As far as I know the offset-crankpin crankshaft was fitted to most (if not all) PRV V6 engines from about 1986 onwards.
The main problem with it is that offsetting the crankpins by 30degrees weakens the crankshaft as a whole. Certainly there were some failures of early R25turbo crankshafts. In order to counter this, the shaft was strengthened, and consequently weighed more.
Overall, the engine was a disaster. Quite how it managed to continue so long is amazing. I can only assume that being a small-selling engine it wouldn't have been cost-effective to develop a new engine straight away.
Diesel SM....
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fastandfurryous
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fastandfurryous
- Posts: 1388
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- Location: On the road, travelling at high speed. Meep Meep.
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I can only think the PRV's longevity had something to do with the French lack of ability when it comes to building large cars. I see that What Car describes the Renault Vel Satis as 'yet another large French car no-one will want to buy' and I suppose really this goes for quite a number.
To some extent this goes with the french tax on larger engined cars (2.8 litres?) but I bet they pay up on loads of BMW's and Mercedes so that probbaly isn't quite the problem - and after all you can always sell a smaller engined car at home.
My own view is that the PRV engine probably represents the end of an era of American inspired cynicism in engineering. In the 70's (when the PRV engine came along) we began to get some interesting engines (Lotus 2 litre 16 valve, Triumph 16 valve for starters) and the introduction of the outstandingly simple Bosch K Jetronic fuel injection as well as electronic that worked and by and large were reliable. The 1973 fuel crisis may have frightened some manufacturers but in reality the large engine still exists (BMW, Mercedes and Jaguar) - and this is presumably because by and large mechanical sophistication stopped at about 2 litres with the odd 2.5.
What I have in mind is Ford Cologne (and Essex) V6 and Rover V8 - push rods - Opel straight 6 - suddenly they discovered crankshaft counterweights in the mid 80's and of course the PRV V6 - strange timing that varied from bank to bank and other things to disguise its shortcomings.
So we have manufacturers condemming their supposedly most profitable range - the large car - to obscurity because they were unwilling to make decent engines! - curiously Volvo - one of the original partners in the PRV deal actualy did something about its shortcomings by making other engines of similar power - the 2.3 litre Turbo 4 cylinder - and the 5 cylinder 850 engine which is Porsch designed and enormously powerful. Still to late to prevent their slide into trouble but I suppose those who styled the 740 must bear some of the blame.
jeremy
To some extent this goes with the french tax on larger engined cars (2.8 litres?) but I bet they pay up on loads of BMW's and Mercedes so that probbaly isn't quite the problem - and after all you can always sell a smaller engined car at home.
My own view is that the PRV engine probably represents the end of an era of American inspired cynicism in engineering. In the 70's (when the PRV engine came along) we began to get some interesting engines (Lotus 2 litre 16 valve, Triumph 16 valve for starters) and the introduction of the outstandingly simple Bosch K Jetronic fuel injection as well as electronic that worked and by and large were reliable. The 1973 fuel crisis may have frightened some manufacturers but in reality the large engine still exists (BMW, Mercedes and Jaguar) - and this is presumably because by and large mechanical sophistication stopped at about 2 litres with the odd 2.5.
What I have in mind is Ford Cologne (and Essex) V6 and Rover V8 - push rods - Opel straight 6 - suddenly they discovered crankshaft counterweights in the mid 80's and of course the PRV V6 - strange timing that varied from bank to bank and other things to disguise its shortcomings.
So we have manufacturers condemming their supposedly most profitable range - the large car - to obscurity because they were unwilling to make decent engines! - curiously Volvo - one of the original partners in the PRV deal actualy did something about its shortcomings by making other engines of similar power - the 2.3 litre Turbo 4 cylinder - and the 5 cylinder 850 engine which is Porsch designed and enormously powerful. Still to late to prevent their slide into trouble but I suppose those who styled the 740 must bear some of the blame.
jeremy
jeremy
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tomsheppard
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Levering the topic back on course, The new Diesel V6 is lighter, torquier and more powerful than the Maserati original. It is also more compact. SMs with blown engines can be found and are not prohibitively expensive.
WOuld you spend £10-15K rebuilding it to 14MPG originality, or a 45MPG mongrel?
Seems like a good idea to me...
WOuld you spend £10-15K rebuilding it to 14MPG originality, or a 45MPG mongrel?
Seems like a good idea to me...
Be happy: it is a way of being wise. (Confucius.)
'92 TZD Estate(Grolliffe), Gone but never to be forgotten.
'95 405 GLX TD Estate. too new to name.
'92 TZD Estate(Grolliffe), Gone but never to be forgotten.
'95 405 GLX TD Estate. too new to name.
Personally I am against locking topics when no rules are being contravened e.g. swearing, racism etc. If members are still interested in taking part in the thread, so be it (however frustrating and contrary to your personal viewpoint)fastandfurryous wrote:Honda.
Could someone please lock this topic... it's going nowhere (and I know, I'm not helping.)
Ian
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Account Ref: 6419
Current Cars
Nissan X-Trail SVE
Saab 2.2TiD
Merc E270 Estate
Past Citroens
2001 Xantia 3.0 Exclusive
1999 Xantia 1.9TD
1997 Xantia 3.0 Exclusive
1995 XM 3.0 Exclusive Estate
PRV
Further information about the PRV engine can be found here.
http://www.delorean.co.uk/
If you click on the section about performance, and then the "Feature" article on PRV performance it will take you back to the future not !
So, although it is about the fitment of the PRV engine into a Delorean, it also contains a lot of other useful information, pictures etc, and is an interesting article. 8)
http://www.delorean.co.uk/
If you click on the section about performance, and then the "Feature" article on PRV performance it will take you back to the future not !
So, although it is about the fitment of the PRV engine into a Delorean, it also contains a lot of other useful information, pictures etc, and is an interesting article. 8)
Offset Big Ends
It also contains further information, and pictures about the offset big ends that fastandfurryous has mentioned about in his previous post.