Is there a 50cc diesel engine out there?

[JemmaUK]

The bio diesel option is cool, ive seen the cooking oil conversion kits for most diesel engines, you would need 2 fuel tanks though, since the oil has to be heated for the first few minutes of a cold start, and the engine uses regular diesel at that time, then switches to the cooking oil.

They used to use a similar system on the old petrol paraffin tractors - start on petrol and run on paraffin when the engine is hot - the only thing was to remember to switch back to petrol before you shut down - else the thing wouldnt go next time. oh, and, really really dont fit the aftermarket turbocharger...

There is a common method to make a small diesel - basically taking a standard engine and making a compression insert for it which is drilled to take a glowplug. This is threaded to allow the insert to be moved in and out of the cylinder (increase/decrease compression).

This will allow an engine to run on diesel although it wont hit the car compression levels of 22:1 or more it will run happily. Incidentally this is the same varicompression system as was used on the Lohmann compression-ignition cyclemotor engine (a massive 18cc single lol) which is said to manage 1mph per cc - scaled up this should mean that a 32cc C/I engine should get the same speed as a 2-stroke 32cc with better torque and probably better consumption..

Its a complicated method and it needs someone with the relevant tools but its doable and would fit our applications very well..

Jemma xx

 

[Tifford]

Thanks Jemma

I thought that either changing the piston or cyc head would raise compression. I wasn't sure if it could be raised enough to run on diesel without causing the engine harm. Then I wondered about the glow plugs. You've answered my questions.

 

[Large Filipino]

I'm starting to dig this idea. Have one of them small diesel engines on a rack mount and have like your sprocket be like 30 tooth. When you start off it would be like the engine barely idling and your going pretty good then as you accelerate... maybe speeds surpassing 40 mph could be possible.
Yea diesels!
Diesels baby!!

 

[KiDD]

I'm seeing it like Large is. They don't rev high but super torque. Zoom Zoom! Even if it was too heavy for a rack mount a diesel pusher trailer could work very well. Lower Center of gravity.

 

[Tifford]

I don't think a 50cc diesel would weigh much more than a 50cc gas engine.

Higher compression would mean that it would have to be better built but we are only talking about 50cc here.

Higher compression I think would also mean slightly more heat given the same rpm but there are 6hp diesels out there without water cooling. Diesels don't need to have the **** revved out of them so they would operate at a lower rpm.


I just wish there was a 50cc affordable diesel out there already. When you start to change components on an engine things get expensive real quick.

I'm finishing up a kit cobra and blew my budget into the nearest black hole because I upgraded here and there.

I see so many good things with a small diesel.
1) Great gas milage
2) We are talking about a small tank of diesel, so by combining your own oil after you've cooked some fries you could really stretch your mpg
3) Good TQ numbers down low on the rpm range
4) I think the sound would be less than a 2 stroke
5) Cranking it might require a little more effort but nothing that can't be overcome.

Lots of benefits. A kit for this would need to be packaged so that it would be simple for the customer to install. The guy who copywrites it and puts a patent on it with mass production could make millions.

 

[KiDD]

An electric start wouldn't be out of the question to start it.

 

[sjackson]

a 20mph speed limit on motored bikes is ridiculous... considering that you can easily reach and maintain that speed on a pedal-powered road bike. Heck, Lance armstrong averaged 32mph on stage 19 in the Tour de France and can sprint well into the 40s... and he's climbing mountains!

 

[JemmaUK]

I remembered something recently that might have a bearing here..

We can get hold of 25cc engines fairly readily and fairly cheaply and there is the expertise with some people on here to do machining and such so here is my suggestion, but first a little history.

Back in the 30s and 40s aircraft designers had a problem. While the average sleeve valve or inline engine would run happily in the lab on expensive high octane fuel they tended to run like a bucket of bolts on what was available in the field especially in countries where high octane fuels were hard to come by..

There was also the problem that in low temperatures aka below -15/-20 petrol engines ice up and are a right royal pain in the proverbials to get going... imagine lighting a fire under a 45 litre V12 in order to get it to run. It was either that or leave the engines idling all night...

So various companies in various countries turned to diesel engines. you already know the problem - per cc displacement diesels are alot less powerful so for a given power you need more capacity....

Well, you do, unless like the Junkers company (and later (by sticking three Junkers Jumo 205's together) the deltic), you cheat...

The trick they used was simple - use a single long cylinder with cranks/con rods/pistons at each outer end configured so that TDC had the pistons close together in the middle of the bore to create the high compression. and hence you have a diesel of effectively half the swept volume and more importantly size of a conventional one for the same amount of effective output and displacement.

The fuel is injected in the space between the pistons and at TDC the compression ignites the fuel and provides a duel power stroke. The engine being started (in our application) using a glow plug and driver and the usual pedal and clutch, recoil etc methods.

Here we hit the snag however. Porting and other requirements are simple as with a little thought the standard config should be useable (or use the junkers method of an 11 degree difference to open/close scavenge ports). However the issue is gearing the output to a single shaft turning in one direction (as to get an engine that has two opposite acting strokes, you have two opposite motions).. once that is fixed I cant see that the system would be at all complicated, or you could use the Junkers method of running off one shaft. In fact trimming the bores to get a calculated compression ratio would mean the engine if set up right could run on straight diesel

just a thought ...

Jemma xx

 

[Tifford]

Two opposing cyclinders.........hummmm.......it could work. The size of the engine would have to be bigger than just running them in a side by side pattern or in a V configuration. It would have to have two cranks and be geared to one shaft.

One engine that I'd like to see more developement with would be the wankle engine used in Mazda cars. While it has it's downsides, it is lightweight. I talked to a cop friend of miine who has one and he says that it uses oil (he keeps having to add oil to the engine??) and that he has to rev the car to something like 5,000 rpm before he shuts it down.

Onto a different topic
Popular mechanics got over a 100 mpg with a 3 cyclinder turboed diesel engine in a light weight car.

Jemma, sometimes I wish I lived over there in the UK. You mates get nice light weight sporty cars. When they come to the yankee side of the ocean the cars are detuned and seem to tip the scales a bit more.

If I were the ruler of the car world I would do the following:
1) get rid of every single regulation with cars here in the USA. There has to be a ga-zillion of them. For an auto maker to start up as it stands right now would take a ton of money. When was the last time a new auto maker was born in the USA? It was a long time ago.
2) I would make a 1,000 pound weight limit on cars
3) Make owning cars more affordable
4) Require all car makers to offer 1, 2, 3 and 4 seat versions
5) State that no one can sue an auto maker. If the car isn't good then let the market weed out the weak links.

The above would have the following effects:
-New car companies would pop up all over
-Gas/petrol would go further
-Instead of driving 4 seats to work you could hope in your one seater to go to work
-The price of cars would drop since no lawyers are needed or wanted
-No recalls.

 

[JemmaUK]

Two opposing cyclinders.........hummmm.......it could work. The size of the engine would have to be bigger than just running them in a side by side pattern or in a V configuration. It would have to have two cranks and be geared to one shaft.


One engine that I'd like to see more developement with would be the wankle engine used in Mazda cars. While it has it's downsides, it is lightweight. I talked to a cop friend of miine who has one and he says that it uses oil (he keeps having to add oil to the engine??) and that he has to rev the car to something like 5,000 rpm before he shuts it down.

Onto a different topic
Popular mechanics got over a 100 mpg with a 3 cyclinder turboed diesel engine in a light weight car.

Jemma, sometimes I wish I lived over there in the UK. You mates get nice light weight sporty cars. When they come to the yankee side of the ocean the cars are detuned and seem to tip the scales a bit more.

>
If I were the ruler of the car world I would do the following:
1) get rid of every single regulation with cars here in the USA. There has to be a ga-zillion of them. For an auto maker to start up as it stands right now would take a ton of money. When was the last time a new auto maker was born in the USA? It was a long time ago.
2) I would make a 1,000 pound weight limit on cars
3) Make owning cars more affordable
4) Require all car makers to offer 1, 2, 3 and 4 seat versions
5) State that no one can sue an auto maker. If the car isn't good then let the market weed out the weak links.

The above would have the following effects:
-New car companies would pop up all over
-Gas/petrol would go further
-Instead of driving 4 seats to work you could hope in your one seater to go to work
-The price of cars would drop since no lawyers are needed or wanted
-No recalls.

It has been used in several applications. It would be bigger than a standard 50cc but as one of those is not available its probably the best engineering option...

Its Wankel - pity the poor guy but hey. The problem with the early rotary engines in cars was the tip rotor seals and the fact that when idling rotary engines sound like a bucket of bolts but get quieter as they spin up - add that to an uneducated driver and you get a bang at somewhere round 15000rpm and a new Ro80 engine on warrenty - one guy went through 7 in a year... Throttling the engine before shutdown is common on high pressure engine oil lubed turbos and also on rotary engines because if you dont do that you get *no* lubrication on start up. The former problem was common on the Renault 'Super-5' GT turbo... not helped by boy racers who thought that the red-line was where you started to think about changing gear...

They arent detuned as such - they just never needed to develop. It used to be that engines here were given ratings of a fictional horsepower - for example the Austin Heavy 12/4 engine was rated at 12hp - for a 2100cc motor that wasnt its output - not even close - it was the RAC rating.

Later we got rated on engine size with tax breaks under certain sizes - one of those being 2 litres - so engine designers didnt want to go over 2L but they needed more power - hence higher compression, turbo, SPi/MPi, variable valve timing and so on - so you got a 2 litre motor that could equal the HP output of the lazy 318/313 V8s from people such as Plymouth/Chrysler but didnt have the torque.

American engines didnt need to develop under those constraints so designers went for swept volume more than they did efficiency. As a comparison the 408cui (6.6L) Cleveland motor as fitted to the Ford LTD put out around 280hp - the 2L Ford cosworth engine of 1992 put out 227hp in standard trim.

It isnt car makers that are needed - its a change in market. Its also not a matter of removing laws its a matter of adjusting them. Forcing the insurance companies to stage pricing and taxes etc for 1L/2L/3L classes would have US makers importing and building their european engines into US packages within a season. 1000lbs is on the low side due to the electronics fits and safety equipment in modern cars

As to seating I think a compromise would be best. A vehicle with the space for four seats - two of which, and the associated hardware and weight to be removable. The problem with single seaters is simple - you spend money and make a car and then someone buys it - what then happens when they need a 4 seater? - they go and buy another - not the most ecological approach

I dont agree with point 5. It would make it too easy for manufacturers to cut corners..

Recalls etc will always happen - some faults need a recall and its mostly the manufacturer that issues, not lawyers.