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Range Rover P38
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Discussion Starter · #1 ·
Greetings folks, I have recently sent my p38 engine for rebuild, long story short the place were a bunch of wasters.
Got the engine back in boxes and bags. I am trying to rebuild from scratch. First thing I notice is the crankshaft states 4.6 on the side, could this have been the original crankshaft or have they just thrown a random one in? i.e. could a 4 litre crankshaft fit a 4 litre block etc.?
I am rebuilding mostly as a learning activity, so am full of random questions. Literature on the subject seems mixed. My block is cross bolted, so I believe it is a 'real' 4 litre, not 3.9.
 

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The differences between a 4.0 litre and a 4.6 is the crankshaft, con rods and pistons. You could fit a 4.6 crank into a block that was originally a 4.0 litre but you would have to use the matching rods and pistons. Crossbolting was only used on one other variant and that was the 4.2 litre engine fitted to the long wheelbase Classic but the Classic engine varies in quite a few other ways, it has a distributor mounted on the front casing so the camshaft is different too.

If you have RAVE (and if you haven't, you need to get it), there is the overhaul manual included with that if you get the full version and not the cut down version that covers all models.
 
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Range Rover P38
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Discussion Starter · #3 ·
Greetings, the stress continues. I have continued the build of my 4 litre V8 for my 1994 P38.
The build was going well, but my concerns have come back because I have purchased pistons for the 4 litre V8 with the intension of replacing the Crankshaft. Being reassured by several dealers that my 4.6 crank will work, I installed it. When cycling (without the head attached) my pistons over shoot the block by about 3mm. Can someone just tell me if this is because my 4.6 crankshaft is oversized or something?
I have a high compression block CR9.35:1 and I have 4 litre pistons. However my crank is a 4.6 HRC 2684. Is this all because I have 'too big' a crank?
 

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With a 4.6 crank, you also need to use the 4.6 con rods and pistons from the reason you've now found. Give Ray at V8 Developments a call (V8 Developments) there's nobody that knows more about these engine than him. I spoke to him the other day, the landline number has a recorded announcement giving Ray's mobile number so make sure you have a pen and paper handy.
 

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Yes, you do need the conrods to go with the 4.6 crank. You could use 4.0 pistons, that would raise compression. Not always a good idea, especially if the heads have already been skimmed.
 

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Range Rover P38
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Discussion Starter · #7 ·
Would i be better to just get a 4.0 litre crankshaft? That way i will have the block as it was constructed?
 

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A 4.6 is 15% better than a 4.0. So unless you can exchange the crankshaft for a 4.0, the logical option would be to keep the crankshaft and get matching conrods and pistons.
 
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