Diesel

[pettycash]

I've been throwing around the idea of converting my T-MAXX to diesel for a while now. This has lead to my studying of model diesels. This has lead me to some ideas. This is purely theoretical, and just for some fun thinking, right now. Just asking for opinions and more ideas.

My idea involves a 4 stroke engine. Take a normal 4 stroke glow engine, and replace the glowplug with somekind of injector using something like inkjet injectors. Fill the crankcase with oil, and mix some model diesel using kerosene and ether. The engine would turn a pump used to create fuel pressure. This is where the problem comes. How much pressure does it take to atomize kerosene? Is there anything similar to kero that is easier to atomize? From this pump, the fuel would go through a valve or solenoid controled by the cam that times injection. From the valve/soleniod, the fuel would then go to, and through the injector, atomizing into the combustion chamber, and igniteing in the hot air created by high compression. Of course, other mods would be needed to bring in only air on intake, fill the crankcase with oil, time the solenoid/valve, and other things of the such. A turbo could also be utilized. I read that roughly 500K RPM's would be needed, and that air powered dentists drills run about that. The turbo could be based on a dentists drill. The engine itself is almost feasible, but at this time the turbo just is not.

So, what's your opinions, ideas? Just something I'm having fun thinking about, and thought everyone else might like to hear it, and think about it.

On a side note, does anyone else like to think of things that are at the edge of feasiblity?

Thanks.

 

[william g]

I think it could be cool

however on a hobby scale to get any performance... I'm doubting it could be cost effective if you could get it to work

 

[Nutz4rc]

Be lotsa work

As you said LIKE an inkjet injector I am supposing you already guess that THAT type of injector might have trouble handling the heat. (I know they get warm in a printer but not inside a diesel engine warm) Plus the injector you do use would have to handle fuel pressure behind it as well as combustion pressure in front of it. The pressures from both ways makes for special needs of course. You would have to machine down the head and cylinder to get the compression high enough and maybe modify the cam and valves/valvetrain so that the piston and the valves do not hit each other. Most all the diesels on the planet are interferance engines. This means that the piston and the valves occupy the same space inside the engine at one point (not at the same time of course) during the running cycles. If the drivetrain fails then the piston will hit one or both valves and the engine makes really $$$$ noises then. Diesels need to run so tight to get the compression to squeeze the fuel tight enough to ignite it with pure compression. The four stroke glow engines use four stroke fuel (not the normal two smoke stuff) as its got extra oil in it that the four stroke motor is designed to let bleed into the crank and cam areas to lube it. It might get enough lube from diesel oil in the diesel fuel and you might need a additive. Putting oil in the crankcase would create issues with it being forced out and making a big mess. Its desgined for a film of oil in it not a spalsh puddle like briggs and stratton. Kerosene is not diesel and may be able to be used if you met its requirements. But is not the same as a lot of people think.

I read that roughly 500K RPM's would be needed

Did you mean 50,000? Modern turbos in cars hit near 120,000 (I have heard 150,000 as well) topped right out. Diesel turboes usually spin less but just because they are huge and dealing with more volume. But for something this tiny you migth be better off with a tiny supercharger. Easyier to make than a turbo and O.S. even made a big four stroke with a factory supercharger on it. A little big for a T-maxx in size but if your going all out what the hey? Most Semis used to have blowers or superchargers on them (same thing) Thats where street hot rodders first got thier 6-71 roots blowers from. Big ole diesel semis. A turbo this small prolley exists somewhere. But funds to buy it might not exist in your bank account.... As for the dentists drill they turn the RPMS no doubt but they use a LOT of air to do it. yu would have to have on board Co2 tanks (heavy) or a hose runniung to the truck from your garages air compressor.

Its not new and not on the edge of feasability (Been done for years) but you have heard of Davis diesel? They make diesel conversion kits for most popular two stroke engines. They make a special head and fuel for them. The head has a threaded screw that pushes the new inner combustion chamber down till the compression is high enough to light the diesel fuel they use (You cannot use pump diesel in these. You need to use thier special fuel.) When running right these motors make more power than thier Nitro versions and use less fuel to do it. Little bit of an oily mess though.

What I think would be cool is figure out a way to hook a turbine into a little truck. Brushless electric now days is tearing nitro records to shreds everywhere. The only thing beating top end brushless is turbines. If you used a turbine like a heicopter does and tapped the power off that shaft and geared it down it would just scream. Big trick here would be to filter all the incoming air. Turbines use a lot of air and they do not like dirt in it. Best of luck if you decide to try this diesel conversion. I have never seen anyone try to make a four stroke one work so if you are successful you may be among the front runners. Bill

 

[pettycash]

Yes, that's all been considered. As for the RPM's of the turbo, all I know is that they typed 500K more than once. I've actually considered a Davis head, but I'm really not a big fan of him, nor the way his system works. I want something that I can understand, I'm going to school for diesel technology, not diesel-hybrid, kinda like, not really, just compression ignition technology. As for diesel/kero and lube, That's really not an issue. Model diesel, as in Davis's fuel, uses a mix of oil, ether, and kero. I'd just take out the oil, and use the oil in the crankcase. The crankcase pressure is another issue that'd have to be worked out. I have a feeling that this is going to turn into a big, informative, technical discussion between us, and many others will get totally lost if they read into it.

About the blowers on the old Detroits:

They where actually considered N/A because they require the blower just to run. On our nitro's, we bring the fuel/air into the crankcase, and pressurize it to get into the cylinder through the ports. The old Detroit 2 strokes had the crankcase full of oil, this prevent scavanging as described on nitro's, so a supercharger is implemented to create the pressure to scavange the cylinder. There's everyone's little bit of fun, useless info for the day.

I'm really just thinking of this for fun. I like to, and enjoy thinking of ways to improve something. I'm just posting to get my ideas out, and maybe, just maybe, with multiple people, we can find all the needed solutions, and get it all to work. It also helps that I have proof I was one of the first to think of it.

 

[Nutz4rc]

Carbed diesel...

Being that the Davis deisel runs off a carb perhaps the fourstroke version would as well? I guess you would have to see what kind of pressure the four stroke makes in PSI and find out what pressure you need to light the fuel off. If you can get the O.S. ( or Saito or??) motor to make (and handle) the compression it might be that easy (wishful thinking...?). Just have to figure out how to make sure its lubed right and it should be a runner. Bill

 

[pettycash]

There are a few people that have made 4 stroke diesels like what Davis makes. One of them was an O.S., but I don't know about the others. I'm thinking more along the lines of a direct injected, true diesel. It would still use model diesel though, in order to have fuel thin enough to atomize at a lower pressure. Carb. diesels also do not have the ability to run forced induction. Boost will change the intake temp, and that'll mess with timing. The problem is that boost changes with RPM, thus the only way for a model diesel to use forced induction is to be direct injection.

 

[SysError]

I have owned a Davis Diesel conversion- pure junk, stay away from them. They just don't run right in a car, ever.

 

[pettycash]

I've heard that from a few, and I've also heard good reports of the Davis conversions on cars from a few. Seems to be hit-or-miss. There are a couple vids of a Davis converted Revo on YouTube. It's awesome. But I want injection, like what real diesels have.