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nivaman Articulating
Joined: 24 May 2006 Odometer: 929 Location: New Zealand
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Posted: Wed May 20, 2009 3:38 am Post subject: Hot Diesel
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What would be the benefits of using a fuel heater to heat the diesel before it is injected?.
I assume the diesel delivery system is a pressurized system and the diesel would combust better once it was injected into the cylinder?.
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terence Guest
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Posted: Wed May 20, 2009 9:33 am Post subject:
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If its pressurized then its already hot.
common rails have fuel coolers, not heaters.
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nivaman Articulating
Joined: 24 May 2006 Odometer: 929 Location: New Zealand
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Posted: Wed May 20, 2009 12:44 pm Post subject:
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My thinking would be the diesel would vaporise as soon as it left the injector, thereby com busting completely.
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Rossko Articulating
Joined: 23 Jan 2007 Odometer: 757
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Posted: Wed May 20, 2009 5:16 pm Post subject: Re: Hot Diesel
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nivaman wrote: | What would be the benefits of using a fuel heater to heat the diesel before it is injected?. |
Why not find out if they use this kind of thing on big lorry or marine engines (where any increase in weight or initial cost is much less important than any possible small gains in power or economy)?
Hint - they don't , they have fuel coolers ....
cheers, Ross K
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cieranc Just got MTs
Joined: 20 Mar 2005 Odometer: 451 Location: Darlington
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Posted: Thu May 21, 2009 10:11 am Post subject:
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Used a new Scania the other day, hire motor, it had a tank heater which was switched on. I asked the guys in the workshop how to switch it off as I couldn't find a switch for it. They said there isn't a switch for it, just leave it on
And I would assume it was a common rail, as are most new commercial engines.
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Kitesurf Difflock Royalty
Joined: 28 Feb 2005 Odometer: 14197 Location: Luton, Beds
1994 Toyota Surf
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Posted: Thu May 21, 2009 11:11 am Post subject:
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cieranc wrote: | Used a new Scania the other day, hire motor, it had a tank heater which was switched on. I asked the guys in the workshop how to switch it off as I couldn't find a switch for it. They said there isn't a switch for it, just leave it on
And I would assume it was a common rail, as are most new commercial engines. |
Maybe the tank heater is on a thermostat and only cuts in below a certain temperature to stop the derv waxing? My Surf (with Winter pack) has a thermostatically controlled fuel preheater.
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Cagey Off-Road Guru
Joined: 20 Jan 2004 Odometer: 1380 Location: Banchory (The frozen North)
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Posted: Thu May 21, 2009 11:24 am Post subject:
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We use Scania engined generators in our hire fleet, same engines as lorries, no common rails yet but most use electronic injectors with solenoids to accurately meter the fuel delivery.
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terence Guest
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Posted: Thu May 21, 2009 12:09 pm Post subject:
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Right ill say it again.
Common rails have fuel coolers, pressurised fuel = hot fuel.
TDi's like heated fuel.
also tank heaters are utilised with veg converted lorries too.( not common rail though)
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cieranc Just got MTs
Joined: 20 Mar 2005 Odometer: 451 Location: Darlington
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Posted: Thu May 21, 2009 4:32 pm Post subject:
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Phil, this was used on an average spring day, not particulary cold and certinly not cold enough for a tank heater .
Terence, heard you the first time, but I don't think it's as black and white as that !
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Nathaniel Difflock Royalty
Joined: 13 May 2003 Odometer: 17901 Location: North, North Yorkshire
1979 Suzuki LJ
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Posted: Thu May 21, 2009 5:17 pm Post subject:
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The fuel cooler on a common rail cools the fuel before it goes back to the tank - to stop it melting the plastic tank.
How hot does the fuel get in a common rail?
I'll put it this way - the heat exchnager uses the engines coolant to cool the fuel!
__________________________________ Nat
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cieranc Just got MTs
Joined: 20 Mar 2005 Odometer: 451 Location: Darlington
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Posted: Thu May 21, 2009 10:32 pm Post subject:
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Hmmm, doesn't matter how hot it gets under compression, as it can't expand, it can't vapourise. Until it gets fired out of the injector.
Under compression, perhaps it's heating limit is it's flashpoint.
You're not going to get near that with a coolant powered heat exchanger!
Will heated diesel still lubricate the injector pump as it was intended to?
Well again, it can't expand under compression, so why not?
Going back to RAF engineering school - Thermodynamics:
Increase in pressure=increase in temperature and decrease in speed,
Decrease in pressure= decrease in pressure and increase in speed.
Ok so these fundamental fluid mechanics apply to airflow, but the same principles appy.
Funny what you can remember when you're pished!
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nivaman Articulating
Joined: 24 May 2006 Odometer: 929 Location: New Zealand
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Posted: Thu May 21, 2009 11:57 pm Post subject:
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cieranc wrote: |
Will heated diesel still lubricate the injector pump as it was intended to?
Well again, it can't expand under compression, so why not?
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I can't see why not, if not then may have to add a wee bit of high quality low ash two stroke oil.
Under pressure the heated diesel would still behave as diesel until injected then would vaporise pretty quickly resulting in better combustion, or am i wrong?.
terence the TDI diesel engine is turbo yes?.
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terence Guest
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Posted: Fri May 22, 2009 10:02 am Post subject:
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TDI =
Turbo Direct Injection.
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TheBigPurpleOne Off-Road Guru
Joined: 06 Oct 2008 Odometer: 1692 Location: Macclesfield
1987 Land Rover 90 TD
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Posted: Fri May 22, 2009 10:21 am Post subject:
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ive been looking at this too
if you heated the fuel to around 80degC it should be fine... (i think diesel self combusts at 120-140)
my understanding of a diesel is that to make it more efficient (hence more powerful) it likes cold air and hot fuel
look at the vapour carbs and vapour fuel systems for the petrols and youl see the efficiency increases theyve claimed (80-200 mpg on a v8 thats been tuned to idle at 400 and rev to 6k)
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Nick
CHEAP YOUNG DRIVERS INSURANCE FROM 8th OF FEB
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nivaman Articulating
Joined: 24 May 2006 Odometer: 929 Location: New Zealand
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Posted: Fri May 22, 2009 12:37 pm Post subject:
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NRS91 wrote: |
if you heated the fuel to around 80degC it should be fine... (i think diesel self combusts at 120-140)
my understanding of a diesel is that to make it more efficient (hence more powerful) it likes cold air and hot fuel
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That was my thinking as well, snorkel to air filter to intercooler from there to turbo inlet keeping everything short as possible.
Add the hot diesel and should be a happening thing.
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Last edited by nivaman on Mon May 25, 2009 1:22 am; edited 1 time in total |
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TheBigPurpleOne Off-Road Guru
Joined: 06 Oct 2008 Odometer: 1692 Location: Macclesfield
1987 Land Rover 90 TD
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Posted: Fri May 22, 2009 12:53 pm Post subject:
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yea except i was thinking twin snorkle with cone filters on top... then twin charged and twin coolers
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Nick
CHEAP YOUNG DRIVERS INSURANCE FROM 8th OF FEB
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TheBigPurpleOne Off-Road Guru
Joined: 06 Oct 2008 Odometer: 1692 Location: Macclesfield
1987 Land Rover 90 TD
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Posted: Fri May 22, 2009 12:56 pm Post subject:
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cieranc wrote: | Decrease in pressure= decrease in pressure and increase in speed.
Funny what you can remember when you're pished! |
you mean temprature im guessing?
still pished?
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Nick
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cieranc Just got MTs
Joined: 20 Mar 2005 Odometer: 451 Location: Darlington
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Posted: Sat May 23, 2009 2:08 pm Post subject:
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Yes
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nivaman Articulating
Joined: 24 May 2006 Odometer: 929 Location: New Zealand
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Posted: Mon May 25, 2009 1:24 am Post subject:
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NRS91 wrote: | yea except i was thinking twin snorkle with cone filters on top... then twin charged and twin coolers |
And increase in lag and fuel consumption possibly.
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TheBigPurpleOne Off-Road Guru
Joined: 06 Oct 2008 Odometer: 1692 Location: Macclesfield
1987 Land Rover 90 TD
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Posted: Mon May 25, 2009 5:34 pm Post subject:
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one super charger and on turbo... like the vw twin charge...
__________________________________ Thanks
Nick
CHEAP YOUNG DRIVERS INSURANCE FROM 8th OF FEB
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nivaman Articulating
Joined: 24 May 2006 Odometer: 929 Location: New Zealand
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Posted: Mon May 25, 2009 11:36 pm Post subject:
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Ah yes i see what you mean now , thought it was something like one turbo blowing through the other.
A friend used the supercharger/turbo idea on his 2LT Toyota Hilux, said it went extremely well, too well and knew that something would happen so took it off again .
Mind you i can see his point, he takes no prisoners when he is driving his truck.
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TheBigPurpleOne Off-Road Guru
Joined: 06 Oct 2008 Odometer: 1692 Location: Macclesfield
1987 Land Rover 90 TD
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Posted: Mon May 25, 2009 11:54 pm Post subject:
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if i had twin turbo it would either have to be double expansion in line or two smaller turbos side by side
anyway thats very OT... so whats the general concensus on heated diesel?
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Nick
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nivaman Articulating
Joined: 24 May 2006 Odometer: 929 Location: New Zealand
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Posted: Mon Jun 01, 2009 12:56 am Post subject:
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It turns out my diesel filter is heated any way so will probably use that, it also has a Bosch pump so will be able to go with WVO or biodiesel.
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