240D Differential swap - Page 3 - PeachParts Mercedes-Benz Forum

swampmonkey · #31 12-05-2015, 08:39 AM

Quote:

Originally Posted by pj67coll

That's an interesting video clip but the speedometer is in KPH not MPH.

- Peter.

i know it is, but i recalculated it, i have no problem reaching 120km/h,
but since you guys mostly seem to be in the us, i thought it seemed more fit to write 75mph.

swampmonkey · #32 12-05-2015, 08:45 AM

Quote:

Originally Posted by t walgamuth

Imperial gallons?

yeah, supposed to. (if imperial is US-gallons)
https://www.google.se/search?sourceid=chrome-psyapi2&ion=1&espv=2&ie=UTF-8&q=0.57l%2F10km%20to%20mpg&oq=0.57l%2F10km%20to%20mpg&aqs=chrome.0.69i59j69i64j69i58.3812j0j1

when doing the math manual i came out with the same answer.

or 0.57l/10km if that feels better. but that was on oldstyle-diesel and the 2.88 and more healthy engine (real diesel that was for the cars 25years ago over here) one can still get ahold of it...

on normal diesel and the other 3.07 i did 0.63l/10km with the 2.65, and a tad lower speed reached the same consumption with the 3.07differential.

the 2.65LSD i had to pair with low-profile 14" to be able to get going properly, while i do highprofile 15" with the 3.07. the rpm/speed came out about the same, but the drag was significantly less with low-profile tires, as far as i imagined atleast.

those drive was utterly economical thou.
mixed driving i get about 0.69-0.7 out of the 3.07 on normal diesel. witch is about 33-34mpg.

ive heard some rumors/knowledge that they geared the cars so that it could incline, say a 10degree hill, at 60mph at fourth gear without loosing speed. or something like that.
the diesels seem to have been used a lot in city trafic aswell, and the european roads was to some degree utter crap compared to today. (besides autobahn etcetc)

the fact that they 1981 swapped from 3.27 to 2.47 in the 380SE
and 2.82 to 2.24 in the 500SE ought to be some hint that Mercedes reevaluated their thought on gearing, + the fact that cars ought to get better mileage etcetc.

t walgamuth · #33 12-05-2015, 09:07 AM

Imperial gallons are bigger than us gallons, hence offer higher miles per gallon results.

UK gal =

US gal lqd * 0.83267

So take .83267 x 40 mpg = 33.3 mpg.

That sounds more like it.

mannys9130 · #34 12-05-2015, 05:04 PM

Quote:

Originally Posted by t walgamuth

Imperial gallons are bigger than us gallons, hence offer higher miles per gallon results.

UK gal =

US gal lqd * 0.83267

So take .83267 x 40 mpg = 33.3 mpg.

That sounds more like it.

Bingo.

swampmonkey · #35 12-05-2015, 10:21 PM

Quote:

Originally Posted by t walgamuth

Imperial gallons are bigger than us gallons, hence offer higher miles per gallon results.

UK gal =

US gal lqd * 0.83267

So take .83267 x 40 mpg = 33.3 mpg.

That sounds more like it.

nope. im talking US mpg, not UK mpg. sorry about the missunderstanding. its not Imperial mpg. but US mpg.

its 33mpg mixed US gallon.
and ive peaked at 41US mpg with real diesel,
and on normal diesel its 38mpg, as best.

or if you prefer imperial gallons, ive peaked at 49mpg.

still, our diesel is a tad better than yours stock, and the 41mpg was with the diesel better than our normal.
and thats not "normal" driving, the 31mpg, thats in the middle of a cold night, and a huge % is only highwaycruising at 55mph

0.57l/10km if you want to do the math by yourself.
or check here.
http://www.markporthouse.net/rangie/fuelconsumptionconversion.htm

Mölyapina · #36 12-05-2015, 10:47 PM

Interesting, but I can actually kind of see that, if you have a 2.88 with an OM616 and stick shift.

t walgamuth · #37 12-06-2015, 08:03 AM

Yeah, I got 35 like clockwork with my 300D euro NA running a 307 diff and the five speed od tranny. It topped 40 on a couple of fills when driven back and forth between Lafayette and Muncie by my #4 daughter on roads with 55 mph limits.

If you could pull it with the same gears and a 240 motor you should be over 50 mpg.

Grzpdlr · #38 12-06-2015, 02:37 PM

Quote:

Originally Posted by mannys9130

The 240D 4 speed I drove was an 83 and I couldn't fathom putting a diff of anything lower in it. It was slow as it was, and you had to wind each gear out to its max if you wanted to merge safely. A 240D with a 2.88 would be undriveable IMO and Tucson is flat. That's taking the diff from a car with twice the horsepower!

Had a chance to drive the car some this weekend and it's no problem starting on a very steep hill from a standing start, even with four adults in the car. On level ground it launches with no discernible difference from before the modification so it's doubtful significantly increased clutch ware will be a problem.
Also if you look at this:

190D 2.2 .................240D-2.88 Rear end
final gear ratio
1. 14.47
2. 8.07 ............................1. 11.232
3. 5.13 ............................2. 6.62
4. 3.42 ............................3. 4.06
5. 2.873 ..........................4. 2.88

The car now drives like it has the 5th gear is so badly needed. Now I can actually keep up with traffic on the freeway without feeling I'm harming the motor. The RPM's at 70 MPH has dropped from 3542 to 2762 (calculated) and, with the 3rd muffler I added, it's now possible to carry on a normal conversation at 70 MPH.
There have been a lot of negative comments on this, none by anyone that's actually tried it, but IMO, it's probably the best modification that can be done to improve drivability.

t walgamuth · #39 12-06-2015, 03:42 PM

If it works for you that is all that matters.

Mölyapina · #40 12-06-2015, 04:26 PM

How high do you have to rev the engine/slip the clutch on a hill start? Now I'm really curious to drive that thing...

EDIT: And how steep is the hill?

t walgamuth · #41 12-06-2015, 05:22 PM

Despite what he says, taking off on a hill would be an adventure. It was with my 300D with the same gearing so a 240 would be worse. Maybe they don't have much in the way of hills where he is from. (Sweden?)

mannys9130 · #42 12-06-2015, 05:24 PM

With a stopwatch, what's your 0-60 now?

Grzpdlr · #43 12-06-2015, 06:06 PM

Quote:

Originally Posted by mannys9130

With a stopwatch, what's your 0-60 now?

I'll check but from a rolling start it should beat yours.
The "hill" was really scary, I parked valet in an underground structure. They returned the car right at the exit ramp which curved up to the left at greater than 45 degrees. I didn't have to "slip" the clutch at all but I did have it floored. Quite frankly I would have been afraid of this hill with the OEM diff.

mannys9130 · #44 12-06-2015, 06:16 PM

Less power than my 190D, heavier, and with a 2.88... I doubt your 0-60 will be faster.

t walgamuth · #45 12-06-2015, 08:21 PM

no way if the engines are equal.