LPG injection

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MAGP
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Re: LPG injection

Post by MAGP »

@Charlescrown, do you have links to any of these aftermarket retrofit liquid injection systems?
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Re: LPG injection

Post by bldnut »

MAGP I used Taurus injector blocks, I cant remember the settings I used as it was a long time ago, but I do remember that when we got it to start I played with the convertor pressure to get the best idle and then started playing with the settings and tunning, also the cold crank times and cold start had to be reduced a lot from normal engine running temp (eg if it ran at 4ms hot it needed to be 2-3ms cold, opposite of what you would expect from petrol), unfortunately I don't have a bin for it as it was on my laptop that got stolen 7 years ago. if you live in a cold area I would recommend pre heating the convertor to help cold start when the temp gets below 4c
MAGP
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Re: LPG injection

Post by MAGP »

Thanks for that, my intent was to get some Prins injectors and 2 regs, put 2 bins on a chip and use the LPG/Petrol switch to switch from 1 to the other.
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psyolent
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Re: LPG injection

Post by psyolent »

ok so reasonably old thread dig.
most vapour injection systems work on a positive pressure converter. the standard old school type convertors are not positive pressure, eg: B2, Impco etc.
these are readily available, as are the injectors.
problem i see is in injector impedance. the stock injectors are 12 ohm, at least on my v8 (give or take) - wired in their current config, the 808 will see 96 ohms of impedance.
with the current lpg injector offerings, 3 ohm is about standard, so 24 ohm in total. you'd need to add a 72 ohm resistor pack so that the 808 will see approx the right impedance (which isn't really the issue, more, the amperage that the driver can sustain before the chip gets too hot and fries) from there the respective tune would then need to be applied to the delco to drive the injectors for a period of time so that things work.
one thing i am unsure of is whether the new LPG injection systems are sequential or batch like the old delco. guessing sequential - so that functionality would be (lost) in the earlier 808 implementation.
how is my logic here?
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Greg aka Sir Burnie Tanington

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Re: LPG injection

Post by antus »

Most of them piggyback the petrol computer so all the factory logic still applys and you get a 2d table to tune petrol milliseconds to equivalent lpg milliseconds. Sorry not much idea about the rest.
Have you read the FAQ? For lots of information and links to significant threads see here: http://pcmhacking.net/forums/viewtopic.php?f=7&t=1396
MAGP
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Re: LPG injection

Post by MAGP »

It really doesn't matter how the injectors are fired, sequential or batch is neither here nor there unless you want sequential. The benefit if sequential is less chance of backfire at startup. Prins and IMPCO/BRC (and I assume Euro 4/5 setups) are all piggyback and work how the main ECU works. They do prefer sequential though. Other setups like Megasquirt fire the way the user designs the system. ProFire, from Perth WA, is sequential.

Injector impedance can be worked around if you fit a driver module to suit. The real problem is the temp/pressure of the LPG but even that can be worked around to a certain extent as indicated by bldnut.
vn5000
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Re: LPG injection

Post by vn5000 »

I converted an old vr 304 manual to dual fuel lpg vapour injection using 808 about 4 years ago
You don't add the injector resistance to get total resistance , they are wired in parallel , i built my own injector driver to drive the 3 ohm injectors using 4 hi power transistors
You can get a 808 to run petrol and lpg reasonably easily using $12p dual maps a and b
You can switch from lpg to petrol and vice versa at idle and not notice any stumble / difference , was excellent on lpg consumption as well
MAGP
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Re: LPG injection

Post by MAGP »

What injectors did you use vn5000?
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Re: LPG injection

Post by psyolent »

interesting. is it reasonable enough to assume that getting a 'signal' from the 808 driver then driving a daughterboard with low impedance trans/fets to drive the gas injectors would make this function?
Cheers,
Greg aka Sir Burnie Tanington

VX1 Berlina V6, VT1 Berlina V6 (Track), VN1 S V6, Hilux RN105 GMV8, Ford XP 170.
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psyolent
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Re: LPG injection

Post by psyolent »

here we are :

http://www.msextra.com/forums/viewtopic ... 67&t=19661
Since the hi-res MS1/extra code can't do a PWM signal on the injectors, the only solution with the standard MS injector drivers is to either use hi-z injectors or use inline resistors. This board allows the use of low-z injectors without any resistors and without setting up any PWM parameter since the chip (LM1949) the board is based on takes care of setting the current correctly no matter what the battery voltage is or what injector is there.
Cheers,
Greg aka Sir Burnie Tanington

VX1 Berlina V6, VT1 Berlina V6 (Track), VN1 S V6, Hilux RN105 GMV8, Ford XP 170.
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