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gofastclint

Subaru Boxer Diesel.

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Well ten years later and it looks like predictions for diesel cars were a tad optimistic. I'm going against the grain in this thread but I for one am thankful 😁

Edited by danny_galaga
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On 27/10/2019 at 1:42 PM, Old Koreelah said:

Using jet fuel also interests me, Jetboy. I learned to drive on a grey Furgie, which started on standard petrol; after it warmed up we switched over to kero. Why can't our aero engines do that?

I buy mine from Bunnings in a plastic bottle now at probably ten times the cost of petrol; in the days you are talkiong about it was cheap enough to take a 20 litre drum out into the paddock and spend a morning burining scotch thistles.

 

We had a petrol/kero International W6 tractor and a petrol/diesel AWD9 and it was a longer starting process, and I always managed to get way down the paddock to the tractor (so way out the road to the hangar), and find the little petrol tank dry.

 

 

 

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All the petrol/kero tractors had a special intake manifold that directed exhaust gases onto the underside of it, to ensure the kero was vapourised enough to ignite.

In addition, the petrol/kero engines had lower compression to enable kero to be burnt reasonably satisfactorily.

Most petrol/kero tractors had radiator shutters, because it was important the engine temperature was kept high to ensure the kero burnt well.

Even at that, the old International tractors had two petcocks on the crankcase - every 10 hrs of operation, you had to drain the kero-diluted oil to the lower petcock, and refill with new oil to the upper petcock level!

Then, of course, there were two types of kerosene - Power Kero, which was specifically for burning in engines, and Lighting Kero, which was much lower grade and far less volatile, and which was used for lamps and heaters.

 

Then there were the petrol/diesel International engines that had a lever that adjusted a plunger in the combustion chamber, that altered the compression ratio.

You started on low compression using petrol, then when you switched over to diesel, the lever was shifted to increase the compression to the level required for diesel ignition.

Edited by onetrack
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I found the full description of the operation of the International Harvester "MD" series of petrol/diesel (gas/diesel to our U.S. friends) engine, which I have cut and pasted below.

The MD IH petrol/diesel was first released in 1941 in the IH wheeltractors and the system was later used in IH crawler tractors as well.

It was a system designed as an alternative to Caterpillars petrol starting engine, which Cat used on their diesel engines from their first diesel in 1931, right through to the mid-1980's, on some of their models.

 

"To start the (IH gas/diesel) engine, the driver operated a compression release lever opening a third valve in the cylinder head, called the starting valve, uncovering a separate combustion chamber that both increased the combustion chamber size and exposed the spark plug. With the starting valve open, the engine had a 6.75:1 CR and used a tiny, fixed-orifice carburetor designed only to run the engine at a fast idle. At the same time, the control disengaged the distributor ground, opened a fuel valve in the carburettor, and a butterfly valve that connected the gas cycle combustion chamber to inlet air, and closed the diesel intake.

The engine was cranked over using a 12-volt starter and would idle at 6-800 rpm. This was enough to warm the engine up as long as needed for diesel combustion to be possible. Though there was a choke, idle speed was not controllable by the driver. After warming the engine up for one to three minutes, the compression release lever was pulled back briskly. That closed the starting valve, shut off the gas to the carb, grounded the distributor (killing the spark), closed the gas intake manifold and enabled the diesel injection pump. The engine then began running on diesel with barely a hiccup. For the shut down, you switched back to gas, and shut the engine off with the ignition switch, making it ready for the next start.

This all seems pretty onerous today, but it was one of the more effective ways to start a diesel before batteries and starting systems had enough oomph to spin a diesel over in cool weather, let along cold. Practical glow plug systems were still a decade or more in the future, again limited by battery capacity. The direct start diesels were a big deal when they debuted in the mid 1950s."

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I was brought up with kero powered tractors. The fuel was called TVO, short for tractor vapourising oil. The reason for using kero was because there was not enough petrol, due to the war. Kero tractors would have much more power if used with petrol, so obviously not suitable for aircraft.

We had diesels back in those days that started with a 12V electric starter, but they were British, not Yank.

The direct injection diesels would start if the fuel was liquid enough to pour, even if you had to light a fire under the tank. Even now we have diesels that need pre heating to start, even though direct injection models start every time first time.

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19 hours ago, Yenn said:

I was brought up with kero powered tractors. The fuel was called TVO, short for tractor vapourising oil. The reason for using kero was because there was not enough petrol, due to the war. Kero tractors would have much more power if used with petrol, so obviously not suitable for aircraft.

We had diesels back in those days that started with a 12V electric starter, but they were British, not Yank.

The direct injection diesels would start if the fuel was liquid enough to pour, even if you had to light a fire under the tank. Even now we have diesels that need pre heating to start, even though direct injection models start every time first time.

Pleaseeease dont get me stated on diesel engines & injection types - Oh & by the way me thinks you have confused direct injection with indirect (at least in some of your comments)

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Kero has a low octane rating so just cannot operate with any normal compression ratio and  therefore doesn't make much power. Unless the engine's very hot the kero ends up in the oil which it dilutes. Today it's significantly more expensive than petrol. Forget it as a fuel for anything except model aeroplane diesels (equal parts kero, castor oil and ether, basically.  Not a bad cleaning solvent /engine cleaner  (hose off with water) and used as a cutting fluid with cast iron. Some fire risk Nev

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43 minutes ago, facthunter said:

Kero has a low octane  .......................

Cetane  rating for diesel (compression ignition fuels) - Octane is for petrol (spark ignition fuels). Yes I know it's not quite that cut & dried, as a hot low pressure petrol engine, with warmed fuel can burn kero/diesel/etc in a spark ignition combustion.

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I try generally to keep my explanations as simple as possible while still addressing the pertinent  points. Yes you CAN use kero in a suitable engine but why would you? I gave most of the reasons why you wouldn't bother and If you have a kero designed engine it will run better in all ways on petrol. Cetane is the opposite of octane but "very low octane" rating explains it  too . Nev

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I do understand direct and indirect injection. dating back to the fifties, when I was a diesel mechanic, before the days of rotary injection pimps.

I run both direct and indirect injection diesels and the direct injection always starts easier. Indirect is supposedly less noisy, but there is not much in it, especially at high power.

What are the current diesel aero engines, direct or indirect?

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Only some of the latest technology petrol engines are "cylinder" injected I would rather used that term for clarity. Early" OIL" engines were hot bulb where you used a blowlamp to preheat a part of the head for starting or slow running as they ran a relatively low compression ratio similar in principle to a glow plug engine. The fuel was injected onto the interior surface of the HOT BULB section. and that could be used with  a  hand operated facility to start the engine which was invariably a two stroke.

        All C I, Compression Ignition motors, bar the model aero ones with variable compression by a contra piston  are cylinder injected. Some earlier ones used an anti chamber. for the bulk of the combustion. A separate chamber connected to the cylinder into which the fuel was injected but these were less efficient due to extra surface area. When that feature was discontinued that may have been referred to a"Direct" injection. Most current injected petrol cars have the fuel injected into each inlet port relatively close to the inlet valve. Earlier ones had it at the throttle body as single point injection.  Virtually a carburetter replacement as to how it's located. Nev

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3 hours ago, Yenn said:

I do understand direct and indirect injection. dating back to the fifties, when I was a diesel mechanic, before the days of rotary injection pimps.

I run both direct and indirect injection diesels and the direct injection always starts easier. Indirect is supposedly less noisy, but there is not much in it, especially at high power.

What are the current diesel aero engines, direct or indirect?

Well - Direct injection is very much the modern way - all your Mercedes diesel and aero conversions thereof are direct injection.

 

Some of the differences:

 

Direct injection "lends" itself to cross flow head, high speed diesels, high pressure common rail injection systems, computer controlled engine management, possibly turbo charging, lower compression ratios, etc BUT direct injection diesels are not so tolerant of fuel quality variations, have a particular dislike of water/contaminants generally and I have never heard of anyone putting vegetable oil (as fuel) through one. I am guessing but direct injection heads are simpler, probably less costly to manufacture. The engines need not be so heavy/robust/costly if lower compression ratios are used. Direct injection injectors must produce a fine aerosol (multi hole jet/pintal) to be effective. Pistons usually have elaborate "mixing" profile in the crown.

 

Indirect injection (there is a small chamber off the main combustion chamber sometimes referred to as a swirl/precombustion chamber) are comparatively tolerant of variations in fuel quality (the choice for converesion to vegetable oil as a fuel). Must use compression ratios in the vicinity otf 22:1 to be effective with consequential robust /heavy/costly construction. Injector need not produce such a fine aerosol so more tolerant to wear. Pistons crowns  are usually completely flat. This system lends itself to industrial relatively low rpm engines. All my old diesel Mercedes (pre 1985) were indiercet. Most tractors/generator/pumps/etc up until recently (introduction of computer controlled engine management) were indirect. There is possibly a relationship between exhaust emissions and the phasing out of indirect injection diesels.

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Tsunamis ...

 

Although often referred to as tidal waves, a tsunami is not a usual wave which is only much bigger.

 

People unaware of the danger may remain at the shore for collecting fish from the exposed seabed oblivious to the looming endlessly onrushing tide that forces its way through any obstacle.

 

Most of the damage is caused by the huge mass of water behind the initial wave front as the sheer weight of water is enough to pulverize objects in its path, often reducing buildings to their foundations.

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I liked the concept of using kerosine instead of petrol for safety and cost - for something like a generator or boat there are advantages, I had a colleague literally blown out of his boat due to the inboard gasoline engine - probably a mtce issue but there you go. When I bought my first new generator, the catalogue had models with the big kero tank and the small gasoline starting tank, but this version not available in NZ. Mate was studying at Med school and with not much money, used to make the 1000km trip home in holidays with the trusty 2 stroke Daihatsu Charade, no modifications, start on petrol, go to the servo and fill up around the corner "home heating fuel" thats not even real kero - put enough in to run out before the ferry terminal, put a bit of petrol in so the car would make it on and off the ferry, back on the boiler fuel for the rest of the trip. And our farm motorbikes we put a 1/16" aluminium gasket under the head and ran white spirits for them. The tax in NZ is more than 100% for petrol, whether you use it in the plane or boat there is no refund for recreational or offroad use. I get my kero from the JetA pump at the airport, so it costs about the same as Diesel. I was using rather a lot in JetCar, wouldnt buy it at the hardware store when youre burning 1L / min.

The reality is that petrol engines are so lightweight and efficient - skyactive X etc. that its not feasable to use the Diesel / kero equivalent in aero applications the extra weight is too much. There are some Smartcar Diesels that might be possible conversions. Getting the engine is difficult as they were not sold here. My last 2 work cars are Diesel and I really like them, currently Ford Escape it runs smooth, not endlessly changing gears and barely any noise. Pity that for reasons not related to the engine itself, they have gone out of favour.

I see merit in Diesel - electric series hybrid with a small battery for boost / regen on aircraft.  

   

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I have a truck fitted with a kero tank from WW2. Its a restoration project.

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22 hours ago, jetboy said:

...trusty 2 stroke Daihatsu Charade...

Didn't know there was a 2T model. Our 1980 model one litre triple 4 stroke was awesome.

Super reliable, economical and we took it on lots of 4WD holidays.

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