engine and drivetrain M10 Vs. M20 - *flame Suit On*

[kid2002]

I agree. It's what I know as well.

Love the power delivery of the M20 even in stock trim and in a lighter package and subtle mods it should be pretty ballsy and reliable.

Part of me wants to keep it "clean" and "period correct" but the fact that I got it for free and that I just finished up the M20, it's hard for me to not take that as a sign! I'm going M20 and not looking back.

Thanks for all the advice and input guys! Can't wait to get this thing driving so I can meet some of you in person!

[Rocan]

7-12 PSI? PSH!! Not enough boost! Ya need one of these

 

 

 

I would happily push 20psi with the right head gasket and studs, but at that point any hope of traction is lost. With enough tire, the diff will tear itself apart. 

 

Next motor I build I have big plans for... going to re-engineer it almost completely. My goal is to build it to withstand 30psi... 

[roadhog0]

I would happily push 20psi with the right head gasket and studs, but at that point any hope of traction is lost. With enough tire, the diff will tear itself apart. 

 

Next motor I build I have big plans for... going to re-engineer it almost completely. My goal is to build it to withstand 30psi... 

I hope down the road when i get some time, money, a cnc lathe, cnc mill, and some other toys, I hope to build a motor where the headgasket isnt the weak point But... Until then....

[Poon]

M20 life



You can easily spend $4-$5k on a M10 to make the same power as a 2.7 M20 stroker.

 

I didn't "want" an M20 swapped 2002, but when my M10 gave up and I couldn't find another good one, I pulled the trigger on the M20 conversion. Now that its all said and done, I can happily say it was the best thing I have done to the car, and do not have a single regret.

[kid2002]

Read through your build thread awhile ago and was really impressed with it. Super clean.

 

Something tells me my engine mounts are closer to being my hands this week compared to last week. Fingers crossed!!

[pkchopp]

A correctly done M10 can be just as satisfying !

[AustrianVespaGuy]

9 times out of 10 I would say stick with rebuilding the M10, but almost every reason I have behind that is pretty much nullified by the fact that you have that M20 sitting there ready to go. . . seems like that ought to make your decision a lot easier!

 

-Carl

[AlanM]

That's exactly the kind of info i'm looking for. Top Notch reply as always. Thanks, Andrew!!

 

Would those mods get you around 150-160WHP?

Hp at the wheels does always seem to depend on whose dyno it is on.  My M10 with 2.3 M3 crank and a little boring is just under 2.2L with an M4 Motec, quad 45mm throttle bodies, 11.5 comp ratio, Schrick 316, with a bit of an ugly set of pipes (RHD) makes only 150Hp at the wheels, but might be convinced to see 160 with some more development.

 

Seems to me the M20 is a better deal in your case as you already have it done.

[kid2002]

That's the plan. Just waiting for my mounts to come in. Parting out the Donor E30 to fund the 02 build.

[Pierre]

Objectively, the M20 is a better engine.  Power, efficiency, reliability, drivability, and even cost:  The M20 is better, no question.

Yes, you can improve an M10, carbs, cams, pistons, jetting, tuning, etc.  You get nostalgia, cool sounds (debatable) and originality, and 150 hp tops and the engine will wear out at 75,000 miles.  And it will cost way more than a stock M20, which is still stronger at 170 hp stock, will last 300K and get you  30MPG.  Turbo?  Why?  BMW made a factory turbo.  170 hp and turbo lag from hell.  Want more.  Turbo an M20.  You can get a very usable and reliable 225 hp.

As was mentioned, car projects do not like deadlines.  They never happen and the rush to complete the job will undermine quality.  Do it once, do it right and take your time.  It is a hobby.

[eurotrash]

At some point, you will lose the ability to hold traction.  And you might want to build brakes to suit  Find the balance at around 200hp, and be happy there. 

 

Oh, and for those of us who don't like BF.com, post your engine recipe/swap in a project blog..

Edited November 27, 2013 by eurotrash

[Simeon]

7-12 PSI? PSH!! Not enough boost! Ya need one of these

I love the chicken wire to keep children and small animals from being sucked into that.

[TobyB]

 

Objectively, the M20 is a better engine.

I'll differ on this!

While the M20 is certainly a more refined design, it suffers from smaller cylinders (and thus, smaller valve area) lighter- weight

connecting rods, and much smaller bearings.  "the M20 is about the only BMW engine that BMW never raced" (Wes Hill)

Plus, it's the only BMW engine to date with a (shudder) timing belt.  Still suffers from the dreaded rocker arm, too. Blech.

The M50/52 S50/52 is roughly the same bottom end, but with a vastly improved head and flow characteristics.  So why not go that way?

 

(this is all for the sake of argument, of course- the M20's a fine engine for what it is, it's just not a race motor.)

 

hee

 

t

[13]

Mainly because the M5X is a bigger engine and basically you have to mod the firewall a bit, and depending on what rad you go with, it's pretty tight.

I've yet to come across a complete m50 or donor car for a decent price whereas m20's are dime a dozen. It can be done but you will probably need to build a beefier rear end for sure. Plus the m20 swap has tons of info available. I'm sure someone might come and say it's even heavier of an engine but eh, whatever works!

[Pierre]

I'll differ too.

 

Smaller cylinders compared to an M10.  But more cylinders.  Can we say Ferrari?  V12 and as small as 1.5 liter.  Smaller cylinders indeed.

Lighter weight rod along with smaller cylinders allow for a higher redline.

 

M20 engines are raced all the time, and  successfully.  The fact that BMW did not race it does not dismiss it.

Build an M10 and an M20 and put them in a 2002.  An M20 will beat the M10 with same driver.

 

Timing belts.  What is wrong with them?  Less noise, less space, more precise timing, simpler design.  Every manufacturer uses it including Ferrari.  Failure of a timing belt is almost always due to lack of maintenance.  M20 timing belts are quite simple to replace.   (Compared to a Honda or a Ferrari or the Porsche 928)

 

An M/S/50/52 is better of course.  It's newer.  Dual cams, 4-valves.  But then, the N55 is better still.  The argument is whether the M20 is a worthwhile swap of the M10.  Taking in consideration reliability, cost of purchase, cost of install, maintenance, power gain and what the 2002s are used for 99% of the time, I say ABSOLUTELY!!!  Including if the purpose is racing.

Edited December 12, 2013 by Pierre