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Discussion Starter #1
Has anyone here road raced a th400 automatic supra?
Key thing is is a non lockup option th400.
I have a sp400 transmission with a PI torque converter. I recently tightened it up a bit. But not nearly enough. I can still hit the brakes and the gas and do burn outs relatively easy from a stop with drag radials with pt74 turbo.

I have 1 transmission cooler. What if I keep the boost somewhat low?
 

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I always just assumed than the th400 was pretty much drag only. I believe its a 3-spd, which with a larger turbo doesnt seem to have as much flexibility to keep it in the powerband. Transmissions arnt my thing so there is a good chance im wrong.

By the way, for what was the th400 OE?
 

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It should be possible, Varian... as long as it doesn't shift in mid-corner... :) Can you control whether it shifts?
 

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You might end up over-working the brakes as well since some th400 setups freewheel on deceleration. There's nothing that says you won't be able to get around the track... it just won't be the most desirable setup.

sushi
 

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The SP400 I will be using in my car has a standard forward-shift manual valve body, which allows for engine braking on deceleration.

While it is possible to roadrace with an automatic car (I did in my old 1989 Turbo T/A), your two biggest issues are overheating and lack of proper gear selection.
 

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You can get around the track in a full drag car that has slicks and skinnies on it... but I sure as hell wouldn't be doing it.
 

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fortes fortuna adiuvat
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like he said /\ anything is possible but i wouldnt do it...no manual = no fun
 

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with a high stall, it might not be so bad. I wouldn't worry too much about engine braking. Use the brakes to brake. I often tell students to focus on using the engine to go forward, and the brakes to stop. While they're learning, its a heck of a lot cheaper to replace brakes than it is clutches, transmissions, or engines.

From what I understand, the TH400 can create a lot of heat. I would be worried about that more than anything else. It wouldn't be the best set up, but i think it could work fine. And actually, with a big turbo, the high stall could be really benificial.

just playing devils advocate...
 

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if Jim Hall could do it in his Chaparral over 30 years ago, why not an auto Supra? ;) ...j/k I know that was a special auto.

I say take care of some basic preps as recommended in the stickies and then get out there and give it a try and have fun. I won't be an optimal road racing setup by any means, but you'll still have fun, maybe learn something new, maybe learn something about yourself, maybe convert to a 6sp ;) and live happily ever after.
 

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I know of at least one Supra that has road raced multiple times with a 400, heat build up is a MAJOR problem. Although last I heard, the car has tons of coolers on it now and seems to be holding up well.

But of course the 6-speed is a much better and more pure experience for road racing.
 

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Discussion Starter #11
Yeah mine has engine deacceleration when i lift off the gas like firearms. It's a manual valve body so mid corner shifts without my intentions wont' be a issue.

Well that's cool it's be done. I wonder what kind of cooling he has on his transmission. I only have 1 transmission cooler with a fan that's constantly on. The th400's soemtimes feel like manuals due to your required shifting
 

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Come out to PIR with us later this year, V. It's a good track to learn on due to the runoff (as long as you don't get wide into a wall). It's also a very fast track which should be well-suited to your car.
 

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Discussion Starter #13
Yeah thinking about it. I've only ran motorcycles at PIR. I woudln't run it that hard though. 15psi
 

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786 said:
like he said /\ anything is possible but i wouldnt do it...no manual = no fun
I am running the stock auto at the road course and having plenty of fun. Would the 6-spd be easier to rev-match - sure. But how many gears do you use at most road courses? I can go 80mph in 2nd which covers a huge portion of most courses I go to, even Road Atlanta. There, I need OD (4th) on the back straight.
Of course, I do have multiple coolers. And if the tranny goes - well, I guess I'll just have to (sniff) upgrade! :naughty:
 
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