M20 building questions

[Digitalwave]

Aqquiring an M50 requires an initial investment, paying shipping/finding a method to transport it, and a good bit of extra storage space. He already has an M20 block.

Something that us "real world" modders like to think about.

-Charlie

What is this real world that you speak of?

[Rob]

An S50 is extremely expensive and really NOT that much better than a stroked M20........................................ Correctr me if I'm wrong.

drive both, you'll correct yourself. I've driven built 2.8 M20s, 3.0 M20s, stock 3.0s, built 3.0/3.2............with the 24v motors, you most definitely can tell that the extra $$$ is worth it.


This is an old debate, at least in relation to the e30 tuning world. But the fact that a STOCK s50 3.0 makes more power than a fully build, questionable reliability built 3.0 m20 says it all. both are expensive of course, but one is factory reliable, the other is not.

[Madhatter]

The maximum you can safely bore it is 1mm to 85mm. You might be able to go to 86mm for a short-use track motor. Why would you not want to stroke it? You're going to need custom pistons anyway, it would be stupid not to swap cranks at the same time and setup the motor properly.

Ii went 60 thou on my previous M20, there was never a problem and it was a high stress engine used just about everyday. There is a fair bit of metal there, you could even look into stainless sleeves, i wouldnt like to guess just how far you can go without xraying the block to see. If you keep shaving metal off, just keep checking the hardness every few thou, when it starts to differ you have reached the limit.

[clutterbucker]

Ok so 170crank+10crank is 180crank, and that's what I said...read it again. Why wouldn't my motor be pushing 180 crank horses? I'd personally be suprised if it weren't.

The S50/M50 swap I've heard is nothing but a pain in the ass. It was built for a different car and although there are many people who have done it successfully, it seems not to be quite "factory reliable"

The stroker motor option only really appealed ot me because it's easier on me and my wallet. I began thinking of this because I wasnted ot rebuild and bore out a bit to smoothen out the walls. I figured while I was in there with everything apart, I might as well upgrade a few things. Then the whole crankshaft and pistons idea occurred to me. I coul dmake a stroker for pretty cheap I'd say, while an M50/S50 motor transplant would be a TOTALLY different story. No one in Buffalo, NY (a hicktown/city) knows what the hell an M50 is or even that it didn't come stock in my car. I would rather not risk it.

Like I said....210rwhp from an S50 isn't all that impressive, considering the money you're putting forth. I'd be happy with the 160-180rwhp/200rwtq put out by a grand or two and some labor time. Anyone see what I'm saying?

[1985bmw325e]

Aqquiring an M50 requires an initial investment, paying shipping/finding a method to transport it, and a good bit of extra storage space. He already has an M20 block.

Something that us "real world" modders like to think about.

-Charlie

What is this real world that you speak of?

duhh he's talking about MTV's new episodes coming up.

[Chris E30 Cab]

A properly tuned stroker will be plenty of power to have a very fun E30. Good luck with it ;)

[Madhatter]

I remember when the original goal of the stroker was to build a cheap engine out of mostly stock bmw parts which produced 150kw at the crank without any problems.

[Digitalwave]

Ok so 170crank+10crank is 180crank, and that's what I said...read it again. Why wouldn't my motor be pushing 180 crank horses? I'd personally be suprised if it weren't.

The S50/M50 swap I've heard is nothing but a pain in the ass. It was built for a different car and although there are many people who have done it successfully, it seems not to be quite "factory reliable"

The stroker motor option only really appealed ot me because it's easier on me and my wallet. I began thinking of this because I wasnted ot rebuild and bore out a bit to smoothen out the walls. I figured while I was in there with everything apart, I might as well upgrade a few things. Then the whole crankshaft and pistons idea occurred to me. I coul dmake a stroker for pretty cheap I'd say, while an M50/S50 motor transplant would be a TOTALLY different story. No one in Buffalo, NY (a hicktown/city) knows what the hell an M50 is or even that it didn't come stock in my car. I would rather not risk it.

Like I said....210rwhp from an S50 isn't all that impressive, considering the money you're putting forth. I'd be happy with the 160-180rwhp/200rwtq put out by a grand or two and some labor time. Anyone see what I'm saying?

Our cars had 164hp stock, and after 100,000-200,000 miles, I doubt its running at even 164hp. Lets say its running at 160... add 10hp, and I think you'd be lucky to even see out 170hp out of an M20 with a chip (3 peak hp), intake (possible loss of HP), and exhaust (2-3hp).

[clutterbucker]

Ok, that's all I needed. He just sounded like he was talking down to me like my motor specifically could never make that power. sorry! ANyway, I thought our cars came with 168 stockhp....plus (going by Dinan's numbers which could be false) 11hp or so, puts my theoretical hp at 179. I assumed that better airflow meant more power and that 1 hp wasn't too much to ask fo that. That's where I came up with the number, but I suppose you're right, my car could be below tat....only one way to find out.
Looks like I'll probably be stroking it and avoiding the motor swap.....thanks for the advice/critisizm.

[Digitalwave]

Ok, that's all I needed. He just sounded like he was talking down to me like my motor specifically could never make that power. sorry! ANyway, I thought our cars came with 168 stockhp....plus (going by Dinan's numbers which could be false) 11hp or so, puts my theoretical hp at 179. I assumed that better airflow meant more power and that 1 hp wasn't too much to ask fo that. That's where I came up with the number, but I suppose you're right, my car could be below tat....only one way to find out.
Looks like I'll probably be stroking it and avoiding the motor swap.....thanks for the advice/critisizm.

The gains for the chip that are quoted are areas in the mid-range. The gain of 11hp is generally in the 4,000-4,500 RPM range. In actual peak HP terms, its a 2-3 hp increase.

[clutterbucker]

Oh ok. Well, one of these days when I have an "extra" $100 laying around, I'll trek over to the dyno and see what happens.

[Rob]

if you're building a stroker, to get the most out of it, you'll want to go all the way with a MAF conversion and SMT6 of megaquirt tuned. Or just do an m50, which has a MAF stock.... :P

[clutterbucker]

alright, so as you all now know, the purpose of me doign this is so that I don't feel unproductive when I go in for a rebuild.

Which route do you thinhk i should take.

524td crank, 1mm bore, new pistons, MAF, and what else? I'm not all too knowledgeable with this.

[Rob]

pro PnP on the head, a cam and associated headwork. MAF+ecu tuning (preferably on the dyno). have a shop (if you cant do it yourself) balance all the parts (ideally) and you should be pretty happy.

[clutterbucker]

Alright...estimated cost for parts there (just so I can be realistic about this)?

and don't cams give you a shitty idle? I could be talking out of my rear, but I could have sworn I heard that somewhere.