Mixing diesel with petrol

[rmay635703]

http://ecomodder.com/forum/showthrea...ine-11163.html

[seifrob]

Interesting.
The only use I have heard of is opposite - to add few liters of petrol into full tank of diesel so you have some antifreeze protection...

[arcosine]

Bad logic, as diesel will not combust entirely and will emit stinky white smoke in a gas engine. Nobody behind you will like you.

Originally Posted by 19bonestock88

I googled the energy densities of the two fuels. I did have to guess that diesel has 0 octane rating, based on the fact that an Otto cycle engine and a diesel cycle engine use the opposite forms of combustion, I couldn’t find a rating...

I guessed at the ratio to still keep the mixture at at least 87 AKI octane, to prevent definite engine damage, averaging diesel in at 0 octane... if it were, say, rated at 60, things would change some, in that you could run more diesel in gasoline and still have a mixture average of 87, but it wouldn’t boost the energy density of the resultant fuel enough to bother with, IMO... if mixing some diesel in makes the fuel mix cheaper than straight gasoline, then it could be a feasible option for reducing your fuel bill but I don’t believe it will boost efficiency enough to see from tank to tank

[gone-ot]

...add a little DDT and you've got a "Mosquito Spraying Fogger" vehicle.

[California98Civic]

Originally Posted by Crashy

... The question still has not been answered: has anyone tried it? https://youtu.be/pCr6bjQMrgU

I have not tried it.

But damage is not just possible but almost inevitable, on a time horizon too near and at a price too dear for anyone on a normal budget and in need of their car on a daily basis.

I watched the "Engineering Explained" vid you linked to as well. But I think he implicitly answers the question of whether this is a good mod for a standard road car in his explanation. The engine he describes was was specially designed with dual ports for differently timed injections of the two fuels. It also had a super high 16:1 compression ratio and outlandishly lean AFRs programmed into the ECU, such as 45:1 at times.

So, I would never try it on my car. I would not expect more than a marginal benefit in engine efficiency from just mixing diesel with gasoline in a conventional gasoline engine. I would expect engine damage, the likelihood of which would depend on how radical you are in the mixture.

[rmay635703]

Originally Posted by Crashy

I watched an episode of fifth gear

The question still has not been answered: has anyone tried it?
https://youtu.be/pCr6bjQMrgU

Yes it has been answered

This guy

Originally Posted by rmay635703

http://ecomodder.com/forum/showthrea...ine-11163.html

Had run a diesel gas mix for years, bigger engines from around the early 2k era work the best.

As for a “FLEXBOOST” Diesel those usually independently inject a diesel “spark plug” to ignite another fuel like e85 or CNG.

This requires separate tanks and a control system, works very well to give a naturally aspirated diesel both fuel economy, simplicity, emissions and power,
Sadly it appears unlikely to happen due to things called laws which have different emissions requirements for diesel or gasoline which would make a real dual fuel beast aftermarket at best,

ah well.

[ASV]

the number is 15 not 0
otherwise it would spontaneously combust
and the diesel engine is more efficient because of 0 throttling AND higher calorie fuel as well as a very long stroke and lean mix.
it all adds up

its simple really

if you want more miles per tank do it
if you want more miles per dollar don't

[wumpus]

I mentioned Jason Fenske's explanation in this thread: http://ecomodder.com/forum/showthrea...cci-36404.html

After googling around I found that propane (and possibly natural gas) kits for diesel engines were a real thing, mostly used for more power (and inevitable damage) but could (barely) increase efficiency. I was mainly interested in natural gas as it is relatively abundant right now in the USA.

These systems don't appear to have near the control of control over the propane inserted into the airflow and don't appear to have much more control over the existing ECU (presumably the driver adjusts the air-fuel ratio with his right foot as you start with a diesel engine).

If you wanted to get the effects from the RCCI research, you would probably have to hack a megasquirt to handle two complete ignition systems (probably buy two and have a master/slave system where the diesel megasquirt gives the gasoline one specific fuel injection levels and otherwise ignores it).

If it works at all I'd expect to see it in commercial trucks. I'd expect them to deal with adding fuel from two pumps for a 20% increase in fuel efficiency, followed by truck stops having gas/e85 next to diesel pumps at truck stops.

My guess is that existing propane kits are unlikely to increase efficiency enough to bother without heavy megasquirt hacking. How much you are into that is up to you. One other interesting thing is that most of the research centered on a single RPM: this is close to commercial truck practice, but also of interest to solar enthusiasts who want generator backup. Presumably 1800 rpm would be ideal (you really need 3600, but you could design the generator with more poles or possibly gear it. The efficiency of 1800 should outweigh the gearing issue).

[arcosine]

That's because he couldn't ignite the lean gas mixture unless he squirted some diesel in. This was done on LP powered locomotive diesel engines in the 80s.

Originally Posted by California98Civic

I have not tried it.

But damage is not just possible but almost inevitable, on a time horizon too near and at a price too dear for anyone on a normal budget and in need of their car on a daily basis.

I watched the "Engineering Explained" vid you linked to as well. But I think he implicitly answers the question of whether this is a good mod for a standard road car in his explanation. The engine he describes was was specially designed with dual ports for differently timed injections of the two fuels. It also had a super high 16:1 compression ratio and outlandishly lean AFRs programmed into the ECU, such as 45:1 at times.

So, I would never try it on my car. I would not expect more than a marginal benefit in engine efficiency from just mixing diesel with gasoline in a conventional gasoline engine. I would expect engine damage, the likelihood of which would depend on how radical you are in the mixture.