TOO-NING !!

Propane, Butane, LPG, GPL, C3H8, C4H10
itsmejto
Posts: 65
Joined: Sun May 21, 2006 2:43 am

TOO-NING !!

Post by itsmejto »

The Hemi is now running well after a week or so of driving and adjusting the settings it now seems to run smoothly.Changeover from gasoline to LPG and back is fine, it idles well, pulls well but with some noticeable loss of performance that I think should be expected with LPG, not a whole lot, but just noticeable, especially at the lower end of the rev range. I'm satisfied with the way it runs overall now. I do have a couple of questions for the resident Guru's.
I bought one of those engine computer "tweaks" which allows you to change various fixed parameters in the main ECU for performance/towing and low octane gasoline among a few other things.
My question is, as the Hemi was designed to run on mid octane gasoline, would running on LPG benefit in any way by setting it up for use with low octane gasoline settings or performance settings which would require 93 octane fuel ? I'm not really interested in high performance as the reason for converting to LPG was for overall running cost reductions. So which setting would the LPG prefer is my real question ? The original gasoline mileage was averaging about 14/15mpg, but after setting up the LPG ecu for optimum running and smoothness etc it now seems to have degraded to an average of about 10/11mpg which I feel is a tad on the low side, so I'm trying to re-tweak it for optimum mpg rather than performance.
Johnny O

franz
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octane

Post by franz »

LPG has 104 octane so setting your tweek to higher octane would indeed help. Since your gasoline system uses an oxygen sensor, if you can nudge the AF mixture readings a tad leaner, that would also help with mileage and not significantly affect performance. Just realize that the O2 sensor will try and pull it back to stoich. If you get too far out of range, the injector pulse width will not have enough authority to control.

Franz

sleepybu
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Post by sleepybu »

is this a vapor system :?

itsmejto
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Post by itsmejto »

Hmmm, I'll try that, though I'm not too sure how to lean the mixture with the available software without effecting the now smooth running and performance. The injector pulse width and timing for the LPG is controlled by the existing injector signals from the Dodge ECU and re-timed by the Voltran ecu, presumable that increases and decreases them depending on a few things, mainly the vacuum which is directly connected to the ecu and vaporize, this together with the main ecu sensors set the parameters required to time things correctly. The Voltran ECU does nothing to set the ignition timing which must be set from the main ecu according to the signals it receives from it's own sensors.
SLEEPY, it's an 8 injected vapor system.
Johnny O

Frank
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Post by Frank »

Does this reprogrammer adjust settings in the Dodge ECU or the Voltran ECU? It sounds as if it adjusts the Dodge ECU's programming. My understanding is modern dual fuel conversions take the OEM injector signals and modify them to properly control the propane injectors so the engine thinks it is still running on gasoline. The OEM ECU adjusts the timing automatically to take advantage of propane's higher octane to the maximum programmed into the timing map based on knock (or lack thereof) sensed by the knock sensor.

If you were able to adjust the Dodge ECU's fuel and ignition maps for optimum LPG operation, your gasoline emissions and fuel economy may suffer. If possible, I would keep a copy of the OEM programming in case you need to start over again or to get an emissions test.

If your ECU reprogrammer has access to both the fuel and timing maps, I would first try to lean out the fuel mixture before making any changes to the timing map.

itsmejto
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Post by itsmejto »

Frank, the programmer is one of the commercially available things that re-maps the timing etc in the dodge ecu with a specific program that is not adjustable by me, it saves the original programming so you can return it to stock if you want to. Offers 3 different programs for economy/towing/performance. I may be confusing you guys, but the LPG system is as you say, makes the original ecu think the engine is still running on gasoline and makes it's own modifications to the LPG injectors etc. I was asking if the higher performance program would benefit the LPG in any way. I would indeed appreciate another opinion.
Johnny O

Frank
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Post by Frank »

Do you know what the differences are between the various programs? Without knowing what each option does exactly makes it hard to say which would be the best. If you can easily change back and forth and back to original, try one out and see how it works. My guess is that the economy option runs a generally leaner mixture with possibly more advance.

Are you sure there isn't a custom set-up option in addition to the 3 listed?

franz
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program

Post by franz »

If the OEM ECU is modifiable between 3 different programs, one of them being a higher octane-high performance setting, I would select that one since it will probably tweak the timing a bit to take advantage of gasoline 93 octane, just what you want for LPG use.

Franz

gravespropane
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Post by gravespropane »

Johnny,

Keep in mind that a gallon of propane has about 25% less energy than a gallon of gasoline. Just using the btu conversion for 14mpg on gasoline 10mpg is where it should be. You can try to adjust your lp computer to lean the mixture a little but the factory Dodge ecu will try to bring it back to stoich like Franz mentioned. I would try to find a tuner that lets you change the timing, your going to want to add as much as you can to take advantage of the higher octane. This in turn will give you a little better mileage( you also might want to keep the tuner in the truck, because when you switch back to gasoline it will ping like crazy on the regular 87 octane stuff). I know that Diablo makes one for Fords so I imagine they would have one for your truck.

I had a similar issue on my personal truck. I have a vapor injection system and am getting 10mpg on LP. My other truck which has the same engine is getting 12mpg on propane, but it has a older style draw through setup. I tried leaning the LP computer but did not gain much mileage. I even tried it down to the point the GM computer tripped the check engine light for too lean and it still didnt help that much. All it did was make the truck run poorly. The only other suggestions I would have is to maybe try a cold air intake and better exhaust.

John

C3H8
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Too-ning

Post by C3H8 »

I agree with Franz. Go after the timing. The fuel mixtures are self adjusting. As for power ,the Voltran vaporizer is maxed out for your engine. They are only good for about 230 HP SAE. Solution, 2 methods. Add another vap. or Voltran has built in a function called split fuel into their ECU. This function allows the use of gas and LPG together if you really cranking on the gas. This gives you your power back and prevents valve recession. Did you get any material on this when they sent you the kit. If not I will have this information in the next few weeks.

itsmejto
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Joined: Sun May 21, 2006 2:43 am

Post by itsmejto »

I tried leaning out the fuel in the Voltran ECU best i could, to the point where it was tripping the Dodge ECU on lean fuel mixtures, so I backed it off a little and it did improve the mileage a small amount, though not enough to make even 1mpg difference. The Hyper-tech ecu tuner he also recommended using the "performance setting" as it advances the ignition somewhat. I haven't managed to find any other ignition mods for the 2003 hemi as yet, though I will keep looking. He also recommended changing the plugs (16 of em) what a chore that will be, for regular style, ie" not the skinny platinum type it has from the factory, told me to decrease the spark gap a little too. i have not as yet tried this as I'm in need of some advice on which ones to use (hint hint)
C3H8, I also did experience some ignition errors set in the dodge ECU while running on LPG, so maybe that's another thing to try. I DO like the idea of using another Voltran vaporizer and I do have a second one same as the original, though not too sure how to connect the second set of pressure and temp wires, if even needed after initial setup of the pressure I guess they may not need two sets of inputs. I'm currently running way above the original specs for pressure too, he recommended 120kpa in the instructions, but then told me to set it to 170kpa, maybe because of the HP limits ? if it can't handle this beast of an engine ... I'd like to see whatever info you could get to me though, sounds interesting .
lastly, I would like to say it does run very well, even at W.O.T. and only seems a tad lumpy in the mid range. Idles smoothly and switches from gasoline to LPG well now. The Voltran software doesn't actually seem to do a whole lot other than allow for a smooth idle, If I tweak it a little to try to get it leaner or richer in the mid to high ranges, the idle goes all to hell. he does insist this kit is good for up to 400hp, is he bending the truth somewhat ?
Johnny O

sleepybu
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Post by sleepybu »

itsmejto wrote: ... he does insist this kit is good for up to 400hp, is he bending the truth somewhat ?
maybe for a minut or two :?

C3H8
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Voltran

Post by C3H8 »

Who's he your referring to (not the name)? Is this a Voltran tech or a NA rep. Voltran factory says 170 Kilowatt max. A KW is .75 HP. 170 KW is about 230 HP. Not sure about the sensor arrangement. I won't be receiving the info from the factory for a few more weeks. I'll post as soon as I get more info.

itsmejto
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Joined: Sun May 21, 2006 2:43 am

Post by itsmejto »

The specs were from a UK reseller, not the Voltran site.
This is a direct quote from the resellers web site in the UK where I bought it all from. He has been very helpful with tech support and suggestions, though I would have thought he would be aware that the parts he sold me were not quite up to the job and tried to sell me a dual vaporizer anyway.

http://www.wtvuk.com

Front End Only --- Engine Kits & Spares, etc.
Step 1: Select Engine Kit & Necessary Parts
Voltran V-SGi or Omvl 21N Engine Kits
3 cylinder Engine Kit Engines up to 135 HP -------- 170 HP on Turbo engines V-SGi £463.00
4 cylinder Engine Kit Engines up to 180 HP -------- 225 bhp on Turbo engines V-SGi £463.00
5 cylinder Engine Kit Engines up to 225 HP -------- 280 bhp on Turbo engines V-Sig £570.00
6 cylinder Engine Kit Engines up to 270 HP -------- 335 HP on Turbo engines V-SGi £570.00
8 cylinder Engine Kit Engines up to 360 HP -------- 450 HP on Turbo engines V-SGi £682.00
10 cylinder Engine Kit Engines up to 450 HP -------- 560 HP on Turbo engines V-SGi £1125.00
12 cylinder Engine Kit Engines up to 540 HP -------- 675 HP on Turbo engines V-SGi £1125.00

It does look like he is overstepping the specs somewhat. Hmmmmm !!!!!
at 360HP he is right on the max HP and just about what the Hemi is rated at. Maybe the twin vaporizer would help.
Johnny O

itsmejto
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Joined: Sun May 21, 2006 2:43 am

Post by itsmejto »

RE: SPECS

After a little more research it seems the rated HP max specs for these units are quoted for 4 Cly. engines and may be doubled for an 8 Cly. The regulator/vaporizer is good for 600 hp if installed and heated correctly.
Voltran make 3 sizes of injectors and say it can handle up to an 8 liter v12 with ease.
Johnny O

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