m50b25 non-vanos questions... fuel efficiency?

[pantelones]

i am in the process of getting an e30 and have been doing a lot of reading about these cars. i plan on doing a 24valve swap, but i also plan on at some point putting a turbo on the car. from what i have read, the m50b25 non-vanos seems to be the best/easiest to boost, but please correct me if im wrong. in the mean time i think im going to tune it for fuel efficiency, so i was wondering if anyone has done this and what kind of numbers they were getting. when i do the initial swap im going to port and polish the head, make a set of equal length headers, and get a set of euro itb's and make them work. i figure with the motor flowing air smoothly, and a good tune i was thinking i could maybe get around 30mpg highway. im not really sure what these motors get stock, and im too lazy to search so if anyone knows please post it.

[nwe30]

heads up, don't get a 4.10 lsd haha. i have a non vanos m50 and i get some shit gas mileage.

[pantelones]

haha, yeah no 4.10 for me. i probably should have stated that ill be running a 3.73lsd (maybe a 3.46 or 3.25) and a getrag 260 trans...

[Adrian_Visser]

im too lazy to search.

Good luck with that.:roll:

If you want gas mileage get a 2.79 or 2.93 diff out of an eta. Mucho low revs on the highway. I don't know how you plan on running ITB's unless you are going to:

a) go standalone and alpha-N tune OR
b) build a plenum and run a MAF with the stock engine management.

[pantelones]

ive been searching forums for the past 8 months and ive come to realize that its better to just ask your question and hope someone is nice enough to share their knowledge. obviously you can find things that are more common relatively easily, but for some, like a step by step how to on an abs delete, it comes up with 15 post asking if their is any info on a abs delete and everyone tells them to search, but there is no/very vague info on the forum about an abs delete.

anyways, yeah a really low ring and pin like you said wouldn’t be a bad idea, but would that only benefit on the highway, or city too? and for the itb's i would be making a plenum and using a miller MAF. i could use the euro intake and a MAF, but id rather just make one since i have the resources to do so.

[Tchao]

M50nv isnt the best/cheapest option to turbo at all.

Go vanos M50. This is coming from a guy with a non-vanos.

[Fusion]

M50B25nv/G260/o3.73 I get about 23.5mpg combo, I once did 27.6 doing 55mph on a long highway trip, and I get around 15mpg at the track.

[CorvallisBMW]

Vanos will net you better fuel efficiency than non-vanos. It simply uses cam timing to optimize engine torque, meaning you can rev the engine less. Less revs/less TB opening = better fuel efficiency

[pantelones]

M50nv isnt the best/cheapest option to turbo at all.

Go vanos M50. This is coming from a guy with a non-vanos.

really? from what i have been reading the non-vanos is better suited for boost. care to share why you would have rather gone with a vanos m50?

M50B25nv/G260/o3.73 I get about 23.5mpg combo, I once did 27.6 doing 55mph on a long highway trip, and I get around 15mpg at the track.

thanks for sharing. 23.5mpg doenst sound that bad with a 3.73

Vanos will net you better fuel efficiency than non-vanos. It simply uses cam timing to optimize engine torque, meaning you can rev the engine less. Less revs/less TB opening = better fuel efficiency

hmm, well if its better to use the m50tu for a turbo build then i guess ill be gaining some mpg's while i raise the funds for a turbo. but then i probably wont go through the hassle of making itb's work since ill have to make them clear the vanos solenoid.

[pr0craztinazn]

Mixed highway and city + 3.25 diff + Getrag 260 + M50NV = 27mpg mixed, and my DME has no speed sensor reference signal, so it is throwing codes and supposedly has the limp mode reduced redline because I have been too lazy to fix it. Keep in mind I get those #s including sitting in traffic for an hour during my commute each day, 5 days a week. If I drive like a douchebag, I get 22mpg, while all highway is just short of 31. The Vanos versions will net you some additional low end and better MPG, but its doable from a NV with the right gearing.

[Wh33lhop]

Best I've gotten with a G260/3.73 is 26mpg on the way to the picnic (cruising 75-90ish). I get about 19mpg mixed, but I drive like a lunatic.

Don't pick an NV over a VANOS to boost, that issue has been debated many times and basically there are no major upsides to the NV besides not having VANOS (cylinder walls are a few thou thicker if anything, the rods are beefier but unnecessarily so = extra reciprocating mass, double valve springs are unnecessary, etc). And this is coming from a NV owner.

[pantelones]

Mixed highway and city + 3.25 diff + Getrag 260 + M50NV = 27mpg mixed

how do you like that setup? i would imagine that it would still be pretty quick and fun to drive right? i just bought an 87 325e which is geared similar and i like the way it pulls, but just wish it were a little faster.

my current dilemma is what to do with the motor. ive been leaning toward putting a 731 head on my rebuilt m20b27 and use 1.3 motronic with all i related parts needed, but i realized today that the cost and amount of work is almost the same as doing a m50 swap. so now i need to look into building a m50 and decide what i would want to do with it, and how much it would cost.

i am also leaning toward no boost, and just making a really efficient N/A motor. the car is just going to be a spirited daily driver, not a track rat. the hassle of making euro itb's clear the vanos solenoid is enough to make me go non-vanos. to me itbs = throttle response, and that makes your car feel more responsive/faster even though your not making any more power.

[highoutput]

Wow, I'm seriously doing something wrong. I recently finished my M50 Vanos swap, and my car gets noticibly BAD gas mileage. I'm talking 20 on the highway....thats not "official" yet, but it seems that way, and its not far off either way. I've done the math, just roughly, not exact.
I DO have S50 cams and a Turner tune......but christ I never thought I'd miss my M10 for any reason at all, lol

[CorvallisBMW]

No reason you shouldn't get 30mpg highway, unless you're running a 4.44 diff

[nwe30]

im getting 15mpg right now with a 4.10 lsd. WTF. and i've been trying to drive alot more economically.