On Fri, 15 Aug 2008 13:18:00 -0400, "Ed Huntress"
wrote:


"Jon" wrote in message
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"Ed Huntress" wrote in message
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"Jon" wrote in message
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On Aug 14, 3:48 pm, "Jon" wrote:
"Ed Huntress" wrote in message

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"patrick" wrote in message
...
"Lotus Engineering is currently developing an engine concept called
the OMNIVORE together with the Queen's University Belfast and Jaguar
Cars Ltd. The OMNIVORE research engine features a variable
compression
ratio, direct injection and a two-stroke operating cycle. It will
run
on a mix of petrol and alcohol."
So says the press release from lotus regarding the engine. They are
trying to develop the engine to run on all three fuels- diesel, gas
or
alky- dunno if they intend it to run on any mix of the 3- that might
prove problematic. Trying to get my head wrapped around how they are
going to manage all the stuff to get the beast to run on all the
different fuels. Do you think that since they can inject the fuel
directly, they are going to be pressure lubing the cylinder walls?
It's a 2 stroke so I'm resuming that it could still have a poppet
valve as opposed to the port exhaust- that would allow some
variability to the timing. Now, as to the variable compression
ratio...how do you think they intend to implement that? Pat

============================================

Most of the major carmakers around the world are working on VCR
(variable
compression ratio) engines. Nissan uses a multi-link connecting rod
system. A German engineering firm has an eccentric-crankshaft
system.
Teledyne-Continental had a variable-piston research VCR roughly 20
years
ago. And there are variations on another one or two themes.

The Lotus project is just a single-cylinder research engine for now.
I
think what's caught so much attention is the combination of the
2-stroke
basic cycle, and a fine job of hyping the government and other
connections
that are involved.

It's a slick idea. We'll see if this one gets anywhere.

--
Ed Huntress

A couple years back, someone had a working prototype with an electric
jackscrew that altered the crank relationship to the top of the
cylinder,
another used hydraulic pressure to effect the same result

One of my customers is working with engineers at WVU on a
low-compression
diesel-fueled engine. It can use modern fuel-injection goodies, or
possibly
even a carburetor. The concept is pretty sweet. It is very practical,
very
simple, no unusual parts or machining involved. No high pressure
injection
pump with close tolerances.

Our military is searching for practical small engines that run on
diesel,
and that's what is driving this project. Think diesel-fueled
powerplant for
tiny little drone aircraft.


How small? There's already the diesel-power military bike based on the
kawasaki KLR650 (all new engine), its about 650-700ccs I think.


Dave

small like 25-100cc

The general rule is that a true diesel, running on conventional diesel
fuel, requires a minimum cylinder volume of something like 250 cc. That's
because there's too much quenching at smaller volumes, in which the
surface area/volume ratio is inversely related to volume.

However, there is an incredible amount of research being done right now
on compression ignition, and dual ignition with spark plugs and glow
plugs. Go to the SAE site and search on "compression ignition." You'll
get over 7,000 hits on SAE papers, the more recent of which are mostly
about HCCI (homogeneous charge, compression ignition) and there are some
on SACI (spark-assisted, stratified-charge).

Everything you can think of is in play, including mixed fuels, mixed
ignition, and more. There are free abstracts on most of the papers:

www.sae.org

You may be aware that model "diesels," which generally don't have
injection and thus are not considered true diesels, use ether as a fuel
and can be very small in displacement volume. Ether has a cetane rating
of something
like 82, so it's very easy to ignite with compression.

--
Ed Huntress

Thanks for the info, Ed. You'll note my carefully chosen description
"diesel-fueled."

The end user doesn't really care how it is achieved, as long as the fuel
is the same as the rest of their fleet uses.

This is why kawasaki developed their diesel bike, to help the military
machines achieve their goals of being "one-fuel" armies

Find the market, fill the market. Sweet. =)

That's always a good idea. d8-)

Well, dual-fuel spark-ignition engines, which warm up running gasoline and
then switch to kerosene (and probably diesel fuel, although I'm not certain
about that) have been around for most of a century. They were popular for
use in pumping water and other utility jobs on farms, and for some
low-specific-output applications in industry. It probably would take
something fancier to get a decent power/weight ratio for small aircraft, but
the concept is well-proven.

The duel fuel spark ignition engines are alive and well in some 3rd
world countries, or were until very recently. I have seen
kerosine/gasoline fuel outboards used in Indonesia fairly recently.

Given the availability of small air cooled diesel engines today I
doubt that the duel fuel engines are really practical as they do not
produce the power that either the pure gasoline or pure diesel
versions do.

Bruce-in-Bangkok
(correct Address is bpaige125atgmaildotcom)