pardon my ignorance, this is just a random question for y'all who know about these things...

i understand (roughly) how a rotary engine works and why it's much more efficient than a typical gasoline engine

i also understand (again, roughly) how a diesel engine works, and why IT'S much more efficient than a typical gasoline engine

so considering we have many different options concerning the types of fuel we put in diesel engines (biodiesel, old grease, peanut oil), and considering the fact that a rotary engine is supposedly a more efficient system, why don't we combine the two to make a reliable, versatile, efficient engine?

9/15/2005 4:53:38 PM

Did you even for a split second think to try google?

Just because you haven't heard of it or it isn't mainstream, does not mean it doesn't exist.

9/15/2005 4:57:33 PM

also research the quasiturbine engine. it is like a rotary, and is able to burn lots of things.

9/15/2005 5:04:08 PM

*sigh*...i apologize that my post was unclear that what i'm asking isn't why they don't exist (i can use google almost as well as a monkey!), but why they aren't common...i'm sure that i lack a core knowledge concerning the internal workings of engines, and while i wasn't really able to find anything on google specifically answering my question, i thought there might be a few people on tww that could englighten me...

...you, sir ^^, are not one of these people and so i encourage you to take your head out of your bum, get in your car, and drive off the nearest bridge, thereby improving all of society

any other comments that don't answer the question?

as for you ^, thank you...i hadn't heard about that one and i do believe i'll try this whole google thing the chimps and capuchins are chattering about

[Edited on September 15, 2005 at 5:08 PM. Reason : arrows]

9/15/2005 5:07:27 PM

http://www.rx7club.com/showthread.php?t=165457&highlight=diesel+rotary

Quote :

"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'm sure it could be done but you wouldn't get much life out of the engine, and I presume that would only be if you ignited the diesel fuel with spark plugs as I quoted ^. You would need some badass seals to take that kind of punishment... figure a typical nonturbo rotary can go 150-200 thousand miles if well maintained and not pushed too hard. I can't see a diesel getting even close to that. Detonation kills rotaries; it's their biggest weakness. Mazda has developed some hydrogen powered rotaries that could maybe some day see some use though.

oh and FYI a rotary is efficient for making power (displacement/weight vs. power output) but it's not efficient for gas mileage.

[Edited on September 15, 2005 at 5:33 PM. Reason : .]

9/15/2005 5:23:59 PM

Umm rotary motors build compression as they rev diesels are violent and don't rev that high but need lots of compression to work.


i'd say thats a pretty good guess at why they don't do it.


and we all know what happens to rotaries when they detonate... and that is all that a diesel ever does...

[Edited on September 15, 2005 at 8:08 PM. Reason : .]

9/15/2005 8:07:50 PM

and we all know what happens to rotaries when they detonate

9/15/2005 8:10:03 PM

they normally pop from detonation ... they have a boost reference tube that dry rots and lets the boost spike occasionally and pop goes the wankle

9/15/2005 11:07:59 PM

^ What exactly are you referring to? Turbo II's have a fuel cut. They run 6.2 psi stock, and around 8-8.5 without a boost controller if you open up the exhaust. They can get a boost spike though if you don't port the wastegate. Most stock rotaries die from a worn out apex or coolant seal.

They only detonate when being modded if you don't tune them carefully, with a wideband. I know a guy who ran a 13.1 @ 105 on his Turbo II with stock ports (rebuilt motor), stock turbo, and stock intercooler. He was smart though and took his shit to the dyno to tune his SAFC.

3rd gens don't have a problem with too much boost as much as they have a problem with too little. They've always got some fucked up actuator or solenoid preventing the secondary from getting full boost.

[Edited on September 16, 2005 at 1:04 AM. Reason : .]

9/16/2005 12:55:05 AM

i just know the 2 friends with the tt ones popped their motors cause of some rubber hose that messed up the sequential setup and over boosted the motor... or so they say... i don't know much about their cars. but i know diesels and rotarys are polar opposites.

9/16/2005 1:29:34 AM

if you own an FD and don't even bother to change the hoses

you deserve what happens

9/16/2005 1:36:00 PM

there are enough problems getting the apex seals to hold up on a turbocharged 13b mazda. my guess is that a diesel wouldn't even have a chance, unless they could be overengineering a lot more than they are now.

9/16/2005 1:40:05 PM

Quote :

"i just know the 2 friends with the tt ones popped their motors cause of some rubber hose that messed up the sequential setup and over boosted the motor... or so they say... i don't know much about their cars. but i know diesels and rotarys are polar opposites."

I'm not gonna defend an FD on the original motor, but I will say that I know a guy who got 110k miles on his original motor. Single turbo FD's are no less reliable than other heavily modified cars, as long as you tune them carefully.

9/16/2005 2:03:59 PM

i think we've all failed to mention that rotary engines while efficient in terms of "displacement" if you can call it that are not particularly fuel efficient which was the premise of the entire thread.

9/16/2005 3:29:57 PM

^ you're right...that was my question...i realized that rotary's got bad gas mileage (just by looking at mpg estimates on an rx-8), but i thought that since they were so efficient in terms of producing hp, and diesel with the higher compression ratio was more efficient in terms of fuel, i thought there might be a happy compromise that could be reached by combining the two technologies (though of course someone had thought of it before)...i just didn't realize how fragile rotaries were

9/16/2005 5:47:35 PM

Quote :

"diesel with the higher compression ratio"

don't think you'd ever get the compression high enough to run a rotary on diesel anyway.

9/16/2005 7:56:22 PM

two words-

apex

seals

9/16/2005 7:59:43 PM

yeah... they'd blow on detonation not only that i think it would be easyfor the motor to kick backwords.

9/17/2005 4:25:36 AM

Diesels detonate, but it is in a timed, controlled manner. When a gas engine detonates, it's usually before the piston gets to TDC (and the equivalent to that in a rotary). The diesel fuel spontaneously combusts, but the injection is timed so that combustion begins at TDC and forces the piston down on the correct stroke, not backwards in its rotation like a pinging gasoline engine.

9/17/2005 8:09:14 AM

the rattleing you hear in most diesels is pre tdc combustion
k thanks

9/17/2005 11:42:45 AM

k no thanks

combustion might start slightly btdc to time it correctly for the trip back down the cylinder, but if it were knocking like a gas engine pinged, it would do the same damage.

[Edited on September 17, 2005 at 4:50 PM. Reason : ]

9/17/2005 4:47:37 PM