too.

[digger]

There is a saying to those who think swapping b25 head onto a b20. Leave the bottom end attached to the head..

[SkiFree]

^ this is why I went with an m52 over building an m20. Stock engine with as much power as a built m20. If you don't have AC you can keep the weight pretty similar to an m20, but all will definitely be heavier than your m10.

.

No, you don't understand. He was comparing the potential advantages of an M20B20 over a 1.8L M10. If he was comparing it to an M20B25, then I'd swap in that in a heart beat.

Much rather take a good M20B25 over a comparative M52.

[lukeADE335i]

If you're having problems with the M40 (assuming it's not an M10 since you mention in your first post the car is from 1993?) and an M20 engine sitting around it's worth putting in the car. Much smoother engine - the 2.0L M20 is actually the smoothest M20 of the lot due to its short stroke - and they are good on fuel.

The M20 should bolt right up to the M40 gearbox, but you'll probably need a 320i driveshaft as the 6 sits further back than the 4 and has a shorter driveshaft.

A boosted 2.0 could be good, but if you're going to that much effort you might as well swap in a bigger engine.

[TobyB]

I dunno, if I had a small six sitting around, I'd put it in just for fun.

but I like relatively pointless projects.

t

[ThatOneEuroE30]

My car came with a b20 it wasn’t fun at all. Makes like 100hp so its basically an m10 with 2 more cylinders

[e30davie]

the big expense really from going to an M20 motor is the manual gearbox. Have you got the manual gearbox to suit m20, clutch, flywheel, tailshaft, ecu, loom etc for the m20?

If you do and you reckon the m20b20 is a runner then its a no brainer to swap out that m10.

If you dont, well you need to buy all of that gear anyway regardless of which m20 you put in.

Any bmw 6clr engine is a great sound and so smooth. even the m20b20 would be alot of fun.

And i see you are in Australia, you can pickup m20b23s pretty cheap. 80% of an m20b25 at 1/4 the cost.

[wworm]

No, you don't understand. He was comparing the potential advantages of an M20B20 over a 1.8L M10. If he was comparing it to an M20B25, then I'd swap in that in a heart beat.

Much rather take a good M20B25 over a comparative M52.

Right, I was referencing AndrewBird's comment about 24v as a more "practical" swap if one is going through the effort to swap, especially since OP said he wanted to get around 200hp, which you can do with a few bolt on's with an m52b28, or a stock s5x.