Autocross season 2 about to start for my 87 300D - Page 3 - PeachParts Mercedes-Benz Forum

Johnhef · #31 05-31-2008, 11:19 PM

All of them over here are automatics afaik.

I'm looking for one of those fenders, some rust from behind those hideous chrome arches cracked the RF fender when we rolled them so now I've got an excuse to put one of that style on now.

babymog · #32 06-01-2008, 12:09 PM

My '87 does that also. The launch is w/o much boost on the stock setup, but full-throttle 1-2 shift is at full power, gives a generous kick in the seat, can't do it if you're on a curve without spinning but straight-line it's just a kick and a squat.

Quote:

Originally Posted by Deni

That's interesting, no wheel spin at the start but in second yes.<>

Deni · #33 06-01-2008, 05:08 PM

Quote:

Originally Posted by babymog

My '87 does that also. The launch is w/o much boost on the stock setup, but full-throttle 1-2 shift is at full power, gives a generous kick in the seat, can't do it if you're on a curve without spinning but straight-line it's just a kick and a squat.

Wouldn't power braking give a faster take off? My 190d spins the rears like crazy if I go over too zealous with the throttle before take off. As far as I've seen keeping it at about 3000 rpm and then dumping the clutch gives the fastest take off with minimal wheelspin. Higher than that and the tires spin helplessly, lower and the engine will bog for a moment.

@Johnhef - Forgot to add that your driving looks great! Very smooth

.

babymog · #34 06-01-2008, 07:33 PM

The torque converter stalls ~2krpm, not enough boost to do much (especially with 2.65 gears) on launch and powerbraking doesn't change that.

I'm considering a higher-stall TC as an alternative to a shorter rear screw for faster launches, would certainly shave .5-1sec from the course time IMO.

I had a 190D 2.5turbo, we didn't get them with the manual transmission over here though. The 300D Turbo is a faster car (by the numbers), one more cylinder and only 300lbs more car. The 190D did have a wheelspin problem even with the auto-transmission, I think the TC stalled closer to 2200rpm.

What's the final-drive ratio on your car? In the US the 190D 2.5turbo is also a 2.65:1.

Johnhef · #35 06-01-2008, 08:26 PM

The 2nd and 3rd runs were started powerbraking to build up 5psi before launch. I had let out too much air in the front tires before the second run and you can hear it in the clip.

hobbitss · #36 06-01-2008, 10:20 PM

Nice... I like the little puffs of diesel smoke...
That course makes me appreciate the facility we are fortunate to have access to here in New England...

Deni · #37 06-02-2008, 06:04 AM

Quote:

Originally Posted by babymog

What's the final-drive ratio on your car? In the US the 190D 2.5turbo is also a 2.65:1.

I have no idea. In 5th at 90 kph I'm at a tad lower than 2000 rpm. 1st gear is 40ish kph, 2nd 75ish kph, 3rd is 120 kph, 4th is 160 kph, then 5th is drag limited I guess (highest I got it to was 195+ kph).

Don't know if you can figure out the diff ratio from those numbers alone.

babymog · #38 06-02-2008, 09:18 AM

You should be able to plug your VIN into http://www.mbclub.ru/mb/vin/?lng=eng and find out.