200hp out of M20

[Stu]

I'm sure you could get some grunt out of an M50 with S50 cams, larger injectors, a GOOD intake and some headers. That might be your best option in terms of hp/cost.

You can get good peak numbers out of them. I've seen a '93 325is with M3 cams/valvetrain, AA intake/exhaust and a good AA tune do 195-200whp. That motor screams from just over 4000 to 7000 and does 7500 on the top. Peak torque was 151 or 152 at the wheels at close to 5000. I'd say you are right about cost/horsepower; but that's all topend. I'd venture to say that the same motor with a 328i crank would do 40-45 more ft/lbs at the wheels at a lower RPM. But...a cam/injector/intake change is much easier than pulling the motor to swap cranks and build the bottomend!

[Stu]

Me and my buddy are just about done with our m50 swap with s52 cams. the m50 only cost us 900 bucks, the motor mounts, trans, brake booster, electric fan, drive shaft work, e36 calipers and rotors, oil pan, new lifters and trays for the cams and probably like two other things cost us just around 1700.

but then we also we have the head port and polished, with a 3 angle valve job, and a dinan chip to open it up. so were shooting for some were around the 200 whp

Nice and cheap swap, hope the rest of it goes well. You may find that the chip you're planning to use won't yield much more than a stock chip in terms of power, but the higher rev limit will be nice.

[LowR3V'in]

How much does these m50 m3 cams cost?

[Fidhle007]

How much does these m50 m3 cams cost?

S50 cams go for around $300 all day on bf.c...

[ukrbmw]

Fidhle,

Gear ratios are free, so 4.10s are a must. I'm still waiting to find out on the swap question. It might come down to a completely stock M50 or having some room for stroking/cams in an M20. Going up in displacement slightly does not cost that many points, but a 3.1 stroker wouldn't work.

It seems that everybody still thinks a stock M50 would be the way to go through.

Alex.

[JGood]

I love my m50 in comparison to my m20. My 2380lb track car has a m20, the 2800lb daily driver has the m50. They are both Dinan chipped with identical headers and 2.5" exhaust. Getrag 260/3.73 LSD in both as well.

The torque down low on the m50 is awesome. It pulls stronger up top as well though. Just for comparison sake: My m50 car (remember, 400lb heavier), ran a 14.4@94. My m20 car ran a 15.4@89.

The track car will likely get an m3 cammed m50 down the road, and the DD will get M3 cams as well. The torque of the s52 isn't worth the extra initial cost of the engine IMO. I've driven an OBD-1 s52 e30, and while the power is nice, it's not THAT nice. It's still not 'fast' IMO. I'd still get blown away on the straights by anyone with 400+hp. And I'm not going to spend $3k+ on a motor and not be fast. I'd rather build a 5.0 foxbody and do a Griggs suspension and destroy any e30 :)

[Emre]

Building a time trial car. Basically, I can do cams, intake, headers, exhaust, head work, tune, and all these mods don't account for many points.

What you're describing is basically a K-Prepared (KP) engine. I don't think they make over 200 hp at the crank. Check the BMW CCA Club Race forums to see what kind of power those things produce.

On the other hand I can do an M50 swap which puts me in the same class. I've been reading up on the swaps and it seems one can be done for about $2,000 - give or take a little.

The only advantage of sticking with the M20 (besides originality...if that matters to you) is that it weighs around 70 lbs less than an iron-block M50. That extra 70 lbs in the nose is certainly noticeable, but probably not the end of the world.

The disadvantages of building a race M20 compared to a stock M50 are:

• less reliability (broken rocker arms; oil starvation)
• more maintenance (valve timing adjustments; timing belts)
• more custom work ($$$)
• narrower power-band

Overall, swapping in a complete M50 is the easy and cheap solution. Getting a race M20 to run properly isnt trivial, especially if you're stuck with crap California gas. There are lots of hidden expenses: you'll want to ditch the cap & rotor ignition; the intake manifold and AFM are highly restrictive; you'll need aftermarket engine management; etc.

Even if you can do all of this work yourself, you'll be facing lots of little problems/challenges along the way.

[jlevie]

So if the swap moves me up to TTD, then I'm back at trying to figure out a way to get some decent power out of M20 without going too far.

PS - Jim, I know all about a built M20. Just ask me for the copy of the BRE bill...However, look at my recent lap times, almost 2 seconds better!

I think you already know how to get "decent power" out of a "stock" M20B25 and what it costs, which isn't an inconsiderable sum. Nor would I doubt that built motor in a Spec E30 is worth at least one second at any track. and two or perhaps more at some tracks. I'll be insane with joy if my built motor takes two seconds off my RA or CMP times. Okay, maybe not insane as I'm already known as the "crazy old dude", but insanity is a relative term and I can get further "into the weeds".

[ukrbmw]

Jim,

Not sure about CMP, since it is not HP bias like some others, but I imagine you'll see at least 1 second at RA, maybe even more.

Yeah, I know about the stock rebuild of M20. Starting to lean more and more towards M50, but of course have to wait on the series director's response.

[ukrbmw]

Well, 325IS is getting bumped up for next year to TTE, so a swap will push me up to TTD, which frankly I don't want to do. So now I'm back to getting good and usable power out of M20. Plan for right now is for 284 or 288 Schrick cam and supporting boltons. At the end of the day I'm ok with less then 200hp, just would like a good 4-6K power band.

[JGood]

Well, 325IS is getting bumped up for next year to TTE, so a swap will push me up to TTD, which frankly I don't want to do. So now I'm back to getting good and usable power out of M20. Plan for right now is for 284 or 288 Schrick cam and supporting boltons. At the end of the day I'm ok with less then 200hp, just would like a good 4-6K power band.

e30 325i/is is getting bumped to TTE from TTF**? Why the hell do they change the rules so much, that just screwed up my entire plan.

[ukrbmw]

Not I, just IS. But I imagine most cars get updated to the IS specs.

[SpecM]

Not I, just IS. But I imagine most cars get updated to the IS specs.

that's funny, Is and ISs are really the same car

[ukrbmw]

I thought IS was the only one with an LSD, but then again I'm a newb with E30s.

[whiltebeitel]

IIRC, you could order an I with an LSD.