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can you convert a 2.5 NA to petrol ?

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hello all , 


just a short question , can you convert a 2.5NA diesel engine to be a 2.5 petrol ?

reason for asking , i have 2 diesel lumps lying around, and 2.5 petrol engine's getting rare (and expensive) , i might as well turn these in to something usefull.



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Short answer is yes. As Mike says, pistons definitely, but ISTR the camshaft is the same though. Need the distributor, inlet manifold and carburettor.

Here in UK, the price of diesel fuel is creeping up, but petrol price is coming down, so from that point of view its a good idea, and the petrol engine is much nicer. 

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18 minutes ago, steve b said:

What about the timing gear drive??


Actually yes. Its always the minor details that get you. The whole front end is different, so unless you have easy access to the parts, its a non starter.

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Yes, I build one myself, combining a 2.5 TD with a 2.25 3 bearing petrol. I used new 2.5 petrol pistons, that fit to the 2.25 conrods. The head fits, but I fitted 2.5 petrol valves which I think are larger, with unleaded valve seats pressed into the head, after having them counterbored. I also had the head skimmed by quite a bit, the total compression ratio was 9:1. The 2.25 camshaft drive chain works, you just need to pull a core plug out of the oil gallery so the tensioner has oil pressure.

I fitted a 2.5 inlet manifold with a weber 2 stage carburettor, and was running it on LPG. the distributor and fuel pump of the 2.25 fitted.

Went very well.


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4 hours ago, miketomcat said:

Not necessarily good, one with a knackered bottom end would work.


I had a completely finished 2.25 which I rebuild using the 2.5 block and crank basically. It Just meant my land rover would be off the road shorter, as I could get the block done first, then pull the 2.25 apart and mount the parts to this 2.5 block. I do remember the 2.5 petrol pistons had a limited amount of over sizes available, so check this before you get the block bored, if this is the plan.

If you decide to go ahead with this build, I can give you all the details for this even in Nederlands, but it was about 26 years ago, and my memory is not getting any better!



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