Diesel motorbike - increasing engine efficiency

[alexander.foti]

Hi all!

I have a Kubota D722 powered Superdream diesel. It has a CVTtech drive from an Aixam microcar.

Some pictures:



It does 80-95 UK MPG with mixed riding. I have been trying things to increase the efficiency. So far, I have done the following:

• Installed oil Tempreature gauge
• Thinnest oil possible
• 40psi tyre pressure
• Insulated sump
• grill block (90%)
• LED lights all around
• advanced injection timing as much as safe
• Oil to Water heat exchanger.
• Windscreen

We are in the winter at the moment and have avg temperatures of 3-5 Degrees C (37-45F). Since I installed the oil temperature gauge, I was surprised that around town, my oil temperature never rose above 35-40 Degrees C, after installing the oil/water heat exchanger it now gets up to 55 quickly but stays there. I haven't ridden on highways yet, as this always gives hotter coolant temperatures.

I believe that getting more heat into the oil/coolant will make it more efficient. I have had many Mercedes diesels that have had an electrically powered coolant heater (powered by the alternator).

I wonder if its there is a net efficiency gain by heating the oil filter housing with a 12v heating element?

Any other thoughts on how I can increase the efficiency?

[ASV]

a large easy flow exhaust
exhaust insulation wrap
a constant flow low volume propane injector
a rear radial car tire
mild boost from an air amplifier
with a cvt keep the engine in high torque RPM band not HP band

don't get your oil to hot or it will break down

don't waste power heating coolant that's for the extreme cold

hope that helps

[alexander.foti]

Originally Posted by ASV

a large easy flow exhaust
exhaust insulation wrap
a constant flow low volume propane injector
a rear radial car tire
mild boost from an air amplifier

don't get your oil to hot or it will break down

hope that helps

Will try exhaust insulation wrap.

Thank you sir. Exhaust is a tubular style and straight through.
Propane injection would be good but no space for gas bottles!
Car tyre would be difficult on this bike as its tiny vs a car tyre.

A very small turbo running 3-5 psi of boost with no additional fuel would give 15% more efficiency I think, but I have no space for a turbo, only location I can have it is on the downpipe underneath the sump so would need scavenge pump etc. Too complicated!!

[ASV]

yes a turbo is complicated that's is why I recommend an air amplifier which is not a turbo.
https://www.zoro.com/exair-air-ampli...QaAsWGEALw_wcB

but it does need a tank

[arcosine]

Improving aerodynamics, can only get so much from an engine. An aero fairing would give the best bang for the buck. You could ride a bicycle and leave the engine at home, theoretically, you could have still a full tank at the end of the work week.

.. Oh by the way very nice motorbike.

[alexander.foti]

Originally Posted by arcosine

Improving aerodynamics, can only get so much from an engine. An aero fairing would give the best bang for the buck. You could ride a bicycle and leave the engine at home, theoretically, you could have still a full tank at the end of the work week.

True, but I would find it difficult to go 200miles a day on the bicycle

Some more aero mods could probably help, I have done the easy ones already (windscreen etc).

[Stubby79]

Impressive machine you've built there. Always wondered if I could stuff my Kubota on to a motorcycle. Always thought it would be too wide...

[alexander.foti]

Originally Posted by Stubby79

Impressive machine you've built there. Always wondered if I could stuff my Kubota on to a motorcycle. Always thought it would be too wide...

Thank you!

It would be narrower without the huge CVT on the left. A friend of mine has had success using the original gearbox and welding a plate to seal it up.

I have narrowed it down by getting rid of the water pump and using a 12v pump.

[ASV]

you can mix a little filtered used motor oil to your fuel.
its calorically worth a little more than the fuel it displaces
but to much could possibly cause injector problems

[alexander.foti]

Originally Posted by ASV

you can mix a little filtered used motor oil to your fuel.
its calorically worth a little more than the fuel it displaces
but to much could possibly cause injector problems

When I originally built this bike, the idea was to run it on biodiesel. Since I built it I have moved and my supply of waste vegetable oil has dried up. This engine doesn't run well on WVO so I have been running it on straight diesel.

I would run waste engine oil, but in the UK its illegal unless you can show you have paid tax on it.