Which engine would you choose for a swap?

[nando]

The point is I have sequential injection on my M20 and it made no difference in fuel efficiency that I can tell. It ended up just being a fun project - the biggest benefit is I haven't had to touch the ignition system in almost 10 years.

BTW, my E30 has run some form of Megasquirt since 2007 - I was likely the first to do MS3 on the M20. :)

[Andrew325is]

If your ok with being down on power and just want a fuel efficient car to zip around and have fun with a M44/M42 with bolt on's should do you good. Cant justify the cost building them when the M54 is a option. I've had my 318is for almost 2 years and Its perfect for around town. I'm sure a shaved 325i flywheel, exhaust, intake and tune would make it even more fun. anything past that seems financially foolish, but to each there own.

I think so too. With so much traffic and stop lights around here I can't get it up to speed much anyways, so more power doesn't really make sense.

Worrying about lack of fuel efficiency and dumping $10,000 on a MM engine does not compute. It's not like you're going to any better gas mileage with a high strung I4 than you will with a stock M54B30, you certainly won't be getting stock 318is gas mileage with a 205hp M42 and an M54 swap's relative cost will take a very long time to make up with a couple extra MPG.

I'm sorry that you got confused. The poll option is for a stroker because I wanted to give people options of engines that are somewhat close in power output, but I would select a stock M44. Upgrades like building a stroker could come later if I wanted. So with a cheap parts car the swap could basically be free. Same as M54, but the M44 still gets a little better MPG and a little better handling. Someone who has both a Z3 1.9 and a 3.0i said they get about 5 mpg better on average with the 1.9. Plus with M54 you need a CAN controller for A/C and things like the OBC and MPG gauge won't work. I can get an M42 coding plug for the OBC (edit: NLA, unless I could find one used.)

[varg]

So this whole time you've been after fuel efficiency and not 200hp? M44 and done it's basically an economy engine, will yield great MPG. Handling? You may not notice a difference in handling there. AFAIK the M54 is lighter than the M20, and the M20/G260 package is 70lbs heavier than the M42/G260 package. CG would be a little further forward, probably a couple percentage points on the F/R balance if you weigh it.

Which would make you smile the most behind the wheel? All 3 produce similar peak power (200+ HP), but each has a little different characteristics and they have their own pros and cons.

Is what I've been operating on, minus the going off track talking about the pros and cons of various motors.

[djjerme]

I’d double check those weights though, the M54 is pretty light for a 6 (all aluminum) and even in my big ass X3 and my heavy right foot, I still manage a 16mpg. That swap is still on my radar for either the Touring or the racecar at some point.


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[Andrew325is]

Yes, fuel efficiency for me, but this thread isn't just for myself. I know other people would prefer to have a more powerful engine. M54 is great. I have one sitting in the Landy, but that vehicle is larger/heavier and needs the extra power.

[digger]

Good info. How about some numbers? And how does that stock M20B25 you're comparing the MM build to compare to an M54B30? Crude 2 bank semi-sequential/part time batch fire fuel injection with limited trim capability vs arguably modern fully sequential fuel injection setup with VVT. E46s get better fuel economy than E30s, they're more aerodynamic but they're also heavier and have more rolling resistance, a few of the factors at play. However, I'm willing to bet an M54B30 swap with stock EMS beats a stock E30 325i in the fuel economy department hands down but someone out there probably can speak from experience on the numbers. If fuel economy is the deciding factor between a $10,000 M42 and an M54 swap which will cost what, half that? You're just not going to recoup that cost in a timely manner.

i was getting 6.5-7L/100km i think its 35 US mpg running motronic with MM cam that was a decade ago. it was 13years ago it was stock b25 but i recall i was luckly to get 7.5/8L/100 on a run. you would really hope a m54b30 would get better economy than any m20. i wasnt suggesting anyone do anything for fuel economy but building a stroker doesnt always cause the economoy to goto shit.

[varg]

State of tune has a lot to do with it. If you don't use mild camshafts and tune to get every last horsepower and ft-lb of torque you definitely do some harm to fuel economy, you can only go so far leaning out cruise areas and transients for economy with an engine that was specced out for peak power. Powerful NA 4 cylinder cars like the S2000 get fuel economy in the mid 20s, and those were tuned with being daily driven reliably and cheaply and passing emissions in mind. Sounds like the MM is tuned to make some unimpressive horsepower to avoid sacrificing economy and emissions passing motor status.

7L/100km is 33.6 US mpg, 8L/100km is 29.4mpg. I've never heard of anyone getting anywhere near that fuel economy with an E30 325i, you must drive like the pedal is made of balsa. Very impressive. You'd have to be out of your head to be dissatisfied with 29.4mpg in a 6cyl E30.

I manage 16-18mpg, that's 13.1-14.7L/100km.

[digger]

State of tune has a lot to do with it. If you don't use mild camshafts and tune to get every last horsepower and ft-lb of torque you definitely do some harm to fuel economy, you can only go so far leaning out cruise areas and transients for economy with an engine that was specced out for peak power. Powerful NA 4 cylinder cars like the S2000 get fuel economy in the mid 20s, and those were tuned with being daily driven reliably and cheaply and passing emissions in mind. Sounds like the MM is tuned to make some unimpressive horsepower to avoid sacrificing economy and emissions passing motor status.

7L/100km is 33.6 US mpg, 8L/100km is 29.4mpg. I've never heard of anyone getting anywhere near that fuel economy with an E30 325i, you must drive like the pedal is made of balsa. Very impressive. You'd have to be out of your head to be dissatisfied with 29.4mpg in a 6cyl E30.

I manage 16-18mpg, that's 13.1-14.7L/100km.

camshaft is most important, just look at what vanos numbers something like an s54/s50b32 cruises at 2500rpm vs WOT 2500rpm. the cam centreline is something like 120-130 cruise vs 70-80 WOT. next to no overlap vs shit load of it. on a fixed cam engine if you dont cop big a hit to fuel economy you are leaving alot on the table for WOT, all depends on priority though

[Shangsta]

M4x with ITBs sounds pretty sweet.

https://youtu.be/0nysqbIuXJY

https://youtu.be/cQyGOB_uwjk

Ill agree with this. I absolutely love the way my itb m44 in my TI sounds

[MrBurgundy]

I really think you'd love an m54 in the e30, since you're going to be running around town mostly..

All the fun is in the middle of the power band. The grunt of that engine is nuts.

[djjerme]

State of tune has a lot to do with it. If you don't use mild camshafts and tune to get every last horsepower and ft-lb of torque you definitely do some harm to fuel economy, you can only go so far leaning out cruise areas and transients for economy with an engine that was specced out for peak power. Powerful NA 4 cylinder cars like the S2000 get fuel economy in the mid 20s, and those were tuned with being daily driven reliably and cheaply and passing emissions in mind. Sounds like the MM is tuned to make some unimpressive horsepower to avoid sacrificing economy and emissions passing motor status.

7L/100km is 33.6 US mpg, 8L/100km is 29.4mpg. I've never heard of anyone getting anywhere near that fuel economy with an E30 325i, you must drive like the pedal is made of balsa. Very impressive. You'd have to be out of your head to be dissatisfied with 29.4mpg in a 6cyl E30.

I manage 16-18mpg, that's 13.1-14.7L/100km.

Just don't look to what car makers were doing in the 70's early 80's to get some of those stupid high economy numbers. The old lean burn systems with crazy 20:1ish ratios. No wonder performance took such a nose dive. But hey, we got something like 30 mpg in our lazy Datsun.

[varg]

And they can't do that anymore because it would fail modern emissions testing.

[Andrew325is]

The best I've gotten in my E30 with the M20 is 9.8L/100km / 24 MPG.

[digger]

The best I've gotten in my E30 with the M20 is 9.8L/100km / 24 MPG.

Hope that's not highway cruising

[Kershaw]

That definitely is. The best I've gotten in my manual ix with highway cruising is 22mpg. I had an automatic ix years ago that I used to get 26mpg pretty regularly. I got 29.5-30mpg in my 325es before that. Standard mileage for a 325i/is that I've seen is around 24-25mpg.