...or maybe it is. How am I supposed to know how you people think?
How much closer can gas engine and diesel engine tech get? With direct injected turbos gas engines are getting very close to each other.
Right now the only differentiation I can think of other than fuel ignition and throttle control methods is that diesel needs to come up with a variable valve timing method.
Anybody know of any other major differences anymore?
Fuel prices?
I have never seen stacks on an ecoboost.
bearmtnmartin wrote: I have never seen stacks on an ecoboost.
Challenge accepted.
Fuel energy density
Pumping losses
Shape of the power curve
I don't think you'll see Diesels ever rev very high due to compression ignition.
Looks like VVT is being used in diesels already: http://www.mandiesel-greentechnology.com/0000516/Technology/Primary-Measures/Variable-Valve-Timing.html
Diesel fuel has more energy in it, so they have that advantage. Now if higher octane gasoline were available in pumps widespread, then higher compression ratios help could close this advantage. Diesels are more rpm limited than gas engines, especially in larger displacements, with all those heavy parts slinging around.
the cost ratio thing is why my SIL switched from diesel to gas for his work truck.
In reply to 81cpcamaro:
That isn't helped by most being OHV multivalve engines either....
Since I don't know much about diesels is there any ever in a street car that has any top end or revs beyond 6000rpm?
I've never really driver a diesel car but i've driven a Starion which has similar powerband, lmao.
In reply to 81cpcamaro:
Higher octane has even less power density. I would think that would make the gap even larger. I am not sure if my comment helps this discussion.....
kanaric wrote: Since I don't know much about diesels is there any ever in a street car that has any top end or revs beyond 6000rpm? I've never really driver a diesel car but i've driven a Starion which has similar powerband, lmao.
Diesel doesn't burn quickly enough to rev. Much beyond 4500 rpm, you start leaving big patches of unburnt fuel in the cylinders, or so I hear.
How close can they get indeed. From Autoblopnik
The diesel community, already reeling from the low 14:1 compression ratio in Mazda’s new Skyactiv-D diesel, were absolutely gob-smacked when Mazda announced that they are developing a new ultra-low compression diesel engine.
The new Skymaster-Z engine uses an 8.5:1 compression ratio, so low that it requires an auxiliary electrical spark system in order to maintain combustion, and requires fuel that is more volatile than standard low-sulfer diesel. Mazda engineers have calibrated the engine to run on ordinary 87-octane gasoline, but this requires retimed single-pulse injectors and a more complicated intake system that premixes the fuel and air in a relatively constant ratio, as opposed to the variable mixture and power-cycle injection used by traditional diesels.
According to Mazda Chief Engineer Ashiro Nakahonda, the Skymister-T engine’s low compression ratio eliminates the need for a turbocharger and allows use of lighter components that can spin faster, raising the redline to 7,000 RPM. The new engine also produces significantly less noise and vibration than a typical diesel and has a markedly different emissions footprint, allowing it to meet 50-state standards with a standard catalytic converter and without the use of an AdBlue-type additive. The trade off is a 75% reduction in torque and higher fuel consumption. The prototype two-liter engine reportedly develops around 140 horsepower but only 135 lb-ft of torque, returning the equivalent of approximately 30 MPG in the EPA city cycle and 40 MPG in the highway cycle when mounted in a C-segment-size car. “While these numbers are not typical of an ordinary turbodiesel engine,” Nakahonda says, “we believe they will be adequate for the American market.”
Diesel nuts who worry about this sort of thing have expressed concern about the lack of upper-cylinder lubrucation due to the engines’ rapid combustion and reduced fuel stratification, but Nakahonda is confident the Skymassive-F engine will achieve a 180,000 mile service life.
Irked at not having anything more technical-sounding to say, Mazda spokesman Jeremiah Burns vamped, “While the Skymatic-P engine does have some trade-offs compared to conventional diesels, we are confident that the lower noise and ease of fuel availability will appeal to American buyers.”
Mazda plans to offer the Skymackerel-Q engine in its popular Mazda3 compact, offsetting its additional cost by making the interior even cheaper and crappier.
Diesels suck. 
In reply to Keith Tanner:
homogenious pre-mixed fuel-air mixture that is ignited by a spark plug? Sound very familiar for some reason.
In reply to Keith Tanner:
Don't forget about Sky Captain when you're talking about the world of tomorrow.....
In reply to Keith Tanner:
Thank you, thank you, thank you. So I am not going nuts, well with respect to the diesel vs gas engine tech gap that is.
Well, alfadriver was paying attention
In reply to Keith Tanner:
Touché
Flight Service wrote: How much closer can gas engine and diesel engine tech get? With direct injected turbos gas engines are getting very close to each other. Right now the only differentiation I can think of other than fuel ignition and throttle control methods is that diesel needs to come up with a variable valve timing method. Anybody know of any other major differences anymore?
Newer gas engines only use the throttle to finely control idle and low load, and some of them only have a throttle as a safety device, controlling engine power entirely with fuel injection and variable valve timing/lift.
Of course, newer diesels have throttle plates on them too, to make the EGR work better.
VVT isn't much of a priority for diesels because the RPM range is so limited due to the combustion characteristics, but it should be noted that camless valve engines are typically diesel right now BECAUSE of the narrow band of engine operation.
Also the SkyActiv gas and diesel engines are both around 14:1 compression, the gas engine is that high for efficiency and the diesel engine is that low for emissions reasons.
Now, the only thing left is spark. And around fifteen years ago there was strong research into combustion ignition gasoline engines, the main problem of which was getting the cylinder mix to ignite at the right time. This was before direct injection was possible... I wonder if they're still working on it.
yamaha wrote: In reply to Keith Tanner: Don't forget about Sky Captain when you're talking about the world of tomorrow.....
I haven't seen that in forever. Weird movie, but I kinda liked it.
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