gas petrol diesel paraffin

[stubate]

for gods sake, children !!
hydro carbons + air = bang at certain temperatures.
the heavier the hydrocarbon ie gearbox oil, the harder it is to ignite.
gas ignites at lower temperatures
petrol higher
paraffin higher
diesel higher
the further the piston goes up the bore in a compression ignition engine the more it compresses and the hotter it gets.
put gas into a diesel and it will crackle and pop because it is preigniting
petrol to a lesser extent
paraffin less but it will run tolerably well but no lube effect and will destroy the injectors and pump
diesel the timing is set just right
heavier oil etc etc etc
stu

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[jimi]

Umm.. daddy ...why do petrol engines have spark plugs?

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[stubate]

duh, cause they are not compression ignition

engines dummy !!

now son, sit down while i explain how a compression ignition engine works.
stu


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[jimi]

Re: duh, cause they are not compression ignition

Daddy, why are'nt petrol engines compression ignition? If they were would'nt that save electricity?

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[snowleopard]

when i was a little lad...

i had a model plane with a compression ignition engine which sucked in a fuel/air mixture and ignitied it by compression.

now i am grown up i have a diesel engine which sucks in pure air, compresses it until it is hot enough to ignite fuel, then injects the fuel which burns instantly. it is not possible to have pre-ignition in a diesel engin unless the injector timing is set wrong.

diesels will run on just about anything flammable that will go through the injectors.


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[tr7v8]

Re: when i was a little lad...

Disagree, diesels preignite by knocking and it wil destroy pistons if allowed to continue. I've seen enough BMC 2.2 Taxi lumps destroyed because of this, mind you the knacked pistons make good paper weights.
Adding petrol to diesel to stop it feezing was very common, certainly in the 70's when I first got involved with them. Winter diesel is a comparatively recent occurence.

<hr width=100% size=1>Jim

Draco 2500

 

[Mirelle]

The exception to the rule

is that true masterpiece of Scots engineering genius, the Kelvin K series, which (hand) starts on petrol, with a magneto and spark plugs, and then is switched to diesel when running. Not the idea auxiliary for a sailing vessel, but some Thames barges had them (maybe some still do?).

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[Weatherlawyer]

When I was a lad.

Don't anyone go putting petrol in a diesel. It will blow your cylinder head.

Deisels work at something like 25:1 compression. Petrol require somewhat less than 10:1. Preinition could get the pistons firing all at the same time with a much higher explosive mixture than oil.

Tractor vapourising oil burners needed to get up heat to fire properly which is why they started on petrol.

No end of vans were ruined in the 70's by fools putting too much paraffin in their tanks -or just a little petrol. The idea was to stop wax forming in the pipes. Heating elements were tried. I heard lots of stories about lighting fires under them.

You couldn't do that in a boat of course. But then the sea usually keeps the temperature high enough so that there was little trouble.

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[tr7v8]

Re: When I was a lad.

Interesting, why would it blow your cylinder head? Based on what bar talk!
Diesel heads are flat, technically a Heron head although very modern diesels have gone to more of a proper chamber and that would be high speed ones made in the last 5-8 years.
So the heads are therefore very strong, my father ran a fleet of over 150 BMC JU which wee 2.2 diesels and BW 35 auto boxes. Most of them were knackered through A. being thrashed and B. the original engine design being errrr... crap. Cracked heads were common and with lack of servicing (most were run on a shoestring) Broken cranks. Broken pistons were common after the cracked heads due to overheating. Most vans in the 70's as distinct from small trucks were petrol, Ford launched the Transit diesel with the Perkins 4/108 and sold a minimal amount, not until the later York engine did they sell more. I earnt damn good pocket money as a 13 year old getting them started on a cold saturday morning and you couldn't see the other side of the van shed with the thick black smoke.
A common thing even up to a few years ago was trucks lighting fires under tanks, because the fuel waxed hence the comment that winter diesel is relatively recent.
Petrol in diesel used to be very common and I suspect an element still it certainly won't cause the castrophic problems people have forecast.

<hr width=100% size=1>Jim

Draco 2500

 

[Heckler]

Re: when i was a little lad...

when iwas a little lad i learned about timing engines and that if you put a lighter fraction thru a compression ignition engine and it was injected at the point it was designed to burn a heavier fraction it then banged instead of burning in a controlled manner and gave the same effect as pre ignition in a spark ignited engine, see my previous post about burning petrol or gas in a diesel engine.
so nah nah di nah nah

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[Heckler]

not quite right

they are not compression ignition, they started on petrol (light fractions ignite easier) when they got warm you switched to paraffin which went thru the carb and the mixture hit a hot spot caused by the warming up and this turned it into a gas which then ignited by spark. in france, spain, portugal etc they call diesel fuel a variation on gas oil, ie gaz huile etc because the fuel is turned one way or the other into a gas to ignite.


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[Heckler]

as was said in a previous post

stick to weather lawyering.

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[Mirelle]

No, sorry, that was the E and F series

some, but not all of which, were built as petrol/paraffin (TVO) engines. I should know, I owned one. The K series are true diesels, i.e. compression ignition engines which run on diesel oil, but which start on petrol. You are safe in assuming that the compression ratio is changed, by closing off an ancilliary chamber, so as to raise it to diesel levels, when switching fuels. Very early Listers had the same idea in reverse - they started on an extremely high compression ratio, to get the fuel to ignite, but once they were running you turned a wheel to reduce the compression ratio by opening an ancilliary chamber.

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[johnsomerhausen]

Re: No, sorry, that was the E and F series

In July 1940 (I was a kid then) we returned from evacuationb in France in the family 1937 Ford (side valves engine). The car was low on fuel and we stop[ped at an abandoned French military auirfield wheere a soldieer let us fill the tank. It must have been some sort of diesel fuel, as the engine ran rough and the trail of smoke exrtended all the way from that airfield to Brussels... But the old Ford did run on that.
john

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[PerL]

On this subject... is it possible to run a marine diesel on bio substitutes such as rape [Brassica Napus] fuel? Are there any known problems?

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[stubate]

i have read

only a little on this subject, but if the manufactureres say it is for diesel, why not?
my only caution is that people in south wales have been buying supermarket cooking oil and using it in cars, the prob lies in that if you expose it to air it oxidises and forms a sticky jelly substance, look at your chip pan, also this used to be the basis of paint, an organic oil (was it castor?) and lead mixed. the oil oxidised and went hard. do wonders for the pump and injectors

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[Weatherlawyer]

Re: When I was a lad.

> Interesting, why would it blow your cylinder head? Based on what bar talk!

Based on stuff like the rest of your trip down memory drain:

> Diesel heads are flat, technically a Heron head although very modern diesels
> have gone to more of a proper chamber and that would be high speed ones
> made in the last 5-8 years.

Deisels were a problem to "time" due to lack of research and development from the time of their invention until WW II. Fuel injection and turbocharging innovation brought rapid changes. In the "oil crisis" of the 1970's ther was a move to better fuel economy and for better reliability due to Japanese competition from then on.

Basically, the problem with pe-ignition is that at 25:1 or so ratios, the addition of a drop of fuel posed no problem at or very near top dead centre.

The volume of gas a liquid produces is something like 50 gallons to the ounce for water to steam or vapour at ntp. I imagine it is similar for all liquids in a straight swap. I've no idea about the volume switch where a chemical change is involved.

I somehow doubt it is less.

If the fuel is ignited when still under compression, by the time the piston gets to tdc the compression ratio is somewhat altered.

> So the heads are therefore very strong, my father ran a fleet of over 150 BMC
> JU which were 2.2 diesels

However nothing was done about bad management in Britain or the USA. That is why 150 JU's were not only made but sold.

> BW 35 auto boxes.

I don't know anything about these.

> Most of them were knackered through:
> A. being thrashed

I wonder if engineering design faults were overlooked because of captured markets. I know it was the death of the motor cycle industry here. When there were too many customers Triumph, for example, sent out machines with faulty parts rather than invest in new production lines and quality control.

> B. the original engine design being errrr... crap.

Ah. So we agree?

> Cracked heads were common and with lack of servicing (most were run on a
> shoestring) Broken cranks. Broken pistons were common after the cracked
> heads due to overheating.
>
> Most vans in the 70's as distinct from small trucks were petrol, Ford launched
> the Transit diesel with the Perkins 4/108 and sold a minimal amount, not until
> the later York engine did they sell more.
>
> I earnt damn good pocket money as a 13 year old getting them started on a
> cold Saturday morning and you couldn't see the other side of the van shed with
> the thick black smoke. A common thing even up to a few years ago was lighting
> fires under tanks, because the fuel waxed.

You kids today; you don't know you're born! Different when I were a lad. We had to shoot people for a living in them days!

> Petrol in diesel used to be very common and I suspect an element still (?)
> it certainly won't cause the castrophic problems people have forecast.

A bit of smoke never hurt nobody, eh? Where there's muck there's brass?

Ah those trips down memory lane; where draining the radiator served as antifreeze; petrol was a good wax soution; trucks were criminally maitained; fuel was something you got away with; deisel fitters were just good old fashioned mechanics and ether was necessary most of the time for men and machines.

Why can't we all live in the past now rather than wait until retirement?

In the meantime if your crank-case is smoking at speed but not under normal load suspect cheap oil and some piston wear. You may just need a set of rings. Some plonker was using petrol no doubt.

Don't use petrol on a boat and keep two stroke outside the main cabin etc; in it's own container where explosive perol vapour will not build up.

You should not need to put extra antifreeze in a boat's deisel if it is at sea. Sea temperatures seldom get below -2*C even in the Arctic. The engine is below sea level and relatively safe.

> A common thing even up to a few years ago was lighting fires under tanks
> because the fuel waxed.

The tank can be warmed with a blow lamp in emergencies. You could even put an heating element in it or a light bulb of some sort under it if you have suspect fuel.

I don't know what goes into red deisel. I'm sure that too will have antifreeze in it in this country as most tanks on land are liable to temperatures considerably lower than sea temperatures around Britain. They tend to be sited in frost pockets at the back of houses for instance.

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[stubate]

i defer to

sensible knowledge
stu

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[PeteMcK]

Haud me back, Jimi!

Cabin fever over petrol - I'm off!!

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[tr7v8]

Re: When I was a lad.

I would respond but someone who can't spell diesel wouldn't be worth the effort!
Since you haven't got a profile I don't know what engines you run, but I wouldn't mind betting it is 70's technology rather than 90's!

<hr width=100% size=1>Jim

Draco 2500