Torque convertor question

[Nero]

What are the pros and cons of upgrading the torque convertor?
cheers
Dave

[Syed Shah]

Pros: Better launching, lessened effect of lag too apparently.

Cons: Drivability.

I have never driven a car with more than stock stall, so I can't really say more than what owners have commented. I think CD has one, maybe he can comment further.

What you looking for/at?

[alex h]

The stock converter is about a 2,200rpm stall converter....this means you can rev it to 2,200rpm before it must engage drive...this is used in powerbreaking etc. The bigger the stall no. the more you can rev it up and get the turbo's spooled before launch, but also the less willing it is to engage drive lower down the rev range. Having said that, a 3200rpm torque converter seems to be very popular with those that want drivability and better launches. Most people who have used one have instantly knocked a second off their 1/4mile time. (13.5-12.5sec).

In summary they are a good upgrade for the auto driver that likes to win the traffic light GP....but a town driver would be less happy with a higher stall TC.

[Martin F]

I think i'm correct in saying that a higher stall torque converter will generate more heat as well. So you need to ensure you have sufficient cooling.

[Chris Wilson]

They can be a PITA on a road car, it's a bit like slipping the clutch up to near to their stall speed every time you set off in a manual. Things they don't always tell you:

Many are crappily made. Some people bend the turbine or stator vanes, some just remove a few, rarely are they done right with correctly formed new vanes.

Balance is often iffy.

I have one here that appears to have an oversize neck on the convertor, and it has picked up the bushing in the gearbox oil pump it runs in, spun it in the pump and done damage.

Engine braking is reduced by at least as much as the stall speed is increased, sometimes by a higher percentage.

Fuel economy suffers badly.

They create a lot more heat in the gearbox fluid, an aftermarket cooler should be considered a neccessity.

"Clever" ECU controlled b`boxes like the MKIV Aisin Warner are mapped, just as the engine is mapped. Buggering about with torque convertor stall speeds means the ecu should also be re mapped to suit. I am not aware of any units that allow this, so operation may well be far from optimal.

I would suggest anyone keen enough on throwing nearly 2 tons of metal up the drag strip would be better fitting a basic hydraulically controlled race auto box like a modified Torqueflite or similar. I admit bias, i think drag racing is daft http://www.mkivsupra.co.uk/iB_html/non-cgi/emoticons/biggrin.gif

[Nero]

what about for example a track day.....how would one fare in that situation.....is the stock one already the best compromise?

[Chris Wilson]

For a stock engine, yes.

[Christian]

Best mod we've done on the car, but it did come with the big twins to start with http://www.mkivsupra.co.uk/iB_html/non-cgi/emoticons/cool.gif

I got a 3800 rpm converter from Sound Performance and it feels like I have more control - like slipping the clutch on a manual to keep the revs up.

I will say though that since it was fitted we generally choose not to take the Supe into London for instance, as the extra noise is a bit of a pain for that kind of journey.

Also, I wonder if there may be a wee problem - as I drove away from having it fitted, after half to one second it felt like it cut out and back in again. I think this may have been a symptom of the TC CW has in at the moment. It does it every so often - more so when not driving hard.