[OT] 99 Octane petrol

I thought the M Series engines were meant to run on Super?

Reply to
Dave Plowman (News)
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Oh dear. Similar happened to me on a Matchless once, which spat out its nice *new* chromed downpipe. Needless to say it got run over. I still picked it up, unfortunately. It was *bloody* hot.

V. strange pop squeak rattle noise, too, I should think, and bad language.

Reply to
Chris Bacon

That's why I said *modern* production cars. Many older ones had extremely poor manifolds and exhausts.

Reply to
Dave Plowman (News)

It seems to me that in many modern production cars the "performance tuning" has already been done...

Reply to
Chris Bacon

The message from Chris Bacon contains these words:

Yes - and no. In many cases there's only minor differences between the rip-snorting version and the grandad version - one is just a crippled version of the other. Priced accordingly.

Reply to
Guy King

Indeed. Unless it's a turbo where you can simply wind up the boost, it's extremely expensive to get a meaningful power increase on most modern engines.

Reply to
Dave Plowman (News)

Here's one:

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Reply to
Rob Morley

Oh, no rechipping will net you lots..at the expense of dire fuel economy usually. Especially if there is a turbo you can screw the waste gate down on :D

Reply to
The Natural Philosopher

I'm an "old boy", now. I worked in the motor trade between 1956 and 1988, approx. I don't think that the "interesting idea" in question is a new one. It _may_ well be standard in many engines. I heard of it many years ago; it may well have been in the 50's or 60's. I can't really add more.

Sylvain.

P.S. Don't let a person's age put you off. We remain "young at heart", most of the time.

Just a thought. Is the Wankel rotary engine still being used by anyone? I believe that Mazda used one in some of their cars not so long ago.

Sylvain.

Reply to
Sylvain VAN DER WALDE

Not on any decent car, it won't. Only those where there are identical engines of differing power outputs where the power is set by the electronics - and these are usually diesels.

That's what I said above. Although you might well shorten the service life of the engine.

Reply to
Dave Plowman (News)

Mazda RX-8. Nice vehicle, but still poor fuel consumption.

Reply to
Dave Plowman (News)

I think advances in materials technology have made it largely irrelevant.

The theory is that it reduces piston sidethrust on the power stroke..

But better materials make piston/cylinder wear (and friction) acceptable up to sensible lifetime limits..gone are the days when the bearings were replaced every 30,000 miles, and pistons at 60-100,000, with the accompanying rebore..

But is a rare bird.

Most interesting design I saw was a twin crank horizontally opposed geared H layout.

Very compact and light..and low CG..

Reply to
The Natural Philosopher

Oh definitely...

I think the point I meant to make is that a commercial engine is optimised for other things than raw power..flexibility, ease of starting, fuel economy, emissions, noise and pure packaging concerns as well as long service life may all be compromised by trying to 'extract the max'

With fuel injection, you HAVE to remap if you start playing around with alteration to the exhaust, valve timing and inlet tracts.

There is at least one installation - forget which one, which is 5bhp down on an identical engine fitted to another model. The difference purely being in the packaging of the exhaust manifold and pipework.

Every tuner knows that if you slap a nice trumpet without (much) air filters on an engine, and put an optimised and really noisy exhaust on it, shove in a high overlap cam, and dump as much fuel into it as possible, a normal car engine can develop about twice the power, at the expense of appalling idling, appalling noise, appalling fuel economy, and a very short but colorful life.

If you also skim the head, and shove 5 star in it, it gets even better. :-)

I suppose your point, that there are no appallingly BAD installations these days that can be EASILY upgraded by SIMPLE changes is also valid.

stuffing 5 star in, being the case in point.

Reply to
The Natural Philosopher

Indeed. Yonks ago some engines - like say the Ford Zephyr - had an appalling exhaust manifold which was just a straight pipe with holes for the ports running along the cylinder head. And a single very small downdraft carb. Changing to a well designed manifold and exhaust and fitting twin SUs etc raised the BHP from about 80 to over 100.

I've never seen it documented that changing to 5 star on an engine in proper tune designed to run on 4 star has made any difference whatsoever.

Reply to
Dave Plowman (News)

The handbook says one will get more power and mpg from super but the minimum RON is 95. Until recently all I could get around here was 97 and it still pinked. 99 from tescos works well but it still backfires when cold. All "perfectly normal".

Reply to
adder1969

Have you taken it up direct with BMW GB - by letter or fax?

I'd not take the word of any UK BMW dealer - crooks, the lot of them.

Reply to
Dave Plowman (News)

I can't think of many very new ideas in engine development - improvements made with materials, maybe.

These engines are why I mentioned head gasket thickness somewhere...

Reply to
Chris Bacon

Practical variable valve timing would be the obvious one with petrol engines, and the removal of the throttle which causes pumping losses. Pulsed high pressure electronic direct injection with diesels another. I'm sure others will think of plenty more.

Reply to
Dave Plowman (News)

Petrol injection? It's not that old.

You've put "your foot in it", Chris. Find out more about these engines, and you'll know why. You wouldn't be testing my knowledge, would you? :)

Sylvain.

Reply to
Sylvain VAN DER WALDE

Um. Petrol injection is a refinement of Mr. Diesel's invention of the

1890s, isn't it? The concept is over 100 years old!

I absolutely do not know why. IIRC someone said that "the thickness of the head gasket influences compression ratio" or words to that effect, & I said that might be true for *some* engine designs...

No, not at all.... would you regard the Wankel as a one-stroke, 1 1/2 stroke, 3-stroke, or four stroke, though? ( here - ;) FWIW ).

Reply to
Chris Bacon

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