Zf auto knowledge

[daslandroverman]

I wonder if anyone with a bit of knowledge about how autoboxes work can help me out here?

I've bought a BMW M52B28 to drop into my 110. 
At present it runs a Mazda SL35 with a ZF4hp22 autobox from a V8 model, and I'm still trying to decide if I should stick with the auto or go with the manual box I have sitting. 

At present the main stumbling block is how the V8 valve block would cope with the BMW. 
My knowledge of autoboxes stretches far enough to know it basically looks at the engine speed (input) the road speed (output) and throttle position to decide which gear it wants to be in, with various settings altered to give different shift points, TC lockup speed etc to suit the engine. 

From this I can deduce that there's going to be some difference as the V8 has its peak torque at 2600rpm, and peak power at 4750, compared to the BMW at 3900rpm and 5300 respectively. 
Add in the functional redline of the V8 is about 5200rpm on a good day, whilst -with an alteration to the ECU settings- the BMW will spin up to 7000rpm.

So, whilst I reckon canny use of the throttle would see the engine and box working fairly well, I find myself thinking that the TC lockup and shift into 4th gear could well find themselves murdering the engine just as it's coming on song rather than making the most of what's on tap. 

Is my thinking straight enough here?

I don't want to fit an EH box and associated controller as my wallet won't allow it, and finding a BMW varient of the 4HP22 to rob the valve block from also seems prohibitively expensive, whilst I wouldn't be best pleased if I'd made up the adapter kit and found it horrible to drive. 

Build it with the manual box seems a more attractive option all the time, but I'd be interested to hear the opinions of others.

[smallfry]

I have a similar dilemma with what I want to do Lexus V8 or BMW M57 diesel.

First you have to decide what you want, manual or auto.

Bear in mind that if you have to have a ghastly stone age dull as ditchwater manual box, you will be wanting to buy a suitable flywheel and clutch, and it will likely be a dual mass jobbie, and by the time you have bought all that, it will be getting on for Compushift money............

Other thing is, is you new engine fly by wire, so there is nothing to operate the hydraulic box kickdown cable. I know the box can be run without it connected, but it still has to adjusted to the correct length, but of course you will have no kickdown facility.

If you want to retain a hydraulic box, I would think you would be better off finding a suitable 4HP22 from a petrol model that uses that or a similar engine which will have more suitable shift points, and swap the innards into the Land Rover case.   

[mickeyw]

Some years ago I had an opportunity to drive a friend's RRC with the Mazda SL35T, V8 spec 4HP22 and 1:1 trf box.

It certainly wasn't short of go, or short legged.

I imagine a 1:1.4 or 1:1.2 trf ratio would have  not suited this engine nearly as well.

Some while later it cracked a flex plate, resulting in loss of drive. Hopefully that was nothing to do with me (eek), as the owner was inclined to frequently tow large trailers with a lead foot. There's one hazard of having a lot of welly on tap

[daslandroverman]

The Mazda was certainly a good engine in its day (still goes pretty well to be fair) but is past its best, a bit of a shame that a proper rebuild would likely be  £2k or more. 

In terms of the autobox, I've done some further reading and if my understanding is correct, the valve block differs between engines with different sized flow restrictors. Interesting, but a brand of Witchcraft I'm not getting involved in for now.

Sorting a working kickdown cable for a fly by wire engine isn't over complicated -although the M52 does still have an old fashioned cable setup- whilst a compushift on an EH box would likely be in the £1200 range before I get started on actually fitting the thing. 

Considering I'm aiming to have done the conversion for no more than £350 -including the engine- it's a non starter, especially as I have a nearly new R380 on the shelf.

Adapter plates are easy, as is a solid flywheel -more than suitable for a nice smooth running six-  which I can use a standard Land Rover push off clutch, rather than the silly dual mass/pull off setup used in SA vehicles and P38's.

As an aside, the M51 with a power chip compares favourably enough with the 3.9 V8 that I reckon the V8 autobox would go very well behind it.