LPG conversion

Joined
Feb 10, 2015
Messages
374
Location
Greece
Solely from an efficiency point of view (maximum horsepower for a fixed fuel consumption number) which LPG conversion kit is best for a naturally aspirated, indirect injection gasoline engine:
  1. A liquid state LPG injection system or a vapor state LPG injection system?
  2. A direct or an indirect injection LPG system? (Of course, if it is possible to choose a different type of injection than the engine's original one.)
Thanks in advance!
 
The service trucks for our electric co-op we LP way back in the late 80s. They didn't convert them until the throttle body injection pickup trucks came out. I can't be sure of how they were set up but my assumption is that the propane was still liquid until it reached the throttle body.
 
Solely from an efficiency point of view (maximum horsepower for a fixed fuel consumption number) which LPG conversion kit is best for a naturally aspirated, indirect injection gasoline engine:
  1. A liquid state LPG injection system or a vapor state LPG injection system?
  2. A direct or an indirect injection LPG system? (Of course, if it is possible to choose a different type of injection than the engine's original one.)
Thanks in advance!
not such thing as a liquid lpg injection systems for efi motor, (except for gdi).. it´s always a vaporiser and then injecting vapor phase.

///it seems dutch prins stopped making direct liquimax systems for gdi.. now only vaporiser systems are available,,,, :(
what a shame, you could run forever exclusively on lpg with that system...
 
Last edited:
not such thing as a liquid lpg injection systems for efi motor, (except for gdi).. it´s always a vaporiser and then injecting vapor phase.

///it seems dutch prins stopped making direct liquimax systems for gdi.. now only vaporiser systems are available,,,, :(
what a shame, you could run forever exclusively on lpg with that system...

Isn't LiquidSi a direct injection liquid phase kit?
 
i have not yet seen this. good find.(y)
injecting into port, liquid gas will vaporize and create freeze effect. cold intake has some benefits.
since it has no vaporiser, no service on that part. (rubber membrane replacement after 100 000km, 40€,,,)
any idea what is price difference ?
 
i have not yet seen this. good find.(y)
injecting into port, liquid gas will vaporize and create freeze effect. cold intake has some benefits.
since it has no vaporiser, no service on that part. (rubber membrane replacement after 100 000km, 40€,,,)
any idea what is price difference ?

As I read on a Greek forum its price in 2017 was 1500 € ($1639).

What about my original questions though? Should the conversion kit be the same type of injection as the engine or could the type of injection get converted too?
 
according to vialle pictures, you need separate lpg injectors. vialle injectors are special ones, two hoses.
pressure liquid input, and low pressure return to tank.
standard lpg systems (vaporiser) have one-input injectors. petrol injectors are untouched.

premium gdi lpg systems have switcher, where petrol or lpg is then sent to car´s gdi injectors.
(gdi motors have petrol injectors drilled inside head, like sparkplugs.)
therefore your question about direct or indirect lpg system, in efi motor is unclear. (you said you have efi motor)
 
according to vialle pictures, you need separate lpg injectors. vialle injectors are special ones, two hoses.
pressure liquid input, and low pressure return to tank.
standard lpg systems (vaporiser) have one-input injectors. petrol injectors are untouched.

premium gdi lpg systems have switcher, where petrol or lpg is then sent to car´s gdi injectors.
(gdi motors have petrol injectors drilled inside head, like sparkplugs.)
therefore your question about direct or indirect lpg system, in efi motor is unclear. (you said you have efi motor)
I have the 4A91 engine, which I think is MPI, right?

According to Vialle the Liquid SI is compatible with MPI engines.
 
Is parallel gasoline injection necessary for liquid LPG injection systems? Some companies use extra systems for valve lubrication and some LPG ECUs support parallel gasoline injection for valve protection purposes, but is it safe to run on LPG fuel alone if we talk about liquid phase LPG injection?
 
The service trucks for our electric co-op we LP way back in the late 80s. They didn't convert them until the throttle body injection pickup trucks came out. I can't be sure of how they were set up but my assumption is that the propane was still liquid until it reached the throttle body.
I would doubt it's still liquid leaving the propane tank.
 
lpg tanks are always sending liquid, classic systems use vaporizer, or it gets injected as liquid (but must have electric pump in tank.
Is parallel gasoline injection necessary for liquid LPG injection systems? Some companies use extra systems for valve lubrication and some LPG ECUs support parallel gasoline injection for valve protection purposes, but is it safe to run on LPG fuel alone if we talk about liquid phase LPG injection?
liquid systems reroute and switch between fuels, you´re using gas OR lpg.
vaporizer systems can use both fuels.
 
lpg tanks are always sending liquid, classic systems use vaporizer, or it gets injected as liquid (but must have electric pump in tank.

liquid systems reroute and switch between fuels, you´re using gas OR lpg.
vaporizer systems can use both fuels.
Liquid systems can assign time slots when gasoline injection takes place in every cycle, but is it necessary for the engine protection or not?
 
lpg is cleaner burning. dont bother with gasoline much.
Obviously, but the idea about the parallel use of gasoline hasn't anything to do with cleanliness. The claim is that the additives of the gasoline protect the valves and contribute to their longevity. As I said it is used as an alternative to systems that offer valve lubrication. I'm not sure how crucial this is. I'm sure though that LiquidSi's ECU has the ability to support "parallel" gasoline injection. Again, I'm not sure if that's a feature that should be utilized.
 
The claim is that the additives of the gasoline protect the valves and contribute to their longevity.
what chemistry exactly ?
problem is the material used in engine parts.
how do you know what kind of alloys were used ?
i´ve heard that subaru can recess valves even if ran only on gasoline. cutting corners ?
dacia/renault have same engine parts, no difference in lpg factory cars. no problems there...
unleaded fuel gives no protection on engine parts, like the leaded fuel did. (gasoline makes soot, it can protect against seat micropitting)

longtime scarecrow- valve flash lube...
read the msds, it contains same chemicals like lead replacement --> what cat&o2 sensor will say over time ??
vaccuum flashlube is the dumbest thing in universe. big vaccuum in manifold (idle)=big dose.
wot= almost nothing. :poop:
 
what chemistry exactly ?
problem is the material used in engine parts.
how do you know what kind of alloys were used ?
i´ve heard that subaru can recess valves even if ran only on gasoline. cutting corners ?
dacia/renault have same engine parts, no difference in lpg factory cars. no problems there...
unleaded fuel gives no protection on engine parts, like the leaded fuel did. (gasoline makes soot, it can protect against seat micropitting)
I don't know. Obviously there is a big difference between engines. There are some prone to problems and others that can be fine "forever".
Another claim is that adding gasoline keeps temperatures lower and that obviously slows down micro pitting.
I have no idea if these claims are true and in case they are if the difference is substantial.

longtime scarecrow- valve flash lube...
read the msds, it contains same chemicals like lead replacement --> what cat&o2 sensor will say over time ??
vaccuum flashlube is the dumbest thing in universe. big vaccuum in manifold (idle)=big dose.
wot= almost nothing. :poop:
There are lubrication systems with an ECU using a pump and not vacuum for delivering the lubricant. I already mentioned one: Prins ValveCare-DI. These systems obviously increase the lubricant's injection rate when the engine load increases.

Personally, I'm not interested in installing an extra lubrication system. I just want to make clear if adding gasoline has a benefit or not. As I mentioned LiquidSI's ECU supports "parallel" gasoline injection, so obviously there is a reason for it. Why does the ECU support that feature?
 
Back
Top