Why not a Compression-Spark Ignition Hybrid?

Instead of gas-electric hybrid with all its batteries to go bad, why not a
diesel-gasoline hybrid? The diesel would get phenomenal mileage in city
stop-and-go driving and the gas would provide power on the open road, also
at great mileage. Gas engines are fairly efficient when they are up on the
power curve; its the idling and part throttle operation where they suck
gas.

I do not propose two engines, one diesel and another gas. I suggest a true
hybrid where one engine does both functions. Its so simple, an Einstein
could do it. The main difference between a compression ignition and a
spark ignition engine is the compression ratio. So, all you need to do is
build a variable compression ratio engine. When in high compression, its a
diesel and you inject fuel oil or corn syrup or whatever and when in low
compression, you burn high BTU gasoline with a spark.

Diesels run slower than modern gas engines, but that's no problem because
they'll do 3600rpm any day of the week and that's fast enough for a high
output when in the gas mode. They are also built heavier - that's a plus
also, since they'll never break on you. What you need is a super simple
method of variable compression. I think that could be done with a third
valve located in the top of a hemispherical combustion chamber. When the
computer says its time to switch from diesel to gas, the valve pops open to
open a new combustion chamber. This lowers the compression instantly.
Simultaneously, the computer directs the diesel injectors to turn off and
activates the gas injectors. This switch would occur when 1. the car
reaches high speed, high loads, 2. the car is low speed, high load, 3. you
manually select which engine you want, 4. when one fuel supply is
exhausted, it defaults to the other. This transition would be smooth,
feeling just like an automatic transmission shift, no worse.

Keep in mind, diesels are an alternative fuel engine, so this hybrid would
really do what the President wants, to kick the Arab oil monopoly in the
keister. Since this engine would burn either alternative fuel or high
price gasoline, its our choice what we fuel it with - one, the other, or
both. What can be more democratic than that? Economy or power; its our
choice, not the government's. Its a win-win for the government, auto
makers, and us in the order of importance to society.

This is a multi-billion dollar idea and I donate it to the car industry
today.

 

Filling it up with two different nozzles would be a pain, unless they
made new ones with both nozzles together to fit into adjacent inlets on
the car.

 

It would also invite misfills.

Ted

 

About 50 years ago my father had an International Harvester TD-9 tractor
that started on gasoline then switched to diesel (but not automatically;
ISTR there were two controls to operate) once it warmed up -- but
accompanied by clouds of black smoke.

So it's certainly not impossible, and now the changeover could no doubt
be automated, as you suggest.

But just yesterday I was thinking: "Why only gasoline/electric hybrids?
What about diesel/electric hybrids?"

Perce

 

And nomen is still an idiot. If you've got a turbocharged diesel-cycle
engine, there's NO reason to have it switch to a spark-ignition mode at
any time. There's no advantage "on the open road" at all.

Also, a diesel-cycle engine doesn't much care (combustion-wise, anyway)
whether you're feeding it diesel, Jet-A, gasoline, or Wesson oil. The
problem current automotive diesels have is that gasoline is too thin for
their injection system to properly meter, and doesn't lubricate
components in the fuel system that depend on the fact that diesel is a
fairly good lubricant. There are military engines that have far more
expensive injection systems that CAN burn anything, but its pretty
cost-prohibitive for a PT Cruiser.

 

With direct fuel injection and a few other low cost modifications, a vehicle
can have close to diesel fuel economy and still run on the fuel commonly
avaliable in North America.

Richard.

 

They already have this coming, in the way of GDI technology. It's gasoline,
running at high compression, VERY fuel efficient, and no spark plugs.

Diesel is dirty, requires very special post combustion treatment to make it
clean (that's why no 2007 VW TDI in the US)

 

Yeah, those are neat. That was during the 6 volt era, and before glow plugs.
Modern diesels aren't available like that anymore. They just pack lots of
battery power and spin 'em over.

I never actually had one, but I have heard that the plugs had a huge long
electrode (extra extra exrta hot) but still fouled out after a while.