I, for one, look forward to the day when turbo-diesels are available in
plentitude in the US. However, I was under the impression that diesel
fuels in the US contain too much sulphur, making emissions compliance
problematic.
Dave Arbogast wrote:
Six months after I started (contractor) at the German-American automaker in
2001, I risked being fired - I directly e-mailed the CEO with a business
proposal to sell the diesel we make to the US market too. To my surprise, I got a
very good response. Basically, top US automaker executives believe most
Americans share the out dated views on diesel that has been expressed in this
forum. So, they are very reluctant to offer them here. That is changing in a
couple of month with Jeep http://www.jeep.com/crd - and already has with
Mercedes - the C320 diesel does 0 - 60 in 5.7 sec, and the gas version is 5.9...
so performance is BETTER with the diesel as is BSFC, at a minor cost & weight increase.
The current higher sulfur fuel we have allows the CRD to meet emissions in 47 states,
and in 3 years in all states (we are lowering the sulfur content by then)
I would not be so quick to dismiss the diesel rotary.
--
-dave
mailto:dave@arb.net
The stuff presented here is up to date Joe. This is from the latest info
available. The Heisler book was published in 1995. By technical book
standards that is up to date. As I said there have been no major breakthroughs
in 50 years since the turbo compound. I don't consider electronic injections systems and high rear axle ratios major break throughs. This goes for all kinds of
IC engines.
Except perhaps the wankel. The electric assisted turbo charger IMHO is
perhaps going to be a major breakthrough. I think you might see some reduction
in the displacement of economy car engines further improving the city mileage.
As far as a diesel wankel is concerned the wankel geometry is incapable of maintaining a useful combustion chamber shape and still reach the compression
ratios necessary for true diesel operation. That is not to say they won't
run on diesel fuel however. They will but you won't get the diesel BSFCs.
No doubt about it. At typical car cruise HP levels the diesel BSFC is much better.
The question is; are people going to buy diesels or are they going to
buy hybrids? My guess is hybrids until enough of them are out there
to firmly establish their disadvantages. I will go out on a limb and predict
that hybrids will eventually disappear off US roads just like the diesel
car did.
About ten years ago diesel car sales were much greater than they are
now. The VW turbo diesel Rabbit was particularly popular for awhile. Since that
time diesel car sales have dropped dead. Perhaps you can find a whole
new crop of diesel virgins to sell diesel cars to in the future :)
Paul Lamar
The big diesel innovations have occurred in the last 5-10 years, and are not
in the book.
Electronic very high pressure diesels allow us to do some very interesting
things.
Notice Thilerts 4 valve head? Ever seen a 4 valve on a small car diesel?
No, because the diesel could not get enough fuel in the chamber to burn the
air that was there, as your article mentioned.
Now it can. Now the shortage is fuel, just like a gasser.
Production Diesels are now producing as good or better HP than production
gas engines per cube, and still growing, which gas is not.
Blocks are being redesigned to make them stronger and lighter. Latest
generation engines suffer a 10% weight penalty, and it will get smaller next
year.
Look at the VolksWagon Golf TDI. Drive the stick shift. If it dont
surprise you, your surpriser is broke.
I question your premise about the rotary Paul. Do you have any pictures of
the rotor Wankel used on there diesel? I believe the combustion chamber
shape was not optimum for a modern diesel. Have you seen a TDI piston? I
imagine something similar would work for the Wankel.
Four valves per cylinder?
Not true Eric. Ever hear of a uniflow scavenged diesel. The GM engines
used in trucks and boats had four valves in the head alone for just the exhaust.
The intakes were 360 degrees piston ported. The Packard aircraft radial diesel
engine of the early 30's had just one large valve that served both intake
and exhaust. We have a guy here in SZP that owns one as I recall.
I also think there is one in the San Diego museum. As I recall the Packard
diesel set an in-the-air-endurance record in the early 30's. Just about every
configuration has been tried.
Unless you make the crankcase out of unobtanium there have been
no breakthroughs there either. If you did come up with a better design
it could be applied to the gas piston engine as well and you would be right back
where you started. The forces are higher in a diesel and that is it.
No getting around that unless you lower the compression ratio. Diesel
engines are SERIOUSLY trying to jam the crankshaft out the bottom of the
block.
As far as I know nobody is using the highly structurally efficient horizontal
opposed layout on a recent (if ever) car diesel engine. Both Porsche, old VW and Subaru have been using it for years to build relatively high power to weight
ratio
gasoline car engines. Renault was smart enough to use it on their aircraft diesel engine.
The gasoline piston engine powered car is the cockroach of the engineering world.
It has been under attack for the last 100 years. First by the electric
and steam car. Then by the Wankel in the early 1970's. Then by the diesel car.
The electric car again in the early 90's and now by the hybrids.
It just keeps evolving slowly to become a moving target. All those
attackers have fallen by the wayside except a small group of loyal rotor
heads like myself and all those on here. (despite ferocious attacks
on the wankel I might add). We appear to be doing better in the U.S.
and Australia than the diesel heads :) Good luck.
All you need to do is look at the wankel geometry. The current Mazda
is about as good as you can get for an acceptable combustion chamber
shape. Probably ANY deviation to raise the compression ratio will
destroy what little is left of the combustion chamber. There is no
room in the rotor for any kind of spherical combustion chamber.
Find a used copy of R.F. Ansdale's book "The Wankel RC Engine". He will
explain the hundreds of configuration Felix went through before he came
up with the current configuration. Prior to ISBN. Library of congress
card number 69-18692. A.S. Barnes and Company.
Juergen Bax president of Wankel Gmbh gave me
an original technical paper in color and large format that Felix
presented to the German engineering society outlining hundreds of these
configurations.
Paul Lamar
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