Quote:
Originally Posted by sendler
Diesel fuel is 11% MORE energy dense than gas. This is the biggest reason diesels always get better mpg. That and the direct injection with no throttle plate.
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Like I stated, I'm no physics guy, but there is absolutely much more efficiency gains that can be realized comparing equally-advanced and equal utility, turbo-charged diesel engines versus naturally-aspired gas engines. The Hayes, stock diesel machine is mechanically injected, naturally aspired and is run on B30 biodiesel during the events. These factors are huge handicaps for the diesel versus the gas engines used in mc's, because, although gas engines can have some benefit using turbo charging, super charging, and/or direct injection, for diesel engines these technologies provide huge performance benefit and actually improve mpg, while gas engines must maintain an air-fuel mix for combustion and therefore has some tradeoffs. According to the CGE table, biodiesel is approximately 104-106% the energy density as regular E10 gasoline depending on the formulation and so now this 11% so-called fuel advantage often used as an argument against diesels drops down to 8% . So this very crude diesel (crude with respect to refinement and performance per cc versus what could be produced from an auto manufacturer taking--say--half of a 1.6 liter, all-aluminum, counter balanced, single cylinder, super-modern diesel) could result in a very refined, much higher-performing diesel than the Hayes engine that was not designed to excel in these areas; and it'd be even more fuel economical.
It just so happens that my mc with an engine derived from the Honda Fit car and the Hayes stock-like bike have nearly the same displacement. Mine obviously has less drag than the adventure-style KTR 650 framed bike. Mine has 47 peak hp and 41 peak foot torque at the wheel and weighs 494 pounds. The Hayes machine supposedly produces 31 horsepower and 35 peak foot pounds torque and weight is likely 20 pounds or so lower than mine, but has been tweaked from stock and is geared to maximize mpg for the events. It has only one cylinder and mine is a twin. Due to cost constraints, any future diesel mc would likely be a thumper. The best possible mpg I could expect in an event w/o tucking is around 83, but the diesel bike can achieve well over 100 w/o the turbo charging or DI that are must haves for diesels. Add in those technologies from auto tech from VW, Peugeot, or BMW, and one would have a bike with much less vibration, and near equal performance and likely better mpg. It would be tough and too expensive but logistically possible. It would be heavier and higher compression than the Hayes engine, but not by much, because this newly-conceived diesel would be a product designed two decades from the time of the project that ended in the Hayes machine.
I totally get what's being stated about the cost and engineering hurdles and the total lack of a market for such an amazingly-efficient and refined diesel bike and that it is for these reasons an impossibility; but I absolutely reject the premise made by some that modern auto technology could not produce a diesel motorcycle at or about the same displacement as my bike (which is amazingly efficient for a gas-powered mc), that would be acceptable auto-like performance, that would be amazingly smooth with only a little more vibration, and at least 30% more economical than my bike.
Fuel density is an irrelevant argument against diesel technologies. All engine types use the most energy-dense fuel possible within cost limitations. Just so happens diesels can run on a more energy dense fuel than spark ignition, but this in no way should be used as a way to diminish the advantage of one engine type over another even if the LeMans circuit unfairly disadvantaged diesel entries to create more parity for the inferior, gas-powered race cars versus the diesel entries from Audi and Peugeot that ran off and left them using equal-sized fuel tanks.
There are some out there that erroneously believe that spark ignition is catching up to diesels in efficiency. They use some of the latest products sold in America to support this theory, but what is really happening is that, even though a diesel can be designed to use all these latest and greatest technologies to reduce fuel consumption just as is done for gas engines; it is often cost prohibitive to employ a diesel with all these other cost increasers. Moreover, some of the most complex exhaust treatment systems employed for diesels, especially the ones that deal with NOx reduction, a group of gasses that are a by product of lean combustion, reduce the diesel advantage, as engineers are forced into designing richer fuel burn than is possible with the technology.