So who's runnin' the 4.10?

[mmsteinwand]

Hey everyone, this is my first thread after spending many hours wading through various topics-great site! So, I want to put a lsd in my '89 325i and I can't deside between the 3.73 (current ratio) or going to a 4.10. I've read the difference in highway cruising is 500-700rpm. Has anyone checked their gas mileage before and after?
I live in the Colorado mountains and bought this car for rallying various 2-lane mountain roads and passes...for this I figure the 4.10 would be sweet. But I don't want to compromise economy too much, as I drive on straight roads as well. Should I go to the 4.10 or stick to the 3.73?

[PiercedE30]

I have a 4.10 but it is in an auto(at the moment), and I still have (on parts car) a 3.73 (with a manual that will be put in the auto). I'm not sure, but I am getting pretty much the same gas mileage with the 4.10 auto as I was with the 3.73 manual, but then again thats compairing two things to each other instead of one thing at a time. But my rpm's are definitely higher with the 4.10 by about 500 rpm's so that should give you a good idea.

[asubimmer]

my car has a 4.10

[92 mtechnic cabrio]

I've only had a 4.10 but I've driven E30s with 3.73s.

All I have to say is that I'll stick to 4.10.

I would guess the fuel economy to deviate by something like 3mpg

[nando]

I have a 4.10 and my gas mileage sucks, but it's not the differentials fault. I went through 1/4th of a tank in 10 miles of "driving" yesterday! :(

on the freeway it's not too bad, the speed limit here is 70 and I still get a good 20mpg. the nice thing is it puts me right into my torque band, so a slight stab of the throttle and I'm doing 90 in no time :D

[JRowe]

I have the 4.10 and, dollar for dollar, I believe it is the single best performance improvement you can make. Incredible difference in torque and acceleration. You do have to shift a bit sooner and it does lower your top speed, but going from a 3.73 to a 4.10, I would never go back. I definately recommend it for a mildly modded engine. BTW, I get mid 20's for gas mileage in mixed driving.

[SpecM]

-I had a 4.10 LSD in a mostly stock '88 325 super-eta. First gear went quick but it really wasn't that bad, all in all. LOTS of low-end, top speed was 115-ish (with a 5300 rpm redline) and about 20-23 mpg.

[mmsteinwand]

So, I guess the consenus is; yeah, it lowers your gas mileage, but the performances is worth it? I was worried about that...

[Axxe]

I've got a 4.10 in my M20B25 318is, haven't driven it enough to give a fuel consumption increase over my previous e30 with 3.73, however it kicks in the pants a lot better, especially with a light flywheel, first is sooooo short :D

[JRKOUPE]

So, I guess the consenus is; yeah, it lowers your gas mileage, but the performances is worth it? I was worried about that...

....I understand your concern to a point. I mean to me the mpg should not be your deal breaker. Its not going to add up to much....maybe a few beers a week. I run a 4.10 on a car I bought w/ a 3 73.......it gives car nice grunt.....but on some tracks a 373 or 391 would be better. Perhaps you should get a chip for increased canyon carving and save over the purchase of a 410. To me it should be about whether you truly want a 4 10.....not the mpg concern...try to drive a local members.........

[92 mtechnic cabrio]

So, I guess the consenus is; yeah, it lowers your gas mileage, but the performances is worth it? I was worried about that...

Where are you from?

[mmsteinwand]

Crested Butte Colorado; 9000 ft. high, mountains all around, lots of snow in winter, 3 miles from the ski resort-most extreme terrain in the country!, and some of the best mountain biking anywhere. And in the summer I roll out my e30; great mountain roads, little traffic, the cops just flash their lights at ya (rather than pull ya over), atleast close to town...But, not alot of BMW entusiaists...all the mechanics in town are bitter old dudes, or they're building up their full size trucks with 16" suspension lifts and 44"s. However, I do make it to Denver/Boulder quite often...

[pennell]

I have a 4.27open on mine and it sucks for highway, but you butter right through 1st and 2nd. 3000RPM at 100km/h. It would be even sweeter if it was an LSD as well. I was going to get a 3.73 but it sounds like it takes the fun away from the car. Is there anyway I can turn my rear end into an LSD? Or I am probably better off just getting a 4.10LSD

[PiercedE30]

buy a quaife locker to throw in there, then you'll have a 427 lsd
btw, what did the 4.27 come out of?

[blueapplesoda]

4.10 lsd. ftw. starts and launch in 2nd real easy.