P38A 300Tdi conversion.

Will it fit?
A mate here has a 1997 300Tdi automatic Disco D1, it is crumbling to rust but is mechanically good, he has been offered a RR P38, '95 or '96 model with a good rust free body and pretty tidy interior, the auto tranny and V8 engine gave up the ghost long back. The Rangie has sat a long while and is for sale for $500. So, is it possible to put a Tdi into the Rangie, it is a legal swap because the engine would be from a slightly newer model, that's all that seems to matter for the vehicle to be compliant.
As far as I know Diesel P38's didn't get sold here in Australia, (and not sure if Tdi was an option anyhow), not since the VM powered RRC's of the late 80's

I believe people have swapped them over. In fact, think a guy on here did it not so long back for the same reasons you've given - he had one lying around.

I’m sure anything is possible. However it would be a huge amount of work IMO.

No idea how easy it would be to get the p38’s electronics working as they should. The Tdi engine itself would be easy to get running as it requires none really. But the BCU and ECU on a p38 talk to each other. So can see potential issues here unless you are an electronics engineer.

I suspect the worst thing is it would likely be dreadful to drive. Auto Tdi’s were total slugs and probably one of the slowest vehicles LR ever produced. A p38 weighs more than a D1 so will suffer even more.

300bhp/ton said:

I’m sure anything is possible. However it would be a huge amount of work IMO.

No idea how easy it would be to get the p38’s electronics working as they should. The Tdi engine itself would be easy to get running as it requires none really. But the BCU and ECU on a p38 talk to each other. So can see potential issues here unless you are an electronics engineer.

I suspect the worst thing is it would likely be dreadful to drive. Auto Tdi’s were total slugs and probably one of the slowest vehicles LR ever produced. A p38 weighs more than a D1 so will suffer even more.

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All good points to consider before committing to the project, the electrikery stuff particularly. He's not a speedy driver and we've already talked about changing out the air suspension for coils, but do you know if the Tdi was ever factory fitted to the P38 in either auto or manual. If there's a possibility of it fitting ok then we could work around any other problems, he's not after a mint RR.
Neither of us are into modern electrikery but he's an old A/C engineer so I guess he'll be able to get the A/C operational again, most important where we live.

Tdi was not fitted to the p38. The only diesel was the BMW inline 6 cylinder 2.5 litre unit. Which is quite a bit more pokey than the Tdi. But was generally considered underpowered in the p38.

Tbh I’d suspect you’ll spend more on gabbing parts to fit a Tdi that it would cost to get a used RV8. The gearboxes are likely the same between the D1 and p38. Both used the ZF. The 4.6 used the stronger HP24 while the others are the HP22 iirc.

The transfer boxes are different. So you’d want to retain the one in the p38.

300bhp/ton said:

Tdi was not fitted to the p38. The only diesel was the BMW inline 6 cylinder 2.5 litre unit. Which is quite a bit more pokey than the Tdi. But was generally considered underpowered in the p38.

Tbh I’d suspect you’ll spend more on gabbing parts to fit a Tdi that it would cost to get a used RV8. The gearboxes are likely the same between the D1 and p38. Both used the ZF. The 4.6 used the stronger HP24 while the others are the HP22 iirc.

The transfer boxes are different. So you’d want to retain the one in the p38.

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I think the D1 uses the HP22 the P38 uses the HP22e, the first uses mechanical selection, the second electronic..

Gazbo said:

All good points to consider before committing to the project, the electrikery stuff particularly. He's not a speedy driver and we've already talked about changing out the air suspension for coils, but do you know if the Tdi was ever factory fitted to the P38 in either auto or manual. If there's a possibility of it fitting ok then we could work around any other problems, he's not after a mint RR.
Neither of us are into modern electrikery but he's an old A/C engineer so I guess he'll be able to get the A/C operational again, most important where we live.

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Leave the engine ECU in place, that will cover some of the electrickery problems.

Datatek said:

I think the D1 uses the HP22 the P38 uses the HP22e, the first uses mechanical selection, the second electronic..

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Thanks

As Datatek said, leaving the ECU in place is the easiest way out - not saying the whole conversion is going to be exactly a walk in the park.

For starters, the 300Tdi being a direct injection engine gives it an edge in terms of efficiency over the BMW unit which is an indirect injection engine.

The 300Tdi in stock form is under stressed and capable of some respectable power figures with suitable inexpensive upgrades in boost, charge air cooling and FIP tuning - if you know what you're doing.

Before marriage and kids, I completed a similar conversion on my D2 with a 200tdi when the stock Td5 died - oil pump drive parted ways with the pump body while on the motorway and the rest is history.

Sourced a 200Tdi out of a D1, complete with its autobox. After removing the Td5 engine with its electronically controlled autobox, sat it side by side with the 200Tdi on the ground to get an idea of where the engine mounts would be going on the chassis legs.

Retained the original transfer box for the D2 so didn't have to modify the transmission mounts if I remember correctly.

With the engine and transmission mounted, made an adapter that allowed the temp sender from the Td5 to sit on the head of the 200Tdi.

To get the tachometer to work again is where the real work comes in - a reluctor ring is needed which would have to be grafted to the flex plate drive, and a hole bored into the side of the transmission to accommodate the sensor which will feed engine speed to the ECM through the connector for the Td5s crank position sensor - getting the right air gap to get the thing working right is another story entirely.

The electronic throttle pedal comes out, and in its place went the cable and pedal from the D1.

The transmission is all mechanical with a kickdown cable run off the throttle linkage on the FIP, so no dramas there.

Speed signal on the D2 is generated by the ABS module so didn't have to do anything there.

Totally doable if you've got the time.

Having that donor vehicle makes things even less complicated, because you don't have to go running around looking for parts.

That was about 10 or so years ago, and I still have the car, even though I hardly drive it anymore.

Running the stock rad and intercooler from the Td5, and for a time, grafted the turbo off a Mercedes 904 engine to it.

With that top end power was good, but turbo lag around town was horrendous, so went back to the stock turbo.

Will take some photos and post them for you later.

The wife doesn't understand why I refuse to sell it.

All the best with yours.

300bhp/ton said:

Tdi was not fitted to the p38. The only diesel was the BMW inline 6 cylinder 2.5 litre unit. Which is quite a bit more pokey than the Tdi. But was generally considered underpowered in the p38.

Tbh I’d suspect you’ll spend more on gabbing parts to fit a Tdi that it would cost to get a used RV8. The gearboxes are likely the same between the D1 and p38. Both used the ZF. The 4.6 used the stronger HP24 while the others are the HP22 iirc.

The transfer boxes are different. So you’d want to retain the one in the p38.

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Not too worried about the power aspect of the engine swap. We have a few rusted out D1 Tdi's to rat for bits and pieces and good facilities to carry out the work plus we're gentleman in retirement, so plenty of time, well at least the rest of our lives, (how long is a piece of string), to get it done.
My mate doesn't want a V8, he likes his Tdi, as I really like mine, and we can afford to run them, they do the job perfectly adequately.
I think we'd try and use the Tdi tranny and transfer case, isn't the P38 transfer box unit a chain drive with that BW VCU, that can be a pain when it fails. All the running gear from the D1 is in good order, just the bodies on all our 3 spare parts Disco's are rotted, so not usable.

Gazbo said:

Not too worried about the power aspect of the engine swap. We have a few rusted out D1 Tdi's to rat for bits and pieces and good facilities to carry out the work plus we're gentleman in retirement, so plenty of time, well at least the rest of our lives, (how long is a piece of string), to get it done.
My mate doesn't want a V8, he likes his Tdi, as I really like mine, and we can afford to run them, they do the job perfectly adequately.
I think we'd try and use the Tdi tranny and transfer case, isn't the P38 transfer box unit a chain drive with that BW VCU, that can be a pain when it fails. All the running gear from the D1 is in good order, just the bodies on all our 3 spare parts Disco's are rotted, so not usable.

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Unfortunately you can't use the transfer case of the Tdi for your P38 because of the location of the differentials on the axles - unlike every other land rover, the differentials on the P38 are on the left.

Gazbo said:

Not too worried about the power aspect of the engine swap. We have a few rusted out D1 Tdi's to rat for bits and pieces and good facilities to carry out the work plus we're gentleman in retirement, so plenty of time, well at least the rest of our lives, (how long is a piece of string), to get it done.
My mate doesn't want a V8, he likes his Tdi, as I really like mine, and we can afford to run them, they do the job perfectly adequately.
I think we'd try and use the Tdi tranny and transfer case, isn't the P38 transfer box unit a chain drive with that BW VCU, that can be a pain when it fails. All the running gear from the D1 is in good order, just the bodies on all our 3 spare parts Disco's are rotted, so not usable.

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I don't know the Tdi, but if it has auto transmission, it will be the HP22, so the HP24 from the P38 4.6 should mate directly with the Tdi you may have to change the torque convertor though as the one from the 4.6 may not fit and the one from the Tdi may not match the oil pump drive in the auto box. Apart from the VCU, there is nothing wrong with the transfer box on the P38.

Gazbo said:

Not too worried about the power aspect of the engine swap. We have a few rusted out D1 Tdi's to rat for bits and pieces and good facilities to carry out the work plus we're gentleman in retirement, so plenty of time, well at least the rest of our lives, (how long is a piece of string), to get it done.
My mate doesn't want a V8, he likes his Tdi, as I really like mine, and we can afford to run them, they do the job perfectly adequately.
I think we'd try and use the Tdi tranny and transfer case, isn't the P38 transfer box unit a chain drive with that BW VCU, that can be a pain when it fails. All the running gear from the D1 is in good order, just the bodies on all our 3 spare parts Disco's are rotted, so not usable.

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Not sure why anyone would prefer a Tdi over a V8. And this is coming from someone who owns 2 x Tdi vehicles.

Don't get me wrong, they are stout engines and simple and easy to maintain. But a V8 is less noisy, more powerful, smoother and more refined. And is also a stout and simple engine to maintain. Plus it's physically lighter and makes a pleasant sound.

The only thing a Tdi has in it's favour is mpg..... but if you can afford the fuel for the V8 then this is no longer a plus point.

Bit of advice, forget about it.

300bhp/ton said:

Not sure why anyone would prefer a Tdi over a V8. And this is coming from someone who owns 2 x Tdi vehicles.

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Head gaskets, liners, front cover, rear oil seal, valley gasket ...

Grrrrrr said:

Head gaskets, liners, front cover, rear oil seal, valley gasket ...

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Head gaskets go on Tdi's too, quite common infact. And the RV8 isn't exactly known for it being a common or major issue as a rule.

Liners, meh maybe. But the RV8 has been used in a huge array of vehicles since the 1960's, and in most cases without any sort of major issue. Real oil seal also goes on Tdi's..... tell me how I know about this (currently prepping to pull the engine to replace an almost new clutch on a 200Tdi due to real oil seal failure).

300bhp/ton said:

Head gaskets go on Tdi's too, quite common infact. And the RV8 isn't exactly known for it being a common or major issue as a rule.

Liners, meh maybe. But the RV8 has been used in a huge array of vehicles since the 1960's, and in most cases without any sort of major issue. Real oil seal also goes on Tdi's..... tell me how I know about this (currently prepping to pull the engine to replace an almost new clutch on a 200Tdi due to real oil seal failure).

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RV8s problems started when they bored the block to 4.0 litres without strengthen it. Then got worst when they stroked it to 4.6. Cooling system must be kept tip top any overheat can cause problems. Later ones i believe had a slight bevel in top of block and liners.

wammers said:

RV8s problems started when they bored the block to 4.0 litres without strengthen it. Then got worst when they stroked it to 4.6. Cooling system must be kept tip top any overheat can cause problems. Later ones i believe had a slight bevel in top of block and liners.

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Not really, as the 3.9 is the same bore as the 4.0 litre. Plus LR used the 4.2 and TVR used 4.3, 4.5 and 5.0 litre displacements too. And not to mention the Australian 4.4 variant.

The RV8 was also used in multiple military applications also.

300bhp/ton said:

Not really, as the 3.9 is the same bore as the 4.0 litre. Plus LR used the 4.2 and TVR used 4.3, 4.5 and 5.0 litre displacements too. And not to mention the Australian 4.4 variant.

The RV8 was also used in multiple military applications also.

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Yes really. The 3.9 is the 4.0 litre. It was good as a 3.5 not so good in other variants. Troubles got worse when running temp was increased for emission purposes. Any over temp can crack the blocks, the cooling system is marginal. Some say Rover had a bad batch of blocks but used them anyway.

The water pump favours a certain side of the block on some RV8's causing uneven cooling.

And of course issues.

The liners drop because the block behind them crack..

The water galleries are off of centre in certain RV8 blocks they crack where it's thinnest..

Coscast blocks i believe they're called were marginally better.

the tooling for these engines was crap at best.

99% of issues is always Human error, and sħit tools.


As for a 300tdi in a p38 forget about it,

Continental drift is faster even in the lighter D1