I recently read a very detailed article about the relationship between Horsepower and Torque. Seems that Horsepower is calculated from Torque. And they say it's torque that gets you going off the line when it comes to acceleration. Now with the high compression ratios of diesel engines and the greater power and fuel economy potential to be had, why don't they make a diesel powered motorcycle? Put a turbo to feed the engine and away we go.

This has been tried, here are some of the issues: weight, limited RPM range, more battery power to crank it, ect, ect. The deisel technology is advancing rapidly and whos to say that in a number of years this may be viable but not right now.

The interesting thing is that, I think it was the LeMan series or Rolex series where the top 4 finishers were deisel. So there is hope. Practical????? Thats not so easy to answer.

I just hope the bike that has a deisel in it won't require a Mack Quadbox tranny. (Has anyone else had the pleasure of driving one of those??)

The Buff

The U.S military had a prototype made several years ago in a Kawasaki KLR frame from memory www.gizmag.com/go/4272/ as great buffalo says been done but like all things usually built for a specific purpose not very marketable ----yet!
800kms to a tank!
Make a great adventure tourer though.
Turbo wouldn't add much bulk would it?

The U.S military had a prototype made several years ago in a Kawasaki KLR frame from memory www.gizmag.com/go/4272/ as great buffalo says been done but like all things usually built for a specific purpose not very marketable ----yet!
800kms to a tank!
Make a great adventure tourer though.
Turbo wouldn't add much bulk would it?

check out this site www.dieselbike.net/ very interesting and informative on diesel bikes.

its possible but i don't see it being used in anything but touring bikes...
turbo would be about the same size as the turbo on the turbo secas

its just going to be heavy and need more to start it
www.motorcyclecruiser....index.html

www.motorcyclecruiser....ndex.html\

www.fasterandfaster.ne...s-for.html

Well, horsepower is basically torque x RPM. That's why low torque engines with very high red lines can still make high horsepower. The question then is whether the gearing of the vehicle is set up to make good use of the peak horsepower area of the engine's power curve. Torque at a given RPM maps directly to accelleration at that RPM.

Diesels make high torque, but have low red lines. So, at lower RPM's you're getting better accelleration and better horsepower out of the diesel, but once you rev past the diesel's peak torque point, the gas engine will start to pull away, because its torque curve will still be rising.

As for weight, the current production Ford Fiesta 1.6 weighs 20Kg (2%) more in its diesel version than it does in its gas version. Some of that's the turbo and some of that's probably a stronger transmission to better handle the extra torque. With modern diesel technology, a bike wouldn't have to weigh much more than a gas engine. In modern engines, both use fuel pumps, ECU's, oxygen sensors, and common rail injection. Even the extra cranking torque is not much of an issue anymore - with modern diesel's being very easy to start. The one trade off is the extra power at startup for the glow plugs versus the fact that, once running, a diesel doesn't need any electrical power for an ignition system.

P.S. It was the 24 hours at LeMans that was won by a turbo diesel Audi a couple of years ago, but the fact that that's an endurance race, and diesel makes it possible for the car to run the race with less fuel stops, has a lot to do with why a diesel won.

Here is (was?) currently the world's fastest BIO-diesel bike doing it's record run Sept. 2007 at Bonneville - "The Crucible" @ 130 mph. Was a BMW 1150RT ... uses converted BMW car engine.

www.youtube.com/watch?v=mmy1DRk_xGY

Bike runs with only 22% of the emissions of a standard diesel engine.
Diesel bike technology is coming on fast and hard.

There are at least 3 diesel bikes in production right now, with many more homebrew versions out there -- spend some time with Google and/or YouTube and you'll find them.

Quote::

Diesels make high torque, but have low red lines.

that is because diesels are being made to have power like that. there is nothing about the injection systems that limit the rpm capabilities, someone needs to make a diesel that WANTS to spin fast. in light of longevity and efficiency manufacturers keep the engines spinning slower. diesels up until recently have been associated with work, not "racing". that is changing fast, look at the lemans cars!

Quote::

Diesel bike technology is coming on fast and hard.

yes it is!!! the engine technology is there already, someone just needs to put the puzzle pieces together on a bike. when they do.....LOOK OUT!!! think about having a bike that can have an extra 100 hp at the flip of a switch carbs? spark plugs? NO! common rail injection, variable geometry turbos, and a bike that will always be tuned perfectly!

for a long tim enow i have wanted to build one from the ground up, but $$$ is not on my side for that one.

I have a prediction that the first practical deisel motorcycle will come from BMW. They seem to be the most foreward thinking company with their heads in both camps.

If Mercedes Benz made motorcycles they would probably be first.

OK, I'll take my Nostradamus hat off now.

The Buff

Zookie400 wrote:

Quote:: Diesels make high torque, but have low red lines. that is because diesels are being made to have power like that. there is nothing about the injection systems that limit the rpm capabilities, someone needs to make a diesel that WANTS to spin fast. in light of longevity and efficiency manufacturers keep the engines spinning slower. diesels up until recently have been associated with work, not "racing". that is changing fast, look at the lemans cars!

I'm not so sure. I lived in Europe from 2004 through 2007. My daily driver there was a 2002 Ford Mondeo TDCi. Nice car. 2.0L, about 130HP, and great on the autobahn (topped out about 130MPH).

There are a lot of little diesels in Europe and they are being made for regular cars and sports cars, not work trucks. They still have much lower red lines and peak torque points than gas engines. Two reasons that you didn't consider are:

1. They DON'T have an ignition system, so timing is determined entirely by spontaneous ignition under compression - i.e. no advance. This can be tweaked a bit by mixture and waste gate control, but I believe it's going to be a limiting factor in how much high RPM power you can make while still making usable power at low RPM.

2. They have longer strokes and heavier pistons due to their higher compression. This means more reciprocating mass, which will also be a limiting factor of red line compared to a similar gas engine.

reciprocating mass its about the only reason that you can't get them to rev higher or if you do you though a rod

if you fumigate the incoming air with propane/menthol and water it will help to spread the flame front so that they will get better combustion more power and more efficiency

faster the flame front the faster the engine can spin
a higher compression diesel will all so have a faster flame front but, because of the higher combustion pressure you will have to beef up the engine, in creasing the reciprocating mass

you could maybe see 6k out of a diesel engine but be cautious the side effects

This bike is the land speed record hopeful in the Bio Diesel unlimited class.

And it has a TAG !

uk.youtube.com/watch?v...re=related

Looks like they sacrificed nimble handling.

We may see diesel touring bikes one day; I doubt we'll see diesel sportbikes before electric hybrids or something else comes along.