Torque converter specs ?

[smallfry]

I am trying to find the rated stall speeds of the torque converters fitted to the various Land/Range Rover ZF gearboxes, and try as I might, I cannot find any info.

I am of course, aware that there is a small, medium, and large type, but are there only three stall speeds, or are there more. Also interested to know why the 4.6 P38 started out with the large converter, but reverted back to the earlier medium type, with presumably higher stall speed.

I cannot seem to find any resource with this information available. anyone out there got any ideas ?

[Aragorn]

tried Ashcrofts?

[smallfry]

Yes, but they tell me they do not know....................................

[Snagger]

The logical explanation is that bigger torque converters need bigger oil pumps to drive them, and going too large on the TC results in the oil flow inside being too slow for the TC to do its job efficiently.  So, LR may have found that the vehicle performed better or had better fuel efficiency with the medium sized TC instead of the large.

[ashtrans]

On 19 October 2016 at 10:09 PM, smallfry said:

Yes, but they tell me they do not know....................................

Hi,

its not so much we don't know, more like this is not an exact science which is why you can't find any set figures, different engines with different converters will all have different stall speeds. As a general rule of thumb, small converter means a higher stall speed but you can also adjust the internal vane angle to change the speed, this is useful if you want a lower stall speed but you can't fit a bigger converter in the bellhousing ie a tuned P38 diesel, has the small converter but the medium one won't fit.

i am also not a great fan of the 'stall test' this involves putting it in drive, foot hard on the brake and then foot on full throttle, even for a few seconds anyone with any mechanical sympathy will cringe at the strain the engine and gearbox are put under and the heat generated is considerable even for a short period.

the stall speed is important to a vehicle driving well, too high and it's all revs and no go, ie a waste of fuel, excessive revs, excessive noise and you rev past the early torque of a tuned engine,

but

too low a stall speed and the engine will just bog down and won't rev, ie you need to let it Rev enough to get onto the turbo to get the torque up and get moving,

Thanks, Dave

[smallfry]

On 20/10/2016 at 10:34 PM, ashtrans said:

i am also not a great fan of the 'stall test' this involves putting it in drive, foot hard on the brake and then foot on full throttle, even for a few seconds anyone with any mechanical sympathy will cringe at the strain the engine and gearbox are put under and the heat generated is considerable even for a short period.

the stall speed is important to a vehicle driving well, too high and it's all revs and no go, ie a waste of fuel, excessive revs, excessive noise and you rev past the early torque of a tuned engine,

Thanks, Dave

I have never been an admirer of the "stall test" either

However, the diesel P38 is precisely the setup I am considering using, but with a BMW M57 engine instead of the M51, and as you have pointed out, I am concerned about revving right through the torque band, and whether the lock up clutch is up to the job.

I do remember a couple of years ago that you offered one of the guys on here an adaptor plate to enable the use of the V8 converter housing with this engine, which would enable the use of alternative TCs. Did anything come of that ? I would have thought it would be a popular conversion.

[ashtrans]

Hi,

we made I think 3 of these kits which used a 15mm adapter plate, 4.6 4HP24 with the big converter and with the adapter plate they ended up the same length as the 2.5 diesel ZF box so the engine stayed in the same place, I think a good M57, big converter, 4HP24 and compushift to control it would be a good setup,

the compushift has advanced significantly recently, we can now set both lock and unlock tables in each gear, so it can shift 1-2, then the converter (TCC) can soon lock, then shift 2-3 and unlock, then lock etc, i.e. use the converter like a splitter gear, with these tables the TCC is no longer a fixed value at X speed, you can set it to lock for example just in 4th and at low throttle (MAP) lock earlier and at high MAP lock later if you are nailing it.

Dave