why has noone made a car engined bike

[gregsfc]

Originally Posted by sendler

Very nice post but I wonder if you should go ahead and copy this to your own thread about the CTX since this thread is wandering all over the place all the way to such ridiculous machines as motorcycles with V8 auto engines.

Yeah. Probably. I was reading through this thread with a renewed interest in powered two wheeling, since I'm riding the CTX700 again after a long hiatus, knowing that I had a bike with an engine that came out of Honda automotive, but not expecting to read a couple of old comments inquiring about my specific model that barely justifies production in sales.

I thought that (hey) someone has asked about the potential of my bike if anyone who owned one ever cared about mpg and mpg tracking . Never expected to come across such a post anywhere; got excited and posted sort of a report or log of my experience, but really don't know the most appropriate way to spout off or even if I should as a new reader.

Just got carried away. But going back to the OP's inquiry, just so everyone who stumbles upon this thread who might care knows, Honda Power Sports developed an mc engine around 2011 that has its roots from Honda automotive with a rev limit at or about 6500 RPM; basically halving a 1.4-liter that is used in the Fit for North America, and developed it for a group of motorcycles that are very efficient for their displacement. They also borrowed some auto-engineering prowess to bring dual-clutch automatic, with sport and manual modes they call DCT. The models include, but are not all available everywhere: NC700S/SD, NC700X/XD, CTX700N/ND, CTX700/D, INTEGRA, NM4. Europe and maybe some other markets have an updated, bored out version of the engine that have the 750 nomenclature. From my perspective, as a whole, except for the small but growing cult around the NC700X and NC700XDCT, the American riding cultures absolutely reject the concept and prospect of Honda's great low and midrange performance and great mpg at the sacrifice of good higher-end performance.

If this Honda engine has been discussed in other threads, I apologize for the rehash above, but the whole premise of the thread starter brings up something near and dear to my heart. This whole idea that the only or best approach for maximizing mpg of mc's (as has been proclaimed by some elsewhere) is to take as small as possible displacement engine to generate minimum necessary horsepower to maintain highway speeds streamlined, is somewhat flawed or at least somewhat closed minded. Even though I'm not really physics and mechanically minded, I can see what I see and when I see Fred's naturally-aspired, larger, heavier, stock-like diesel bike, running on a less-dense fuel, with 31 hp and 35 peak pound torque, exceed the mpg of 250 cc and below stock bikes that have far less peak numbers, in a lighter package, resulting in comparable overall performance of the two approaches, that shows me that, using auto engine tech and even handicapped diesel technologies can produce at least equal mpg performance as does the minimalist approach.

So my only point is that, even though I don't have the knowledge to explain why it is so, I feel confident that there is some mpg benefit to added midrange power via higher, low-end torque that we get from the auto engine industry, and that, if there were ever an all-out manufacturing effort to produce high mpg mc's that were reliable, durable, and refined, the engine would be auto tech inspired; it would be bigger displacement than 250-350 cc class, it would be heavier than the current streamlined bikes, and if costs made it possible, it would be an all-aluminum, sequential turbo, direct -injection diesel with limited compression ratio on the order of at or about 15:1, because the state of modern diesel tech is way ahead of what many have assumed on this thread by some and there is alot of possibilities of diesel applications these days and that, really, the only things that limits diesels these days are costs and emissions compliance complexities, but that this latter hurdle is somewhat relaxed due to the lower standards for mc's.

[sendler]

Originally Posted by gregsfc

I can see what I see and when I see Fred's naturally-aspired, larger, heavier, stock-like diesel bike, running on a less-dense fuel, with 31 hp and 35 peak pound torque, exceed the mpg of 250 cc and below stock bikes that have far less peak numbers

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.

[Grant-53]

The higher compression ratio of the diesel may be even more important in terms of efficiency. Weight and vibration are keenly felt on a motorcycle. If I wanted to build a diesel bike, I'd start by looking at a Kubota 3 cylinder engine in the 700 - 900 cc range.

[gregsfc]

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.

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.

[sendler]

Do you keep a fuel log for your CTX700 anywhere?

[gregsfc]

Originally Posted by sendler

Do you keep a fuel log for your CTX700 anywhere?

Just Fuelly.

Determined vehicle trip meter error 2.2% optimistic. Edited new values and adjusted down. Just like with my F150 though, my results are far from typical. I think the statistical mode on the bike is 69 and I'm currently at 76. With the truck, with the same engine, the mode is 17; I'm at 24. The disparity seems more reasonable for the truck, because of all the configurations and level of work duty. I've got the smallest, lightest version, highest gearing and ride with an empty bed 80% of the time.

I'll look at posting my Fuelly average in my sig if that can be done here.

[Christopher Jordan]

A few rat-rod trikes- 0 to 16 (2 V-8s) cylinders google search:
https://www.google.co.nz/search?q=ra...M3BiHMX4_0M%3A

[cRiPpLe_rOoStEr]

I've been looking at the specifications of those Royal Enfields and, even though they rely on single-cylinder engines with a pushrod valvetrain, their power and torque figures are quite proportionate to nearly half the output of the Brazilian Opel Corsa (rebadged as a Chevrolet) fitted with a 4-cyl 1.0L OHC engine on which I learned to drive.

[freebeard]

https://www.google.com/search?q=single-cylinder+motorcycle+with+wooden+forks

[cRiPpLe_rOoStEr]

That steampunk design actually looks cool, but doesn't seem so practical.