range rover p38 4.6 block id

iwallace said:

i will let you know what im doing with it
cheers ian

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Thanks Ian

If RPI built it, it will likely have a piper 270 or 285 camshaft, upgraded tappets / timing chain. Are your heads ported? Post a pic of the exhaust ports if you're not sure

Missed the head pic, inlets look ported, exhaust will be more obviously larger and require larger than standard gaskets (v8 developments / rpi)

cooltide said:

Missed the head pic, inlets look ported, exhaust will be more obviously larger and require larger than standard gaskets (v8 developments / rpi)

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im not 100% but the exhaust side seems to match the ex gaskets

Ported

just spoke to rpi about my lump.
4,6ltr supplied brand new in 2012, low comp pistons, 285 camshaft, upgraded tappets and timing chain, stage 1 head work ,re mapped ecu and secondary airway,
looking at the honing marks, i dont think this is run in yet,..

I would take some of that with a pinch I did not think there was a re map for the Thor engine in 2012. Why low comp Pistons. What is a secondary airway? Still what a great find must have cost a small fortune to do. £4000 +

All head w

johnnyb70 said:

I would take some of that with a pinch I did not think there was a re map for the Thor engine in 2012. Why low comp Pistons. What is a secondary airway? Still what a great find must have cost a small fortune to do. £4000 +

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All head work was done last February. Secondary airway for lpg as far as I'm aware..re mapped same time as head work....Well it's says that on invoice ...

That'll be a Marc Adams remap then.

Looks like you got a result there.

sorry to bring this one up again, but can anyone put me right,
if i use 4ltr pistons in this block, does it make it a 5ltr...is it just pistons i change.
i have a 4ltr gems waiting to be split, are the pistons the same, gems and thor.
any one recommend a engineering company in hampshire to get it top hated.
if im going to keep it, and rebuild it with other pistons , might aswell get it top hated.
cheers ian

iwallace said:

sorry to bring this one up again, but can anyone put me right,
if i use 4ltr pistons in this block, does it make it a 5ltr...is it just pistons i change.
i have a 4ltr gems waiting to be split, are the pistons the same, gems and thor.
any one recommend a engineering company in hampshire to get it top hated.
if im going to keep it, and rebuild it with other pistons , might aswell get it top hated.
cheers ian

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4.0 litre pistons will only increase the compression ratio.........the swept volume will remain the same ie 4.6 litres

Moron said:

4.0 litre pistons will only increase the compression ratio.........the swept volume will remain the same ie 4.6 litres

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thanks for the quick reply,
thats them plans gone now then.
thanks anyay

I would use acr in deeside ( north Wales) or Turner's.top hatting isn't as straightforward as falling off a log. Acr have a superb technique for acheiving this. Turner's also. I've had some experience of a badly done top hat job and it's a bit depressing and annoying.

Also if you consult these guys they can increase the cubic capacity without compromising the reliability.

johnnyb70 said:

Also if you consult these guys they can increase the cubic capacity without compromising the reliability.

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Increase the capacity past 4.6? Hear that music? That's G'N'R, Appetite for Destruction!

thanks for all them replies.
really not sure where i heard it from about changing the pistons over to make it a 5ltr,.
i was told the diff in the top of the 4ltr piston gave it that extra cc.
but im glad i asked here first.
cheers ian

The cc of an engine is the swept volume Ian. It's the diameter of the piston (bore) x the crank throw (stroke). What goes on above the piston will affect compression ratio, but not cc of engine
Larger capacity than the standard 4.6 is achieved by bigger bore/ longer stroke crank or a combination of the two.
Standard 4.6 bore is 94.04 mm, larger bores of up to 96.5mm can just about be achieved.
Longer stroke cranks are available, but you're into expensive territory there, with different rods etc.

Taking a set amount (.020 inch?) Is considered normal from the cylinder heads for a clean up. Rave shows where to measure the amount already taken off. Past this they don't recomend it. Although mine had the max off the cylinder heads and also at least 2 good skims on the block(another .020?) And no problems. I'm guessing the cr must be higher than allowed normally. Mines already a hc engine as well. Roland at acr now makes wildcat heads btw.
I really enjoyed measuring the crank and big ends and measuring oil clearances etc. Also the actual assembly was fascinating. Measuring the torque needed to turn over the engine shows the resistance of all the surfaces( albeit smeared with assembly lube). I can say mine is a looseish engine being rebuilt with a polished Thor crank( no grinding) it was at the loosest tolerance( gems engine) I run it on 10/50 full synthetic because of this. I would say measure the big ends and journals. Use plastigauge on the mains.
You realise this friction is a basic drain on the energy your engine can produce.