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18th July 2015, 11:00 PM
#11
Smart like tractor
Wouldnt a petrolium or spirit based fuel ignite a different point of the compression cycle?
96 GQ coil/Cab
08 G6eT
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18th July 2015 11:00 PM
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18th July 2015, 11:33 PM
#12
Patrol God
Originally Posted by
Ben-e-boy
Wouldnt a petrolium or spirit based fuel ignite a different point of the compression cycle?
I think that's the point. From what I can gather the diesel ignites under compression and once the fire is "lit" then the gas ignites to burn itself and the remainder of the diesel to give more oomph to the power stroke.
Also by igniting the unburnt diesel it releases energy that would otherwise be blown out the exhaust so is more economical.
Hello from Under Down Under!
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18th July 2015, 11:50 PM
#13
Smart like tractor
Originally Posted by
taslucas
I think that's the point. From what I can gather the diesel ignites under compression and once the fire is "lit" then the gas ignites to burn itself and the remainder of the diesel to give more oomph to the power stroke.
Also by igniting the unburnt diesel it releases energy that would otherwise be blown out the exhaust so is more economical.
I could be wrong but I dont think the lpg would ignite after diesel. I think it would burn first, pre ignite. Just using my logic or lack there of, if it were to be ignited by the diesel you could theoretically run a sparked engine on lpg and up the compression to 20+:1 without drama
Happy to corrected though
Edit. If it is either side of combustion wouldnt that be 2 seperate ignitions? And extra shock loading on the crank?
Last edited by Ben-e-boy; 18th July 2015 at 11:58 PM.
96 GQ coil/Cab
08 G6eT
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19th July 2015, 12:17 AM
#14
Patrol God
Gas like petrol will pre ignite on anything really above 14:1. Hence when people turbo petrols the decompress the engine down to even 7:1 as the added heat from the added pressure will pre ignite the fuel causing pinging etc.
Lpg does the same on the diesel. It ignites well before the diesel has even been injected. You would have far more benefit from running water methanol.
Lpg on a diesel is bad!
There is also the added problem of an extra fuel system to diagnose. Where do they put the tank? Its a lot of money to outlay on something tha really has mimimal gain if any.
Last edited by nissannewby; 19th July 2015 at 12:19 AM.
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taslucas (19th July 2015)
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19th July 2015, 12:22 AM
#15
Smart like tractor
Originally Posted by
nissannewby
Gas like petrol will pre ignite on anything really above 14:1. Hence when people turbo petrols the decompress the engine down to even 7:1 as the added heat from the added pressure will pre ignite the fuel causing pinging etc.
Lpg does the same on the diesel. It ignites well before the diesel has even been injected. You would have far more benefit from running water methanol.
So if it pre ignites above 14:1 would that mean that the lpg is starting to combust at 2/3 of the compression stroke
96 GQ coil/Cab
08 G6eT
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19th July 2015, 12:32 AM
#16
Patrol God
Originally Posted by
Ben-e-boy
So if it pre ignites above 14:1 would that mean that the lpg is starting to combust at 2/3 of the compression stroke
Pretty much. Even if its after that (although it is much more likely before that due to temps inside the combustion chamber already) the amount of added pressure in the cylinder from a fuel firing while the piston is still trying to get to tdc is extreme.
My logic and understanding of it.
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19th July 2015, 12:33 AM
#17
Patrol Freak
Originally Posted by
Ben-e-boy
So if it pre ignites above 14:1 would that mean that the lpg is starting to combust at 2/3 of the compression stroke
1 to 3 milliseconds (millionth of a second) before the diesel ignites yes..............
not at 2/3rds of the stroke
dont forget, at 1200rpm, thats 20 rotations every second
Tidy Whitey - 99 GU TD42Ti - Diesel Gas, (GUIV Turbo & Intercooler 8Lb boost), 33" Micky T's Baja MTZ's, Dual Batt's, Cargo Barrier, rear draws, HID Super Oscars, winch, Grinch & witch attached and more goodies to come
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19th July 2015, 12:36 AM
#18
Patrol Freak
most gas systems for diesels, the gas is injected into the inlet manifold, not into each cylinder.
Tidy Whitey - 99 GU TD42Ti - Diesel Gas, (GUIV Turbo & Intercooler 8Lb boost), 33" Micky T's Baja MTZ's, Dual Batt's, Cargo Barrier, rear draws, HID Super Oscars, winch, Grinch & witch attached and more goodies to come
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19th July 2015, 12:39 AM
#19
Patrol God
Originally Posted by
Bigcol
1 to 3 milliseconds (millionth of a second) before the diesel ignites yes..............
not at 2/3rds of the stroke
dont forget, at 1200rpm, thats 20 rotations every second
Only 10 of those are firing strokes..
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19th July 2015, 12:41 AM
#20
Patrol Freak
Originally Posted by
nissannewby
snip
Its a lot of money to outlay on something tha really has mimimal gain if any.
the OP has asked about a Patrol that already has Diesel / Gas fitted
it is not worth the coin to fit it after, for the amount of gains you get v's how long it would take to pay for itself
but there is significant gains to be had from the system if it is already fitted - as per OP
Tidy Whitey - 99 GU TD42Ti - Diesel Gas, (GUIV Turbo & Intercooler 8Lb boost), 33" Micky T's Baja MTZ's, Dual Batt's, Cargo Barrier, rear draws, HID Super Oscars, winch, Grinch & witch attached and more goodies to come
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