"For driving more than 100 mph: + 6 psi" - Page 2 - PeachParts Mercedes-Benz Forum

Brian Carlton · #16 04-14-2006, 11:44 PM

Quote:

Originally Posted by Craig

If I ever need to replace my differential, I'll have to look into a 2.88 too.

Brian, Tom, how much do you think that would improve my mileage?

Oh, I'm quite convinced you'll get at least 35 mpg when you switch from a 3.07 to a 2.88. Walgamuth has convinced me with his data.

sailor15015 · #17 04-14-2006, 11:47 PM

I was really impressed the couple of times I got brave enough to do about 85 on the interstate with how much it feels like its still pulling. I like to cruise about 75 and with the turbo giving a good boost already, the power just kicks right in when you need to pass at those speeds. I also really like how well it handles. The bimmer at 90 was all over the road. It needs some front end work so maybe that had something to do with it but there was no comparison.

pawoSD · #18 04-14-2006, 11:47 PM

I hit 100+ all the time in my SD, at least twice every highway trip....

I cruise at 80-85 during the day on the freeway around here all the time, its what everyone else in the right lane is going!

Today I hit probably around 105 or so.....and it was on Soybean Oil!!!

I had a brew of 5-6 gallons of diesel, 2 Gallons of RUG and 9.5 gallons of pure sams club soybean oil in there....WOW is it quiet in the city though, at lights I can't hear it!!! And when I got back tonight (144 miles on blend today!) it was idling sooo quiet when I parked it. I love the soy stuff! and it smells cool.....too bad it costs more to use....if diesel goes over $3 thats all I am going to run though. I love it!

My car tops out around 110-112mph or so.....I'm guessing because it hits the 4900rpm governor at that point.....our '83 does the same thing, they both pull strong right up to the 4800/4900rpm mark then they just hold it.....with a 2.88 I bet you could squeeze 125 out of a 617, maybe the same on a 2.47 diff but I bet it'd run out of torque around 115-120 or so.

JimmyL · #19 04-14-2006, 11:48 PM

For a minute I thought you dozed off at your keyboard...

I have 2.88's, but the tach doesn't work, so no idea what 70 is like in rpm's.

Quote:

Originally Posted by Brian Carlton

Oh, I'm quite convinced you'll get at least 35 mpg when you switch from a 3.07 to a 2.88. Walgamuth has convinced me with his data.

pawoSD · #20 04-14-2006, 11:51 PM

Oh, and on tire pressure, I always keep all four around 36(front)-38(rear)psi. Rock hard ride, but good cornering/smooth on the freeway.

Brian Carlton · #21 04-14-2006, 11:51 PM

Quote:

Originally Posted by JimmyL

For a minute I thought you dozed off at your keyboard...

I have 2.88's, but the tach doesn't work, so no idea what 70 is like in rpm's.

.......nah........I live here.

With stock tires, you are probably at 3100 rpm or so.

rchase · #22 04-15-2006, 12:03 AM

You do realize that our cars are designed for 100% throttle cruising pretty much all day. Not many other car makers design their cars to do that but Mercedes Benz does. Of course our cars being on average 20+ years old it might not be a great idea to test that 100mph cruising concept. My 1982 300SD has the "Jimmy Carter Edition" spedometer..... So anything over 85mph is unknown to me

pawoSD · #23 04-15-2006, 12:42 AM

Quote:

Originally Posted by rchase

You do realize that our cars are designed for 100% throttle cruising pretty much all day. Not many other car makers design their cars to do that but Mercedes Benz does. Of course our cars being on average 20+ years old it might not be a great idea to test that 100mph cruising concept. My 1982 300SD has the "Jimmy Carter Edition" spedometer..... So anything over 85mph is unknown to me

Our '83 has a 160mph speedo (tested to be exactly 7mph fast, as it was never recalibrated)

My car has the 85 speedo....I count it though, once it pegs, and I am still going, once I let off the throttle I count the seconds till it starts falling from the 90 or so where it pegs, and then compare that with the mph it falls per second once I can see how fast its going. Probably fairly accurate.....I know I was over 100mph when it takes over 4-5 seconds for it to "unpeg" once I let off the throttle

Matt SD300 · #24 04-15-2006, 01:01 AM

What a snob!!!!!!!!!!!!!!

Using... unused cooking oil on a Benz???

Get with the program! WVO is the only way to go!!

LOL!!!!!!!!!!!!!!!

Install a 12 volt fuel pump at the rear tank & Fattys injector line line heater & your set! (for blending)

www.fattywagons.com

pawoSD · #25 04-15-2006, 01:13 AM

Yeah....I like the clean unused oil

My main reason for no WVO is that there really isn't any around here, the city collects it for free from businesses and makes biodiesel out of it for their truck fleet (which is large). So...very little available. In the neighboring suburb about 10 mins away from my house there's a couple asian buffet's and restuarants though, I am going to go ask at those pretty soon when I have some more free time (am done with school in a few weeks, then I have lots of wvo hunting time....) I'd love to use it, if I can find it. Till then, the $13 cubies of pure, clean, readytodumpintomytank oil is right over at sams club.

But only if petro diesel goes above about 2.95 a gallon....thats when the extra cost and 3-4 mpg loss balance out financially.

andmoon · #26 04-15-2006, 09:10 AM

Quote:

Originally Posted by sailor15015

Hopefully I won't get in any trouble for saying this but he's still really active at the "other forum".

Is there another MB oil forum I am missing out on?
Hints on getting there?

bbeardb · #27 04-15-2006, 03:57 PM

Quote:

Originally Posted by Brian Carlton

Yep, I got the Sony head unit and 4 replacement speakers in the SD.........it'll drown out that roar with ease.

Actually, with the 2.88 and the larger tires, it's very quiet at 3K which translates to just about 70 mph.......about as fast as you can go around here.

It is interesting that our rpms at 70 are about the same, even though we have different rear ends. It's confusing me.

PS. Completely unrelated, but I finally got a mityvac yesterday.

Brian Carlton · #28 04-15-2006, 04:11 PM

Quote:

Originally Posted by bbeardb

It is interesting that our rpms at 70 are about the same, even though we have different rear ends. It's confusing me.

PS. Completely unrelated, but I finally got a mityvac yesterday.

I think it's gauge errors.

With my 215's, the engine speed at 70 mph should be about 2800.

With your 205's, the engine speed at 70mph should be about 3050.

I'm putting the speedometer recalibrator in this weekend so, hopefully, I'll have more accurate numbers when I get done. I've had to estimate the difference with the 2.88 and the 215's.

Good job in getting that Mityvac........you'll need it.

Check out the climate control system. Coming off the main vacuum line is a red plastic line with a green?? stripe. Pull this line and apply vacuum and see if it holds. If not, then you've got the same problem with the pods as I did.

#29 04-15-2006, 04:47 PM

Quote:

Originally Posted by Brian Carlton

I think it's gauge errors.

With my 215's, the engine speed at 70 mph should be about 2800.

With your 205's, the engine speed at 70mph should be about 3050.

That sounds right, my 300D has 205s and a 3.07. I run about 79-80 mph at 3500 rpm, 3050 rpm at 70 mph is consistent with that.

bbeardb · #30 04-15-2006, 05:52 PM

Quote:

Originally Posted by Brian Carlton

Good job in getting that Mityvac........you'll need it.

Check out the climate control system. Coming off the main vacuum line is a red plastic line with a green?? stripe. Pull this line and apply vacuum and see if it holds. If not, then you've got the same problem with the pods as I did.

I don't have a problem with my climate control, but I'll do that anyway. I have the transmission problem.