Discussion
)funbobby said:
so are the later engine type a bit more reliable or is it a much of a much?
The serpentine front end engines are in general better (like for like) because of the much improved oil pump arrangement mainly. The original oil pump was of marginal capacity when pumping thin, hot, oil at high temps - especially with any more than minimal wear in the bottom end.
The old gear-type pump is driven off the end of the distributor drive shaft which in turn was driven from the skew gear on the end of the camshaft. The whole arrangement was pretty unsatisfactory from an engineering point of view and whilst probably ok in the original buick / oldsmobile application - with a red line at 4000 rpm and very modest levels of tune it was always a weak point in the UK engines and ever more so with increasing capacity, tuning and engine speeds. Wear in the soft aluminium pump housing also is a problem and causes falling pumping efficiency at relatively low mileages.
The serp engine has a modern style epicyclic pump driven directly from the nose of the crank within the timing cover and has plenty of pumping capacity so concerns about marginal oil delivery under high load / temp or hot idle are pretty much a thing of the past as are problems with excessive wear of the distributor drive gears due to oil pump loads.
Whilst the gear-pump was increased in capacity for the Rover SD1 the problem reamined that the more oil you made the pump deliver and the higher the pressure - the greater the strain on the drive gears and these could wear alarmingly and fail, so ultimately the capability of the early pump was always limited by this.
The other main difference is the drive arrangement for the ancillaries, changed to a poly-V serpentine belt (hence the term) driving all items as opposed to the older multiple narrow belts. The new arrangement is more efficient, reliable and changing the belt can be done on about 2 minutes.
The other key difference between earlier and later engines is around the main bearing location details which was another area of weakness in earlier engines and recieved at least 3 revisions during the engines production life, but that's another chapter..... If you want to be a sad anorak like me read books like David Hardcastle's "The Rover V8 Engine" and Des Hammill's "How to power tune Rover V8 engines"
, but dont encourage me I'll be writing chapter and verse.... 
funbobby said:
tahiti i see you have a 450 im due to be looking at one this weekend. its the first 450 ive tried so curious to see how it compares with 400s and 500s
As you know the car is essentailly the same as any later (post 97) chimaera in terms of everything except the engine. My preference for the 450 is that because the engine is based on the production 4.6 (Range Rover) unit they are all serp's and all have cross-bolted bottom ends (leading on from my comment about main bearing location) which makes the bottom-end more or less bullet-proof, so particularly ideal if, like me, you are interested in developing the engine. Some of the 500s are cross bolted but AFAIK this is not always so and the 400s generally arent. The 450s all have vernier timing sets as do the 500s. The shorter stroke compared with the 500 makes the engine (in theory at least) more "revable". In terms of power - the stock 450 is probably more than half way to the 500 compared with the 400. Some 450s (such as mine) are fitted with the big valve heads with some simple porting work and pocketed pistons (as per 500) but this isnt visible from the outside obviously (I only found out when stripping the engine). It is well known that TVR quoted power figures are very optmistic and genuine flywheel figures for the stock 400, 450 and 500 are more like 210, 250 and 280bhp. If you are only interested in road use and dont want to push the envelope or tinker and modify then there isnt a lot to chose between them other than a bit more grunt with the bigger engines. For me the 450 was a considered choice as summarised above.
My modification programme has completed phase 1 (major engine and head work) and moving to phase 2 soon with induction and engine management mods, with a target of around 300 to 330 bhp and a rev limit of no more than 6500 (to protect the standard cast pistons).
)Looks like it. It'll have to be the right one mind. 
http://www.pistonheads.com/sales/275104.htm
P.S. Sorry to hijack the thread a bit
http://www.pistonheads.com/sales/275104.htm
P.S. Sorry to hijack the thread a bit
Edited by pwd95 on Wednesday 16th January 22:13
The later 450 blocks were also all x-rayed and pressure tested at Land Rover so the porous block issue isn't a problem. Alledgedly.
450 is a standard Rangey block, as Tahiti said some got big valve heads and some didn't. Mine, I was happy to see has the heads and the cross bolted block. My specialist however has rebuilt TVR 450 engines that had one big valve head and one standard head from the factory! Obviously they fitted whatever was lying around at the time.
450 is a standard Rangey block, as Tahiti said some got big valve heads and some didn't. Mine, I was happy to see has the heads and the cross bolted block. My specialist however has rebuilt TVR 450 engines that had one big valve head and one standard head from the factory! Obviously they fitted whatever was lying around at the time.
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