300bhp/ton
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It's 6 of one and half dozen of the other. An RV8 might be perfectly fine, and so too might a 2.5 diesel. But both could have issues.
4.6 vs 2.5 tdi
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It's 6 of one and half dozen of the other. An RV8 might be perfectly fine, and so too might a 2.5 diesel. But both could have issues.
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So let us sum it all up into an easy to understand statement. If you want the ultimate Range rover P38 go for a petrol engine. If you want an ultimately reliable Range rover P38 remove the petrol engine and fit a diesel. Job sorted. 
300bhp/ton
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Can't really agree with that. We've had two 4.6 p38a's with no issues at all. And have had 7 or 8 other V8 RRC's and D1's. Only one had an engine issue, an early EFI 3.5, but in fairness the engine was knackered when bought.
I have nothing against the diesels, although haven't owned a p38a diesel. I know someone who's had two and had engine issues with both. Although I think only one was major.
We've owned plenty of Tdi's and a 2.5VM RRC. All of these have been brilliant, the VM especially so.
I have nothing against the diesels, although haven't owned a p38a diesel. I know someone who's had two and had engine issues with both. Although I think only one was major.
We've owned plenty of Tdi's and a 2.5VM RRC. All of these have been brilliant, the VM especially so.
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Simple fact of the matter is that a looked after diesel engine is far, far more reliable than a looked after petrol engine. There was a five cylinder Gardner on some remote island in the Caribbean that was coupled to a generator. Last i heard apart from stopping for oil changes and servicing had run continuously for 44 years without any mechanical repair.
300bhp/ton
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That's nice, but what does it have to do with the relatively modern and complicated 6 cylinder BMW unit?
I don't deny that there used to be trend that older diesels where very durable, but this is mostly because they where overbuilt, heavy, quite simple and relatively low stressed. None of which has any real relevance to the BMW M51 engine.
Yes, the M51 can be reliable, but it is nothing intrinsically to do with it being a diesel.
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There is nothing more complicated about an M51 other than the overhead camshaft than earlier diesel engines. Only thing different in modern diesels that may make them less reliable than earlier ones is the RPMs they now go to. Same with petrol engines. Extra RPM means more mechanical stress and more heat to disperse. That is why petrol engines can never be as reliable as diesel engines.
tomcat59alan
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In the old days, or so I was told
, if you did a recorded 1 million miles with a Gardner engine they would replace it with a new one FOC. They would wear out the driver before the engine gave up.
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OHC and Turbocharged and ECU controlled. And based on a petrol 6 pot architecture & basic design. (doesn't it use an aluminium head too?)
It's a loong long way from a simple 2 or 4 stroke single or twin cylinder generator.
BTW - I think 5000-5200rpm is pretty on par with today's high revving diesel engines.
BMW M51 - Wikipedia, the free encyclopedia
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Ok get a new M51 and a new Rover V8 red line both of them and tell me which one blows up first.
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And that proves what? Apart from the test being an f'ing stupid idea.
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And that proves what? Apart from the test being an f'ing stupid idea.
The petrol engine will expire first. They always do. That's the way it is. We can argue all year but it won't alter anything.
300bhp/ton
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What that stupid non real world tests are pointless.
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What that stupid non real world tests are pointless.
Diesel engines are more reliable than petrol engines what part of that do you not understand?
Datatek
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V8's are the work of the devil, one cylinder head too many too many plugs and valves, poor access to manifolds etc.
There was an excuse for them in the States when petrol was $0.50 a gallon, big lazy unstressed engines in big lazy cars that ran for ever.
No excuse now with diminishing oil reserves and high prices.
Most trucks have reverted to in line 6 cylinder engines, better power to weight ratio and easier access for maintenance, that should tell you something.
There was an excuse for them in the States when petrol was $0.50 a gallon, big lazy unstressed engines in big lazy cars that ran for ever.
No excuse now with diminishing oil reserves and high prices.
Most trucks have reverted to in line 6 cylinder engines, better power to weight ratio and easier access for maintenance, that should tell you something.
Just a quote from somewhere...
To say the diesel engine (in general) is more reliable than a petrol is absurd. There is little between them in all honesty nowadays. (Equivalent) Petrol engines MAY be cheaper to repair, due to the nature of the different parts, but then again, the liner issues on the P38 V8's may well balance this out more.
The problem here is that some diesel owners appear to be of the oopinion that the M51 is almost without fault, despite this clearly not being the case. The V8's aren't without fault either though.
On a purely cost basis though, I believe my V8 P38 was a good £1000 (probably more like £1500) cheaper to buy than the diesel equivalent. But it will cost me £500 - £600 more to fuel the car for the year. Obviously the diesel will command more money when I sell it on though, but as far as total ownership costs go, there will be little in it between them I'm sure.
And then, on top of that, I get a RR that isn't too slow, and sounds nice. And doesn't smell so bad.
tomcat59alan
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Datatek
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True and getting fatterYou forgot the big lazy fat drivers.
tomcat59alan
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true and getting fatter
:d:d
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No engine is faultless. It is just that some are less prone to faults than others. Diesels in general are less prone to faults than petrol engines. That is a simple fact of life. Or at least it is if you have been involved with engines both petrol and diesel for over fifty years. My P38 diesel is anything but slow. I can't think of a reason with todays speed restrictions and roads you would want a quicker motor. If diesel P38s cost more than petrol versions year for year they are obviously regarded as more desirable or they would be cheaper.
