GTR Forum banner

1 - 14 of 14 Posts

·
Registered
Joined
·
8,804 Posts
Discussion Starter #1
mentioned in another thread, has got me wondering...what are these things? Beefed up GM automatics? Are they streetable?
 

·
Registered
Joined
·
3,029 Posts
"Some automatic transmissions modified or designed specifically for drag racing may also incorporate a transmission brake, or "trans-brake," as part of a manual valve body. Activated by electrical solenoid control, a trans-brake simultaneously engages the first and reverse gears, locking the transmission and preventing the input shaft from turning. This allows the driver of the car to raise the engine rpm against the resistance of the torque converter, then launch the car by simply releasing the trans-brake switch."

and...

"For certain applications, the slippage inherent in automatic transmissions can be advantageous; for instance, in drag racing, the automatic transmission allows the car to be stopped with the engine at a high rpm (the "stall speed") to allow for a very quick launch when the brakes are released; in fact, a common modification is to increase the stall speed of the transmission. This is even more advantageous for turbocharged engines, where the turbocharger needs to be kept spinning at high rpm by a large flow of exhaust in order to keep the boost pressure up and eliminate the turbo lag that occurs when the engine is idling and the throttle is suddenly opened."
 

·
Registered
Joined
·
374 Posts
Sean, have you ever used a prepped auto on a jap turbo engine? Im thinking of doing this with Nissan SR20DET and would be grateful for any ideas at the moment. Was wondering if a C4 box would be ok with 10 or 9 inch converter. The car will have around 500hp(fly) and idelly used on the road with some drag work. The cost of these boxes is relatively cheap compared to uprated jap boxes and are known to handle the power easily, so could be the way forward for me.
Cheers
Tony
 

·
Registered
Joined
·
3,480 Posts
Sean, have you ever used a prepped auto on a jap turbo engine? Im thinking of doing this with Nissan SR20DET and would be grateful for any ideas at the moment. Was wondering if a C4 box would be ok with 10 or 9 inch converter. The car will have around 500hp(fly) and idelly used on the road with some drag work.
A friend of mine, Ivan at AMS/ Turbo240.com

runs a C4 behind his KA turbo 240. He has also ran a 300ZX TT auto tranny behind it. Its gone 9.22 @ 156 mph.

Automoto Sports Copyright&copy AMS 2006

The thing with autos is getting the converter right. Too loose is lots of heat. Too tight and it wont come up on boost without a big shot of spray.

I see all these guys in UK and Japan running these sequentially air shifited trannies. $10k-$15k trannies. You can get an insane turbo 400 for 5k.

An auto is much more consistant. I can't see the point in running a sequential in a 10 or 9 second car.
 

·
Registered
Joined
·
374 Posts
A friend of mine, Ivan at AMS/ Turbo240.com

runs a C4 behind his KA turbo 240. He has also ran a 300ZX TT auto tranny behind it. Its gone 9.22 @ 156 mph.

Automoto Sports Copyright&copy AMS 2006

The thing with autos is getting the converter right. Too loose is lots of heat. Too tight and it wont come up on boost without a big shot of spray.


An auto is much more consistant. I can't see the point in running a sequential in a 10 or 9 second car.
Got to agree with that Sean, plenty of super gas (9.90) cars using autos all season without any trouble.

When does heat in a loose converter become an issue? Is it just holding on the line or general use too ie even cruising?

Tony
 

·
Registered
Joined
·
58 Posts
It takes a good driver to manualy change gear 5 / 6 times on a 1/4 mile run:bowdown1:

what skill do you need to push a button to work a airshifter
or even worse just having to keep your foot on the floor with a auto box
 

·
Registered
Joined
·
3,480 Posts
It takes a good driver to manualy change gear 5 / 6 times on a 1/4 mile run:bowdown1:
what skill do you need to push a button to work a airshifter
or even worse just having to keep your foot on the floor with a auto box
Last I checked, they only gave the prize money to the guy that wins, not to the guy that shifted it 5 or 6 times.

Shifting takes time. Time that could be better spent accelerating. An auto turbo car does not lose all its boost between shifts like a manually shifted car.

Have to shift is just an excuse when you lose to an auto car.

If the excercise is A to B quickest possible, then autos the way to go. If you want to go and **** your self off, shift it as many times as you like.
 

·
Registered
Joined
·
366 Posts
Ive seen 2 speed powerglides behind 1000hp 2JZs.

Hell anything is possible if you have the time and money. Put a feckin TH700-r4 behind your RB if you want.

There are companies that will build you an adaptor to your spec.
 

·
Registered
Joined
·
3,480 Posts
Ive seen 2 speed powerglides behind 1000hp 2JZs.

Hell anything is possible if you have the time and money. Put a feckin TH700-r4 behind your RB if you want.

There are companies that will build you an adaptor to your spec.
700R4 is weak. I know. I have broken about 7 of them behind my Syclone and Typhoons. My Syclone has a broken trans in it right now.

The 4L80E though. Thats a four speed turbo 400 equivalent. At least one 8 second Syclone with a 4L80E.
 

·
Registered
Joined
·
1,717 Posts
C4 Autos only weigh about 75lbs, so they are not that heavy, and can support over a 1000hp if built correctly. For drag racing, autos are the way to go. The one I have will support 1000hp, and it cost me £300 for everything. Although, I will need to mess with different TCs, to see what the car likes. The weight of the car can mess with the stalls, and I am not sure what stall, and how tight this TC is that came with the trans.
 

·
Registered
Joined
·
374 Posts
C4 Autos only weigh about 75lbs, so they are not that heavy, and can support over a 1000hp if built correctly. For drag racing, autos are the way to go. The one I have will support 1000hp, and it cost me £300 for everything.
Wouldnt mind a deal like that :chuckle: Have you got a contact for boxes?

Tony
 
1 - 14 of 14 Posts
Top