Which engine for boost? (M20 vs M50)

All boost related things here. Turbos, SuperChargers, FMUs, Megasquirt, et al.
User avatar
blasphemy101
I <3 E30's
Posts: 1041
Joined: Sat Apr 07, 2012 9:20 pm
AntiSpam: No

Which engine for boost? (M20 vs M50)

Postby blasphemy101 » Mon Jan 13, 2014 6:00 pm

So I *MAY* have an upcoming opportunity to pick up an early E36 325i for dirt cheap.I like E36s, but definitely can't afford/justify a car, so I would just be buying it for the engine and parting out the couple of aftermarket parts and junking the rest to recover the cost of the car. It's still very tentative (I haven't seen the car/heard a solid price), but for the sake of academic discussion...Which is a better engine for ze tarbo boosts?

From the little bit that I've seen online, the M50 generally winds up with a better power curve and flows more (makes more power) for given amounts of boost. On the downside, its higher compression (among other things?) seems to make it more fragile. Of course with the engine out of the car, this may be easier to remedy. Anyone have experience with thicker MLS headgaskets and/or M42 pistons/M52 rods?

My M20 has been rock solid so far at 10 PSI, but with my big turbo the power band sucks, and a swap might be fun to do. It also might wind up a huge headache...
User avatar
Yoshi
Site Admin
Posts: 9085
Joined: Thu Feb 26, 2009 7:47 pm
AntiSpam: No
Location: North VA
Contact:

Re: Which engine for boost? (M20 vs M50)

Postby Yoshi » Tue Jan 14, 2014 1:05 am

fragile? hell no. It's much more stout. The average M20 turbo I see puts down 300whp at 15psi. I put down over 380whp at 15psi on a holset HX35 on my non vanos. And that's the chocked version of the motor. With a good turbo and nice tune, you should be able to do 400whp on an M50 based motor.

The M20's biggest issue is that it can't breath. Vanos/dohc/better intake all help that side. A better manifold and dohc for the exhaust helps evacuation. Better atomizing injectors and sequential ignition/injection eek out that much more power.

Hands down M50 simply from a paper/theoretical standpoint. Now, you still got to swap the motor and all that crap.
Image
Status: HG repair. 488wtq though!
User avatar
blasphemy101
I <3 E30's
Posts: 1041
Joined: Sat Apr 07, 2012 9:20 pm
AntiSpam: No

Re: Which engine for boost? (M20 vs M50)

Postby blasphemy101 » Tue Jan 14, 2014 2:50 am

Yoshi wrote:fragile? hell no. It's much more stout. The average M20 turbo I see puts down 300whp at 15psi. I put down over 380whp at 15psi on a holset HX35 on my non vanos. And that's the chocked version of the motor. With a good turbo and nice tune, you should be able to do 400whp on an M50 based motor.

The M20's biggest issue is that it can't breath. Vanos/dohc/better intake all help that side. A better manifold and dohc for the exhaust helps evacuation. Better atomizing injectors and sequential ignition/injection eek out that much more power.

Hands down M50 simply from a paper/theoretical standpoint. Now, you still got to swap the motor and all that crap.


I acknowledged the M5x motors make more power. It just seems like it takes more work to run boost on them. All an M20 needs is engine management and head studs. It seems like everyone on bimmerforums (the only resource I know for E36 turbos) takes lowering the compression as a requirement.
User avatar
Yoshi
Site Admin
Posts: 9085
Joined: Thu Feb 26, 2009 7:47 pm
AntiSpam: No
Location: North VA
Contact:

Re: Which engine for boost? (M20 vs M50)

Postby Yoshi » Tue Jan 14, 2014 6:31 pm

There are a bunch of off the shelf tunes for stock motors with stock compression. Just like the M20, shove some studs on it and go. I wouldn't mind lowering compression with an MLS gasket. To each their own though.
Image
Status: HG repair. 488wtq though!
User avatar
M20_fever
Größter Vorsitzender
Posts: 11026
Joined: Fri Feb 27, 2009 1:28 pm
AntiSpam: No
Location: Northern IL

Re: Which engine for boost? (M20 vs M50)

Postby M20_fever » Tue Jan 14, 2014 8:44 pm

dropping compression with a thicker head gasket ruins the quench and squish areas. The right way to lower compression is with custom pistons. A big ass turbo on an m5x is going to be nearly as laggy as on an m20. with proper head work an 885 head will flow more than enough air to make 400whp. Stick with your m20 and focus on improving the components of your current setup.
Image
Midwestern Councel C Prepared class champion 2012
North Suburban Sports Car Club C Prepared class champion 2012
HSAX Instructor

GET YOUR E3P GEAR HERE: http://www.cafepress.com/e3pgearshop
pr0craztinazn
I <3 E30's
Posts: 490
Joined: Sun Aug 16, 2009 2:01 am
AntiSpam: No
Location: MD
Contact:

Re: Which engine for boost? (M20 vs M50)

Postby pr0craztinazn » Wed Jan 15, 2014 4:35 am

The quench area gets killed with a MLS on a M50, but it still makes more power everywhere with the same sized turbo than a M20 will with the same amount of work into it. There are canned tunes for the 413 DMEs that will be as easy as the M20's 173 chips, but yes, the MLS or some similar thicker headgasket is required. Some have run stock compression with boost, but the highest amount of power I've seen with that combo is 12psi and 346whp.

I'd take the M50 any day of the week and twice on Sundays if you are going to boost it. Even factoring in having to do a swap to get it in the bay, it's just easier to deal with. However, if cash is tight, don't even bother starting the project until you have more saved up.
User avatar
blasphemy101
I <3 E30's
Posts: 1041
Joined: Sat Apr 07, 2012 9:20 pm
AntiSpam: No

Re: Which engine for boost? (M20 vs M50)

Postby blasphemy101 » Wed Jan 15, 2014 4:46 am

pr0craztinazn wrote:The quench area gets killed with a MLS on a M50, but it still makes more power everywhere with the same sized turbo than a M20 will with the same amount of work into it. There are canned tunes for the 413 DMEs that will be as easy as the M20's 173 chips, but yes, the MLS or some similar thicker headgasket is required. Some have run stock compression with boost, but the highest amount of power I've seen with that combo is 12psi and 346whp.

I'd take the M50 any day of the week and twice on Sundays if you are going to boost it. Even factoring in having to do a swap to get it in the bay, it's just easier to deal with. However, if cash is tight, don't even bother starting the project until you have more saved up.


Well my M20 is already boosted, so there's that...

There's a slim possibility that a E36 might be falling into my lap for a REALLY good price, so it raised a few questions.
User avatar
Yoshi
Site Admin
Posts: 9085
Joined: Thu Feb 26, 2009 7:47 pm
AntiSpam: No
Location: North VA
Contact:

Re: Which engine for boost? (M20 vs M50)

Postby Yoshi » Wed Jan 15, 2014 12:36 pm

It's a fun project. Bottom line, the M50 will net more power with the identical setup. It's just whether or not you want to swap and deal with the rest.
Image
Status: HG repair. 488wtq though!
User avatar
blasphemy101
I <3 E30's
Posts: 1041
Joined: Sat Apr 07, 2012 9:20 pm
AntiSpam: No

Re: Which engine for boost? (M20 vs M50)

Postby blasphemy101 » Wed Jan 15, 2014 3:38 pm

Yoshi wrote:It's just whether or not you want to swap and deal with the rest.


Definitely not scared of the swap at this point. I think it could be a fun project. I've never swapped an engine before...

It's just a matter of whether this guy comes through on the E36. If he doesn't, I'll just keep going with the M20.
User avatar
blasphemy101
I <3 E30's
Posts: 1041
Joined: Sat Apr 07, 2012 9:20 pm
AntiSpam: No

Re: Which engine for boost? (M20 vs M50)

Postby blasphemy101 » Wed Jan 22, 2014 7:42 pm

Meh - he's asking 1000 OBO. He told my friend (his neighbor) he'd probably take 800. It sounds like it might be a little too rich for my blood, given how well the M20 is running and its appetite for rear tires...

Hopefully I'll get a chance to check it out this weekend. I'll post up pictures.
User avatar
Yoshi
Site Admin
Posts: 9085
Joined: Thu Feb 26, 2009 7:47 pm
AntiSpam: No
Location: North VA
Contact:

Re: Which engine for boost? (M20 vs M50)

Postby Yoshi » Thu Jan 23, 2014 12:02 am

Yea. not worth it.
Image
Status: HG repair. 488wtq though!
User avatar
blasphemy101
I <3 E30's
Posts: 1041
Joined: Sat Apr 07, 2012 9:20 pm
AntiSpam: No

Re: Which engine for boost? (M20 vs M50)

Postby blasphemy101 » Thu Jan 23, 2014 4:25 pm

Yoshi wrote:Yea. not worth it.


Looking on craigslist, it's a decent price for a running E36, but I'm starting to think about how much the ~$400 the whole swap would end up costing could do for the M20.

On the other hand...It's a 94 manual, so I'd get almost everything needed for the swap in one car, and I'd know for sure what kind of condition the engine was in.
User avatar
Yoshi
Site Admin
Posts: 9085
Joined: Thu Feb 26, 2009 7:47 pm
AntiSpam: No
Location: North VA
Contact:

Re: Which engine for boost? (M20 vs M50)

Postby Yoshi » Thu Jan 23, 2014 9:16 pm

shitty getrag 250 trans. Meh
Image
Status: HG repair. 488wtq though!
User avatar
M20_fever
Größter Vorsitzender
Posts: 11026
Joined: Fri Feb 27, 2009 1:28 pm
AntiSpam: No
Location: Northern IL

Re: Which engine for boost? (M20 vs M50)

Postby M20_fever » Fri Jan 24, 2014 1:49 am

You already have traction problems with your M20, what are you really going to gain for all the cost and work?
Image
Midwestern Councel C Prepared class champion 2012
North Suburban Sports Car Club C Prepared class champion 2012
HSAX Instructor

GET YOUR E3P GEAR HERE: http://www.cafepress.com/e3pgearshop
User avatar
blasphemy101
I <3 E30's
Posts: 1041
Joined: Sat Apr 07, 2012 9:20 pm
AntiSpam: No

Re: Which engine for boost? (M20 vs M50)

Postby blasphemy101 » Fri Jan 24, 2014 4:18 am

M20_fever wrote:You already have traction problems with your M20, what are you really going to gain for all the cost and work?


Lol the traction problems are due to all-season tires...

The biggest benefits would be the better power band and being able to go over the engine. It just seems like it might be nice to pull everything out and drop in a nice, clean setup. It was much more attractive when my friend was talking like 500-800; that would have made it an almost-free swap, versus a cheap swap.

I understand completely where you're coming from, though. It would probably just be easier/cheaper to pull the M20 and refresh it if I really want a new motor that badly.

Oh well. I'll still check it out this weekend, since my buddy was nice enough to try and arrange the deal.

Return to “Forced Induction”

Who is online

Users browsing this forum: No registered users and 2 guests