Why is my SD so FAST? - Page 4 - PeachParts Mercedes-Benz Forum

#46 06-03-2006, 06:52 PM

Quote:

Originally Posted by Hatterasguy

With a 617 you might gain a bit by short shifting it, they seem to max out power wise right around 4k. Someone needs to run a bunch of zero to 60 times and see what doing that does.

Very true. OM617 owners can shave ~1 second off the 0-60 by shifting before 4Krpm. If you take it all the way to 4500-4800 you can actually ADD a few seconds to it.

MBeige · #47 06-03-2006, 08:17 PM

Quote:

Originally Posted by sixto

I wonder if the advantage of cars that do better than spec has to do with shifting. I never timed the SDL but it felt quicker without the engaging the kickdown switch. It revved a couple hundred rpm higher with kickdown but then lingered against the governor wasting precious time.

It doesn't seem like John, MBeige and DslBnz row through the gears manually to achieve their times so maybe it's more the transmission's state of tune than the engine's. Thoughts?

Sixto

Isn't it that if the transmission shifts harder, it shifts quicker? Kind of like a blip instead of a shwoosh...

But like I said I fiddled with the linkage, not the transmission. If you look at the injection pump there's usually a gap between the throttle stop bolt and the lever that touches that. I tried minimizing the gap but I think on those 11 second runs, I overdid it, hence the quick acceleration.

By the way a friend of mine whose overboost valve is also bypassed, can do 0-60 runs in 9.5 seconds. His is a 300D.

#48 06-03-2006, 09:13 PM

Quote:

Originally Posted by MBeige

By the way a friend of mine whose overboost valve is also bypassed, can do 0-60 runs in 9.5 seconds. His is a 300D.

Unless you guys are getting injection pumps from MynäDiesel, I'd bet money that there is something wrong with your time measurements.
For a 82-85 300D to do 0-60 in less than 10 seconds, you need to do ALOT more to the engine than just bypass the overboost valve.

Hatterasguy · #49 06-03-2006, 10:21 PM

That makes sense, the 617 doesn't seem to do much over 4k but make noise. Didn't someone dyno a wagon and the power took a nose dive above that rpm?

vstech · #50 06-03-2006, 10:28 PM

ok, I have timed it a few more times and it is still in the same range. I still do not have the gps working, so... we will see. I do not floor the pedal, I hold it just above the kickdown switch, and it MOOOVES. the transmission has less than 1000 miles on a TOTAL rebuild. maybe all you naysayers of speed have slipping trannys? i DON'T KNOW, but it is fast. I don not know waht the rear gear ratio is, but I have bought a 2.47 geaar, so I belive the fast times are over. well they will be when I get around to installing it.

John

#51 06-03-2006, 10:35 PM

Quote:

Originally Posted by Hatterasguy

That makes sense, the 617 doesn't seem to do much over 4k but make noise. Didn't someone dyno a wagon and the power took a nose dive above that rpm?

First dyno run
My last dyno run

mybenz123 · #52 06-04-2006, 12:11 AM

Why is my SD so FAST?

Strange?

Most would say "Why is my SD so SLOW?

Sorry couldn't help myself.

With my 84 w123 wagon a lot seems to depend on
what rpm range I keep it.
It's tricky but if I can keep the rpms just right
the engine will pull strong in all the gears and
the tranny will shift just right.
And when the turbo kicks in it takes off like a
rocket.
If I let the rpms drop just slightly the whole balance
is off and the car seems alot slower.

Louis.

#53 06-04-2006, 12:36 AM

Quote:

Originally Posted by mybenz123

Why is my SD so FAST?

Strange?

Most would say "Why is my SD so SLOW?

I was thinking the same thing, I would avoid using "fast" and "SD" in the same sentence, unless I was comparing it to my 240D, or a 5-year old on a Big Wheel.

Hatterasguy · #54 06-05-2006, 05:40 PM

Ha good point!

I guess compared to the 5 second Accords and various other new cars out there all our cars are dogs.

Interesting dyno results. About what I expected, power seems to peak right before 4k and drop from their.

bbeardb · #55 06-26-2006, 03:18 PM

Did you ever get the GPS up and running to verify this?

stephenson · #56 06-26-2006, 09:14 PM

I believe 10 sec in a modified SD before 28 at 80 on a 5L S class ...

vstech · #57 03-08-2007, 10:35 AM

whiew! it's been a while since I started this thread.
GPS in and my Speedometer is dead nuts accurate.
my tranny has quite a few more miles on it now, and it doesn't shift as firm as before, and we are running ULSD and Winter mix fuel, so it should be slower than before. I will set up a camera and see what I can see.
the car sure feels quick still, I will let you guys know.
John

winmutt · #58 03-08-2007, 01:20 PM

Quote:

Originally Posted by vstech

the exaust looks basically stock to me.
and also, everything I have read about a free exaust or straight pipe even, says there will be no noticeable power changes from exaust. POSSIBLY slight turbo spool time reduction.
John

When you do your times are you averaging between runs in BOTH directions on the bit of road?

vstech · #59 03-08-2007, 01:34 PM

no, I am doing it on the highway, no way to exactly duplicate the reverse course. my area is quite hilly, so finding a flat area is not simple. stupid ordinances got rid of all the race tracks but nascar ... so that's out. I suppose I could use an airport runway to get more accurate results. but are you others out there being overly precise in your calculations? I have had as high as 12.2 seconds to as low as 9.55 seconds depending on how I vary my foot positon for shifting.
John

GRIESL · #60 03-08-2007, 01:43 PM

Quote:

Originally Posted by vstech

no, I am doing it on the highway, no way to exactly duplicate the reverse course. my area is quite hilly, so finding a flat area is not simple. stupid ordinances got rid of all the race tracks but nascar ... so that's out. I suppose I could use an airport runway to get more accurate results. but are you others out there being overly precise in your calculations? I have had as high as 12.2 seconds to as low as 9.55 seconds depending on how I vary my foot positon for shifting.
John

Just wondering, when people do 0-60 times, are you spooling up the turbo on the line? Or do you just come to a stop and stomp the pedal? I have a boost controller and I've let some turns out of the ALDA, and I get anywhere between 13 and 18 seconds depending on how much monkeying around I do with the boost controller and ALDA.

PS: The last time I tried 0-60 with boost at 12.5 and ALDA screw turned all the way as far as it will go, I powerbraked it on the line to spool up the turbo and actually did a burnout! Holy crap, never would have thought it could do that on dry pavement!