Sylvain VAN DER WALDE wrote:
"Chris Bacon" wrote in message
exhaust system gives lesser results in comparison with the effects of
tuning the input system (by quite a lot)

I believe that 2 stroke (racing?) engines were greatly improved (over a
narrow revolutions band) by tuning the exhaust.

Absolutely! However, tuning the induction side of things, which with
many 2-st. engines is very interesting, is still the place where
the bigger gains are made. Extreme tuning has the unfortunate effect
of producing a narrow "band" of power, so lots of ratios are needed
to keep things "on the boil", e.g. 0-5600 RPM=3BHP, 5601-X RPM=50BHP!
Tuning the exhaust pipe itself is somewhat of a black art IMO.

raden wrote:
Chris Bacon
Can't see how I've upset *you*. Stupid boring non-contributing
*******s perhaps....

Me - a non-contributor?

To this thread, maybe

and quiet of late because I've been busy saving the world,

but hardly a non contributor

Of course not you, you great gonk! Thre's a plural up there ^. I will,
for your delictation, re-phrase: "Can't see how I've upset *you*, but
I may have perhaps upset some stupid boring non-contributing *******s".


... but then, you're a bit of a newbie and as such, blessed with the
ignorance which goes with it

Thank you for your consideration.

In message , Chris Bacon
writes
raden wrote:
Chris Bacon
Can't see how I've upset *you*. Stupid boring non-contributing
*******s perhaps....
Me - a non-contributor?
To this thread, maybe
and quiet of late because I've been busy saving the world,
but hardly a non contributor

Of course not you, you great gonk! Thre's a plural up there ^. I will,
for your delictation, re-phrase: "Can't see how I've upset *you*, but
I may have perhaps upset some stupid boring non-contributing *******s".


... but then, you're a bit of a newbie and as such, blessed with the
ignorance which goes with it

Thank you for your consideration.

Send contributions to ...


--
geoff

In article ,
Chris Bacon wrote:
As the piston rises to T.D.C. (top dead centre), that fuel/air mixture
will be compressed to an extent determined by the stroke/bore ratio of
that particular engine and the capacity of the combustion chamber.

You're sort of getting there, in that you've added the bore as well as
the stroke, which was missing from the quote I included above.

I just didn't think it necessary to give chapter and verse - I assumed
since the only way a combustion chamber can me measured is by volume, and
a ratio must be between like measurements, stroke of the *piston* would be
understood to be the volume moved by it.
However, what would this group be without pedants - including me. ;-)

--
*A journey of a thousand sites begins with a single click *

Dave Plowman London SW
To e-mail, change noise into sound.

in 530088 20060507 183910 "Sylvain VAN DER WALDE" wrote:

However, tuning the
exhaust system gives lesser results in comparison with the effects of
tuning the input system (by quite a lot)

I believe that 2 stroke (racing?) engines were greatly improved (over a
narrow revolutions band) by tuning the exhaust.

Not just racing engines - in the 1950s I had a 125cc BSA Bantam.
One day the nut holding the exhaust end-cap on came off and the entire
contents of the exhaust were shot out backwards. This affected the engine
power output to the extent that I could barely ride back to pick up the pieces.

The octane rating of a fuel gives little indication of its energy
content,
except that most higher octane substances have lower energy content.

Heptane has an octane rating of 0 IIRC, so where does that
leave the above peculiar statement?

Well, for a start, n-heptane with a RON of 0 has more energy content than
iso-octane with a RON100, so it fits into the general pattern. However,
there are genuine counter-examples out there, although most just have a
lower octane than you would expect for the energy. Finding a high octane,
high energy fuel is more difficult!

The common octane improvers, such as benzene and toluene, which have octanes
in excess of 100, have lower energy content. Toluene, for example, has
40.5MJ/kg, compared to 44.4MJ/kg for iso-octane.

When you start adding oxygen (i.e. alcohols, rather than pure hydrocarbons),
you get much lower energy content for a massive increase in octane.

Christian.

Chris Bacon wrote:
The Natural Philosopher wrote:
Quite right. The old A series high comp engines in midgets and the
like worked better on 5 star, especially once you got them to breathe
a bit better and sorted out the timing a bit.

They WERE designed to work on 5 star. Especially once I had finsished
with em.

OK, you say you've done some performance tuning on "A" series engines.
What did this comprise of. Be specific. I don't think you know what
you are talking about, so here's a chance to redeem yourself.

I never intended to, but the engine I was about to install fell over and
broke its exhaust manifold and an LCB after market was cheaper than I
could find a cast iron one.

I had bought that one off some ad in 'Motoring news' so it MIGHT have
been a little hotted up...but it ran up on standard needles and timing
so it can't have been TOO modified if at all.

All I can say is that it ran better in damp cool weather, and on 5 star.
I didn't set it up for that - being flat broke at the time it ran 4 star
mainly. No idea about fuel consumption, just that it wasn't so hard on
ignition. And developed more power.

Dave Plowman (News) wrote:
In article ,
The Natural Philosopher wrote:
However, tuning the
exhaust system gives lesser results in comparison with the effects of
tuning the input system (by quite a lot).

Another sweeping generalisation that is only correct 50% of the time.


But a true one. Exhaust gases are under highish pressure. Inlet merely -
at best - atomospheric. On the cylinder head and inlet manifold attention
to the inlet tract by reducing restrictions etc that shouldn't be there
but are due to the costs of removing them in manufacture, etc will pay far
more dividends than the same work carried out on the exhaust ports. And
most production cars are already fitted with free (enough) flowing
exhausts.

Not at all. Certainly in my tuning days, the SINGLE most effective way
to increase power in MOST stock engines was to hit the exhaust first.

On my old Triumph Spitfire, the gains were well known. about 10bhp
increase from a free flow exhaust, then about 7-8 from fitting bigger
carbs, and a hotter cam, and then another 5 from fitting gas flowed
head, manifold and webers rather than SU's. I went as far as a fast road
cam, better carbs, and better exhaust. Still go that car. Must get it
back on the road some day..

Similar results on BMC A series engines.

The situation was almost reversed on B series BMC engines - that engine
had a ghastly cylinder head and no amount of anything made much
difference until that was re-ported and gas flowed with better valving.

Gas flow is all about removing the major bottle necks first. If you
think exhaust is irrelevant stuff a potato in the exhaust pipe and see
how the power drops off;-)

Dave Plowman (News) wrote:
In article ,
The Natural Philosopher wrote:
I've been around long enough to know that most who find differences in
petrol are fooling themselves - unless using too low an octane rating
for the design of the engine.

Quite right. The old A series high comp engines in midgets and the like
worked better on 5 star, especially once you got them to breathe a bit
better and sorted out the timing a bit.

Since I had a two 1275 Midgets, I'm quite well up on that engine. I've
also totally re-built several.

Neither of mine was 'better' on 5 star. Of course if you modify the
engine, you're starting a new ball game. But that's not what you said
originally.

They WERE designed to work on 5 star. Especially once I had finsished
with em.

By 'working' on them it would be possible to make them only suitable for
aviation petrol. Or to run on 2-star. But that's not what they were
designed for - my point.

They WOULD work on 4, with slightly retarded ignition, to stop them
knocking, but they weren't as good.

Mine both ran on standard timing. And didn't pink on 4-star. Perhaps your
timing technique or timing marks were inaccurate? Or perhaps they just
simply needed a de-coke. Also, a slightly weak mixture encourages
detonation.

Mine din't pink on 4 star. They juts ran better on five thats all.

Chris Bacon wrote:
Sylvain VAN DER WALDE wrote:
"Chris Bacon" wrote in message
exhaust system gives lesser results in comparison with the effects of
tuning the input system (by quite a lot)

I believe that 2 stroke (racing?) engines were greatly improved (over
a narrow revolutions band) by tuning the exhaust.

Absolutely! However, tuning the induction side of things, which with
many 2-st. engines is very interesting, is still the place where
the bigger gains are made. Extreme tuning has the unfortunate effect
of producing a narrow "band" of power, so lots of ratios are needed
to keep things "on the boil", e.g. 0-5600 RPM=3BHP, 5601-X RPM=50BHP!
Tuning the exhaust pipe itself is somewhat of a black art IMO.

That's more a case of having wild cam timing on a 4-stroke.

VVT has more or less sorted that..but anyone who fitted a race cam to a
road going engine knows how ghastly they were on idling, and part
throttle fuel consumption - most of which went straight down the exhaust
pipe.

Rob Morley wrote:
In article .com
wrote:
snip
Tescos 99 stops my M3 from
making horrible low rpm pinking noises.

So would fixing the timing :-)

It would, but BMW say it's normal and won't do anything.

Dave Plowman (News) wrote:


But a true one. Exhaust gases are under highish pressure. Inlet merely -
at best - atomospheric. On the cylinder head and inlet manifold attention
to the inlet tract by reducing restrictions etc that shouldn't be there
but are due to the costs of removing them in manufacture, etc will pay far
more dividends than the same work carried out on the exhaust ports. And
most production cars are already fitted with free (enough) flowing
exhausts.


Generally increasing the inlet flow means you get more charge in the
cylinder and more power. Increasing the exhaust flow reduces
backpressure and helps the inlet charge too but to a lesser extent.
Becasue there's less backpressure you get better mpg. Increased inlet
flow increases power. Do both and you're onto a winner.

"Chris Bacon" wrote in message
...
Sylvain VAN DER WALDE wrote:
[ engine tuning/ compression ratio ]
Comments: The length of the stroke is controlled by the combined design
of the cranckshaft and connecting rod.

Why the *combined* design of the crackshaft and the contorting rod?
Surely just the throw of the crank?

"Belt and braces", I suppose. I've forgotten a lot, and am playing safe.

Sylvain.

"Rob Morley" wrote in message
t...
In article
Chris Bacon wrote:
Sylvain VAN DER WALDE wrote:
[ engine tuning/ compression ratio ]
Comments: The length of the stroke is controlled by the combined design
of
the cranckshaft and connecting rod.

Why the *combined* design of the crackshaft and the contorting rod?
Surely just the throw of the crank?

The crank can be offset from the bore, in which case the length of the
con rod makes a difference.

I mentioned that in my answer to Chris, but then decided that it might not
be relevent, and deleted that entry. I believe that the reason for this
offset is to reduce the pressure on the thrust "face" of the piston, and
thereby reduce wear.

Sylvain.

Sylvain VAN DER WALDE wrote:
"Rob Morley" wrotet...
Chris Bacon wrote:
Sylvain VAN DER WALDE wrote:
[ engine tuning/ compression ratio ]
Comments: The length of the stroke is controlled by the combined
design of the cranckshaft and connecting rod.

Why the *combined* design of the crackshaft and the contorting rod?
Surely just the throw of the crank?

The crank can be offset from the bore, in which case the length of the
con rod makes a difference.

I mentioned that in my answer to Chris, but then decided that it might not
be relevent, and deleted that entry. I believe that the reason for this
offset is to reduce the pressure on the thrust "face" of the piston, and
thereby reduce wear.

That's certainly an interesting idea - do you happen to know
which engines this is used in?

In article .com,
wrote:
Tescos 99 stops my M3 from
making horrible low rpm pinking noises.

So would fixing the timing :-)

It would, but BMW say it's normal and won't do anything.

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

--
*There are two sides to every divorce: Yours and **** head's*

Dave Plowman London SW
To e-mail, change noise into sound.

Bob Martin wrote:
"Sylvain VAN DER WALDE" wrote:
I believe that 2 stroke (racing?) engines were greatly improved (over a
narrow revolutions band) by tuning the exhaust.

Not just racing engines - in the 1950s I had a 125cc BSA Bantam.
One day the nut holding the exhaust end-cap on came off and the entire
contents of the exhaust were shot out backwards.

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.


This affected the engine
power output to the extent that I could barely ride back to pick up the pieces.

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

In article ,
The Natural Philosopher wrote:
Not at all. Certainly in my tuning days, the SINGLE most effective way
to increase power in MOST stock engines was to hit the exhaust first.

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

--
*Geeks shall inherit the earth *

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:
The Natural Philosopher wrote:
Not at all. Certainly in my tuning days, the SINGLE most effective way
to increase power in MOST stock engines was to hit the exhaust first.

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

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

The message
from Chris Bacon contains these words:

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

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.

--
Skipweasel
Pay no attention to that man behind the curtain.

In article ,
Chris Bacon wrote:
It seems to me that in many modern production cars the "performance
tuning" has already been done...

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.

--
*Aim Low, Reach Your Goals, Avoid Disappointment *

Dave Plowman London SW
To e-mail, change noise into sound.

In article
Chris Bacon wrote:
Sylvain VAN DER WALDE wrote:
"Rob Morley" wrotet...
Chris Bacon wrote:
Sylvain VAN DER WALDE wrote:
[ engine tuning/ compression ratio ]
Comments: The length of the stroke is controlled by the combined
design of the cranckshaft and connecting rod.

Why the *combined* design of the crackshaft and the contorting rod?
Surely just the throw of the crank?

The crank can be offset from the bore, in which case the length of the
con rod makes a difference.

I mentioned that in my answer to Chris, but then decided that it might not
be relevent, and deleted that entry. I believe that the reason for this
offset is to reduce the pressure on the thrust "face" of the piston, and
thereby reduce wear.

That's certainly an interesting idea - do you happen to know
which engines this is used in?

Here's one:

http://www.cleangreencar.co.nz/page/prius-petrol-engine

Dave Plowman (News) wrote:
In article ,
Chris Bacon wrote:
It seems to me that in many modern production cars the "performance
tuning" has already been done...

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.

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

"Rob Morley" wrote in message
t...
In article
Chris Bacon wrote:
Sylvain VAN DER WALDE wrote:
"Rob Morley" wrotet...
Chris Bacon wrote:
Sylvain VAN DER WALDE wrote:
[ engine tuning/ compression ratio ]
Comments: The length of the stroke is controlled by the combined
design of the cranckshaft and connecting rod.

Why the *combined* design of the crackshaft and the contorting rod?
Surely just the throw of the crank?

The crank can be offset from the bore, in which case the length of the
con rod makes a difference.

I mentioned that in my answer to Chris, but then decided that it might
not
be relevent, and deleted that entry. I believe that the reason for this
offset is to reduce the pressure on the thrust "face" of the piston,
and
thereby reduce wear.


That's certainly an interesting idea - do you happen to know
which engines this is used in?


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.

Here's one:

http://www.cleangreencar.co.nz/page/prius-petrol-engine

In article ,
The Natural Philosopher wrote:
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.

Oh, no rechipping will net you lots..at the expense of dire fuel economy
usually.

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.

Especially if there is a turbo you can screw the waste gate
down on

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

--
*Experience is something you don't get until just after you need it *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Sylvain VAN DER WALDE wrote:
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.

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

--
*You can't teach an old mouse new clicks *

Dave Plowman London SW
To e-mail, change noise into sound.

Sylvain VAN DER WALDE wrote:
"Rob Morley" wrote in message
t...
In article
Chris Bacon wrote:
Sylvain VAN DER WALDE wrote:
"Rob Morley" wrotet...
Chris Bacon wrote:
Sylvain VAN DER WALDE wrote:
[ engine tuning/ compression ratio ]
Comments: The length of the stroke is controlled by the combined
design of the cranckshaft and connecting rod.
Why the *combined* design of the crackshaft and the contorting rod?
Surely just the throw of the crank?

The crank can be offset from the bore, in which case the length of the
con rod makes a difference.
I mentioned that in my answer to Chris, but then decided that it might
not
be relevent, and deleted that entry. I believe that the reason for this
offset is to reduce the pressure on the thrust "face" of the piston,
and
thereby reduce wear.

That's certainly an interesting idea - do you happen to know
which engines this is used in?


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.


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..

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.

I think so.
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..



Sylvain.

Here's one:

http://www.cleangreencar.co.nz/page/prius-petrol-engine

Dave Plowman (News) wrote:
In article ,
The Natural Philosopher wrote:
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.

Oh, no rechipping will net you lots..at the expense of dire fuel economy
usually.

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.

Especially if there is a turbo you can screw the waste gate
down on

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


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.

In article ,
The Natural Philosopher wrote:
I suppose your point, that there are no appallingly BAD installations
these days that can be EASILY upgraded by SIMPLE changes is also valid.

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.

stuffing 5 star in, being the case in point.

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.

--
*Give me ambiguity or give me something else.

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:
In article .com,
wrote:
Tescos 99 stops my M3 from
making horrible low rpm pinking noises.

So would fixing the timing :-)

It would, but BMW say it's normal and won't do anything.

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



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".

In article .com,
wrote:
I thought the M Series engines were meant to run on Super?



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".

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.

--
*Warning: Dates in Calendar are closer than they appear.

Dave Plowman London SW
To e-mail, change noise into sound.

Sylvain VAN DER WALDE wrote:
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.

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


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.

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

In article ,
Chris Bacon wrote:
I can't think of many very new ideas in engine development -
improvements made with materials, maybe.

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.

--
*The closest I ever got to a 4.0 in school was my blood alcohol content*

Dave Plowman London SW
To e-mail, change noise into sound.

"Chris Bacon" wrote in message
...
Sylvain VAN DER WALDE wrote:
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.

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

Petrol injection? It's not that old.


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.

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

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.

Sylvain VAN DER WALDE wrote:
"Chris Bacon" wrote...
Sylvain VAN DER WALDE wrote:
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.

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


Petrol injection? It's not that old.

Um. Petrol injection is a refinement of Mr. Diesel's invention of the
1890s, isn't it? The concept is over 100 years old!


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.

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

You've put "your foot in it", Chris. Find out more about these engines, and
you'll know why.

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...


You wouldn't be testing my knowledge, would you?

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 ).

In article ,
Chris Bacon wrote:
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...

It's certainly true with conventional engines - it alters the volume of
the combustion chamber and therefore the compression ratio. (The volume
swept by the piston stroke remains unchanged)

It's rather like having a warped head skimmed true. This also alters the
compression ratio.

--
*Why don't sheep shrink when it rains?

Dave Plowman London SW
To e-mail, change noise into sound.

"Chris Bacon" wrote in message
...
Sylvain VAN DER WALDE wrote:
"Chris Bacon" wrote...
Sylvain VAN DER WALDE wrote:
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.

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


Petrol injection? It's not that old.

Um. Petrol injection is a refinement of Mr. Diesel's invention of the
1890s, isn't it? The concept is over 100 years old!


Diesel engines have had fuel injection from the beginning.
Petrol engines had carburetters first.
There is a difference.

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.

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

You've put "your foot in it", Chris. Find out more about these engines,
and you'll know why.

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...


The Wankel rotary engine has no removable cylinder heads. Actually, it
hasn't got a cylinder head as such.
It does have a combustion chamber, of course.
If memory recalls, it has a rotor with lobes.
You need to read up on it, to understand its very unusual
design concept.
This engine bears no resemblance whatsoever to the usual piston engine. It
doesn't have any pistons.

You wouldn't be testing my knowledge, would you?

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 ).

I need some time to think about this. I may not be able to answer you. I
_did_ know, but my memory has probably let me down.

Sylvain.

Dave Plowman (News) wrote:
In article ,
Chris Bacon wrote:
I can't think of many very new ideas in engine development -
improvements made with materials, maybe.

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.

Not that many to be honest.

Biggest leap was electronics, to replace all that nasty carb/distributor
rubbish with a nice bit of ROM...but honestly, the rest has all been
around forever, its just not been cheap enough to be worth doing until
legislation forced it on us.

Mainly material technology has been the biggest thing, and precision CNC
machining.

Sylvain VAN DER WALDE wrote:
"Chris Bacon" wrote in message
...
Sylvain VAN DER WALDE wrote:
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.
I can't think of many very new ideas in engine development -
improvements made with materials, maybe.

Petrol injection? It's not that old.

Only about 70 years I suppose.


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

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.

Sylvain VAN DER WALDE wrote:
"Chris Bacon" wrote...
Sylvain VAN DER WALDE wrote:
"Chris Bacon" wrote...
Sylvain VAN DER WALDE wrote:
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.
I can't think of many very new ideas in engine development -
improvements made with materials, maybe.

Petrol injection? It's not that old.
Um. Petrol injection is a refinement of Mr. Diesel's invention of the
1890s, isn't it? The concept is over 100 years old!

Diesel engines have had fuel injection from the beginning.
Petrol engines had carburetters first.
There is a difference.

I wonder when petrol injection came in, then.... would it have been in
the 1920s? I was just saying that the concept is old - improvements in
manufacturing and materials make old ideas viable. There aren't very
many new ones!


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.
These engines are why I mentioned head gasket thickness somewhere...
You've put "your foot in it", Chris. Find out more about these engines,
and you'll know why.
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...

The Wankel rotary engine has no removable cylinder heads.

That's why I said that might be true for *some* engine designs.


Actually, it hasn't got a cylinder head as such. It does have a combustion
chamber, of course. If memory recalls, it has a rotor with lobes.
You need to read up on it, to understand its very unusual design concept.
This engine bears no resemblance whatsoever to the usual piston engine. It
doesn't have any pistons.

If you'd like to see an animation, there's one at:

http://www.keveney.com/Wankel.html

You wouldn't be testing my knowledge, would you?
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 ).

I need some time to think about this. I may not be able to answer you. I
_did_ know, but my memory has probably let me down.

It's sort of a joke question, really... the answer is there, though!