"Jon" wrote in message
news:_bgpk.3$5C.2@trnddc02...

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
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"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