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Diesel in a gas 2 stroke?!?

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Old 08-27-2010, 08:36 PM
tag187 tag187 is offline
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Default Diesel in a gas 2 stroke?!?

I was doing a search across the web on single cylinder diesel motors for another project and came acoss an old thread on another forum about a guy who claims he runs bio diesel in a single cylinder 2 stroke motor on his bike. I read on and he claimed that it is ok as long as it is 90cc or above.

Now I went to school for diesel engines and worked in that field for a few yrs but no longer, my point is this doesnt seem very possible to me, but I learn new stuff everyday so I figured I would ask some 2 stroke experts. So what is ya'lls take on this one.
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Old 08-27-2010, 08:50 PM
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Default Re: Diesel in a gas 2 stroke?!?

my only experience with diesel conversion was with the R/C smaller mostly engines, they sold a "davis diesel conversion kit" had a head that increased compression to around 19:1, and a special glow plug. They worked well enough, low rpms, maybe 6500(on a motor using nitro and methanol would see 12,500rpm) but they were torque monstors, could swing a hugh prop at good speed. saved allot of fuel $$

Mac
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Old 08-27-2010, 09:01 PM
ridingpistonbroke ridingpistonbroke is offline
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Default Re: Diesel in a gas 2 stroke?!?

as far as putting pump diesel in and riding off, i would
say its virtually impossible. bio diesel could mean anything,
and modifying the motor would be needed. the spark plug would need
to be swapped to a glow plug. the fuel would have to be a
mix to get it to detonate properly,with- Ether,Castor oil for the
motor,Kerosene and probably very little diesel.timing may need
adjusting as well as the method of fueling it. the fuel would be costly,
and somewhat of a pain to get hold of everything and mix it.
the compression would more than likely be to low aswel.

not trying to hinder your dreams,its possible and i would like to see it.
but trying to get it to run on diesel is about as hard as getting it to run
on steam (which is possible,and pretty cool i reckon). i know most of this
because i looked at converting one myself.the diesel motor in principle
works similar to a 2stroke. similar. thats about it.

maybe someone with a bit more knowledge can chime in.
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Old 08-27-2010, 09:10 PM
tag187 tag187 is offline
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Default Re: Diesel in a gas 2 stroke?!?

I am not thinking of or even dreaming of running diesel in my 2 stroke. I am just curious as to if it is possible.

The way the fellow made it sound was that aside from swapping a glow plug he just threw some diesel in and bam the sucker ran. I wish I could find the thread again. I will keep looking.
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Old 08-27-2010, 10:00 PM
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Default Re: Diesel in a gas 2 stroke?!?

My diesel experiance is limited, but I loved my 79 diesel rabbit...

Years ago when diesel was cool for like a month I believe it was oldsmobile that tried to refit their gas engines to run on diesel to capture the "emerging market" It was a boondogle, they took gas engines and reinforced them for higher compression, and a few other things, but the big problem was that the reinforcement was not enough and the higher compression tore the engine apart in short order. That being said I think a small two stroke might work.

Here is my thinking on it...I believe the compression issue increases geometrically, not linear so as the engine gets bigger the forces and higher compression ratio multiplies instead of adds, (I could be wrong, but it sounds good) Plus a smaller engine may be able to take more stress than a larger displacement because a 1/4 inch of steel is porportianal greater when lining a 50cc chamber as opposed to a 100cc chamber.(numbers are off but you see my theory, again I could be wrong). So by the above theories the engine might handle the higher compression....maybe....If the HT can take and produce a low end 15:1 ratio

If they engine could handle the compression the rest is cake. The glow plugs are just needed to start the engine, once it gets going the compression alone keeps the motor going. So in theory on a hot summer day might not even need the glow plugs...

The problem I see with diesel in a HT two stroke is the injector. Gas vaporizes pretty easy, suck it through a carb with a slight vacuum and you have your mix. Diesel needs to be "pushed" through an injector. How are you going to power the injector/pump? Spark timing is a non issue, but injector timing would be critical.

So put an injector where the spark plug belongs, close the intake port, and figure out your pump and away you go...I almost think it is doable....
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Old 08-27-2010, 10:44 PM
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Default Re: Diesel in a gas 2 stroke?!?

A Diesel can run on filtered french-fry oil, I guess Bio-Diesel has some additives to the fry-oil to help it flow through injectors and whatnot.

Good points Ferball, but imagine trying to kick that sucker over... You'd have to be going down a huge hill doing 75Mph with 200lb over the back tire!

Top Fuel engines actually 'diesel' at full throttle because of the insane compression, the spark-plugs are just to get'r goin'

Add electric start to the list :P
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Old 08-28-2010, 12:53 AM
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Default Re: Diesel in a gas 2 stroke?!?

I did a bit of research on this last year and about the only way to make it work would be to use a high ether/kerosene/naptha mix like they do with the old RC diesel engines. Other then being a novelty it would be quite cost prohibitive just to make the fuel.

You don't need a glow plug to start a diesel, I've started diesel cars and trucks that have had failed glow plugs with straight either starting fluid. Some old semis actually had an either starting system and no glow plugs at all, the either tank looked like a propane tank behind the cab.

And finally, when a top fuel engine "diesels" things tend to go boom, it's called pre-detonation and that's very very bad.
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Old 08-28-2010, 02:00 AM
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Default Re: Diesel in a gas 2 stroke?!?

That's cool Kevlarr. Who would want to spend $30+/gal of some sweet fuel, ...well besides a few death-racers, eh?

/offtopic
Top Fuel is absolutely insane!

Check out this vid, okey, now this is just one of eight injectors, it starts out at idle, then full throttle. Imagine this much fuel going into anything other than a super-tanker.

YouTube - Top Fuel Dragster Fuel Pump Demo single cylinder

/ontopic


There's always turbochargin+Nitros If you reall want to blow it up good:
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Old 08-28-2010, 02:13 AM
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Default Re: Diesel in a gas 2 stroke?!?

Quote:
Originally Posted by Kevlarr View Post
I did a bit of research on this last year and about the only way to make it work would be to use a high ether/kerosene/naptha mix like they do with the old RC diesel engines. Other then being a novelty it would be quite cost prohibitive just to make the fuel.

You don't need a glow plug to start a diesel, I've started diesel cars and trucks that have had failed glow plugs with straight either starting fluid. Some old semis actually had an either starting system and no glow plugs at all, the either tank looked like a propane tank behind the cab.

And finally, when a top fuel engine "diesels" things tend to go boom, it's called pre-detonation and that's very very bad.

Should see the kayos when one runs away in the shop!
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Old 08-28-2010, 08:58 AM
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Default Re: Diesel in a gas 2 stroke?!?

When I worked in a Chebby dealership back in the 80's we had a Olds diesel run away and start running on the oil in the crankcase. Everyone made a beeline for the overhead doors and it looked like the building was on fire for about 5 minutes.

That same mechanic told a story about how he was working on a Detroit Diesel semi that ran away and the only thing he could think of was to cover the open air cleaner box with a piece of 3/4" plywood. He said it sucked a perfect airbox shaped hole in the plywood instantly and he felt no resistance as the sheet went around the airbox.
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