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Propane in gasoline fuel injection engine

OK here is the question, if you are running a normal gasoline engine with fuel injection at a steady state, say 65 on the freeway, and you start to bleed some propane into the intake, will the engine controls sense the added fuel and back off on how much gasoline it injects ??

Bill
 
I'm doing that conversion in a months time .
but am doing it with propane injectors .........the system piggy backs the main ecu and gets its signal to fire the LPG injectors from the cars main ecu.

This is the system im fitting
http://www.centralgaragecarcroft.co.uk/downloads/OMVL_DREAM_IT-GB.pdf

what you are doing is risking a back-fire situation .......could split your inlet manifold and plenum chamber ..if it's made of plastic like most are today.

all the best...mark
 
I think the PCM has the ability to "learn" what is going on via the oxygen sensor and make changes.

However, the ability is small, say 5% or so before you are going to set a code and drop into open loop which trashes any semblance of fuel economy.

The powertrain control systems of today are extremely complex, there can be cam AND crank sensors, and the scan rate on the PCM is fast enough that it can compare the angular accelerations from each power pulse, sort them relative to ignition event, and pick out a "weak cylinder".

The good news is that they are even better at self-diagnosis. The bad news is without the appropriate interface pendant (scan tool) which displays data and can get into the various categories of codes, it's nearly impossible to DIY-fix unless there's an obvious mechanical problem or a wire is hanging off.
 
I don't see how you can meter a charge of low pressure gas from a distance and possibly get to the cylinder in time. It looks like this system would be several rpm off. Even a common rail system couldn't get the gas there in time, could it? Perhaps it just chatter-rates the volume some distance back in the plenum instead of actually sequencially injecting?
 
The ECU is not gonna' like that... you are gonna' throw a code, most likely "fuel trim out of range", or possibly a MAF or O2 sensor bad code. It's also gonna' drive poorly, because (IIRC) the fuel trim is a comparatively slow adjustment. What you need to do for such a system is to piggyback on the injector signal with a microcontroller, and reduce the gasoline flow while you are increasing the propane flow... and direct-port propane injection would not be a bad idea, either.
 
I have heard with SOME fuel injections setups that you can add nitrous (ford mustang stuff) and NOT have to add any fuel, the system will compensate if you add a higher volume fuel pump. That prompted my question about going the other way.

The engine I would consider it on would be a 91 chevy 2.5 liter, and it has throttle body injection so adding fuel to the plenum should not cause a backfire.

Bleeding a decent quantity of non road taxed propane into say a vacume port at cruise conditions would be pretty simple, and what if it doubled gasoline mileage ??

Bill
 
Ahem, IMHO, if you are running 'the bottle' and you don't have your own overfueling device, sooner or later you are going to be investigating a very impressive catastrophic base engine failure. Really it's something everyone should see the aftermath of once in person to see how "it's not supposed to be"

Pieces of piston can get into the most incredible areas you never thought possible!

"Hey, what's that rod sticking out of the side of the block for?" :D
 
With the Ford cars, I'm sure there is a limit to what you can do before you get into trouble, I have seen some good n20 related explosions, and the aftermath, once you show an inbred redneck how n20 works they think if some is good more is better, and even more than has to be even better.

The guy I know was into sand drags with a big block chevy 4x4...seen a couple he blew up that all they salvaged was the intake manifold.


Bill
 
I have heard with SOME fuel injections setups that you can add nitrous
aghh... but you don't cruise along on nitrous.

Nitrous is only added when you are accelerating like crazy .and then only for a few seconds.

why not just buy the whole LPG kit .they are plentiful and available.

Your idea requires you to have to make several actions to turn it off if you were to meet up in with an emergency situation ...not safe .

The system in the above link is about £700 UK pounds for front end system.........im using the old tank out of my previous car in mine........and it will pay for itself in less than 10,000 miles .....

So fit install do your 10,000 miles .......then reap the rewards.

It has umpteen safety gadgets fitted to it ,and is not likely to bugger something up........what would your insurers say if you had an accident and they spotted all your gizmo's and a half empty propane container connected up.

Not worth racking your brain about something that has already been perfected and is readily available and safe ..to boot.

all the best.mark
 
Natural gas is not propane, not by a long shot. The NG vehicles have high pressure tanks not like 85psi propane. There is less BTU content in propane like 40% less than gasoline(both in liquid form)therefore you need 40% more propane for the same amount of work. If the cost of propane is more than 40% cheaper than gas you could save money, if less than 40% cheaper it will cost you more per mile than gasoline.

It is odd that the goverment has made the oil companies add ethanol to gasoline, and now is leading the charge that the gas cost too much. By adding ethanol at $2.65 per gallon and about 65K BTU's to $1.70 base gasoline and 115k BTU's per gallon. You end up with 110K BTU fuel that costs $1.80 per gallon, and will get you 4% less miles per gallon. So now you need 4% more fuel to save on oil.

I love it when a plan comes together.


my wheels don't slow me down

I love it when a plan comes together
 
I don't know about the 40%.........tiz wrong
more like 20% less energy...........but you gain on this because the stuff is 110 octane .......so you move the timing to take advantage ..

With the modern LPG injection systems...there is less than 10% difference in fuel consumption between LPG and petrol.

in the UK its half the price of petrol


natural gas is at 3000 psi ,so i believe .........they use an adapted scuba compressor to compress it.

all the best..mark
 
I remember an episode of Trucks where they were installing an LP injection system on a diesel PU for more power. You might look in this direction for more info on the subject.
 
No need to be sorry you are right
the dream "m" system works with cng.

mine is a dream "n"
unfortunately in our country no one uses CNG ..except a few local authority vehicles and experimental test vehicles..so really i cant be of more use to you .

what I do know is that there were plans for cng here ..that didn't take off.
it would have involved putting/installing a modified for gas scuba compressor into a hole in the wall of your house .......your gas supply would then be compressed overnight to fill your tank of your car.........as you can see buy the thinking and logic of it ...it could be very expensive to do this on initial cost and set up .....so it never took off.


all the best...mark
 
Timw

Back in the late sixties, some of my neighbors were injecting lp in their tractors. They ran like scalded dogs till the tops of the pistons got soggy and the exhaust valves burnt down to the guides. They pooted and scooted till they stopped.
 
but you gain on this because the stuff is 110 octane .......so you move the timing to take advantage ..
This is true only if you can bump up the compression ratio. It is unlikely that any modern engine will have been designed/built with any 'excess' compression that greater 'anti-knock' fuels can help utilize with a simple timing change. There are some exceptions to this but generally that will be the case. This does not necessarily mean you can't make more power with that same engine; see the last paragraph.


All of the 'oxygenate' type additives have lower energy density than the pertoleum HC's and reduce economy and output ITO HP/unit fuel. This is true for MBTE and all the others. Any alcohol could be classed ths way; the '-OH' on the end of the molecule is what makes it an alcohol after all. That last hydrogen is therfore partially oxygenated(burned).

This does not mean that you can't make more power in a given engine by burning alcohol. You can, but you do it by putting in A LOT more fuel. You can do this because the stoichiometry is much richer for alcohols because they already contain some of the O2 needed for combustion.

Makes sense, right?

Jimbo

Jimbo
 
have heard with SOME fuel injections setups that you can add nitrous (ford mustang stuff) and NOT have to add any fuel, the system will compensate if you add a higher volume fuel pump. That prompted my question about going the other way.
I had a similar setup on my 2000 Camaro. What it does is spray the nitrous in front of the MAF sensor, so the ECM actually sees the airflow and compensates by enritching the fuel mixture. It's only good up to about 100-150hp for most 8cyl cars though, beyond that you've exceded the limits of the stock tuning, injectors, and pump. If you really want to go big, you still need to go with a huge pump and a "wet" system, that adds a fuel/nitrous mixture behind the MAF sensor. Since the mixture is already metered to the correct air/fuel ratio, the MAF does not need to see it to make any mixture changes.
 








 
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