Question for Ashtrans re ZF Torque converter

[Philip A]

David,
I have a 3.9 RRC to which I have fitted a Thor manifold and other mods to raise low down power by about 50%.
This has made my Torque converter very loose.
Is it possible to fit a 4.6 converter in front of the 4HP22 without any other mods? Will the lockup work correctly at 85Kmh?
Any other comments on practicality?
Regards Philip A

[DL]

Hi Philip,

Have you considered getting one made?

Autoflite in Thomastown, Melb made mine to go between Chev and C9 and did a great job. Any stall speed you want and heavy duty. Cost about $460 from memory.

cheers, DL

[Philip A]

AFAIK, the lock up clutch is a ZF specific unit. My main reason for lowering the stall would be to increase economy, so I do not want to lose the clutch.
Regards Philip A

[... rick]

David,
I have a 3.9 RRC to which I have fitted a Thor manifold and other mods to raise low down power by about 50%.
This has made my Torque converter very loose.
Is it possible to fit a 4.6 converter in front of the 4HP22 without any other mods? Will the lockup work correctly at 85Kmh?
Any other comments on practicality?
Regards Philip A

What is a Thor manifold, and what other mods have given a 50% increase?

[ISUZUROVER]

David,
I have a 3.9 RRC to which I have fitted a Thor manifold and other mods to raise low down power by about 50%.
This has made my Torque converter very loose.
Is it possible to fit a 4.6 converter in front of the 4HP22 without any other mods? Will the lockup work correctly at 85Kmh?
Any other comments on practicality?
Regards Philip A

What is a Thor manifold, and what other mods have given a 50% increase?

THOR manifold
This was fitted to post MY 2000 rovers with bosch injection. Some people have come up with the idea of fitting a pair of throttle bodies to each plenum. This manifold is good for a 4x4 setup but less so on a car, due to its long thin runners. Uses one large throttle body of 68mm.

Jonathan Douglas Comments: 'the throttle body has a 68 mm throttle as standard and again, we often take this out, in this case to 71.5 mm. The Thor manifold, when used with either a standard cam or a mildly tuned cam, gives a strong torque peak at around 2,000 rpm, much higher than that achievable with the Lucas plenum design, but even with careful gas-flow work the power is limited. We find it difficult to achieve more than around 280 bhp with this manifold, where a similar amount of effort on a Lucas Plenum manifold will yield 320 bhp (but with less torque below 3,500 rpm'

[... rick]

Thanks for that Ben, this is cool, I am learning something about Rovers everyday!

Rick.

[Philip A]

The Thor uses "Hemholz resonance" to increase low down power by having tapered long runners, which use the velocity of the air charge to push extra air into the cylinders, sort of like supercharging at a particular revs. It works brilliantly on an auto.
I also have
Unichip which gives much more advance
Modded heads
free flow exhaust
And now closed loop ( which has reduced power a bit)
To see
http://www.mez.co.uk/ms12.html
Regards Philip A

[DL]

Hi again Philip,

I would ring Autoflite and ask all the Q's you like. From my experience dealing with them I got the impression they can make a torque convertor to do anything you want, including lock ups, etc.

cheers, DL

[ashtrans]

David,
Is it possible to fit a 4.6 converter in front of the 4HP22 without any other mods? Will the lockup work correctly at 85Kmh?
Any other comments on practicality?
Regards Philip A

Hi Phillip,

you will need to fit the 4HP24 front end to the auto and internals as well if you are going to do it, as well as the bigger converter you will also need the 4.6 flexplate and crank boss.

as mentioned you should be able to find a rebuild shop that can lower the stall speed for you,

either option the lock up speed should stay the same as this is controlled in the valve body.

We are currently installing a prototype control unit for the electronic ZF4HP22/24 which will allow you to adjust the shift points and firmness as well as the lock up speeds and a bunch of other variables such as the percentage throttle required to unlock the converter Etc,

should be good, fitting it to a 2007 2.4 Puma Defender now,

[Philip A]

Thanks for that David.
I will talk ot some locals about stall speed drop.
Regards Philip A