Converting the multi-fuel to pure diesel...

[patracy]

I've got a Cummins in my pickup, I'd rather have the multifuel capabilities. If I were to do a Cummins, it'd be a 12v p-pumped engine though. VE's just aren't going to stand up to heavier fuels like a P-pump will.

 

[Heath_h49008]

Patracy is right. We could.. but can that Cummins run on waste oil, methanol, and/or propane?

It would be great if so, and I honestly think it's possible, if done right, for many engines to operate with such flexibility. The vast bulk of effort is required to build the block, heads, support hardware, etc in a system... so why not give it as many functional options as we can?

 

[patracy]

It will run on a mixture of WMO. No diesel engine will run solely off propane. Methanol, not sure why you'd want that.

 

[plym49]

After reading about tractor pulling engines built on these bottom ends living happily at 4000 RPM with just a balance job, I'd be tempted.

Let me finish paying off this truck and my overpriced college education first, and I might get on that. Sounds like fun!

One other thought, that may be better on a stationary engine than a truck mounted, would be a dual mode MAN and Diesel system that would allow waste oil AND gaseous fuel operation. Some compressed air ignited fuel MUST be present to provide ignition, of course.

The alternate method would be a set of gas injectors on their own timing circuit, but linked to a common control, that would allow the diesel to lean as the hydrogen/propane/woodgas/methane/Taco Bell flattulence/etc was injected later in the cycle. A near universal fuel engine would be handy for generators/pumps in rough areas hospital/essential services backup.

These Hypercycle engines are not at the end of their life as a design...

Oh BTW... this was where I learned about the design and combustion process for these. It's not a horribly technical read either, although those are out there as well.

PRINCIPLE OF HYPERCYCLE OPERATION

Thanks for the link - it was very helpful. It helped answer some of my questions. It turns out that the fuel is not injected as early as all that. On the upstroke the piston is compressing air and swirling it due to the shape of the bowl in the piston. At 27 degrees BTDC the fuel is injected. Only 5% of the fuel ignites at that point - basically, the portion of the fuel initially atomized. Combustion continues as the piston passes TDC where the remainder of the fuel burns.

Based on this description, I wonder if a crude yet operable multifuel could be created with a set of custom pistons. If the donor diesel engine has a reasonably shaped combustion chamber, that should be enough. Of course injector timing would need to be appropriately set and the static compression ratio would need to be in the ballpark.

This might not be the most efficient multifuel out there, but if you are running on WMO, so what?

 

[patracy]

It's not so much the combustion chamber being the problem. It's the injector placement and angle that's the issue. A 12 valve cummins could be used to get you close, but the injector tip placement will never line up like you'd want. Custom cutting the pistons wouldn't be that hard. Designing a new head design to reposition the injectors, that's where the money part comes in that I keep mentioning. You might be able to design some custom tips for the 12v cummins to help promote a directional "swirl". But it's not going to be as effective as the mutifuel's design.

 

[plym49]

It's not so much the combustion chamber being the problem. It's the injector placement and angle that's the issue. A 12 valve cummins could be used to get you close, but the injector tip placement will never line up like you'd want. Custom cutting the pistons wouldn't be that hard. Designing a new head design to reposition the injectors, that's where the money part comes in that I keep mentioning. You might be able to design some custom tips for the 12v cummins to help promote a directional "swirl". But it's not going to be as effective as the mutifuel's design.

Yes, I am not doubting you on that. I'm just wondering if the motor would be workable with pistons only - looking at the cost/benefit ratio. A converted diesel that can burn WMO but that is only, say 70% as efficient as a 'real' multi might still be reasonable (depending on your needs, of course).

 

[patracy]

I would say it would be workable on Diesel, Kerosene, and oil blends. But not gasoline.

 

[plym49]

I would say it would be workable on Diesel, Kerosene, and oil blends. But not gasoline.

You raise a good point. To me, the value is being able to run fluids like WMO, even if cut with diesel. Gasoline is not particularly important to me but for others it may be.

 

[mudguppy]

it's been said on here many times and i've challenged it many times: except for gasoline [which isn't economically viable based on power output and mileage], many more modern diesels will run popular blends currently used in the MF (WVO, WMO, kerosene, etc). therefore, what's this huge perceived benefit of MF capability over other engines?

 

[Heath_h49008]

To see if we can. Maybe we find out some new methods, maybe not. Either way, we have fun and learn more about engine design.

If we just wanted the easy/rational way to do anything, we would all be driving 100hp Focus types whenever we were not hauling things, not drink, chase women, or blow things up.

I fear that more than death...

I LIKE people who build amazing things from mundane parts.

 

[plym49]

To see if we can. Maybe we find out some new methods, maybe not. Either way, we have fun and learn more about engine design.

If we just wanted the easy/rational way to do anything, we would all be driving 100hp Focus types whenever we were not hauling things, not drink, chase women, or blow things up.

I fear that more than death...

I LIKE people who build amazing things from mundane parts.

Agree 100%. That's my religion.

 

[Mt_Man]

What a great thread! Learning tons! brain trust!

So I have been wanting to find/make other vehicles to run wmo/watf ect in. So far 12 valve ppump 6bt cummins seems to be the best place to start. People say they can run 50% wmo in them already without modding. Is this really true? If so then it would not take much to get it to run reliably at 70-85% wmo which is where I run my deuce most of the time. Now I am talking ease of starting, lower smoke at idle, use of one fuel tank not dual like wvo, and less soot (or ability to clean itself out when loaded up) on that blend. Not looking for a power monster, just daily driver with cheap fuel and some hauling ability. Maybe a "light boat," gen-set, tractors, pump applications too.

Has anyone heard of anyone doing the pistons and injector tips to try it out in a 6bt? now that it has been a few years...

I bet the best method would be a run heated oil and dual fuel tank system anyways though.

 

[Mt_Man]

found this link on another site thought it was cool old article

https://books.google.com/books?id=D...ontinental multifuel military engines&f=false

 

[red]

i wonder if lowering the compression to 18:1 would affect the ability to burn gasoline? would allow for higher boost from a more efficient turbo leading to higher power and still burn all the other fuels

 

[rustystud]

i wonder if lowering the compression to 18:1 would affect the ability to burn gasoline? would allow for higher boost from a more efficient turbo leading to higher power and still burn all the other fuels

If you bring the compression down that far you won't be able to burn oil anymore. Remember you need at least 16:1 to actually be a diesel engine. As far as gas goes. It would be easier to burn at that lower compression.

 

[red]

Cummins 6bt is able to run on straight veggy oil and they are either 16 or 17:1. So at 18:1 it wouldn't be a concern with oil.

Yes I'm familiar with the minimum for a diesel engine being 16:1, and that gassers are much lower compression.