|Oct 31, 2012, 08:38 PM|
spark ignition diesel...
and why not? i have heard refferences to *(very) old 2 cycle spark ignition diesels. one guy on youtube got pretty good atomization from SVO (straight vegitable oil) buy running it at 200 bar (1 bar = 14.7 psi, so 280 psi) though a jetta TDI injector.
diesel is about 7 times thicker than gasoline. stociometric AFR is 14.6 :1 vs gasolines 14.7 to 1.
biodiesel (meth ester something or other) is pretty close to diesel, and when properly made has a ph of 7. seems to have very little real world problems with rubber seals, tho the current E90 at the pump has caused failures as well.
BTU of biodiesel seem to be higher than gasoline.
so why not use a fuel injected, biodiesel in a spark ignition engine?
|Nov 21, 2012, 07:58 AM|
1) Because you don't need to.
2) Petrol will "Gassify" under pressure, and sprayed in. Bio-Diesel will turn back into a liquid in the intake track.
3) If you spray it into a combustion chamber that has low enough compression, so the fuel doesn't auto-ignite (to control timing with a spark) you won't have enough pressure and heat to properly burn the fuel. (you will make a lot of soot) To get my Cummins to run clean... the engine starts at 22:1 compression, and then runs 32 psi boost. That would bring the static compression up to 6x a typical gas engine. (at about 800 to 1000 psi compression, under boost)
So... I'm all for experimenting... but what would the reason be, behind this experiment? If you want to make bio-diesel... burn it in an engine that is designed to burn some kind of "Oil." You got to remember... the original diesel engines were designed to burn peanut oil, and not this petroleum crap that the oil companies want us to use. Diesel was the original "Green" fuel, and we can make Bio-Diesel out of dam near anything. (Pressing any vegetable mater, old coffee grinds, algae, grass, or used oils) Heck... I pour old engine oil, and transmission fluid directly into the tank of my 2001 Dodge Cummins. (runs fine)
Basically... making bio-diesel can come from 100's of waste sources. To make bio-Petrol (alcohol) it has to come from prime food sources (Corn, sugar cane, sugar beats) and that's BAD for the economy. (and just stupid since the power out is nowhere near the power in)
|Nov 21, 2012, 11:29 AM|
what is 'gassify'?
i did not know you could turn a liquid into a gas, i always thought you just made smaller drops.
the reason i was wanting to was to avoid paying 4 a gallon and to see if it could be done.
i figured if you get the droplet size small enough, you would have complete combustion and avoid soot. a cummins diesel is totaly differnt than a spark ignition engine, so im not sure if the two apply.
ususly what is good for th economy is bad for my bank account
|Nov 22, 2012, 06:56 AM|
Don't get me wrong... If you think that you can get it to work... then go for it, and let us know what happens. Also... I totally agree. $4/gal sux. But, get a car/engine that is designed to burn it.
I've been tuning engines for a long time (see the screen name)... and I've played with dang near every fuel that can be used. Along with that... I own a custom bike shop, and I like diesel. (Oh... and I have a degree in experimental Physics)
I can help with any info you may want, to help you with your experiment.
The problem with using oil for a fuel (Any form of diesel) is that it burns slow, and is hard to ignite. So... way back when... rudolf diesel decided to make an engine that would simply raise the temps, internal of the engine to the oil's auto-ignite temp. In doing that... he also was compressing the fuel to a point that would accelerate the burn.
Above, you say "A Cummins is different than a spark ignition engine." And you are absolutely right. As I already said... the main difference is in the cyl pressures before ignition. With the relatively low cyl pressure of a typical spark ignition engine.. you won't be able to extract enough energy out of the fuel before the end of the "Power" cycle. You make mention of "Complete combustion"... but an engine turning 3000 RPM only has a fraction of a second to make that combustion happen. (With out exploding the fuel)
With that said... how do plan on getting complete combustion inside an engine with low cyl pressure, and volumetrically designed to spin as high 6000 RPM? (FYI... my Cummins has a redline of 3200 rpm, and makes peak torque at 1900)
As a final FYI... Back in the late 70's, early 80's... Chevy tried to do a similar experiment. They basically took their 350 gas engine, and put high compression heads on it... with dished pistons... and tried to sell it as a diesel. It was a piss-poor engine, and it didn't live long. Also, it was HIGHLY inefficient. Most of the world is split 50/50 gas/diesel... but in the USA... we are mostly gas in the consumer market. And that's mostly becasue of the F-ups that the "Big 4" did in the 70's... and that kept the market from growing. And... to this day... they keep saying... "The American Market doesn't want diesel !!!" Personally... that's a bunch of bull !!! If the car companies would bring in some good diesels, and give the same incentives as gas... people would buy them. (The MPG alone would sell them) Since you are looking at Diesel... here's some things to think about.
1) VW's "Sign and drive event" that is currently going on... EXCLUDES the TDi cars.
2) Toyota has been selling diesel versions since the 60's. They won't bring them into the USA because of our "dirty fuel." Well, we now burn ULSD, and they still won't bring them into the country.
3) Ford, Dodge, and Chevy all had a 1/2 ton diesel truck ready to come out... and then they never were released because "of the bad economy." Cummins designed a brand new V8 5ltr engine for the Ram 1500, and the project was scrapped.
4) The only government subsidies for Bio-Diesel is to produce fuel from Soy. Soy beans have almost NO oil in them, and the extraction process uses caustic chemicals. You can get more oil out of old (used) coffee grounds. (and that's reusing waste, not a farm product)
As I said before... I like diesel.
|Nov 22, 2012, 07:21 AM|
And... as an FYI to this... a modern "Common Rail" diesel engine will run pressures around 1600 BAR in the rail. Yep... that's 23,000 PSI.
As I recall... the pressure in my VP Cummins is around 29,000 PSI. AND... I've hear of some systems going as high as 45,000 psi.
|Jan 14, 2013, 11:49 PM|
in doing some more reading, ive found some refferences to old tractors that started on gasoline, then used the engine heat to 'thin' diesel and burn it.
but at this point you need to redesign the fuel system and pretty sure you need a computer controling it.
edit: some quick rearch show diesel fuel at 190F has a viscosity of 1.1
gasoline is .88 (i asume at 60f or 20C)
water is 1.0 (at 20F)
so if you can preheat the fuel to 190F (my car runs at 195 and has coolant lines to the carb), then this is not so far fetched.
|Jan 11, 2014, 10:07 AM|
sYes one can convert a 12:1 compression ratio gasoline car from the 1960s era and earlier down to 1940s to run on diesel and paraffin and kerosene .It requires the heating up of the fuel by passing it over the hot exhaust so that the fuel will vaporize better .However it often requires the engine to be started with gasoline to get it hot enough .Efficiency will not be good and soot content will be very much higher and MPG will drop I don't know if the same applies to modern cars with 10:1 compression ratio but i suspect it will work but not very well and would require removal of all anti smog and CATS as they would clog up fast
Paraffin which is cheaper fuel often for tax reason and its lower fire risks it was very common for fishing boats to use this fuel with converted gasoline cars. Often the spark ignition was replaced with a glow plug that was heated up with a blow lamp
In the 1920 and 30 and second world war all these things were done to run engines
Very interesting to read is the story of the tractor vapor fuel TVO fuel they used for WW2 agriculture
best I can figure these were hybrid diesel gasoline engines that ran on combinations of gasoline and paraffin and kerosene fuel.
Best i can figure the engine had 12:1 compression ratio typical for car of that era who lead to stop pre ignition .Modern cars with unleaded fuel have lower compression of 10;1 and use 5% ethanol to suppress pre ignition .
These tractors would start on gasoline and then switch to using some mix of paraffin or kerosene. Typically they mixed 4 parts gasoline to 7 parts kerosene for light work like going to site of work .The mix for heavy work like plowing was often 2 part gasoline 8 parts kerosene .(Best i can tell Kerosene is 1 part gasoline 7 parts paraffin)
There is another issue that diesel fuel we use in modern cars best I can tell was originally yellow kerosene
The diesel fuel we use for agriculture in Europe is actually a much heavier fuel often dyed red to make it illegal for road use .
using light molecule diesel kerosene fuels we often use for road car use will probably work better than trying heavier molecule off roads diesel fuels
Most diesel cars from before 2000 era would happily work with combinations of kerosene and road diesel interesting for those who have a kerosene heating tank in their garden but often illegal as it avoids road tax.The risks are the less lubrication from the kerosene fuel compared to diesel fuel might wear out the fuel pumps that need the diesel fuel for lubrication .A new fuel injector pump costs a lot but kits exist for less than $150 I know for a fact the 1993 Toyota Carina 1974cc non turbo diesel car will run for 120,000 miles with no problems on kerosene fuel as the guy i bought that car from a aircraft mechanic ran it that long on that fuel .I have run it on diesel often red diesel cheaper for another 60,000 miles no problem s touch wood. Some of these non turbo Toyoto carina have done more than a million miles .However the new diesel car with new formula diesel with bio fuel added and the more dry cyclinder walls from less diesel oil fuel wasted using common rail seems to only last ~200,000 miles Thats similar to many gasoline engines so the lack of the extra oil lubricating the engine seems to mean fast engine wear compared to 1990 era diesel engines
Gasoline solutions that work best are natural gas that fuel is often 30% cheaper than gasoline fuels and even with drop in MPG with NPG fuel its often saves 25% to 50%per mile
depending on local natural gas fuel costs
natural gas can over time scald the valves .Old cars from the 1960s era needed the lead in the fuel to seat the valves .Using unleaded fuels these engines will wear out valves much faster unless the fuel get special additives to reduce this effect
The ultimate experimenter on fuel MPG endurance was the USA guy bob (something cant remember his second name) who flew a ~5kg model plane across the Atlantic ocean from Newfoundland to Ireland
He used modified 4stroke ~10cc ignition engine on super lean mix of Colemans gasoline fuel ( a low ~70ron octane gasoline fuel for clean burning camping stoves or Zippo lighters which will vaporize very easily and become gas easy peasy ) using pre heating fuel to vaporizer it and using some 2.5 kilos of fuel or less than ~2 onzes fuel per hour crossed the Atlantic . However the first three attempts engines leaned out too much and those planes were lost into the sea so it not easy .Hats off to Bob who died some time back who advanced fuel MPG knowledge world wide broke all sorts of model plane endurance contests sadly he didnt live long enough to cross the pacific ocean . (Search RCGROUPS model plane crosses the Atlantic about year 2000 to 2004 cant remember exactly)
The reality is the ~1920 era the gasoline fuel they used was more like Colemans fuel and the car the 3000cc model T ford had 20BHP and compression ratio of 6:1 It could run also any mix of ethanol mixed with gasoline or pure ethanol .The Model T ford had way to advance or retard the ignition depending the fuel they used . The low compression ratio made for low power .The ethanol fuel if put into high compression engines of 12 :1 or higher would burn more efficiently . If you mix fuels like low octane ~80 ron gasoline and high ~110 octane ethanol you increase the octane of the fuel over all to the ~87 to ~90ron that is popular in the USA
. the higher the compression the engine runs the better is the power to weight ratio but often the higher is the amount of fuel wasted out the tail pipe and the higher the pollution of NOx and CO which the modern CAT then will reburn outside the engine
aircraft power to weight were the first to bump up the compression ratio . they added chemicals and other slow burning high octane ingredints to slow down the burn rate and stop pre ignition .Often these chemicals dont burn inside the compression explosion in the engine and will burn outside the engine in the exhaust stack Its about 80% the fuel burns outside the engine with modern high compression gasoline engines
Later guys in the 1930 to 1990s made carburetors that would vaporizer the gasoline fuel better and would get 50 to 100MPG
However every success was blocked simply the oil companies changed the gasoline fuels so the fuel vaporizing carburetor wouldn't work
In the 30's depression years some farmers found ways to make the tractors run on water once the tractors was started up and others added water to improve MPG says a source in the USA http://www.shazizz.com/shazizzradio.html
Great show for alternative energy debates every Saturday and Sunday morning USA time from near to Kansas which has also got some sort of look into experiments laboratories as they do open source energy solutions
Gasoline engine will give slightly better MPG in damp air than dry air so adding water to carburetor was reputed to reduce the MPG fuel demands of the WW2 bombers
After WW2 the oil companies shut down these inventions
modern car gasoline fuel formulas were more stable until about ~1970 .One could park a car come back after two years and rive away no sweat .The olil companies changed the gasoline formula about ~1974 and the fuel now goes bad after 3 months
best i can figure is the modern gasoline is a mix of Colemans type fuel with other slow burn stuff like Toluene and other stuff to stop knocking .These fuel mixes will separate more easily than the older formula s. The fuel gasoline in Europe looks to be much higher Toluene contents than USA fuels and this results in much worse MPG figures than USA cars of the same type even taking into account the USA gallon is 17% smaller than the UK gallon
The big problem is Toluene when it burns often forms benzine which exits the tail pipe when CAT is cold which is so toxic you would never drive a car if you knew how toxic it was
there is youtube video fromCosta Rico where the guy boils gasoline and condenses off the lighter distillates that are basically Colemans fuel from it and there is about 15% crud left in the bottom of the home brew cracker he made
(Heatlh safety notice warning Kids and many adults Dont do this at home you can blow your house to bits poison the air with benzene and toxic explosive gas .Also it could ruin the taste of your dinner and worse create a good reason for the other half to sue you for a expensive divorce from you )
The other solution mixing Hydrogen Oxygen HHO mix gas to fuel looks like at best saves 4% to 10% fuel
This is often done usin g alternator to crack the water into HHO gas and injecting the HHO gas into carburetor
it requires some ~2200 liters of HHO to replace the energy of ~1 liter of gasoline
It takes some ~135 watts of energy to make 1 liter of HHO
the global efficiency of the alternator is about ~5%.
It takes 5 BHP of engine power to give back 1 BHP of power at alternator
To get some 5BHP of power from engine took some "5BHP of uel to give you that
QED the alternator is the worst way ever invented to give you power
However gasoline burns only a bit 17% the fuel it gets the rest is burnt in the CAT
Adding HHO a very rapid burn fuel can allow the faster flame front to burn the gasline better
Also the stociometric AFR rate for gasoline is 14:7 to 1 where HHO can be anything from 30:1 down to they say as low as 80:1.
This suggests in theory that only ~800 liters off HHO could replace one liter of gasoline fuel but there might be some loss of BHP and issues with throttle response .
Best I can say is HHO the jury is out on it and the Field is full of crazy experimenters and worse thieves that have wild claims many which prove not to work at all
This guy Dave Parker https://www.facebook.com/dave.parker.90 from the USA claims with new high fuel pressure injector system some 1000 psi he can double or quadruple the MPG for fuel injector gasoline cars
quote from the alternative energy FB site https://www.facebook.com/groups/freeenergyparty where he says this
This is an invention of mine. It is called the megapressure pump. Also the diamond-sapphire injection system. The pump delivers 1,000 psi for gasoline and 3-4 thou for diesel. The orifices offer the small capacity to nozzles that go with the pump to offer complete fuel vaporization. — with Deanna Munson."
However other experts out there say Dave Parker has claimed this for some time now so they remain skeptical that it can really hack it as gasoline fuel formulas vary so much from season to season from state to state that the device might not work in most of the USA with out serous expensive mods for each individual car and region
Important to note in Europe most Diesel fuels have at at least ~7% bio fuel in them to replace the loss of lubrication from extracting the sulfur content down to 50PPM for particle filters which would probably stop most modern fuel saving devices out there working so well
Some engines are real multi fuel engine such as jet turbine engines which often can run most any fuel that can burn .Got no J4 mix 10% gasoline with 90% diesel seems to be popular mix
It seems modern gasoline and diesel cars like BMW and Mercs and even the Royals Royce and other makes seems to have increased the a lot MPG with a method where they recirculate the burnt fuel back into the engine to re-burn again . It seems the original mix from the first explosion in the engine has still got unburnt fuel in it so they scavenge it back plus the heat helps the new fuel which enters to burn better .
Also the average car only requires about ~20Kilowatt to go along at 55MPH. .Many cars are about ~5% efficient global .The engines are ~30% efficient at the output shaft . However air drag brake drag rolling Resistance transmission losses give typically ~12% efficiency at steady 55MPH on the high way .throw in urban travel stop start ~5% is often where its at .
The hybrids solve some of this with storing energy in expensive heavy batteries between stops and starts However hybrids dont work so well compared to many diesel cars in steady speed high way driving .
One trick that does really seems to improve MPG with gasoline fuels is to add ~2 to ~3% acetone to the fuel .If you can source the acetone cheap enough in bulk . It seems fuel saving of ~10% per mile are possible doing that
Hope that helps fuel experiments guys
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