Very nice article that dispells some myths on eta cranks and provides key info such as what rods/cranks. etc for different displacement options.I know MM is expensive but this serves as a really good guide for the DIYer.
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I'm surprised they give out even that much information.
I like how they openly admit to their "3200" motors being 3.1L. What happened to that kid that was convinced he had a 3.2L M20? -
One specific thing to pay attention to with MM's stuff is their rod length. Stroking a M20 is not the way to go if you want maximum power on a budget. The longer stroke will necessitate a custom piston with a small compression height and longer rods in order to maintain a desirable R:S.Comment
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good read. I wonder how much they want for their oil pan baffle and pistons? also, I didn't know it was safe to bore the M20 to 86mm.Comment
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IE now has something new listed under engine: oil pan baffle for m20 48$
pistons are around 1000, i think i might buy mine from here.
As time went on, the factory developed the car each year, making it faster, more comfortable, and capable of handling at higher speeds.
You don’t want this. You want the trickiest, most dangerous, oldest model you can find. Only then can you prove to the world that you’re a man.Comment
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So is it safe to bore to 86mm? I know MM does it on all their engines but i remember hearing differently.
Will switching to lighter forged internals ie. pistons/rods compensate for a not-so-optimal rod ratio(1.55-1.65)?
As time went on, the factory developed the car each year, making it faster, more comfortable, and capable of handling at higher speeds.
You don’t want this. You want the trickiest, most dangerous, oldest model you can find. Only then can you prove to the world that you’re a man.Comment
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Its an interesting article which addresses a number of 'weaknesses' of the stock M20 and how they are improved on.....most notably the reduction of reciprocating mass. However, its been well documented that one of the M20s biggest bottlenecks is the cylinderhead. I would like to know what MM does to improve this part of the M20. Call me a skeptic, but I think some of the figures he's claiming are a bit on the inflated side. That aside, I still like my stock M20....a durable mill which has yet to let me down.
JonRides...
1991 325i - sold :(
2004 2WD Frontier King Cab
RIP #17 Jules BianchiComment
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if you are paying for forged pistons you can use any rod you want basically.. that's one reason why going with forged pistons is better because you can use the longer rods and not kill your r/s ratio. with an 81mm crank and 135mm rods, you'd be within an acceptable range (1.67, but not quite as good as the stock B25's 1.8 ). personally I don't think there is any other way to do it, you can make a stroker without forged pistons but that doesn't mean it will run well or make good power.Originally posted by madjurgen
also, yes the head needs work. but I think jordan proved that it's very possible to improve the head by quite a bit. I'd go with a dual pattern 284/272 cam instead of a straight 272 personally (I'm soooo addicted to it now). and btw, I was looking at pictures of Dave's head (of the stroker mtech2 cabby fame), and I'm not surprized at all that he made such poor numbers for a 3.0. None of his ports are close to the same shape or size, the finish looks horrible and it's likely that they decreased the flow of his head rather than the other way around.Comment
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same here, if Im doing this stroker, Im doing it right.
86mm s50b30US crank
most probably MM forged pistons
forged rods (i think i can fit 139.5mm in there)
shot-peened rockers
+1 valves (not sure about this one yet)
284/272 cam
maf
smt6 or unichip
and of course extensive headwork
long headers
port matching, extrude honing
still unsure about how much i want to bore it out
probably come out to around 6k$ but give me a decent rod ratio of 1.62 and cut down internal rotating mass by about 25%. In my head this makes for a very revvable 3L engine.
comments?
wasnt dave running on stock engine mngmt?
As time went on, the factory developed the car each year, making it faster, more comfortable, and capable of handling at higher speeds.
You don’t want this. You want the trickiest, most dangerous, oldest model you can find. Only then can you prove to the world that you’re a man.Comment
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Yes...including a stock chip (the aftermarket chip created ignition problems). As mentioned, the issue with Dave's motor had a lot to do with the head set up. He did enlarge the valve size, was running a hotter cam (a 272 grind IIRC), larger injectors, an M30 AFM and bored throttle body. The shortblock he built up was pretty stout despite having lower C/R pistons (I speculate this was due to California's 91 octane fuel), but it was the head set up where he was robbed of that motors' true potential.Originally posted by madjurgen
JonRides...
1991 325i - sold :(
2004 2WD Frontier King Cab
RIP #17 Jules BianchiComment
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I agree 100% with the 284/272 cam. Intake closing is the MOST important aspect of a camshaft, and that extra 6 degrees will make A LOT of difference. The single pattern 288 cam is too big of a compromise in drivability due to the large overlap (which really isn't as important as some people make it out to be anyway).Originally posted by nandoComment
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I wouldn't waste money on +1 valves unless you have cash to burn. maybe on a race motor, but the cost just doesn't seem worth it to me for a street car. proper headwork will make a bigger difference anyway. new stock valves are pretty cheap, too.Comment
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Originally posted by nando
but if youre already spending a crapload then might as well do it if it helps
As time went on, the factory developed the car each year, making it faster, more comfortable, and capable of handling at higher speeds.
You don’t want this. You want the trickiest, most dangerous, oldest model you can find. Only then can you prove to the world that you’re a man.Comment
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I dunno, they cost more than twice as much, and you have to buy 12 of them ($$$). Also with the M20's combustion chamber design, making the valves larger might not help at all anyway, since they are so close together and close to the edges of the chamber you could end up with shrouding problems and end up losing efficiency.
And don't forget that bigger valves will weigh more (x12), a consideration for revving ability. I just don't think any gains you might get would be worth the cost. I'd rather spend that extra money on losing the AFM and dyno tuning, that's where most of the real power gains are anyway.Comment
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Doing this to a M20 could cost around $6000? How much does a M50 conversion cost? Which one would give better power?Comment
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