Turbo automatic question

[Datsrboi]

I know stock turbo automatic supra exist. I have been messing around lately with a few ideas and I was wondering. If an automatic tranny does not perform well with boost in between shifts, what does the supra have that is keeping boost out when it shifts if theres any? Or how about if you do a NA-T on a nonturbo automatic supra. What would you need to keep boost out in between shift especially on WOT? Someone can tell me how the supra does it and how to do it on just any NA automatic cars to turbo?

 

[jdub]

The A340E is the same for the turbo and NA motors. It is actually better holding boost for the turbo motor due to the speed at which it shifts...you don't have to let up on the gas like you do with a manual. A well built A340 will beat a manual tranny (same HP motors) on a straight run every time due to the near zero delay shift. The auto will hold/build boost all the way to peak HP...floor it and enjoy

You do have greater HP loss from the crank to the wheels with an auto vs a manual tranny. And a big disadvantage is the level of HP the A340 will hold. If you are going for HP over 350 or so, it would be wise to have it built to handle it. That is fairly expensive.

 

[Dan_Gyoba]

The TCCS does nothing to limit boost while the auto shifts. It leaves boost on. This is one advantage to an auto on a turbocharged car. No waiting for the turbo to respool after a shift. The boost comes on, and stays on until you let off the gas.

The automatic version of the TCCS does seem to react differently to the type of throttle input where you let off the gas to shift a manual. Some people doing a 5 speed swap, or a swapping a turbo into an NA, but only have an auto ECU have reported that it takes longer to build boost back up, or that the engine does not necessarily respond as well to going back to WOT suddenly. I don't know for sure, but this seems likely to be a programming change.

 

[Datsrboi]

So my guess is that there are no real way to shut off boost on an automatic? So all those turbo cars you see on the street are actually shifting in between boost unlike what some people claim that it isnt? interesting.

 

[MassSupra89]

Why would you want to "Shut off boost"? I don't understand what you're trying to say?
Who claims they "shift without boost"?

 

[IJ.]

Some turbo/auto cars do limit boost on shifts to help save the Auto.

In the old days it was damn hard to get an auto to last in a turbo application as the make more power/torque right as the shift happens so slip the friction materials.

 

[Nick M]

The wastegate is mechanical, the actuator is by vacuum/boost signal. There is no correlation with the ECU. Some newer cars do come with electronic boost control. Not ours.

And the slippage of the torque converter will have different characteristics than a manual trans. The auto does not lose boost when shifting, as pointed out.

 

[supraslo]

If you run an auto, be sure to add a hell of a tranny cooler with fans. I went through about 5 trannys last season before finally finding a way to bring tranny temps down.

 

[supraman7mgte]

no vroom pshhhh vroom = good

 

[supraslo]

If you are Johnny on the stick you can acheive that with a manual tranny, too!!

 

[ZFast300Z]

Clutch in rev limiter in your good old manual trans. WOT shift all day long and fully use the clutch. Never looses boost.

And I have to agree with Supraslo, a hella good tranny cooler goes a long way in saving the life of the trans.

 

[kyle1jzsupra]

mines na-t with a na auto tranny and it just keeps on

 

[supraslo]

Well the NA auto tranny I had lasted one pass, while the turbo versions lasted a weekend. That is until I figured the cooling issue out, so I don't know what exactly is different, but there is something different between the two. I was laying down about 430whp with 500ftlb and spraying 150hp shot of go-go juice on mine. I much prefer the R154 for reliability, but I have often considered a Chevy TH-350 or 400 tranny.

 

[jdub]

Dude - there is no difference and you cannot compare due to the differences in the former life of the trannys. Unless you have an A340 "built", anything over 350 HP will produce a very limited life...less if it's hit hard.

 

[IJ.]

Turbo Trans has some more clutch plates.

 

[jdub]

How do you tell the difference? (assuming you have just the tranny sitting in front of you)

The foward clutch does have 1 additional disc/flange and the 1st/Reverse Brake has 1 additional disc/flange. Every thing else is identical from what I can see.

 

[IJ.]

Ummm errrr check the car to see if it has a Turbo
(you'd have to open it up John)

 

[gofastgeorge]

Turbo Trans has some more clutch plates.

Yup, and possibly the input shaft too......
I talked to Level-10 about their billet case torque converter,
and they said it will not work on the non-turbo auto.

 

[IJ.]

George: Converter splines are the same until the JZ series they have a different spline count.