Bi-Phase Liquid Propane Injected GMC Sierra Denali!!!!

Propane, Butane, LPG, GPL, C3H8, C4H10
Steptoe
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Re: Bi-Phase Liquid Propane Injected GMC Sierra Denali!!!!

Post by Steptoe »

but the vehicle computer expects to to see inputs from two sensors.
m8 I work with computers all day...last thing I want is to have to work with a bloody computerised car in my spare time
All my stuff is old school carb..the closest thing to a computer is the GM HEI module in the dizzy lol
I dont even have electric windows....my van doesnt even have a window winder it slides up and down...bulit that way in 1951. :shock:
I have to get my head around the whole stoich/lambda issue first.
I find it easier to work in one or the other...AFR I know where I am...
Check out wikapedia that has good explantions of how O2 converts to lamba...but keep in mind if reading petrol lamba. lpg lamba will be wrong.
My Spelling is Not Incorrect...It's 'Creative'

jpgmtech
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Re: Bi-Phase Liquid Propane Injected GMC Sierra Denali!!!!

Post by jpgmtech »

The narrow-bands are the only units that will work with the stock VCM. Closed loop mode will automatically shoot for stoich (or 1.0 Lamda) regardless of the fuel used during cruise. That means that closed loop fuelling will shoot for 15.7:1 on propane automatically. I'm not sure that disabling closed loop and manually tuning for leaner cruise values would be very effective, for the reason that the injector flow rates do not appear to remain constant - more explanation below.

The PE tables are calculated open loop, and are not always bang on if you log with a wideband. I would recommend putting in a wideband and checking the actual fuelling under PE.

The other problem I have had with that truck which may be part of your cold-start issues is the injector flow rate drifting around. It was starting absolutely perfectly in all conditions the first time I tuned it. It came back in a few months with starting issues. I retuned it again, worked ok but not perfect. He replaced the injectors for misfires and other driveability concerns, and I retuned it again - again it started perfectly for a while. So you may find yourself tweaking quite a bit. Monitor your fuel trim values, shouldn't go too much beyond +/- 12% with those injectors or you know something is drifting. I had also thought that fuel pressure could be somewhat variable with temperature with that unit, and that could also be one cause of injector flow rate drift.

jpgmtech
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Re: Bi-Phase Liquid Propane Injected GMC Sierra Denali!!!!

Post by jpgmtech »

turbine guy wrote:Throttle response was very soggy, which is typical of all GM trucks, 2001 through 2006. I reduced a lot of the torque management in the transmission tables which has helped considerably. Throttle response is now just about on-par with the pre-2001 cable actuated throttle GM trucks.
Hmm... throttle response was anything but soggy when I last tuned it. Something is moving around on you.

Joel

turbine guy
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Re: Bi-Phase Liquid Propane Injected GMC Sierra Denali!!!!

Post by turbine guy »

Joel,

Thanks for the tips. Likely I will have a "winter" and a "summer" tune, to roughly follow fuel rail pressure. The truck was definately sick when I first picked it up. Would not start cold, and throttle response was quite lazy.
It's doing much better now though. I understand the stoich issue better now too, and to clarify, I do not plan to force open loop. If the stock norrow band O2s will run propane stoich in closed loop, good enough for me. I have a wide band sitting here that was planned for another project, but it will be going in the Denali, just to see what things are doing. Right now, I'm getting good crossover switching on the stock narrow bands, so things should be ok, but I like to see what is going on with a calibrated wide band too.
Throttle response is a relative term. My daughter's '99 6.0l Silverado 2500, with cable actuated throttle makes the Denali seem weak by comparison. As does my '05 Trailblazer SS. By reducing much of the heavy handed torque management, the throttle response is now much better, and I've successfully used these tables on quite a few '01 through '06 Sierras and Silverados without a cooked transmission yet.
BTW, I've picked up a couple ex-Shwans Bi-Phase liquid injection kits, and now have lots of parts and injectors to play with. I'm looking at potentially fitting another one of my trucks with liquid injection.

Robin Sipe.

turbine guy
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Location: Fort St. John, BC Canada

Re: Bi-Phase Liquid Propane Injected GMC Sierra Denali!!!!

Post by turbine guy »

Back from the dead. (Post subject that is.) A new question, where does one find the "additive" to reduce polymer biuldup in the liquid injectors? How does Roush get around this issue, does he offer additive to the customers who purchase his liquid injection trucks? How about Shwans, does anyone know if they put additives in their tanks to prevent injector fouling? (Franz, I send you a PM on this subject.)
Propane available locally seems to be quite good, but occasionally we will get a stinky load delivered and there can be quite a bit of junk come off the bottom of the tank. Obviously, this can't be good for liquid injectors.

Robin Sipe.

Steptoe
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Re: Bi-Phase Liquid Propane Injected GMC Sierra Denali!!!!

Post by Steptoe »

Stinky.. The chemical added for the stink is Styrial mecaptain and in VERY small amounts...This is a surfactant..ie a detergent type chemical often used in window cleaning products like the old pink windowlene.
As to poloymer build up...There are also lubricants added into liquid LPG to lubricate pumps..which tend to drop out in convertors if mounted incorrectly over very high milage...
As build up in tanks..this doesnt happen.....
It does happen on heater and non automotive tanks because the vapour is taken off from the top where as automotive is like a petrol tank and takes off from the bottom, maintaining a clean tank.
Mercaptan is added in very accruate amonts in bulk tanks....do some basic math and one soon sees to add small amounts to a very large bulk, expremently high accrucaies can be easy obtained with very inccruate scales...therefore errors or tollerances are insignificant.....
u will find a 'stinky' batch can be put down to atmoshereic conditions on that day.

I did a lot of work on filtering lpg blends thru micro seive columns to allow it to be used as proleents in pruducts like air fresheners, polishes etc.
My Spelling is Not Incorrect...It's 'Creative'

turbine guy
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Re: Bi-Phase Liquid Propane Injected GMC Sierra Denali!!!!

Post by turbine guy »

Thanks step toe, I've worked in the gas industry for many years and am familiar with Captan and Mercaptans. When i say "stinky", I mean really stinky, as in condensates. Regarding polymers, Turbocohen on Eng-Tips website talks about an additive being needed with liquid injection systems to prevent injector fouling. I'm just following up on this subject with you guys.

Robin Sipe.

MLGPropane2
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Re: Bi-Phase Liquid Propane Injected GMC Sierra Denali!!!!

Post by MLGPropane2 »

turbinguy

Roush uses an onboard Liquid Phase Coalescing filter. Energy Additives, has manufactured

LPG additives for many years. All US gasoline has "scrubbing agents" Example Chevron

Techron. these are usually "Amines" which remove the Olefin's...that could repolemerize

and build deposits on intake valves and spark plugs. Propylene (Propene) is an Olefin

Best Regards

Roger

turbine guy
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Re: Bi-Phase Liquid Propane Injected GMC Sierra Denali!!!!

Post by turbine guy »

Thanks Roger. I will take a look at Roush's filter, and maybe incorporate something along those lines. So far the consensus is; No additives needed. Or, that they are ineffective, and/or dubious results.

Robin Sipe.

MLGPropane2
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Re: Bi-Phase Liquid Propane Injected GMC Sierra Denali!!!!

Post by MLGPropane2 »

turbine guy

"no additives needed" I agree..especially in Canada..where there is only

one grade of LPG..that is unlike here in Calif...one grade for Commercial / Residential

and another spec for Engine Fuel. The Sarnia (chemical valley) pipeline provides Canada

with some of the cleanest LPG in the World.

Best Regards

Roger

patooyee
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Re: Bi-Phase Liquid Propane Injected GMC Sierra Denali!!!!

Post by patooyee »

Am I understanding this conversion correctly? You just ran a line from the tank to the fuel rails with no pump? What injectors were used? Stock?

C3H8
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Re: Bi-Phase Liquid Propane Injected GMC Sierra Denali!!!!

Post by C3H8 »

It's not quite that simple. The BiPhase system was developed in Minnesota by a man named Dave Bennet. He wanted to run LPG off the factory computer. Initially he designed it on Ford products including the Crown Vic, E series van and then the F series trucks. His initial target was the Police CV's, and one ton E series. He had a tank designed that had an integral fuel pump. His fuel lines were unique in that the return line was inside the delivery line. It was routed to a fuel rail that looked very much like a gasoline fuel rail. The purpose behind the return line being inside the delivery line was the delivery fuel cooed the return fuel so it did not heat up the fuel in the tank too much. The fuel rail has a pressure reg to maintain the proper pressure for the injectors and then send the excess fuel back to the tank through the return line. I believe but can't quite remember exactly that the pressure was kept at about 35 PSI over tank pressure. Once he had this worked out he manufactured new injectors carefully sized for fuel flow for a specific engine with liquid propane. He had to overcome several issues common with LPI., LPI systems tend to vapourize the fuel in the lines during shutdowm leading to hot start issues. Proper starts required turning the key on for several seconds and waiting for liquid to purge the lines. A surmountable but annoying issue to owners. One of his solutions was to add a remote unlock to the kit which also cause the pumps to start up and purge the lines before the operator reached the vehicle.

Eventually he sold the company to an ice cream delivery company called Schwans. They ran thousands of vehicles on LPG. All of them were GM Top Kicks with 454 engines. They carried on his work in developing the kit for there own units. They considered selling kits but the price offered to dealers was very high. Retail price would have been in the 12K area.

A similar system was actually designed by Chrysler on its B250 vans. They used a Thiokol aluminum tank and had two fuel pumps in it. They also used 35 PSI delivery pressure but had separate delivery lines. They programmed there ECU to use injectors similar to the gasoline.

turbine guy
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Re: Bi-Phase Liquid Propane Injected GMC Sierra Denali!!!!

Post by turbine guy »

Bringing this old thread back to life, yes, I still own and drive this vehicle, the Bi-Phase system is still functioning well! I did change the heads on this engine (2005 GMC Denali, with the Q-Code 345 hp 6.0l engine.) due to intake seat recession. (All 8 cylinders were affected.) at 118,000km. I went to the newer spec L97 type heads from a 405 HP 6.2l Escalade engine, which have higher flowing intake ports/larger intake valves. This truck now has 131,000km total accumulation. My observations of owning a dedicated liquid-injection vehicle: There is no compensation for the change in liquid propane btu content per volume per temperature. What this means is (And it was counter-intuitive for me at first.) that when it is cold outside (Below-6c) the on-board computer cannot reduce the short term & long term fuel trims enough, and the engine runs too rich, tripping a MIL light. When its warm out in Summer (above +25c) the opposite happens and the truck runs "lean", with the short & long term fuel trims adding as much fuel as the computer can. I don't know if newer Schwans 8.1l conversions, or if the Roush Ford conversions addressed this issue, but for the circa 2005 B-Phase systems, this was an oversight. As I am reasonably proficient with HP Tuners (ECM reprogramming software.), I simply dump in a "Winter Tune" in autumn, telling the ECM that the injectors are larger than they actually are, and in Spring, dump in a "Summer Tune" telling the ECM that the injectors are slightly smaller than they actually are. When the tuning is correct, this vehicle runs very strongly, total horsepower likely somewhere between the original 345 Q-code 6.0l and the 405 6.2l engines. Over the years, I have accumulated several sets of liquid propane injectors, fuel rails, tanks and pumps. Not sure what exactly why, but its a hobby.
Turbine Guy.

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