Had anyone thought about designing a diesel rotary engine?
 

I'm just curious as if anyone has and how it'd work.

since the rotary isn't very thermally effecient, it would be difficult.

Besides, diesels don't have spark plugs, they basically detonate themselves into running with really high compression ratios. That's why they sound funny... constant detonation. And we all know how apex seals respond to detonation.

well, the detonation is made to occur at a certain compression. not just constantly. otherwise you would eventually still kill the motor. i guess if they used the glow plugs. hmmmmmmm

Two seconds on google turned up these two links.

http://wankel-rotary.com/locr_e.htm

http://www.smartplugs.com/engines/ro...nglerotary.htm

I can't find the text right now but I know I have read that Felix Wankel experimented with a diesel version of the rotary during early development but I believe it failed due to lack of technology in seals around the time of WWII.

BTW: if you can read German or can find a good online translator there is a bunch of information about Felix Wankel's life (for example he was sent to prison during the early 30's for exposing corruption in in local government).

John Deere built an expiramental tractor in the early eighties that had a 2 rotor diesel in it. They ran it on veggie oil and several other oils. It was reported to sound more like an Indy car than a tractor and they had trouble with gear ratios since it wanted to rev.

I have also read about either a 1200 hp or 2000 hp 2 rotor Ingersol Rand natural gas rotary. They had a ton of sealing problems and ditched them - also an early 80's project.

How high of a compression ratio do you need to ignite diesel fuel?

Some diesels run at 20:1! :D

* Brings yet another thread back from the dead *

I'm really interested in finding out more about diesel rotaries, what it would take to turn a 13B into a diesel, for example, and how it would run.

I'm also interested if anyone has done this, or has a sound clip of a rotary running like this.

You would need custom high compression rotors and a lot of other things. I dont know where you would get the rotors so I would imagine this would be next to impossible.

been done, works good

I'm not MAKING one myself. I'm just wondering what it intails.


I know THAT . I want INFO!!

bring a thread back from the dead is the same as a repost.:D

Newbie throwing in here, I'm new to rotary's but I've been an academic gearhead for years, I read a lot but due to not having enough space and gear I can't really experiment.

My plan for a diesel rotary. Poke holes in my idea or try it out, just share what you know. The same thing should work wether you start with a junkyard 12A or a 13B, just don't mangle a good 20B for this.

1. Spark plug delete. Fill in one plug hole on each housing with threaded plugs or by welding.

2. Rotors. The rotor has a tub in it. This tub controls the compression ratio because changing the rotor and housing shape for an experimental motor is expensive and hard. For the higher compression required by a diesel simply fill in the tub, with a 9:1 (about) gasoline compression ratio filling in the tub a bit over halfway should give you roughly 18:1.

3. Fuel. IIRC all diesels are injected, the fuel is squirted in as compression nears its peak in a piston engine, just before TDC. The leading plug hole in a rotary would work well for placing the injector.

The basics aren't that hard. Nor would timing the two injectors, the existing distributor could be used as a trigger mechanism to control the firing of the injectors. Air isn't a problem, stock intake will work nicely.

Now whats wrong with my idea?? Lets figure out why this won't work and solve those problems. It'll be a nice diversion till winter is over. If anyone near Ohio is looking to work on this I'd be happy to help.

Filling the tubs ?

I think you would cause a LOT of vibrations by doing that as you couldnt fill exactly the same amount on each rotor face - it would send the engine into heaven ;) (read - broken eccentric shaft)

I can't remember the site i wasw at the other day that was talking about deisel rotary's but i just found another. we have to remember that the rotary engine is used only in cars. there have been motor cycles, alot of planes, radio controlled modle cars, and boats. check out this website it as a deisel rotary. http://www.boatingnews.com/rotarymarine.htm

Hey good link. That marine engine is based on a 13b. So it can and has been done. Now we just have to buy that engine and find a rolling chassis to put it in.

I assume the rotor could be balanced like crankshafts and flywheels and such.

yea and the engines on that site put out some crazy horsepower numbers. i wonder waht theyare doing out ther eon the water? guess more research for my self. This is a good idea lets keep this thread going for a bit

'

That seems awfully heavy for a 13B though. 240HP out of 340lbs and it relies on the water its in for cooling.

For those still trying to figure out how the diesel engine works ;) -> http://auto.howstuffworks.com/diesel1.htm Also one good thing about diesel is it's got more 'oil' substitute compared to regualr gas, which would help keep all those apex moist :) pretty much like the oil inserted in the combustion does right now.

The diesels do not detonate, it is a combustion like normal otto cycles engines.
A rotary cannot be diesel since the rotary cannot have high compression ratios, cannot recall exacly why but will try to find out that research i made during university for that
For the injection, to inject directly in the combustion chamber you need a very high pressure, you'll need special injectors and a high pressure pump, not just a normal injector running with diesel
plus a bunch of more minor problems

diesel engines usually mean more torque. so does this mean that if a diesel rotary engine would actually have torque?

One was built here (New Zealand) in the late 70's, supercharged I think... was not a great success, but can post a pic if anyone is really keen ?

At the risk of beating an old thread to death the "diesel" wankel is not a true, compression-ignition engine at all. It is instead a stratified charge engine that uses spark-plugs to ignite the mixture. Two injectors are used, a small primary that sprays onto the spark plug with the resulting flame acting like a super ignition source for the (lean) main injector spray. Compression is around 8.5:1 for turbo engines which most are because this system doesn't make as much power as a "normal" rotary of the same size. Advantages are low stress (read: weight) compared to a "normal" diesel, smaller size, high rpm (limited by injector technology mostly) and multi-fuel capability (anything liquid that will burn...). Disadvantages? 10% greater fuel consumption than a simular rated diesel. It's the HUGE weight difference that the makers are pushing mostly; a 1000hp turbo diesel (marine) weighs well into the tons range. Figure 1/2 that for the Wankel "diesel".

BTW: It was Curtiss-Wright (yes, THAT one!) that invented this variant, along with most of the development of the modern Wankel configuration. Mazda did most of the production research and solved the longevity/fuel burn/affordability problems.

Sanspistons for better living :D

Alot of good points in the threat about the subject but it comes down to a few things that you REALLY need to make an engine use "heavyfuels". ALOT of it has to do with temperature. To get the fuel to burn something needs to make it atomize (Like a Diesel injecter) or you make it vaporize (like steam). You only have to get it to about 140deg to vaporize. So, YES you can use a factory injector just maybe in a different way. To make it simple if you can't get the fuel to burn your not going to start the engine. That is why you have glowplugs. I would use a spark plug because compression ignition in a rotary is BAD news. That is what makes a diesel run and what makes a rotary fail. I know all of you heard detonation is bad. That is one reason why diesels are so god damn heavy, they are built to handle it. Also another big thing is a "bowl" in the piston. I don't know of any diesel engines without it. How would you fit that on the side of a rotor? To make a long story longer it can be done although I have not heard of any that worked extremly well. Anyway. If you want to read a little about getting a gasoline engine to run on "heavyfuel". Checkout this website http://www.sonexresearch.com/ I work there. Oh by no means is this post hinting on how to make a rotary run on "heavyfuel". I'm just stating the obvious.