[scott-462]

I was wondering which transmission would be better for straight line acceleration, an auto with stall converter or a manual trans? It would be in a 3800lb car with apprx 450HP. I think a manual would be much funner to drive, but seems like the auto would be faster in the quarter. The auto would likely be a TH400 or 200-4r with a 3000rpm stall and maybe trans brake, and the manual would be an original 4 speed trans or maybe a newer 5 speed with a racing clutch and short throw shifter. I know the auto will be much more consistent and shifts faster than a human, but they also rob more power than a manual and in the horsepower realm i'm in i'm not sure where the shift delay VS HP loss pros and cons lie.

[goatless]

For most people the auto will be quicker... and there will be less breakage!

[steve25]

A manual trans also beats the livin daylights out of the drive at a much faster rate than a auto.
With the weight of your car and even just 450 HP a factory 4 speed will not last too long depemdant if you run slicks and how many passes you make.
Comsistancy is the name of the game in bracket racing and a auto has the upper hand in that regard, so dont fight it!

[Keith Seymore]

Also - with an automatic you get the initial torque multiplication of the converter.

The manual is 1:1 during that same timeframe (because of the lock up of the clutch against the flexplate).

K

[scott-462]

This is a daily driven car that will see the track a few times a summer with some slicks, and some sticky DOT tires the rest of the time. I've always had a lot more fun driving a manual trans, just my style.. But if a high stall auto would be as much as 3/4 sec faster in the quarter than i would be tempted to stick with one. It being a daily driver, i wont be driving hard all the time like a track car would be so i wouldnt think durability would be a major factor on the street with some DOT and occasional stompings.

[steve25]

It depends what your defination of fun is when your at the track.
If fun time at the track is winnig, then the auto is the way to go, if you just want to have braggin rights when you get back home as to how fast you went at the track then go with the 4 speed.
No question a 4 speed on the street if you do not live in over populated area is far more fun than the auto!

[goatless]

The durability in regular driving on the street shouldn't be an issue. Dumping the clutch with sticky tires at the strip is hard on parts. You'll find the weak link quickly.

[scott-462]

Ok, maybe i should reiterate. An auto shifts faster but has more HP loss. A manual shifts slower but has less HP loss. In a 450HP 3800lb car which would be faster in the quarter mile? I feel the manual is going to be much funner to drive daily, but is there a noticeable difference in ET? Disregarding durability of the drivetrain.

[The Champ]

Originally Posted by scott-462

I was wondering which transmission would be better for straight line acceleration, an auto with stall converter or a manual trans?

It depends on the person operating the manual transmission...

Bracket racing is all about consistency, not about potential. That's the primary reason for the automatic's popularity in that type of racing.

But if a high stall auto would be as much as 3/4 sec faster in the quarter than i would be tempted to stick with one.

I doubt the difference would be anywhere near that much - on equally prepared cars. Probably no more than a tenth or two.

Bottom line, go with the transmission that you will enjoy the most.

[goatless]

Like I said in my first response- the auto will be quick for most people, most of the time. The auto will be easier to launch well and more consistent on shifts. Manual trans will usually have slightly slower ET, but a higher MPH. ET (and reaction time) is what wins races.

[ta man]

Originally Posted by goatless

For most people the auto will be quicker... and there will be less breakage!

I agree..for the average driver..and most street cars...The auto will be quicker by .5 or more seconds depending on driver skill and traction and no breakage.

[Chris65LeMans]

Originally Posted by scott-462

.. But if a high stall auto would be as much as 3/4 sec faster in the quarter than i would be tempted to stick with one. It being a daily driver....

High stall auto and daily driver don't mix very well. It was always funny to watch my former neighbor try to get his roadrunner in the garage without driving through the back wall. ditto guys that leave the car shows early with their high stall and have to gingerly move through the crowd without killing anybody.

[Lee]

JUST the torque converter can make over a 2-second e.t. difference, for some cars. If you have a torque converter that is optimized for your engine/suspension/tires, then a manual tranny in an otherwise identical car will have a hard time keeping up.

But, the best tranny for dragstrip performance may not be so great for normal street use.

With a manual, you can launch the car at ANY rpm. You can vary the launch rpm to compensate for better/worse traction conditions. You can even get some clutches that are tunable, making them even more like quality torque converters. You can drive it mildly on the street, then do high-rpm launches at the track - an option you don't have with automatics.

Sticks can be very fast and very fun, but the odds of breaking things are higher, and the heavy-duty stuff is rather expensive.

[455-4+1]

Originally Posted by Keith Seymore

Also - with an automatic you get the initial torque multiplication of the converter.

The manual is 1:1 during that same timeframe (because of the lock up of the clutch against the flexplate).

K

Dont forget to factor in the total starting line ratio. The difference may not be as much as you think.

Typical TH400 1st gear is 2.48 x say 3.73 rear is 9.25 SLR

Typical 4 speed 1st gear is 3.25 x say 3.73 rear is 12.12 SLR

This is a significant difference in just the gearing, add a little slip in the clutch (Mcleod softlok or similar) and the engine stays up there and the clutch catches up

Take a look at the tach video of my street TA with a pump gas 455. Shifting is foot flat with a travel snubber on the clutch set with feeler gauges on the disk. Note the engine RPM doesnt drop back to where the gearing split indicates it should as the clutch slips on the shift and then recovers. This is essential in reducing parts breakage if your car hooks.

http://www.youtube.com/watch?v=CVHEZ77gUxQ

If you get it right you can also pull the front wheels in a lowly 11 sec, low RPM street 455 in 2nd gear as well as first. Doubt the auto would allow for that with the same low power.

They are great fun BUT as mentioned ............... Parts breakage can be a BITCH !!!!!!

Dont try it with a stock trans, it may last for a while, but it will break

[James408]

Originally Posted by Chris65LeMans

High stall auto and daily driver don't mix very well. It was always funny to watch my former neighbor try to get his roadrunner in the garage without driving through the back wall. ditto guys that leave the car shows early with their high stall and have to gingerly move through the crowd without killing anybody.

If you get say a Continental 3200 Jim Hand special, that is not an issue. Mine drives like a stocker and actually creeps in gear at idle. You only notice the 3200 at the right moment. WOT. If you go with an auto, do not skimp on the converter. I learned the hard way with wasted money, low performance and a damaged transmission.

[Keith Seymore]

Originally Posted by 455-4+1

Dont forget to factor in the total starting line ratio. The difference may not be as much as you think.

Good point; I hadn't considered that.

K

[geeteeohguy]

The first gear ratio on my early M20 is 2.56. The first gear ratio on the later M20's is 2.52. Pretty darn close to the TH400. That said, I agree with all the posts previously made: sticks are more fun, less consistent, and brake more parts. That said, the 'right' driver can shift a stick as fast or faster than an automatic. These guys are mostly grizzled old timers now, and thinning out in ranks. It takes a lot of skill and courage to bracket race a 4 speed car. Some guys shave with a straight razor, others shave with an electric razor. It's all about your personal style.

[455-4+1]

Correct on the stock stuff 1st gear ratio. Some of the later super T10 stuff had higher ratios from memory.

When using 3.25 etc I was quoting the old Doug Nash (which I ran) and the Richmond 5 speed street stuff (3.28 and upwards for first) which would be suitable for the application as a swap without changing rear gears and still allowing good highway cruise.

Rated at 450ft/lb for the Richmond they are OK for street use, but still a bit "fragile" with slicks at the track. (esp in a heavy car, mine weighed 1850kg) Even their Super T10 Plus is rated over 100 ft/lb less than this.

The straight cut Nash was rated similar from memory but will survive ALOT more with the right clutch, it is a PITA on the street though.

There are alot more offerings now with even higher ratings and good 1st gear ratios butall need a good clutch setup to work well with slicks

[lust4speed]

I'm one of those guys that admit that I can't race a stick despite practicing since the car was new in 1967. When I got a little more serious in drag racing (read frustrated in trying to be consistent with a stick) and installed a T400, the car picked up a little over .4 second, and became deadly consistent. Winning or loosing in drag racing is decided by hundredths of a second, and my plus or minus a tenth with the stick guaranteed an early trip home from the races. Of course we never stop "improving" our cars for drag racing, and eventually it was a pain to drive on the street. At that point I found another car to continue the addiction with, and the original car was returned to street duty with the 4-speed back in it. I had forgotten just how much fun driving a stick on the road was, and the memories of the frustrating runs at the drags quickly faded away.

[Skip Fix]

Hard to beat to fun of a 5000 side step! But I have broken less driveline parts with an auto.