When in my 1995 C280, and stopped, then if I floor it to the floor (before kickdown), the engine will only rev up to about 5600 RPM. But if I floor it and use kickdown, the engine will rev to redline @ 6400 RPM. Now I know that peak horsepower is at 5500 rpm for this car. Is there any benefit of keeping it floored past kickdown to get the max RPM out of the engine when accelerating? What is the point of it being like this?

Now I do notice that on all electronic transmission (722.6/ 1997 +), putting the pedal to kickdown makes not difference at all. You don't even have to floor it all the way to get it to get right near redline. I have experienced this on a 1999 S420, 2001 CLK320, and a 1999 E430, so I know this is consistent and the way it's supposed to be.

Also, does anyone know if MBUSA does their 0-60 with it in kickdown (prior to 97, I suppose)??

IF you let the engine shift before redline the engine will slow down TOO much for the next gear & will take much longer to get the rev's up to the higher HP area. HAVING 5 gears(1997+ later) instead of 4 allows the engine to build revs quicker. Also the rear axle ratio can be changed due to the "overdrive" ratio in the 5-speed. Better mileage & acceleration!

Ok, I think I have it...
So in essence, I will get better acceleration if I floor it into kickdown because that will leave my revs at full RPM when shifting, thus retaining a higher RPM to the next shift to gain maximum horsepower again...
Why is it different on the electronic transmissions?

With the electronic transmissions, when driving on the highway around 70 or so, if you push full throttle the tranny will downshift to fourth. If you push kickdown, it will shift down to third.

Ali Al,
Yes I know this... I am not talking about downshifting, but rather the upshifting upon full (kickdown and no kickdown) throttle for the non electronically controlled transmission.
THanks anyway. :)

What about torque? Higher torque means quicker acceleration, does your engine perhaps develop the maximum torque above maximum hp? It is not likely, but could explain this. Is the range between 5600 and 6400 dead?

Steve

I am not positive about torque, but I think max torque is at 5,000, I will have to check. But I'm pretty sure that max torque is not at 6400. I thought about this though.

What you want is for the engine to fall when shifting to the peak of the torque curve. What that means is when the car ****s it will probably drop about 1000 to 1500 rpm right to the top of the torque curve from 6400 rpm, giving you the best acceleration.

I'm not sure about when the torque curve spread is, but max torque is at 3,750 RPM (199 lb/ft). It will fall to just under 4,000 rpms after shifting out of first into second gear (without kickdown).
You know, I've never known this.. what exactly is torque?

Torque is what you feel under your pants
when you stomp at the gas pedal.:)

Dave, torque is a measurable "twisting force". This quite simply put is the amount of twist your engine can apply to the drivetrain. It is, all other things considered equal, what gets you and your car moving at a prodigious rate of speed. Longer piston stroke usually produces higher torque. Measured in foot pounds (US). I remember a chevy 454 large block we built (in my old or should I say my younger racing days.) With these engines, it was not necessary to do much with the displacement, bore and stroke (pretty big already). With a Holley 3 barrel, oversize valves, ported/polished heads, Edlebrock cross ram intake manifold, Crane high lift, long duration cam, Simpson roller lifters, etc, etc, we got an easy 735 hp@6500 rpm and 575 ft/lbs torque@5200 rpm. This was on a chassis dyno too!! This beast wouldn't idle below 1000 rpm. But I can tell you, it left nothing to the imagination when you dumped the clutch at 5000 rpm. It was that big torque number that got you down the track real quick. I hope this helps your understanding. You may get other responses which may be more scientific, but, when all is said and done, the torque your engine produces is what gives you that "seat of the pants" feeling previously described. The engines used in most MBZ's are long on rpm's, short on stroke (good for the upper limit of revs) and, depending on the engine, average to above for bore.

[Edited by jeffsr on 07-19-2001 at 08:40 PM]

talk to me like I'm 4
 

SOmeone help...does my 1990 190E have this kickdown we are talking about? After reading all this I don't know what we are talking about any more...exacly what are we doing to " put it in kickdown" Is there something I am missing here?
I was under the assumption that we were talking about pushing the pedal down far enough to put pressure on the switch that reduces the tranny gearing to the next lower gear...help

Your assumption about pushing the pedal to the floor is correct, there should be a resistance point at the end of it.
I replied to your other post about how this works. Check with the car off and notice the resistance point at the end of the pedal when floored.
If you do not feel anything, then your kickdown switch has probably broken (my worst fear..! J/K). Not sure what involves replacement.