Rover V8 - Crap ?
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ghce said:Rover could design a gas turbine engined car but couln't do a Quad cam V8, just like all Genius there is always some common sense missing
Graeme
Didn't they do a quad cam V6, loosley designed on the Rover V8 with two cylinders chopped off, for their 6R4 rally car?
I am sure I read somewhere that some chap modified the OHC system, had some cams made up, and fitted it to his Rover V8.
webmaster
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The 6R4 engine went on to become the XJ 220 engine.
Also the KV6 was a quad cam v6 used in the 800 and 75 (although suffers very regular head gasket failures in the 800, extensively redesigned for the 75)
Rover have always had the technology / skill for this type of thing, not quite Citroen but always well up there with the latest kit. Not sure why they never did any extensive redesigns on the V8.
However you also need to remember, a lot of the yank v8's are still 16v pushrod designs, they seem to have ignored the OHC completely, even though some of them have things like titanium rods / dry sumps etc... What the pushrod design does give you in a v8 is a very compact unit, overhead cam heads stuck out at 90 degrees make for a very wide engine. I believe the current all alloy chevy v8 (about 7 litres worth) is lighter and smaller than the rover v8.
Also the KV6 was a quad cam v6 used in the 800 and 75 (although suffers very regular head gasket failures in the 800, extensively redesigned for the 75)
Rover have always had the technology / skill for this type of thing, not quite Citroen but always well up there with the latest kit. Not sure why they never did any extensive redesigns on the V8.
However you also need to remember, a lot of the yank v8's are still 16v pushrod designs, they seem to have ignored the OHC completely, even though some of them have things like titanium rods / dry sumps etc... What the pushrod design does give you in a v8 is a very compact unit, overhead cam heads stuck out at 90 degrees make for a very wide engine. I believe the current all alloy chevy v8 (about 7 litres worth) is lighter and smaller than the rover v8.
PeterB76
Member
quattro said:
Yeah, the development for the Metro 6R4 involved a chopped down Rover V8, but this was later changed for a bespoke quad-cam V6 (Later used in the Jaguar XJ220 in turbocharged form, as said).
Makes me laugh when I read that the Rover V8 is 'crap'. As we all know it's far from it, and wouldn't have lasted for over 40 years if it was even remotely so.
The thing is, the Rover V8 isn't really about maximum horse power as you all know, it's about Torque, which it has dollops of in any form. It's a fabulous unit mean't to be effortless and refined in our application, which it excels in my view when they're running right and performing as they should.
It can also be a right little fire-cracker too of course.
I adore these engines, as I'm sure most of you do too.
webmaster
New Member
Funnily enough, PPC have a "track day" rolls royce, which they have turbo charged, on the basis that "adequate" wasn't.
http://www.youtube.com/watch?v=0IIAmlYjDuU&feature=player_embedded
http://www.youtube.com/watch?v=0IIAmlYjDuU&feature=player_embedded
Responding to Richard's point about V8's tending to avoid OHC's. Of course a well designed pushrod system can be the equal of an OHC design. By mounting the cam high in the engine - as is forced on you in a single cam V8 - the length of pushrods can be minimised and careful materials choices and design can go most of the way to matching the reciprocating mass of the valve train to that of an SOHC set up. Pre and just post war Riley and BMW (and Bristol copies) are cases in point. SOHC's with a decent combustion chamber design (ie inclined valves in a pent roof chamber) invariably have some valve train mass in the same way as a pushrod design. Purists would never do anything other than cams acting directly on the valves (ie at least two cams per head) and driven from the crank by a gear train, but that is a very expensive solution. I speak as someone who once worked on the ultimate medium sized engine ever to be buit in the UK, the Armstrong Siddeley built Maybach MD870 V16 with SIX valves per cylinder, DOHC across individual heads and a built up tunnel crank with all rolling element bearings. For a large bore, moderately short stroke engine many of us would contend that two valves per cylinder is a better solution. It is easier to maintain gas flow speeds and hence swirl, efficient combustion and torque at low engine speeds, and with a high ratio of cylinder head area to swept volume the valve area need not restrict breathing at high engine speed. I know I'll never persuade M16/T16 enthusiast Richard, but ultimately it's the results that count and well designed 2 valve engines are generally a better all round solution.
Chris
Chris
I got Sparky on a Dyno earlier - How disappointing was that??
Max power at 5,200rpm, at the wheels was 152.6 BHP :shock:
I was hoping for at least 180 which is what I was told it was by the seller.
Torque at the wheels was 158lb/ft at 1,300 rpm, peaked at 177 lb/ft at 3250rpm and finally dipped below 170lb/ft at 4,200rpm.
Max power at 5,200rpm, at the wheels was 152.6 BHP :shock:
I was hoping for at least 180 which is what I was told it was by the seller.
Torque at the wheels was 158lb/ft at 1,300 rpm, peaked at 177 lb/ft at 3250rpm and finally dipped below 170lb/ft at 4,200rpm.
All these different measurement systems are dreadfully confusing - and us classic car owners have it worst! Nowadays all cars are measured to the same standards thanks to the EU, so you can compare apples with apples. In the 70's DIN was relatively new and no use at all if you were trying to sell to the US as Rover were. US horses have always been deeply dubious, in cars, and in a livery stable!
There are actually only two valid sets of measures in my view. The first is on the road performance figures as generated by the likes of Motor and Autocar. Second is the raw rear wheel figures obtained from a suitably certified dyno. Whilst the first is reasonably comparable across a wide range of vehicles thanks to the number of published tests, the second is invariably disapointing cos there isn't the library of results widely available to compare.
A freind of mine recently developed a new set of dyno software to convert raw data into flywheel figures using the technique mentioned here of measuring "run down" resistance to obtain an estimate of flywheel power stripped of the transmission losses. We reviewed all the assumptions and equations used together, and although I was happy the result was pretty good, it is still an approximation and might be significantly adrift where the car tested diverges significantly from the norm. The P6B Auto might well fall into this bracket as it doesn't have lock up on the torque convertor. The only reason there is a demand for this number is because there is a reservoir of customers with "Trick" turbocharged etc motors who don't understand the physics and just want to see a big number to justify the huge amounts of money they have spent on their engines!
For my money you can get a view of the potential trackday performance of a car by looking at maximum power outputs and best 0 to 60 etc times. But the much more relevant figure for a road car is what happens when you floor the throttle at a realistic road speed - you could debate 50 mph or 60 mph! On this sort of measure the P6B does rather well as do modern diesels, and this reflects their perceived on the road performance and driveability. If you insist on driving everywhere like a teenager on heat (stand up Jeremy Clarkson and crew!) then OK these cars may dissapoint, but for the rest of us I'll pick a flexible engine any day for putting up record beating point to point real world times! And I don't wish to have to drive up my local high street at 4000 rpm in 2nd just to avoid stalling and transmission judder!
For those feeling aggreived at dyno figures, get hold of a decent set of timing equipment and replicate Autocar type figures for your car. I guarantee you'll have some serious bar room cred! Also remember that any fool can get a car off the line rapidly by lowering the overall gearing (eg by fitting undersize wheels or a diff from another model), but by the time they've hit 50 after multiple gearchanges you will be vanishing over the horizon. Such cars are only good for the traffic lights drag, and who wants to lower themselves to that?!
Chris
There are actually only two valid sets of measures in my view. The first is on the road performance figures as generated by the likes of Motor and Autocar. Second is the raw rear wheel figures obtained from a suitably certified dyno. Whilst the first is reasonably comparable across a wide range of vehicles thanks to the number of published tests, the second is invariably disapointing cos there isn't the library of results widely available to compare.
A freind of mine recently developed a new set of dyno software to convert raw data into flywheel figures using the technique mentioned here of measuring "run down" resistance to obtain an estimate of flywheel power stripped of the transmission losses. We reviewed all the assumptions and equations used together, and although I was happy the result was pretty good, it is still an approximation and might be significantly adrift where the car tested diverges significantly from the norm. The P6B Auto might well fall into this bracket as it doesn't have lock up on the torque convertor. The only reason there is a demand for this number is because there is a reservoir of customers with "Trick" turbocharged etc motors who don't understand the physics and just want to see a big number to justify the huge amounts of money they have spent on their engines!
For my money you can get a view of the potential trackday performance of a car by looking at maximum power outputs and best 0 to 60 etc times. But the much more relevant figure for a road car is what happens when you floor the throttle at a realistic road speed - you could debate 50 mph or 60 mph! On this sort of measure the P6B does rather well as do modern diesels, and this reflects their perceived on the road performance and driveability. If you insist on driving everywhere like a teenager on heat (stand up Jeremy Clarkson and crew!) then OK these cars may dissapoint, but for the rest of us I'll pick a flexible engine any day for putting up record beating point to point real world times! And I don't wish to have to drive up my local high street at 4000 rpm in 2nd just to avoid stalling and transmission judder!
For those feeling aggreived at dyno figures, get hold of a decent set of timing equipment and replicate Autocar type figures for your car. I guarantee you'll have some serious bar room cred! Also remember that any fool can get a car off the line rapidly by lowering the overall gearing (eg by fitting undersize wheels or a diff from another model), but by the time they've hit 50 after multiple gearchanges you will be vanishing over the horizon. Such cars are only good for the traffic lights drag, and who wants to lower themselves to that?!
Chris
webmaster said:
Manual LT77
He didn't have the flywheel figure as he didn't have the figures to use on a P6? Apparently there are a set of figures you can use on modern cars to work out the flywheel power and the P6 is too old.
Saying this, Sparky's torque curve is almost flat and I am very happy with the way it goes, so the lower than expected BHP figure is not much of a concern. I have 158lb/ft of torque at the wheels at 1,300rpm, meaning that I can cruise out of a 30mph limit in 5th and just ease the trottle down to effortlessy get to 60 in a matter of seconds.
Just managed to measure the MPG at 26.5 as well - so all in all not bad.
webmaster
New Member
The only problem with timing 0-60 runs etc, yourself is that so much depends on driving style. I've done it myself and runs can deviate by several seconds, based on launch and gearchange technique. The other problem comes if you compare your timed runs with manufacturer quoted figures for other cars, I would put money on the fact that if you were to time yourself in these other cars you wouldn't get anywhere near the quoted figures, the manufacturers spend ages tweaking and playing to get the best figures, not to mention getting the best drivers they can find.
On the basis that you generally only use a fraction of a cars available performance on the road, all this talk is a bit pointless !, I've done a few track days in various vehicles and the difference between that and road driving is incredible, I've seen nearly new tyres reduced to sliks in a matter of a few laps on the track, and brake pads worn out in a couple of sessions.
My favourite saying is "most people don't find the limits of their car until 1/2 second before they crash"
On the basis that you generally only use a fraction of a cars available performance on the road, all this talk is a bit pointless !, I've done a few track days in various vehicles and the difference between that and road driving is incredible, I've seen nearly new tyres reduced to sliks in a matter of a few laps on the track, and brake pads worn out in a couple of sessions.
My favourite saying is "most people don't find the limits of their car until 1/2 second before they crash"
webmaster
New Member
Probably the best use for the rolling road is to measure improvements from tuning work etc, the most important aspect of this is a baseline run, which you now have. If you do make further changes, as long as you go back to the same rolling road, you should have comparable figures (or at least the best you are likely to obtain), and can see how the changes have affected the car.
So many people tune the car, then take it to the rolling road, then compare the figures to the book figures, usually finding they have less power than it "started with", of course if they'd taken a baseline figure they would have found they had significantly less to start with, and have probably improved quite a lot.
Gains, losses and as you say the shape of the torque curves are the most important aspects, not the headline figures.
So many people tune the car, then take it to the rolling road, then compare the figures to the book figures, usually finding they have less power than it "started with", of course if they'd taken a baseline figure they would have found they had significantly less to start with, and have probably improved quite a lot.
Gains, losses and as you say the shape of the torque curves are the most important aspects, not the headline figures.