M10 Vs M42 (realistically)

[StophinHousen]

Hiya, 

So I know this is a sore subject and I've looked into it but they are old threads and I think since then the s14 has become too much of a unicorn, the m42 swap has become more of an option and I want to here some opinions.  The reason I'm bringing it up is my built up m10 decided to start to knock hello and although the M10 is neat and a Icon its never been quite what I've been looking for and Im thinking of swapping rather than another rebuild. I live at 8,000 FASL and can go as far as 12,000, part of me thinks the DOHC and modern fuel injection would benefit me greatly (and with the option of going with a supercharger even at low psi to make up for lost power)  what is everyone's thoughts ? (And again for those who hold the m10 as a saint I respect the motor) but is the m10 realistically going to be able to push out the same amount of HP on a street-able build ? at the very least at altitude? I had hightop pistons, 292cam, Hbeams, weber 38, Msd and dizzy, and some other goodies. Was not bad but i don't know if i had ever made it to or over 100hp at the wheels.  older post show dynos only getting 110 or a hair or two more (I'm not sure what altitude they were at)  Ive seen some people say that set up "will make 150 and blow away a m42" but eh im skeptical of those numbers . What do you all think swap or rebuild ? (I do know I will keep all my m10 stuff so if I change my mind I can always go back.)

[Einspritz]

Consider calling Dave Redszus at Precision Automotive Research about the M42. In the '90s, they created an engine and suspension package for the 318iS. With cams and a few other modifications, they were able to get good Hp gains to make the 318iS competitive with the M3 and S14.

 

Remember the Italian and Portuguese 320is had a 2.0 Liter S14 which had similar Hp as the (U.S.) 2.3 liter engines, just at a different RPM.

 

Perhaps that is what you want; in a word, cams.

[Mike Self]

I've never driven an 02 with an M42, but I do have a somewhat tricked out E30 318is (chip and various suspension enhancements) and absolutely love the engine.  Even pulling 3-400 lbs more in the E30 than in a 2002, it's no slouch.  Pair it up with a 3.90 diff and its high revving would match the '02's nimble handling.  

 

Back when Z3s only came with an M42/M44 there were turbo kits that really boosted the engine's performance--well above 150 hp.  Find one of those, hang it on an M42 and stuff it in your '02, then prepare for some fun (with suitably enhanced suspension and brakes, of course).  While an M20 will give you more torque and horsepower, it's also heavier and will change the 02's handling.  But it's actually an easier install on an '02 than an M42.  Both will require firewall and tranny tunnel housing modification.

 

IMHO

mike

 

 

[TobyB]

DASC notwithstanding

(Downing Atlanta SuperCharger)

 

the M42 is just a 'step up' from the M10, and it's

not a big step.  It is also a redheaded BMW stepchild with

the unique front chains and guides costing 3x what you can buy

running complete engines for.

 

Yes, you can strap on turrrrbbboooo for real power (r3vlimited M42 subforum for more details)

but at that point, you can also strap turrrbbboooo onto an M10 for the same order of expenditure magnitude,

and the M10 bottom end is about 4x as stout as the M42 (not that the M42 is weak, mind you).

 

The M42 is now a vintage BMW engine, and it's not the icon that the M10 is.  It's a BETTER engine

(DOHC being 'better') but it was a relativelty short- lived transition to the M44, then it disappeared.

 

I wouldn't.  But if you like it, you certainly can.  It's just not going to blow you away like an S14 or M54 would.

 

t

 

[StophinHousen]

No I'm not looking for mind boggling speed, Im just looking for a step up or even a step sideways from where I was with my built up m10. I Don't have the money to build another block and head the right way, and I dont want to just throw together one of our tired motors and blow it up too. (I've put off suspension for close to 5 years now because I keep having to go back and spend money on the m10)  Im still deciding what to do, I loved this car and I shipped it to and from Hawaii because I couldn't part with it, but this last summer with its oil burning, rich and stinky exhaust I grew distance from it, always had to do something before I could take it to work and when it decided to start knocking (after i made a emergency run to the parts store for our troubled e34) it broke the spirit some and made me doubt keeping it. 

[reyes02]

It is also a redheaded BMW stepchild with the unique front chains and guides costing 3x what you can buy running complete engines for.

Comment of the week [emoji23][emoji1417]


- Reyes

[Schnellvintage]

Here.... M10 with 10.5:1, H beam, 284 IE cam, match ported. 318i TB. Megasquirt.
Balance everything.
RWHP max 128 (127.2), RW Lb ft 133. Simple.... W/ 91 octane pump gas.

New motor with less than an hour running.  can't wait til she is broken in...so far 3500 miles. still running strong.
Matt



Sent from my iPhone using Tapatalk

Edited September 23, 2018 by Schnellvintage
correction

[jrhone]

Jakeb from ClassicDaily.net does m42 swaps and has done m42 turbos pushing about 350hp.  It’s doable.  Me personally I’m leaning towards the m20 when I do a wild build.   

[Harv]

Has the low oil pan issue of the M42 been addressed? I like the fuel injection on an M10 idea. That Webber isn’t doing you any favors in Aspin. 

 

John

[StophinHousen]

If I do go with another m10 I will go with a EFI set up. The weber (both 38 and 32/36 and the solex) have never played nice. my Carb has 130 mains and 200 air corrector's and I still run black with my AF dropping out of range quite often.  

 

I like the m20 as a build too, for me though id hate to cut the nose of the car to make it fit, with the m42 if I hate it I can relatively put the car back together and just have some extra holes.  Plus with a m20 I need to re fresh/ beef up the suspension and with that i wouldn't be road ready till like 2020 

[irdave]

A little relevant as I'm in FC at 5,000'.  '72 tii with Kfish still in there.  I just built an engine with the relevant bits- 11:1, 1.8i head with +1 valves, stock cam.  I need a limited slip diff.  You could easily run 12.5:1 compression with stock everything and not have problems- as long as you stayed up there- coming down to Denver or GC could give a little knock- so maybe 11.5 or 12 instead?

 

And from jetting motorcycles up here, down be afraid to go lean- nobody on the planet is driving a 2002 as high as you are...

 

And from the years I spent in Summit County, everything is slow.  What about the guys at Flyin' Miata?  They're just down the street and have a ton of turbo experience- there's a manifold for sale now in the classifieds...

[AustrianVespaGuy]

My Megasquirted M10 is very, very similar to @Schnellvintage's build, just with 9.5:1 IE pistons.  Don't have the dyno graph to prove it but also puts out about 130 HP at the crank.  Now for the interesting part: I've been surprised but come to the conclusion that it's also just a tad faster than my new-to-me 325iS with the stock M20 up to about 80MPH or so.  Above that the larger displacement M20 can better keep pushing the air out of the way, but on the street I've decided that built M10 > stock M20.

 

ALSO, at ~130HP, the M10 has a specific output (65HP/Liter) EQUAL to the 282 HP/4.4L DOHC, variable valve timing, COP, etc. all fancy modern M62 in my 2000 540i!

 

What I'm saying is, from my point of view, properly built internals are what make an engine, almost regardless of starting configuration.  Maybe a DOHC engine has more potential overall, but the M10 has a LOT of overhead that can pretty easily be squeezed out of it!  Build and install M42 if what you want is a 2002 with an M42, but you'll have a hard time convincing me that a stock M42 is enough 'better' than an M10 all on its own to warrant the swap on that premise alone.

 

Also for high altitude, see if you can find ethanol-free gas.  Not only does pure gas have more energy density than the diluted stuff (gasoline has 1.5x more joules/gram than ethanol!) but carbs like it better, and it's less likely to boil off and cause you issues with vapor lock!

[kbmb02]

On 9/22/2018 at 7:26 PM, Schnellvintage said:

Here.... M10 with 10.5:1, H beam, 284 IE cam, match ported. 318i TB. Megasquirt.
Balance everything.
RWHP max 128 (127.2), RW Lb ft 133. Simple.... W/ 91 octane pump gas.

 

 

Data point: M10 curves tend to look similar on the dyno.

 

The dyno sheet below is with a Weber 38/38 carb, 9.6:1 compression, custom cam grind and a few other tricks. Of course, it probably doesn't idle as cleanly or smoothly as a the megasquirt build, and tuning requires a screwdriver. -KB

 

[KenH]

As I have posted in other threads on this topic, I went with a turbo M42.  On a Dynapack dyno it posted 259 hp and 255 torque. These numbers were at 12lbs of boost.  Do I really need that much, not really.  Do I use all of that all of the time, nope.  Is it a hoot to drive, you bet :)

 

Just driving around town the car is pretty mellow to drive.  When you do get on it, it LOVES to go.  The Garrett ball bearing turbo starts to spool around 2500 rpm give or take. It certainly feels and drives a bit different from a NA engine.  This is my first turbo car and I'm really enjoying the heck out of it.

 

Is this configuration for everyone, nope.  That is the great thing, there are choices pick what is best for you.  It shouldn't be which is best, but which is best for you.

 

 

[AustrianVespaGuy]

48 minutes ago, KenH said:

As I have posted in other threads on this topic, I went with a turbo M42.

What might be most interesting for the OP is: what led you to select the M42 for your turbo build rather than the M10? Looks great and LOTS of ponies in a 2002 though, that's for sure!