Mr.Clutch?

Born out by performance figures. Unlike maker's BHP claims, they don't lie if from a respected source.

Which MKII Jag and which BMW?

More a question of age. The way BHP is measure changed over the years.

I had two of them. Nice enough cars, but a bit over-hyped. Apart from the looks, of course.

What didn't I like? The dreadful steering. Low geared and still heavy. The pedestrian gear change.

MrCheerful explained on 02/07/2017 :

That has not been my experience of the modern cheapo tyres, now they would seem to be comparable to the better brands. Mine has been wearing wide cheapos for the couple of years, FWD and despite doing a lot of towing I find I can pull out absolutely fine.

I had no problems with cheapos on the Focus in warm dry weather (except when pulling out quickly and turning) But when the weather goes colder and wetter they become a menace for wheel spin and side slip (I don't drive hard on the brakes). Swapping to the winter tyres is a bit like turning the clock back to a dry summer, as far as grip goes.

I never buy cheapos, the Focus ones came with it, and were a completely unmatched set, including a 'Ling-Long' !

About half my customers source their own tyres, the others get Michelins and like them.

One customer had to get two tyres as a distress purchase on holiday. A few months later at his service/mot, he asked me to investigate why his MPG had dropped significantly, I asked if it coincided with getting the two cheapo tyres (replacing Michelins), his jaw dropped and he had a lightbulb moment (I wish I had it on camera)

Easy mistake to make, but Partac was the OP.

My last Focus came with 'Teflon Tyres'. They were almost new, so I decided to keep them for a while.

It was pouring with rain when I picked the car up. That 3 mile journey was enough to convince me - the next day I went out and put a proper set on it.

FWIW, I like Dunlops. Wet grip is good, and they seem quieter than anything else.

Chris

I know. I didn't make a mistake.

In this context, I consider the poster who asked in the last week to be the one who needs the information.

Chris

Then a misunderstanding of newsgroup etiquette.

Are you denying the OP was Partac? Convention says he was.

I certainly agree that 'loveworm' was the more recent poster to ask a question.

People like you are one reason why there are only a handful of folk here now.

Chris

OK, then, here we go:-

Engine size nominal BHP Weight (kg) 0-60 (seconds) MkII Jag 3.4 210 1499 11.5 BMW E39 3.0 231 1605 6.9

And as regards interior space and boot, a 3 Series is closer to a MKII than a 5 Series.

you stated 'much better ' power to weight ratio. using your figures above jag 140 per tonne bmw 144 per tonne

using car folio figures you get: jag: 210 and 1448 gives 145/tonne bmw : 228 and 1605 giving 142/tonne

Neither vehicle by either set of figures is 'much better', it is a tiny difference (about 2 percent or so either way) and could be negated by a tank of petrol, different octane fuel, or a fat driver or even where you get your car weight figure from

I can't see how 0 - 60 figures are irrelevant when it comes to power. Twice the time suggests 1/2 the power.

I would say skinny / fat tyres are starting to become insignificant, as would an extra second in gear changes.

It you want to compromise as say 'power at the wheel' then we could all move forward, otherwise the numbers / times speak for themselves.

The performance figures prove that the quoted output by Jaguar was extremely optimistic - to say the least. Also car weights are quoted differently these days too. Jaguar would have removed everything possible to get the weight down. No fluids of any sort, for example.

Those figures are obtained under the very best traction conditions - a high grip test track. Even with skinny tyres the MKII had excess grip on a decent surface. And even the old Moss box could be changed as fast as you could move the lever - provided you ignored the crunching noises.

We're not talking about a tiny difference either in the 0-60 times.

You could also look at the Rover Vitesse which is much closer in age to the MKII Jag. It is 1488 kg unladen Slightly larger engine at 3.5 litre - but a pushrod, rather than twin overhead cam. Same beam axle at the back and skinny tyres by today's standards. And only 190 bhp. Yet it will leave that MkII for dead.

Not sure they do - a 5% increase in bhp/torque leads to a much quicker car - 8.5s in the case of the 3.8:

Yes. Backing up my theory that Jaguar weren't too accurate about the BHP output in the older days. But then no different from other makers.

If you remember Rolls Royce refused to quote a power output on their cars. Just referred to it as adequate. Whether because so many fiddled theirs or not, I dunno. But BHP isn't a true guide of on road performance anyway.

Nor are 0-60 times etc. On paper my new car isn't that much quicker than my old one but on the road, the performance is SO much more useable.

Tim

You are right - but the 0-60 benchmark is the one easy to find quoted. But does involved thrashing the nuts off the thing. So a peaky engine can give good results for that but feel slow in normal driving.

First you have know what sort of ponies you are taking about.

Wheel - where it counts. Flywheel (Net) - nearly useful but depends on transmission. (DIN power, current SAE) Gross - utterly useless (old SAE). This is what Jaguar quoted back in the 60's. They run the engine on dyno with no ancillaries. No oil pump. No coolant pump. No generator. No air con or power steering drive belts. No air filter, it's running in a nice clean dyno cell and they aren't bothered about it lasting 250k miles. No silencers, just a big drain pipe from the header going out a hole in the wall. Deduct at least 12% for 4 cyl, 16% for 6 cyl and 20% for V8. More for DOHC as it needs more oil to feed cam bearings.

Torque is useless. No one sets a 0-60mph time using peak torque, its run though peak power rpm, changing up at the redline every gear. If you drive at peak torque rpm then you are losing the race. If happy with the performance could have bought a car with 1/2 the power - except then have to rev it to the peak power rpm and that may be too much fun for some. I redline my 140bhp/ton (net including driver and fuel) every day in 2nd.

Tiff Needell said Hyundai V6 mkIII coupe is "adequate", 116bhp/tonne,

For power/weight ratios you also have to know what standard of weight was used. DIN/SAE/JIS, these all have different amounts of driver and fuel/oil/coolant and have changed with revisions to the standards over the last 50 years. Clearly in real life and for setting a 0-60mph time you need a driver (75kg), full oil/coolant (about 10Kg) and some fuel (10-40Kg). Installing a lighter weight fit woman (60kg) in the drivers seat will improve recorded 0-60mph performance figures.

Aston Martin claimed +15% for the DB4/5 inline 6.

Marek had, at John Wyer?s suggestion, researched horsepower claims on American engines and had found a mean discrepancy of 32 per cent ? John Wyer?s reaction was ?We can?t lie that much, we can only lie 15 per cent?.