MNISB good post. New stuff on the market since I played with drag. I had a lot of fun and bought a lot of parts for the heavy mopar four speeds. No help from electronics, but slick shifted, vertical gate, etc. Pedal went to the floor and stayed there. Just a good tap to break it loose. I have a hard time envisoning the five speed and especially the six speed in this envoroment. Also did a lot with automatics in that era. Automatic was more reliable both mechanical and in repeating times, but the manual was faster. Been a lot of years, tell the kids (grown) of some times with the big blocks and they reply "yeah dad" ;D

 

Look pro drag car... No autos. Exept for bracket racers.

Hey I make over 500 hp from a 2 liter four and dont burn out or break traction ever so long as it is'nt wet. My shift lever is 4" tall if that and the travel is very short.


The car in the clip would while laying rubber on the dyno put down almost 700hp. It probably made much more at the wheels but it went into making tire smoke. That was when the timeslips said around 10secs. The car weights the same but now runs 8.7 or so. How much is it making now... I can figure it out with some math..... It is still a 2.0 four cylinder as well.

On MY car at low 500hp I do go thru a clutch a summer as I use the clutch as the "shear pin" if you will. Big Power + Big traction + small trans = broken trans or clutch life reduction. I'll wear out the clutch it's cheaper and less destructive.

As for when you have weight behind a rig. The more gear ratios to play with on a manual and less power being used by the transmission should easilly outpull an auto with a good driver. Like one who picks the right gear for the load and speed.

With the truck I'll do it like I did the car. Start slow and as I get the thing mastered then crank it up. I am looking at eventually maybe making the same kind of output as the banks sidewinder or nipping at it's heels. That is like the end goal over like 2 years. Except I'll use a ATS exhaust mani and my own exhaust system. I like DIY. I also like VGT so I'm hoping to see it on the new trucks but may need to get a used 03 for economic reasons and add a VGT controller of some kind. It's not as simple as a controlling a wastegate and can be difficult to get right which is why few shops do them.

 

I'll do some more research. But things like a 4k kit and rear end ratios matter. As does seeing an actual dyno. From there I can figure out optimum shift points and I am thinking that some gears may need to be skipped for the best ET's especially on a 4k'd motor.

FWIW you can get them to shift faster than most think... not as fast as a sports car manual but still very crisply considering the size of the gearbox. These truck trannies will never go from say 2-3 in as short of a time frame as a auto goes 2-3. This does'nt mean the truck wont be accelerating faster. The lost time during the shift is more than offset by the gearing and efficiency of the transmission.

 

I still feel the Auto will be faster in the 1/4 mile.

I've been on the drag racing scene a little while, and I have experianced it personally. I got ran down by an auto with my 6-speed. I like to think I can shift fairly fast, but I can't convince anybody of that over the internet.

Prove me wrong,, that a manual can beat an auto.

Merrick Cummings Jr

 

I'm with Mins. With the right technique the stick is advantageous.

Take a look at ANY car reviewed by your magazine of choice and the stick always comes out on top in a head to head drag race, turbo or not. Given that, I have to call bullshift on the +100 ponies.

Driven sanely in a method to safe parts, fuel, toad, etc., the auto might be faster showing off and I guess you could always pick a speed range that isn't as conducive to the stick's power band.

 

I dont know. ??? Like I said, I have never driven a Cummins with an auto behind it but I will say these arent the quick shifting manuals that sports cars use. I suppose you could slam gears but you would be sure to break something soon. Any automatic vehicle I have driven seems to be more forgiving to driver error as where with a stick if your not carefull you will fall out of the power curve. So I could see why people think auto's are quicker. But then again it takes more HP to turn an automatic.
I'm getting off the subject here. The main question asked was for a Cummins only with a heavy trailer.

 

I just like the control of a stick...I'm in command. Uphill, downhill, level, cruisin, jammin, etc. How much grunt do I need/want for that task, at that time, is up to me. Like someone said above..a stick is a driver's trans and an auto is an operators trans.

The stick is annoying if you do a lot of stop and go. Even with 2nd gear start, you're shifting to 3rd before you're across the intersection.

 

The auto, given the same crank hp/ft.lb output should beat a manual from a standstill unloaded, and have the same acceleration loaded IF the TC is locked.

As mentioned before for the most rapid acceleration, it is critical to keep the boost up and constant, which the auto provides.

Accelerating a heavy load, would give the edge to a manual, as the loss to the TC, even a good TC would be significant.

 

I don't know how these upgraded trans work...but in a regular auto the converter won't lock up when there's substantal load on the drivetrain.

 

[quote author=oilbrnr link=board=4;threadid=20905;start=15#msg200132 date=1066881672]
The auto, given the same crank hp/ft.lb output should beat a manual from a standstill unloaded, and have the same acceleration loaded IF the TC is locked.

As mentioned before for the most rapid acceleration, it is critical to keep the boost up and constant, which the auto provides.

Accelerating a heavy load, would give the edge to a manual, as the loss to the TC, even a good TC would be significant.
[/quote]

What he said, good post.

 

Thanks Haulin, but now that I think about it, I'm not sure that there are but a couple of situations that a manual CTD would pull away from the same auto. Those would be sustained high RPM 1st or 2nd gear pulls with a load in tow.

A TC actually multiplies torque at lower RPMs giving the avantage to the auto, at high RPMs though the opposite is true, and this is why there is a lockup on the TC. Since the 47RE will lock in 3rd and 4th, 1st and 2nd would be the weak spots.

 

Here's the final word:

the auto will beat the stick to the dealer for a new trans...