Dynaflow vs 3-Speed transmission

[Guest]

Now that the discussion has deviated from Dynaflow and 3-speed standard shift transmissions, my next question would be: Is Dynaflow faster than 3-speed step gear automatic. There is a local club member who has a modified '54 Buick (322 with TH350 adapted and 3.2 rear gears vs stock 3.4). I would like a few runs against that one, but street racing is out (fine for street racing in Texas starts at $2K). Is there anyone out there with a smart phone or ipad that can suggest an app to accurately determine 0-60 and 1/4 mile times? Independent runs would be safer, but less dramatic of course. I'm betting on the dynaflow of course.

Willie

All things being equal. Same engine, same engine dyno hp, same rear axle ratio and same weight of vehicle. A T-400 would kick it's butt no problem, and a T-350 would kick both the Dynaflow and the T-400's butt. Why would the T-350 kick a 400's butt?? It takes 50 hp less to operate and the 1 & 2 gar ratio's are a little lower, but the T-400 is a stronger trans.

[NTX5467]

With all due respect, when I read about the "power absorption" of the three Chevy automatics, the PowerGlide was least, at 15 horsepower. THM350 was next at about 30. The THM400 was the most hungry at about 45 horsepower. When I saw that, it made sense why the big-time drag racers had been using PowerGlides for years . . . or aftermarket versions thereof.

BUT . . . somewhere in that mix, between the PG and the THM350 is . . . the THM200 and THM200-4R automatics. As the original THM200 was designed to go behind 4 cyl and V-6 engines, it has to have less power consumption than other GM automatics of that time (later 1970s) of its introduction. Now, it seems that the aftermarket vendors have gotten behind this trans (abandoning the THM700 OD automatic in the process) and now offer beefier "guts" than the original trans had, even the version which came behind the GN's turbo V-6.

Due to the lower rotational mass in the THM350, compared to the THM400, it'll accelerate that mass sooner, so it should out-accelerate the same car with a THM400 in it, just on that fact alone. THM350 has 2.52/1.52/1.00 ratios and the THM400 has 2.48/1.48/1.00 ratios, so not enoough difference there to make any significant difference.

The THM200 has 2.74/1.74/1.00 ratios, so that little bit of extra "gear" might make a difference, in addition to the less roational mass in the trans, in putting more "spin in the tire". The THM700 OD starts with about a 3.09 1st gear, then to a 1.72 2nd gear, and 1.00 and .70 (approx) round things out. That deeper low gear got it "instant drool" from the drag racers, by observation. A large as that 1-2 gear ratio gap was, those trans shifted over it very smoothly, surprisingly, even at WOT.

It seems that the THM200 family trans transplant is something our ROA associates have done many times, from reading some of their earlier forum posts.

Let me get my K+E slide rule out! It knows about figgerin' car stuff!

Just some thoughts,

NTX5467

[Guest]

With all due respect, when I read about the "power absorption" of the three Chevy automatics, the PowerGlide was least, at 15 horsepower. THM350 was next at about 30. The THM400 was the most hungry at about 45 horsepower. When I saw that, it made sense why the big-time drag racers had been using PowerGlides for years . . . or aftermarket versions thereof.

BUT . . . somewhere in that mix, between the PG and the THM350 is . . . the THM200 and THM200-4R automatics. As the original THM200 was designed to go behind 4 cyl and V-6 engines, it has to have less power consumption than other GM automatics of that time (later 1970s) of its introduction. Now, it seems that the aftermarket vendors have gotten behind this trans (abandoning the THM700 OD automatic in the process) and now offer beefier "guts" than the original trans had, even the version which came behind the GN's turbo V-6.

Due to the lower rotational mass in the THM350, compared to the THM400, it'll accelerate that mass sooner, so it should out-accelerate the same car with a THM400 in it, just on that fact alone. THM350 has 2.52/1.52/1.00 ratios and the THM400 has 2.48/1.48/1.00 ratios, so not enoough difference there to make any significant difference.

The THM200 has 2.74/1.74/1.00 ratios, so that little bit of extra "gear" might make a difference, in addition to the less roational mass in the trans, in putting more "spin in the tire". The THM700 OD starts with about a 3.09 1st gear, then to a 1.72 2nd gear, and 1.00 and .70 (approx) round things out. That deeper low gear got it "instant drool" from the drag racers, by observation. A large as that 1-2 gear ratio gap was, those trans shifted over it very smoothly, surprisingly, even at WOT.

It seems that the THM200 family trans transplant is something our ROA associates have done many times, from reading some of their earlier forum posts.

Let me get my K+E slide rule out! It knows about figgerin' car stuff!

Just some thoughts,

NTX5467

I like the ratio's of 1940-1956 Hydramatic 1st 3.82, 2nd 2.63, 3rd 1.45, 4th 1 to 1

And controlled coupling 1956-1964 is 1st 3.97, 2nd 2.55, 3rd 1.55 4th 1 to 1

Our 59 Catalina used a 3.08 posi for the street and a 3.90 and a 4.10 for the strip. Now think of how fast it shifts with from 1-2 with a 3.97 first gear and 4.10 posi rear. Now imagine 389" 429 ft lbs torque 345 horsepower and a 3,900 lb car. It ran a consistent 13.90 @ 101-102 mph for ten years.

[MartyWorld]

Greetings.

I have driven both 3 speed and Dynaflow.

The 1956 Buick Special with a 3 speed was fast, but so was the 56 Buick Super I drove with Dynaflow. I guess

it is what you prefer. Performance with the Dynaflow was outstanding.

Marty