1998 defender Cummins swap

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Kelsey1997

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I’m planning on doing the Cummins conversion in the new year but I’m wondering if anyone has a list of all the bits I’d need to do it so I’m not missing anything
 
Kelsey1997 said:
I’m planning on doing the Cummins conversion in the new year but I’m wondering if anyone has a list of all the bits I’d need to do it so I’m not missing anything
Click to expand...
Welcome to LZ.

I don't. But there was a thread on the forum about it years ago. To be honest, I think it is a bit needless, and will put a lot of strain on your half shafts and other components.
 
Just always wanted to do one that’s all, and no I’m not new to land rovers, been around then since I could crawl just always been knows as defenders round us not being picky about weather it’s a 90 or not
 
I reckon you would be better with the 4bt, rather than the 6bt, there is a vid on youtube of a guy fitting a 4bt into a disco 1 or 2 model.
The 6 is a serious lump of metal, 4 are quite rare.
Dont buy an ex bus 6bt as it will be shagged beyond belief.

 
Kelsey1997 said:
Just always wanted to do one that’s all, and no I’m not new to land rovers, been around then since I could crawl just always been knows as defenders round us not being picky about weather it’s a 90 or not
Click to expand...
Ignorance of the law is no excuse for crime! :D

Try forum search, there is a huge thread about it, although it is a six cylinder, not a four. I can't remember who posted it, or what it was called, it was many years ago.

Also, try posting in Introduce yourself, telling us a little bit about yourself.
And posting somewhere other than the 200Tdi section, it will get a bit more interest there.
 
Kelsey1997 said:
I’m planning on doing the Cummins conversion in the new year but I’m wondering if anyone has a list of all the bits I’d need to do it so I’m not missing anything
Click to expand...
I love the Cummins engines, but they are big and heavy!!! I think something like 900lbs, which another poster on here said is the about the max front axle loading.

I haven't been in a LR powered by one, but I'd really have to question their suitability. Esp in a 90, as it would make them extremely nose heavy relative to their wheelbase.
In terms of all the bits, surely that depends on the soec and version you are going for. The engine comes in many flavours, 12v and 24v versions and with fully mechanical or electronic control. I know in the UK people often get them from a DAF truck or something. But these are low powered (125hp I think) units. Not sure what needs to be done to bring power up. But at this sort of power level, a tuned Td5 is a much more suitable engine IMO.

On the flip side these engines can make loads of power 300hp+ and insane levels of torque (900ft-lb) if you are getting one out of a Dodge Ram. But you'll need a truly stout drivetrain for this this. From gearbox/transferbox right through to axles....
 
Last edited:
300bhp/ton said:
I live the Cummins engines, but they are big and heavy!!! I think something like 900lbs, which another poster on here said is the about the max front axle loading.

I haven't been in a LR powered by one, but I'd really have to question their suitability. Esp in a 90, as it would make them extremely nose heavy relative to their wheelbase.
In terms of all the bits, surely that depends on the soec and version you are going for. The engine comes in many flavours, 12v and 24v versions and with fully mechanical or electronic control. I know in the UK people often get them from a DAF truck or something. But these are low powered (125hp I think) units. Not sure what needs to be done to bring power up. But at this sort of power level, a tuned Td5 is a much more suitable engine IMO.

On the flip side these engines can make loads of power 300hp+ and insane levels of torque (900ft-lb) if you are getting one out of a Dodge Ram. But you'll need a truly stout drivetrain for this this. From gearbox/transferbox right through to axles....
Click to expand...
I would think autobox would give the drive train a much easier ride, and imagine that is what would be used in a Dodge Ram, although I have never driven one.

Another concern with the increased weight would be the impact on steering ball joints, rods, boxes, swivel pins, etc.
 
Ram's could be had with an auto or 6 speed manual with the Cummins. Personally I'd want the manual for the fun of driving.
 
Hi, I have a Cummins converted 90. It's a fantastic conversion depending on what you want from it. Mines used for towing on the weight limit and as such the ex lorry engine is perfect.
 
300bhp/ton said:
Ram's could be had with an auto or 6 speed manual with the Cummins. Personally I'd want the manual for the fun of driving.
Click to expand...
The autoboxes fitted to the Rams aren't up to the job. Manual ZF 5 speed from the Daf 45 is the way to go as it's designed for the power and easy to mate to the LT230
 
300bhp/ton said:
I love the Cummins engines, but they are big and heavy!!! I think something like 900lbs, which another poster on here said is the about the max front axle loading.

I haven't been in a LR powered by one, but I'd really have to question their suitability. Esp in a 90, as it would make them extremely nose heavy relative to their wheelbase.
In terms of all the bits, surely that depends on the soec and version you are going for. The engine comes in many flavours, 12v and 24v versions and with fully mechanical or electronic control. I know in the UK people often get them from a DAF truck or something. But these are low powered (125hp I think) units. Not sure what needs to be done to bring power up. But at this sort of power level, a tuned Td5 is a much more suitable engine IMO.

On the flip side these engines can make loads of power 300hp+ and insane levels of torque (900ft-lb) if you are getting one out of a Dodge Ram. But you'll need a truly stout drivetrain for this this. From gearbox/transferbox right through to axles....
Click to expand...

TD5 will not see which way a 130bhp (lowest output) Cummins powered 90 went if you have 3 tons on a trailer behind it. The Cummins makes as much torque at idle as a TD5 makes at max, and it makes 130bhp from near idle to redline. If grunt is what you want you will not get more. The difference between a 130 and higher power (up to 180) is just pump mods and injectors. Remember power is relative. 180bhp is enough to pull 18tons of lorry or pull a 6 furrow plough with a 5.9 engine! Above 180bhp you need a different pump. With turbo mods you can then go as far as you like... 600bhp if you like. The cranks and rods are huge and will take way more than you can give!

It's a heavy engine and box combo for sure but it doesn't drive any different than it did. Still under the front axle weight on my 90. Air clutch and more steering pump pressure make it a nicer drive than a normal 90 too...
 
Rough list of parts needed....
Engine, any turbo'd with VE or P pump (older DPS pump on early 130bhp (non intercooled) is fine but not tuneable)
Gearbox, zfS5-42 or the old Spicer box
1.003:1 or 0.9:1 transfer ratio gearset
Conversion gear ZF to LT230
Joi ing adapter ZF to LT230
Engine/gearbox mounts, I used MK4 transit rubbers and made my own metalwork
Radiator/Intercooler if desired, mines a V8 rad but TD5 complete cooling pack works
Transit or TD5 alternator if going 12v (includes vac pump on alternator, mines 24volt so I use a separate vac pump)
Sump oil pickup pipe, sump has to be turned around
PAS pump, I kept compressor and pump and altered relief valve to suit defender steering box but most lose all that and use an electric pump.
HD rear springs for the front
Propshafts, require altering, I did my own
Exhaust
Gearbox top mount gear lever turret, I made mine but some standard out there
1" bore clutch master cylinder or non assisted slave (various options as DAF clutch is air assisted, depends if you keep compressor or not)
Linkages for transfer box levers etc
Obviously bits of wire, pipe, hose, cables etc
You'll need to alter the tunnel to fit the gearbox
That's about it really
 
300bhp/ton said:
I love the Cummins engines, but they are big and heavy!!! I think something like 900lbs, which another poster on here said is the about the max front axle loading.

I haven't been in a LR powered by one, but I'd really have to question their suitability. Esp in a 90, as it would make them extremely nose heavy relative to their wheelbase.
In terms of all the bits, surely that depends on the soec and version you are going for. The engine comes in many flavours, 12v and 24v versions and with fully mechanical or electronic control. I know in the UK people often get them from a DAF truck or something. But these are low powered (125hp I think) units. Not sure what needs to be done to bring power up. But at this sort of power level, a tuned Td5 is a much more suitable engine IMO.

On the flip side these engines can make loads of power 300hp+ and insane levels of torque (900ft-lb) if you are getting one out of a Dodge Ram. But you'll need a truly stout drivetrain for this this. From gearbox/transferbox right through to axles....
Click to expand...

12v cummins can be tuned for 1000bhp, think the block is the weak point.
Iirc rough rule is bosch ve pump = 150bhp, bosch inline pump = 210bhp.

Theres a few vids of cummins powered lrs on youtube, if you watch a few you soon notice every driver without exception molly coddles the gearchanges, I assume for fear of wrecking something on the drivetrain.

Some good vids and info on fitting the Merc OM606 to a lr, now thats an engine, all alloy capable of serious bhp.
 
lynall said:
12v cummins can be tuned for 1000bhp, think the block is the weak point.
Iirc rough rule is bosch ve pump = 150bhp, bosch inline pump = 210bhp.

Horses for courses really. The OM606 is a great engine for a general use LandRover but can't match a Cummins if grunts your goal.

The drivetrain is fine if in good condition, as usual half shafts are the weak link but they are cheap fuses! If you're doing a lot of wheel spinning or off roading then the defender drive train is not really up to it. But I wouldn't use a Cummins if that was the intended use.
Theres a few vids of cummins powered lrs on youtube, if you watch a few you soon notice every driver without exception molly coddles the gearchanges, I assume for fear of wrecking something on the drivetrain.

Some good vids and info on fitting the Merc OM606 to a lr, now thats an engine, all alloy capable of serious bhp.
Click to expand...
 
300bhp/ton said:
What a completely and utterly stupid thing to say. Why the frak would you be trying to race with a 3 tonne trailer.
Click to expand...

You misunderstand my meaning... What I mean is 130bhp from a Cummins isn't the same as 130bhp from a 2.5 litre engine.
The reason I fitted a Cummins is that I tow a lot, up big hills. With a 2.5 litre engine this is perfectly possible but you have to use high revs/boost and if you can't carry momentum, which is often impossible with 90 degree bends and the bottom of steep hills this means you're stuck in first or second gear to the top of the hill. With the 5.9 I can roll around the corner in 3rd at idle speed, put my foot down and accelerate up through the gears as I would with a 2.5 litre on flat ground.
I'm not talking about racing anyone.
 
Just checked some figures and a Cummins site says a dry but dressed 5.9 is 1100lbs (almost 500kg). A wet Td5 with flywheel & clutch is 244kg. Which is a pretty big difference.

I'm not knocking the engines, but if you can't notice 250kg+ over the front axle, there is something wrong with your driving.

Also worth noting that this will also reduce your maximum payload by at least 250kg, but possibly more as I'm guessing the gearbox weighs more and maybe other changes you've made to the vehicle. Not sure what spec 90 you have, A fully optioned Station Wagon comes in at 1976kg kerb with a GVW of 2505kg, i.e. 529kg payload. With the Cummins engine you are at best down to only 279kg carrying capacity, but possible even under 200kg depending on how much the other stuff weighs. The reality of this means, depending on spec of your vehicle. If you had 2 average sized adults (driver & passenger). Then you might legally be down to about 35kg carry ability in your 90. And you'd be illegal and overweight if you had 3 or 4 people (inc driver) on board.

If you vehicle is a no option 90 pickup, then there is capacity for 200kg extra hauling ability over a fully optioned CSW.
 
Breathless5.9 said:
You misunderstand my meaning... What I mean is 130bhp from a Cummins isn't the same as 130bhp from a 2.5 litre engine.
The reason I fitted a Cummins is that I tow a lot, up big hills. With a 2.5 litre engine this is perfectly possible but you have to use high revs/boost and if you can't carry momentum, which is often impossible with 90 degree bends and the bottom of steep hills this means you're stuck in first or second gear to the top of the hill. With the 5.9 I can roll around the corner in 3rd at idle speed, put my foot down and accelerate up through the gears as I would with a 2.5 litre on flat ground.
I'm not talking about racing anyone.
Click to expand...
That's why they have low box.
 
300bhp/ton said:
Just checked some figures and a Cummins site says a dry but dressed 5.9 is 1100lbs (almost 500kg). A wet Td5 with flywheel & clutch is 244kg. Which is a pretty big difference.

I'm not knocking the engines, but if you can't notice 250kg+ over the front axle, there is something wrong with your driving.

Also worth noting that this will also reduce your maximum payload by at least 250kg, but possibly more as I'm guessing the gearbox weighs more and maybe other changes you've made to the vehicle. Not sure what spec 90 you have, A fully optioned Station Wagon comes in at 1976kg kerb with a GVW of 2505kg, i.e. 529kg payload. With the Cummins engine you are at best down to only 279kg carrying capacity, but possible even under 200kg depending on how much the other stuff weighs. The reality of this means, depending on spec of your vehicle. If you had 2 average sized adults (driver & passenger). Then you might legally be down to about 35kg carry ability in your 90. And you'd be illegal and overweight if you had 3 or 4 people (inc driver) on board.

If you vehicle is a no option 90 pickup, then there is capacity for 200kg extra hauling ability over a fully optioned CSW.
Click to expand...
That would be my take on it, Cummins are a good engine, in a truck or a boat.
But a bit too heavy for a Landrover.
 
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