Using ship fuel as aviation fuel?

Hi Gord,

Not so much on us automotive engineers today... A lot of modern
automotive engines are run right along the knock limit for
efficiency, with knock control constantly operating. To do this,
there has to be a knock event every now and then for the knock
control to be able to detect the limit. (Knock control just detects
knock events and retards the ignition. When there is no knock,
ignition is advanced again until the next knock occurs.) This
normally works fine. However on some (not all) engine types, on high
load testbed runs this has recently led to very rare statistical
occurence of "super-knock" events, with disastrous results.


Yes, that's quite interesting to me, and it backs my opinion of
using low test fuel in my cars...I never use high test fuel at
all, mind you, I only use standard domestic vehicles but I
consider high test wasteful in modern engines with 'knock
control'.

Well, it depends...

Normally you won't damage an engine with knock control by using lower
grade fuel than recommended, however within limits. If you use very low
octane fuel on a high compression or a turbocharged engine, ignition
might occur before the spark just from the compression, as we
discussed. There is nothing knock control can do about that. Also,
depending on your driving profile, you might find that fuel consumption
increases with the lower grade fuel, as retarded ignition reduces
engine efficiency. This is especially valid at high engine loads and
low engine speed, where the biggest retard is neccessary. Wether the
increase in consumption will eat up the price advantage of the lower
grade can only be determined by experiment.

Yes, I understand that, another good system that GAMI is looking
at is their accurate fuel injectors to enable automobile engines
to be run lean.

Now that is a new one to me! I know about GAMIs injectors for GA piston
engines and all the LOP-operation stuff, wich are around for a while
now, and which I think are a big improvement. I didn't know that they
are planning on entering the automotive market and I'm quite surprised.
Automotive engines, different from aviation, run stoechiometric
basically anywhere on the map exept full load. (stoechiometric mixture
is more or less peak EGT). Due to their design, mostly liquid cooled,
temperatures are not a problem. Of course you could run such an engine
lean (LOP), but you won't pass any emissions test for sure. I don't
think you really need special injectors to do it, but you would need to
retune the ECU. And the fuel savings compared to running stoechiometric
are only a fraction of what you save if otherwise you have to run rich.

The Japanese car makers had lean running engines on the market for a
while, and some of the direct injection gaoline engines being developed
now also run lean by creating a stratified charge. But that's far
beyond an aftermarket improvement.

We run (perhaps ran might be more accurate) large
recip aircraft engines at '10% lean from best power' (by manually
leaning them during cruise) for many thousands of hours and they
worked fine in that condition, matter of fact they'll continue to
run fine as much as about 30% lean before they get unstable, they
seem to love lean mixtures!...

Do you by chance know whether these had direct injection (injecting the
fuel into the cylinder instead of the manifold)? To my knowledge there
have been direct injection piston engines among the big radials, but I
haven't found any further information about it so far.

regards,
Friedrich

--
for personal email please remove "entfernen" from my adress

"Friedrich Ostertag" wrote:

We run (perhaps ran might be more accurate) large
recip aircraft engines at '10% lean from best power' (by manually
leaning them during cruise) for many thousands of hours and they
worked fine in that condition, matter of fact they'll continue to
run fine as much as about 30% lean before they get unstable, they
seem to love lean mixtures!...

Do you by chance know whether these had direct injection (injecting the
fuel into the cylinder instead of the manifold)? To my knowledge there
have been direct injection piston engines among the big radials, but I
haven't found any further information about it so far.

regards,
Friedrich

Well, just a comment about domestic automobiles, I didn't mean to
indicate that I operate them below the manufacturers specified
octane ratings, after all, I believe that the manufacturer knows
his engine best and I'd never try to second guess him, but I have
all kinds of friends and relatives who use hi octane fuel in
their cars even though low octane is recommended. (complete waste
I feel) Another thing that I NEVER do is 'recommend to anyone'
what fuel to use. You're bound to get blamed sometime in your
life because a friend's wife got preggy if you do...

About the direct injection, the Argus (ASW aircraft) used by the
Canadian Armed Forces had Wright R-3350-EA1 engines (3700 BHP)
which had direct fuel injection into the cylinder (not just prior
to the intake valve). The Wright R-3350-89A fitted to the
Fairchild C-119 Packet had 'spinner injection', where the fuel
was injected into the spinner of the supercharger, and the P2V-7
Neptune was set up this way too.

--

-Gord.

Hi Gord,

Well, just a comment about domestic automobiles, I didn't mean to
indicate that I operate them below the manufacturers specified
octane ratings, after all, I believe that the manufacturer knows
his engine best and I'd never try to second guess him, but I have
all kinds of friends and relatives who use hi octane fuel in
their cars even though low octane is recommended. (complete waste
I feel)

Ah, you're absolutely right there! Sorry for the misunderstanding.
There is no point in using higher octane than what the engine was
designed for. Even knock control will not advance ignition beyond the
calibrated map for the designated fuel.

However a lot of people over here fell for a marketing trick of Shell
Oil: Instead of the 98 octane highest grade fuel sold in Germany and
most euroean countries they offered a 100 octane (by the way, this is
ROZ, not ROZ+MOZ/2 as in the US) fuel called "V-power" with supposedly
all kinds of mysterious additives at 10 ct / Liter premium over other
oil company's 98 octane. Lots of car magazines and also the ADAC (your
AA) tested it in various models and found no difference whatsoever in
power and consumption. Yet Shell sells 10% of it's turnout in V-Power
while the other's only sell 5% 98. Talk about snake oil...

Another thing that I NEVER do is 'recommend to anyone'
what fuel to use. You're bound to get blamed sometime in your
life because a friend's wife got preggy if you do...

:-)

About the direct injection, the Argus (ASW aircraft) used by the
Canadian Armed Forces had Wright R-3350-EA1 engines (3700 BHP)
which had direct fuel injection into the cylinder (not just prior
to the intake valve). The Wright R-3350-89A fitted to the
Fairchild C-119 Packet had 'spinner injection', where the fuel
was injected into the spinner of the supercharger, and the P2V-7
Neptune was set up this way too.

I always find it intriguing, that almost everything we develop today as
supposedly latest techology has been there half a century ago. The only
really new thing in engines today is electronic control.

regards,
Friedrich

--
for personal email please remove "entfernen" from my adress

"Friedrich Ostertag" wrote:


I always find it intriguing, that almost everything we develop today as
supposedly latest techology has been there half a century ago. The only
really new thing in engines today is electronic control.

regards,
Friedrich

Exactly...and it's one of the reasons that, although I consider
myself quite knowledgeable engine wise, when I open the hood of
an ailing engine I quickly close it and get on the fone for a
towtruck...there's just so much complication in all the
electronic sensors, computers etc to squeeze every ounce of
efficiency out of a litre of fuel that I find it daunting.

My wife's Corolla just finished it's lease and I bought it and
leased another Toyota for her. A 'Matrix'. They have an
intriguing feature called VVTi (Variable Valve Timing). Neat
system!...hope it's rugged!...

Cheers
--

-Gord.

On Sat, 24 Apr 2004 17:29:50 GMT, "Gord Beaman" )
wrote:

"Friedrich Ostertag" wrote:


I always find it intriguing, that almost everything we develop today as
supposedly latest techology has been there half a century ago. The only
really new thing in engines today is electronic control.

regards,
Friedrich

Exactly...and it's one of the reasons that, although I consider
myself quite knowledgeable engine wise, when I open the hood of
an ailing engine I quickly close it and get on the fone for a
towtruck...there's just so much complication in all the
electronic sensors, computers etc to squeeze every ounce of
efficiency out of a litre of fuel that I find it daunting.

I like to think I know a pretty decent amount about engines, enough to
do my own maintenance when I was too poor to go to garages. But when I
got the Puma, I didn't even bother opening the bonnet. I knew I
wouldn't recognize much of what was under there and that the key
things would be hidden from view. All I needed to convince me that the
running gear was in excellent shape was a flying trip down the local
dual carriageway :-) (Happily 3 years later nothing serious has gone
wrong)

My wife's Corolla just finished it's lease and I bought it and
leased another Toyota for her. A 'Matrix'. They have an
intriguing feature called VVTi (Variable Valve Timing). Neat
system!...hope it's rugged!...

This is on the Puma too, as Variable Cam Timing. I think it's fairly
failsafe. Taking a mechanical engineer (which I'm not - I'm an elec)
view, I'd say they do it by retarding/advancing the valve timing
according to revs and load. So if the system fails or degrades, the
valve timing wouldn't adjust but the cams would still go round and the
valves would go up or down. Not heard of rampant engine trouble in the
variable timing cars so they must have got it licked.

It seems to work on the Puma ... I moved from Rover 2.0 16 valve to
Ford 1.7 16 valve and the Ford unit has just about equal power but
it's far more flexible across the rev range. The Rover unit was fairly
quiet until about 3250 rpm where it would take off. The Ford unit has
usable power down at about 1800/2000 rpm.

Pete Lilleyman

(please get rid of ".getrid" to reply direct)
(don't get rid of the dontspam though ;-)

"Friedrich Ostertag" wrote:


I always find it intriguing, that almost everything we develop today as
supposedly latest techology has been there half a century ago. The only
really new thing in engines today is electronic control.

regards,
Friedrich

Exactly...and it's one of the reasons that, although I consider
myself quite knowledgeable engine wise, when I open the hood of
an ailing engine I quickly close it and get on the fone for a
towtruck...there's just so much complication in all the
electronic sensors, computers etc to squeeze every ounce of
efficiency out of a litre of fuel that I find it daunting.

My wife's Corolla just finished it's lease and I bought it and
leased another Toyota for her. A 'Matrix'. They have an
intriguing feature called VVTi (Variable Valve Timing). Neat
system!...hope it's rugged!, looks expensive if it comes adrift
in flight...

Cheers
--

-Gord.

On Fri, 23 Apr 2004 21:58:30 +0200, "Friedrich Ostertag"
wrote:

Hi Gord,

Well, just a comment about domestic automobiles, I didn't mean to
indicate that I operate them below the manufacturers specified
octane ratings, after all, I believe that the manufacturer knows
his engine best and I'd never try to second guess him, but I have
all kinds of friends and relatives who use hi octane fuel in
their cars even though low octane is recommended. (complete waste
I feel)

Ah, you're absolutely right there! Sorry for the misunderstanding.
There is no point in using higher octane than what the engine was
designed for. Even knock control will not advance ignition beyond the
calibrated map for the designated fuel.

However a lot of people over here fell for a marketing trick of Shell
Oil: Instead of the 98 octane highest grade fuel sold in Germany and
most euroean countries they offered a 100 octane (by the way, this is
ROZ, not ROZ+MOZ/2 as in the US) fuel called "V-power" with supposedly
all kinds of mysterious additives at 10 ct / Liter premium over other
oil company's 98 octane. Lots of car magazines and also the ADAC (your
AA) tested it in various models and found no difference whatsoever in
power and consumption. Yet Shell sells 10% of it's turnout in V-Power
while the other's only sell 5% 98. Talk about snake oil...

Definitely agree with you there ... The Puma that I have has a
reaction to the higher octane 98 RON Optimax fuel that Shell sell over
here.

It's not a good reaction, like increased power or economy, it's a bad
one. The bad reaction takes the shape of the engine management
struggling for the first couple of miles to get used to the differing
octane rating. Symptoms included poor running including reluctance to
idle. I suspect that the anti-knock control was self adjusting itself
for the increased octane rating. It also takes a little while to get
used to 95 RON unleaded when that goes back in.

Anyway, no measurable economy improvement (I nerdishly track my mpg)
and no perceptible power improvement. Although other people reckon
they see power improvements with other cars.

Pete Lilleyman

(please get rid of ".getrid" to reply direct)
(don't get rid of the dontspam though ;-)