M50NV DD: G240 or G260 on 3.73?

[StereoInstaller1]

Hai guyz.

I am seriously thinking about swapping in a few more valves.

Lets be really clear about the goals of this swap though; this is NOT a race car.

Here is what I would like:
1. Better mileage
2. Quieter valvetrain/mechanicals
3. Cooler looks under hood
4. Less maintenance
5. Less RPM cruising on the freeway
6. about 10 to 20 more HP/TQ, and at lower RPM.

last but not least
7. Working A/C!

Currently, I have a nearly 300,000 mile M20, coming up on a timing belt shortly. Starting to leak LOTS of fluids, and has no working A/C.

My U-joints are getting crunchy, so the driveshaft will need to be rebuilt anyway, so that part of the equation is out.

Yes, I drive aggressively, but the car is a sport cruiser, does zillions of miles a year and is pretty beat. The 3.73 LSD is in OK shape, so I really don't want to change it.

Here is the big question: I want lower RPM on the freeway. I would like a bigger step between 4th and 5th, but in no way am I gonna spring for a 6 speed, or even swap the rear end gearing. The 3.73/G260 combo is 98% perfect, but just a few hundred RPM while cruising will make me happy.

The strength issue is moot as I will likely only put down 155ish RWHP with a bone stock M50NV, right?

I already own both of these transmissions, so cost of that part is NBD.

Fresh clutch is needed anyway, and flywheel is NOT gonna be lightened. Stop and go Seattle traffic, remember? No racecar bullshit at all, this is the DD for the foreseeable future.

What say you, R3V?

Luke

[416stroker]

Go with the 260 the 240 has a closer 123 IIrc.

Crusing on the high way isn't that bad with the 260 3.73 combo. At 75 im at a lill over 3200rpm with 205/45/16

[StereoInstaller1]

OK, I iz bumping this back up.

I needs some answers NAO!

[E30FTW]

Luke. I would recommend you go with a Getrag 240 or 260. I myself prefer the 240 for 250BHP or less M/S5x swaps. They have low gear ratios somewhat close to what was originally mated to the m50, but it still has the 18-19% overdrive 5th you are going to want. Either trans with a 3.73 is a great combination. Good acceleration out of the hole and reasonable highway revs. Also a cheap price of admission.

There is absolutely no way in hell you are going to grenade a 240 with ~200bhp in front of it. Get up to 300bhp, and get a hardcore clutch.. and then you will have issues.. but 200bhp and a stock m20 flywheel/clutch? No worries!

[StereoInstaller1]

From that chart (thank you very much, BTW) it looks like the 240 has a slightly higher engine speed in 5th?

[smonkbmw]

g260 and a 3.64. you basically have to shave the flywheel there by making it lighter when you swap regardless. but its nothing that will make a difference in traffic.

[416stroker]

I DD my car and its set up how you want yours. The only difference is i have a 8lb flywheel and it drives fine it vibrates a lill at idle thats about it.

[JGood]

Any reason you want lower RPM's? With my m50b25tu/260/3.73 in my 85 325e, I get much getter gas mileage at 65mph then I do with my m20 325is. I'm averaging 33-34 at that speed vs. 27-28. And the throttle response is different... it's hard to explain but it just feels better at 3k RPM on the highway vs an m20. I'm not sure how to explain it. The m50 feels like it's not doing any work and not straining the motor at all. The m20 sounds and feels like it's being really pushed to cruise a 3k.

And don't underestimate an m50. Mine pulls hard in comparison to my m20. Ran a 14.4 @ 95 vs. a 15.4 at 89 in my m20 car.

I did my swap for the same reasons as you (250k miles, leaks, burning oil, sick of belts/adjusting valves, etc...), and ended up spending nothing (literally, after I sold my old motor stuff, I broke even). You'll be very glad you did it. I couldn't be happier.

[E30FTW]

From that chart (thank you very much, BTW) it looks like the 240 has a slightly higher engine speed in 5th?

1% rpm difference.

[416stroker]

Any reason you want lower RPM's? With my m50b25tu/260/3.73 in my 85 325e, I get much getter gas mileage at 65mph then I do with my m20 325is. I'm averaging 33-34 at that speed vs. 27-28. And the throttle response is different... it's hard to explain but it just feels better at 3k RPM on the highway vs an m20. I'm not sure how to explain it. The m50 feels like it's not doing any work and not straining the motor at all. The m20 sounds and feels like it's being really pushed to cruise a 3k.

And don't underestimate an m50. Mine pulls hard in comparison to my m20. Ran a 14.4 @ 95 vs. a 15.4 at 89 in my m20 car.

I did my swap for the same reasons as you (250k miles, leaks, burning oil, sick of belts/adjusting valves, etc...), and ended up spending nothing (literally, after I sold my old motor stuff, I broke even). You'll be very glad you did it. I couldn't be happier.

I Get about the same fuel milage.

[SamE30e]

My G240 with a 4.10 M50NV sits around 3500 at 125km/h.

I would say a 3.73 would be at about 3000.

G240's break around 250 crank hp if you beat the shit out of it. My setup is 11lbs M20 single mass flywheel, Z3 1.9 shifter, E36 5spd driveshaft, E30 CSB backwards, M20 starter stock 318 tranny x member and mounts.

I beat the piss out of it and it hold up all day and I'm putting out a bit more then stock (Dinan chip, headers, full exhaust, CAI) I've seen a stock E30 M50NV put down 170whp.

[StereoInstaller1]

Wow, this thread is a month old and now I am getting some decent responses.

Thanks, guys!

Since I love how my 260 shifts, I think it should stay.

Now I have to get more parts together!

Luke

[dude8383]

Luke,

Is there a reason why you want the MV over a VANOS motor? The vanos motors are pretty cheap nowadays.

I'm running a Getrag 250 with a 3.25 rear and at 80mph rev's are aroud 3.5k.

[zav3n]

ive been driving on my 240 w/ 3.73 for a while now (2 years), no problems.

[StereoInstaller1]

Luke,

Is there a reason why you want the MV over a VANOS motor? The vanos motors are pretty cheap nowadays.

I'm running a Getrag 250 with a 3.25 rear and at 80mph rev's are aroud 3.5k.

Because they are worth less, and there is one with about 70,000 miles sitting at the shop.

I can get it CHEAP, or damn near free, maybe even free. Needs an intake manifold, harness, accessories. All of which I can junkyard, basically.

Also, less cost with the VANOS stuff, less ECU (MS is easier if I wanna), less special tools, etc. Considering my needs of better fuel economy, better looks and less maintenance, the NV is fine.

Don't bother debating the better looks part, either....M20s and M30s (fuel THAT? Fuck no) the 24Vs win.

Don't get me wrong, I love me some 12V motors. I love the M30 torque, the feel is awesome...but this is the DD, not a hot rod.

Luke