holy 2.47 sleeper - Page 2 - PeachParts Mercedes-Benz Forum

#16 05-17-2006, 09:55 PM

Quote:

Originally Posted by 85chedeng300D

hey guys, any idea on the ratio of an '85 300D Turbo - CA ?
70 MPH @ 3000 RPMs
100 MPH @ 4000 RPMs

I believe you are going to be closer to 4200 or 4300 rpm at 100 mph, which is just about where you are starting to lose power. I suspect you will run out of power before you run out of rpms if you go much higher than 2.88 anyway.

85chedeng300D · #17 05-17-2006, 10:20 PM

Quote:

Originally Posted by boneheaddoctor

Believe its a 2.88.......for the '85 US market version. The 82-84 is a 3.07 ratio as is stamped on the rear side of the lower ear of the differential housing. Not the cover. Clean it off and you will see a string of numbers.

hmm! 2.88. the thread title is --- holy "2.47" sleeper. is the lower ratio the better? my 300D runs fast on interstate but not as quick on stop and go and uphill. is it the advantages and disadvantages of lower ratio?

85chedeng300D · #18 05-17-2006, 10:28 PM

Quote:

Originally Posted by Craig

I believe you are going to be closer to 4200 or 4300 rpm at 100 mph, which is just about where you are starting to lose power. I suspect you will run out of power before you run out of rpms if you go much higher than 2.88 anyway.

yeah! you're right Craig! its around that neighborhood, depends on the grade of the interstate. obviously if the road is uphill, i have higer RPMs compared to flat and level and going down as well. i notice it runs quiter and smoother when i'm running high RPMs, between 3500-4500 when in top or 4th gear than when high revs at "S". is it because of the faster relative wind going in the intake or the car is just too fast and leaves the noise behind?

on the tachometer, it doesn't have any redline on it? it's from 0 to 5 to 60 X 10. i wonder how much RPMs is the red or danger zone? do you happen to know it by chance

#19 05-17-2006, 11:13 PM

Quote:

Originally Posted by 85chedeng300D

i notice it runs quiter and smoother when i'm running high RPMs, between 3500-4500 when in top or 4th gear than when high revs at "S". is it because of the faster relative wind going in the intake or the car is just too fast and leaves the noise behind?

on the tachometer, it doesn't have any redline on it? it's from 0 to 5 to 60 X 10. i wonder how much RPMs is the red or danger zone? do you happen to know it by chance

I'm not certain, but I suspect the engine is happier when it is running nearly fully loaded in high gear, than when it is revving high at lower power. I believe that the rpm is limited by the IP at some maximum valve (in the 5000 rpm range, I think). I'm sure someone here has the exact value.

85chedeng300D · #20 05-17-2006, 11:19 PM

Quote:

Originally Posted by Craig

I'm not certain, but I suspect the engine is happier when it is running nearly fully loaded in high gear, than when it is revving high at lower power. I believe that the rpm is limited by the IP at some maximum valve (in the 5000 rpm range, I think). I'm sure someone here has the exact value.

so, if the IP has something to do with the limitting of the RPM to keep the engine from overspeeding, is tweaking the ALDA to the max output will have a chance of an over-revving engine above 5000 RPM

#21 05-17-2006, 11:21 PM

Quote:

Originally Posted by 85chedeng300D

is tweaking the ALDA to the max output will have a chance of an over-revving engine above 5000 RPM

Nope. The IP governer works separate from the ALDA.

#22 05-17-2006, 11:21 PM

Quote:

Originally Posted by 85chedeng300D

so, if the IP has something to do with the limitting of the RPM to keep the engine from overspeeding, is tweaking the ALDA to the max output will have a chance of an over-revving engine above 5000 RPM

I don't believe so, but I'm not the best person to ask. Anyone?

Mister Byrnzoil · #23 05-17-2006, 11:37 PM

could you pull off a 2.47 w/ a manual tranny? seems like there'd be hella clutch slippage off the line. I'd think it would be really unpleasant around town.

reinier · #24 05-18-2006, 05:30 AM

Quote:

Originally Posted by t walgamuth

i have no facts just a gut feeling. i think it would be something i would be very careful about before shelling out (i assume) a good sum for the 6.9 diff. the 115 mph is what i think the 300turbo will do max with the 247 gears.

i hope the diff fits. cool feature.

tom w

He want 250 euros for the 6.9 diff, which is not much i think. And he lives near me, so in case it doesnt fit, or makes to much noise, i can easily go back to him.
Checked for the diff parts, about 140 euros for all the bearings in it, new, and under 200 euros for all the new friction plates off the limited slip.

So in case i need to rebuild it sometimes, and the gears are ok, it doesnt cost me a fortune.

Rashakor · #25 05-18-2006, 09:12 AM

Quote:

Originally Posted by reinier

He said that it would fit.
I dont know, never even seen a 6.9er let alone the diff.
I'll ask him again when i talk to him.

Why would you think that it wouldnt fit? Mounting holes different?

Well if it does not fit in your w123 can i take the differencial from the 6.9 and install it in my 300SD (W116 of course). hehehehe!!! Now that would be hell fun. I already think the 116d is pretty peppy stock (more so than the 300Dt's for some reason i still wonder),

mespe · #26 05-18-2006, 11:05 AM

I have a differential from a 1985 380SE. Car has ABS, so there is an opening for the sensor. From what I've read, it's a 2.47, but I will check to make sure.

Anyone wanna make me an offer on this differential?

Marty

www.benzbonz.biz

Chopperguy7307 · #27 05-18-2006, 09:49 PM

102MPH@4250RPM
Took about 3.5 Miles to get it there though!

pawoSD · #28 05-18-2006, 09:56 PM

Quote:

Originally Posted by Chopperguy7307

102MPH@4250RPM
Took about 3.5 Miles to get it there though!

Wow....my car pegs the rpms around 4800/4900 within 20ish seconds if I floor it all the way down from about 80mph.....I suspect I am going around 110-113mph at that point....maybe a bit more if its downhill.

boneheaddoctor · #29 05-19-2006, 10:24 AM

Quote:

Originally Posted by 85chedeng300D

hmm! 2.88. the thread title is --- holy "2.47" sleeper. is the lower ratio the better? my 300D runs fast on interstate but not as quick on stop and go and uphill. is it the advantages and disadvantages of lower ratio?

better on open highway running. SPecifically where you will have higher top speeds. Will keep the engine closer to its optimum operating range in that case....but around town acceleration will suffer. Is it best for you? That depends on where most of your driving is done.

boneheaddoctor · #30 05-19-2006, 10:26 AM

Quote:

Originally Posted by reinier

He want 250 euros for the 6.9 diff, which is not much i think. And he lives near me, so in case it doesnt fit, or makes to much noise, i can easily go back to him.
Checked for the diff parts, about 140 euros for all the bearings in it, new, and under 200 euros for all the new friction plates off the limited slip.

So in case i need to rebuild it sometimes, and the gears are ok, it doesnt cost me a fortune.

I recomend reading up on the special tools a Benz differential needs to be set up correctly. They are mighty hard to find, very few shops have them.