Thread: Custom gas injection??

Originally Posted by isuzurover

Look. This is tedious, can we end the tennis game now.

MANY things "burn" - even magnesium.

Patience.... what about patience.... maybe we found the never ending source of a new fuel!!!

Dr.B - Increasing fuel for the same amount of air will increase temperatures, no ifs, buts or maybes. Regardless of what that fuel is. The increase might not be the same for each fuel, but it will increase.

The Heckler from the front row - No problem with oxidation and burning. But is it always the case that more fuel equals greater temperature? I recall that lean petrol mix causes burnt valves. Is this not due to extra heat which is overcome by increasing the fuel in the mix?

He does have a good point Dr. B........

But to refute the Heckler "Sir, your point is out of order!! The Good Dr. B. didst clearly point out "Increasing fuel for the same amount of air..." hence staking sufficient merit to his higher educational claim!"
Good work Dr.B., continue.....

Originally Posted by slug_burner

No problem with oxidation and burning. But is it always the case that more fuel equals greater temperature? I recall that lean petrol mix causes burnt valves. Is this not due to extra heat which is overcome by increasing the fuel in the mix?

It's the evaporation of more fuel that can't burn (not enough air) which lowers the combustion temps in a petrol running richer than stoich. The slightly lean mix is showing the normal temperature, leaning it out further (if you can still get ignition) causes the temps to drop.

But diesels always run excess air, so we never see that phenomenon. More fuel always increases temps, less fuel decreases.

Originally Posted by Dougal

It's the evaporation of more fuel that can't burn (not enough air) which lowers the combustion temps in a petrol running richer than stoich. The slightly lean mix is showing the normal temperature, leaning it out further (if you can still get ignition) causes the temps to drop.

But diesels always run excess air, so we never see that phenomenon. More fuel always increases temps, less fuel decreases.

good

I think we are all missing some thing here, that is initially the LPG replaces some diesel, hence the cooler running. BUT when we get to full bore ( which after reading your posts is what you are referring to) and you start to up the fuelling, with lpg you can go just that little bit more, and that’s only because the burn is more complete and a bit more even after that yes more fuel pinged pistons.
I don’t think what the original poster was told. That 30% gain would be sustainable; maybe 15% would be better for a prolonged loading.

Originally Posted by clean32

good

I think we are all missing some thing here, that is initially the LPG replaces some diesel, hence the cooler running. BUT when we get to full bore ( which after reading your posts is what you are referring to) and you start to up the fuelling, with lpg you can go just that little bit more, and that’s only because the burn is more complete and a bit more even after that yes more fuel pinged pistons.
I don’t think what the original poster was told. That 30% gain would be sustainable; maybe 15% would be better for a prolonged loading.

My understanding in all this is LPG doesn't replace the Diesel at all , It mixes with the Intake air to acts as a catalyst to burn diesel more efficiently ,more complete burn results in less amount of diesel used to produce same amount of power.

And because there is less Un-burnt diesel exiting the Engine into Exhaust manifold the unburnt fuel is no longer still burning inside the Exhaust manifold and hence lower EGT.

UUGHHHH!!! PEOPLE!!
LPG has a lower flashpoint than diesel. CR requirements to spark ignite LPG is around 9-10:1.
Your average common diesel runs a CR of 14-19:1, some even higher.
Diesels with a lower CR will display lower EGT temps than higher rated CR's.

LPG, having a lower flashpoint, is used as a flame catalyst to INCREASE the ignition temp just prior to diesel ignition point providing a flame front into which the diesel is injected into to increase the burn rate. THIS INCREASES IGNITION TEMPERATURE TO COMPLETE THE BURN THUS INCREASING EGT'S REGARDLESS OF COMPLETE OR PARTIAL BURN. Plus the faster it burns, the higher the rate if heat is concentrated on the piston crown. This is what melts them.

I have seen a number of engines that have had conversions done, namely Nissan TD42 and Toyota 1HZ's and 2 1HDFT engines that have come back with gaping holes in the pistons and sumps spotted with molten aluminium.
The biggest mistake made with each of these engines is that no rolling road tuning was done, just tweaking the levels without any load in a workshop, installer lightening the owners pocket of a few $$$ and saying "thankyou very much.." and denying all responsibility when their installation fails costing the owner another $7-8K for a new engine.
The other mistake is that its a bunch of mechanics who think they can capitalise on a "new thing" charge a bundle for it and pull the wool over unsuspecting general public saps that get suckered into it thinking they can save on fuel, when in fact you are now paying for two fuels.

Nowhere do you see Caterpillar, Cummins, Isuzu, UD, MTU Detroit, Toyota, Mitsubishi, Scania, Mercedes Benz, Volvo, Waukesha yada yada yada doing any mixed fuel engines.
They are either diesel or gas, end of story.
This is no different to another post on this forum about turning a std 4 stroke diesel into a 2 stroke but still using 4 stroke induction and exhaust principles. ITS A CHEAP (RIP OFF) WAY OF DOING SOMETHING WITHOUT DOING IT CORRECTLY.
If this method was so good, why havent all the worlds biggest engine manufacturers who spend MULTI BILLIONS of dollars every year in R&D to keep in with worldwide emissions regulations, utilised this method? Why, because its BOLLOCKS!

Any manufacturer who needs to utilise 2 different fuels to make an engine work would face financial Armageddon should they put it into production.

The biggest reason for a diesel blowing smoke is its never maintained correctly, beit servicing and particularly injector and pump adjustment.

A little tip for those who may not know GET IT SERVICED AND YOUR INJECTION TIMED AND SET UP CORRECTLY!! If it didnt blow smoke out of the show room floor, you should be able to come to the conclusion that something is out of adjustment when it does.

One final note, Long_stroke, just to elaborate on Larns post, that guy is a total and complete f***wit. What happens when his car has a fault, ignites the gas line, catches fire and explodes endangering other innocent bystanders?? Yes, that IS why we have rego checks and Standards Laws to protect people from halfwits like that.

Clean32,

Wrong, more temp will add greater excitement to any material within the combustion chamber = more HP BUT there is a point where the expansion rate diminishes with temperature. If we were to look at the basic elements and molecules that are within the combustion chamber then look at how that behave at different temperatures and so on. With a diesel turning up the screws at some point will result in the diesel gassing off in the expansion chamber and not burning ( LOL as much as it would normally) evaporated diesel will add more push than hot co2 or nitrogen.


An example. water turns to steam ( not a gas and not evaporate) diesel will do the same. now if you understand that its is much harder ( constant temp) to compress steam or diesel gas back to a liquid than it is to say compress CO2 into a liquid ( 120psi) then you will have an idea of what pushes the piston down ( and its not Temp)

you spend way too much time on google and/or wikipedia. Diesel is a heavy fuel oil not an aromatic and WTF are you on about?????
What pushes the piston down is the compression inside the engine which causes an accelerated rate of temperature increase beyond the flashpoint of the fuel, hence ignition. The higher the CR, the more fuel can be injected resulting in higher horsepower outputs. WTF has steam and CO2 got to do with it?????

But if you want to part with your money, go ahead. I give free advice, a torched engine I charge for but the "I told you so..." that depends how much much of a shonk the sales guy was that suckered you in the first place!!

Originally Posted by LOVEMYRANGIE

LPG, having a lower flashpoint, is used as a flame catalyst to INCREASE the ignition temp just prior to diesel ignition

I wouldn't call it a catalyst because it's consumed as fuel. Accelerant fits better.

BTW, take a look at this video of my engine running on lpg. I measured the fumigation rate at approx 0.4% (+/-0.2%) of the inlet air.
LPG into an Idling Diesel. | OffroadExpress 4wd Forums

Originally Posted by Dougal

I wouldn't call it a catalyst because it's consumed as fuel. Accelerant fits better.

Indeed.

Originally Posted by Dougal

I wouldn't call it a catalyst because it's consumed as fuel. Accelerant fits better.

BTW, take a look at this video of my engine running on lpg. I measured the fumigation rate at approx 0.4% (+/-0.2%) of the inlet air.
LPG into an Idling Diesel. | OffroadExpress 4wd Forums

Thats the word I was looking for....