Turbo conversion on a 2.5 nad ?

[2a-rich]

I very soon going to be fitting a 2.5 NAD engine in my Series 2 ,Ive been told you can easly put a turbo on these without any probs ,is this true ? I have already got a turbo & pump ready to fit ,do i need to get the injectors also ? just need some advice please ,thanks in advance

[Jon White]

Advice would be as follows:-

1. Remove bonnet

2. Remove NA diesel

3. Throw NA diesel away

4. Fit 200Tdi

5. Refit bonnet.

Not worth pissing about mate now 200Tdi's are so cheap!

Jon

[SteveA]

What exhaust manifold are you going to use? The Lightweight I have been working on recently had a engine and exhaust manifold from Bearmach, which had the a different manifold to take the Garret turbo.

The engine has done great miles now and was getting close to throwing out and burning as much oil as diesel, so as part of a complete re-build, as Jon White also suggests, a 200tdi is going to go in next.

[Mark]

As has been said, the 200TDI is a far better engine, and pretty easy to get hold of now.

The Turbo version of the 2.5 NAD is known to be quite stressed, and not one of LR's better creations.

I believe the block is different between the NA and the Turbo as well, to take account of the extra stress, so bolting a turbo to an NA block sounds like a recipe for problems to me...

Mark

[rusty_wingnut]

not a good idea. someone is lying to you.

[Phil Hancock]

TD block has an extra oilway for the turbo oil feed plus the crank and main bearings are different to cope with the extra stress, also the pistons are a different material to cope(???) with the extra heat.

[headdamage]

TD block has an extra oilway for the turbo oil feed plus the crank and main bearings are different to cope with the extra stress, also the pistons are a different material to cope(???) with the extra heat.

The 2.5na, 2.5TD, and 200TDI all use exactly the same crank shaft.

[88inchthing]

The 2.5na, 2.5TD, and 200TDI all use exactly the same crank shaft.

Well i would'nt know. What is more important is the aparent lack of oil feed/return for the turbo and difference in pistons. I was taught years ago that when an engine was fitted with a turbo the compression is normally reduced. Not always the case but unless you know for sure asume they are the wrong pistons.

As stated before fit a 200TDI now, it will save you doing it in future. Also a TDI will increase resale value.

[FridgeFreezer]

Jeebus, this comes round every few weeks - the 2.5NA cannot take the stress of a turbo without spending a load of cash on new bits, far outweighing both the benefit of the turbo and the price of just buying a TDi or better. It was a reasonable idea for about 5 minutes 10 years ago.

[DaveSIIA]

Jeebus, this comes round every few weeks - the 2.5NA cannot take the stress of a turbo without spending a load of cash on new bits, far outweighing both the benefit of the turbo and the price of just buying a TDi or better. It was a reasonable idea for about 5 minutes 10 years ago.

Oh, I must have missed something - the turbocharged 2.25 in my IIA has done 35k miles. Apart from melting a piston (too much boost) at 3k miles, it has been reliable. I did the conversion in 1995 when Tdi's were somewhat very expensive.

If I was looking to do something similar these days then a Tdi would be the starting point.

[Phil Hancock]

The 2.5na, 2.5TD, and 200TDI all use exactly the same crank shaft.

Not the pre 12J43824C ones they dont. 12J43825C and later yes and they can be easily identified by the plugged oil feed and return ports in the block.

[headdamage]

Not the pre 12J43824C ones they dont. 12J43825C and later yes and they can be easily identified by the plugged oil feed and return ports in the block.

I've stripped several 2.5na diesels over the years but they have all been late 80's and early 90's military units, they all have the same crank.... I've just checked the parts book and there are two numbers for the 2.5na so there is some difference I would guess.

[FridgeFreezer]

Oh, I must have missed something - the turbocharged 2.25 in my IIA has done 35k miles. Apart from melting a piston (too much boost) at 3k miles, it has been reliable. I did the conversion in 1995 when Tdi's were somewhat very expensive.

Claiming it's been reliable apart from melting a piston seems like a fairly broad disclaimer to me

[DaveSIIA]

Claiming it's been reliable apart from melting a piston seems like a fairly broad disclaimer to me

Yes, a broad disclaimer. However, the failure was due to the wastegate sticking and boost pressure rising to 13-14psi when it should have been limited to 5-6psi. I measured the air temperature going in to the inlet manifold at 13psi boost and recorded ~160C. I don't have notes for the temperature at 5psi, but recall it was around 60C. A significantly different thermal load. Now there's a big boost gauge (think Fred Dibnah style) in a prominant position on the dash so I don't hit the same problem again.

The key points are:

1. It has done 32K miles since diagnosing the cause of the piston failure, and fixing it. Those miles have been fairly hard (there is something wrong with my right foot which seems to make it heavy on the pedal ), generally motorway and fast A roads but also includes heavy towing 2.5-3.5 tons. It has been totally reliable ever since. The engine still starts easily and pulls a SWB IIA quite well, but hasn't been my daily driver for 10 years or so.
   
2. Everybody told me at the time that it was a recipe for disaster, but I went ahead anyway - more for the engineering challenge - because I wanted more life out of the 2.25NAD. The aim was to match or better the 2.25P without going to a V8.
   
3. It was fun to do and is different. I understood the risks associated with turbocharging an antique engine, and the consequences of failure were acceptable. Not everyone wants to run a vehicle which is close to its ragged edge.
   
4. I wouldn't bother with the conversion these days because Tdi's are readily available at low cost. They are also inherently more reliable and easier to work on (particularly the 300). I'm looking at replacing the 2.25 with a 300Tdi when I rechassis the IIA.
   

Most people would just settle with point 4 above as it would satisfy what they want from the vehicle.

[Phil Hancock]

I've stripped several 2.5na diesels over the years but they have all been late 80's and early 90's military units, they all have the same crank.... I've just checked the parts book and there are two numbers for the 2.5na so there is some difference I would guess.

Yes the visible difference is that the turbo spec crank has the big end oil feed drilling in the main bearing journals going right thro the crank to keep the oil feed constant as the lateNA/TD/200Tdi has a plain bottom main bearing shell to increase the bearing area and without the thro drillings the oil feed would be cut off to the big ends for half the crank rotation.

[headdamage]

Yes the visible difference is that the turbo spec crank has the big end oil feed drilling in the main bearing journals going right thro the crank to keep the oil feed constant as the lateNA/TD/200Tdi has a plain bottom main bearing shell to increase the bearing area and without the thro drillings the oil feed would be cut off to the big ends for half the crank rotation.

That would be it... I had noticed the plain bottom bearing shell in the TD but not the extra oil way in the crank. Thanks.

[Snagger]

It's a really bad idea to try to charge an NAD. LR uprated the pistons, conrods and big ends to cope with the additional stresses for the TD, and it was still very prone to cracking heads and pistons. A converted NAD will be worse. One melted piston in 32k is surprisingly good, but I doubt it'd do 100,000, so won't justify the cost and effort.

I have had a 12J (2.5NAD), two 19Js (TD) and now a 200Tdi in my 109, and would strongly advise against trhe 19J or any turbo charger modified NAD.