turbo with LPG?

[xlr8_87]

just wondering what the issues are with putting a turbo on an LPG car??

would it need some work with the computer?

and regarding injection of LPG, would it still be injected into the intake pipe, in the attached pic would it be after the BOV?



just any info would be awesome cheers guys

[VN_Luke]

I could be 100% wrong here

I was under the impression that lpg injection worked on pressure in the LPG tank, and vacuum of the motor sucking in the LPG from the tank...

once you're in a booooooosty goodness atmosphere, you would be blowing back lpg and air into the lpg tank, by means of a traditional setup!

do some reading on calaisturbo about a car GAS 747? or LPG 747 or something to that extent...

there's also an 11 second XE falcon blue thing scooting around on LPG with a turbo on it on fullboost.com.au (a while ago)

reading is your friend.

[somerandom]

there is a first 9 second turbo car on LPG - XE Falcon so anything is possible

[somerandom]

Originally Posted by VP_Luke

there's also an 11 second XE falcon blue thing scooting around on LPG with a turbo on it on fullboost.com.au (a while ago)

reading is your friend.

i need to correct you sorry :P

Jason's Ghiller's 4.0-litre turbocharged XE Falcon going 9.97 at 132mph. This is the first car in Australia to run a 9-second pass on LP Gas fuel.

will post video when i upload it cause you can't direct link from fullboost cause you need an account

[Cheap6]

The details depend on which particular type of LPG system we are referring to.

The pressure in the LPG tank will always be much greater than that in the intake system = not possible to blow back into tank, regardless of whatever else is also in the way of that occurring.

If the pressure regulator/convertor is referenced to the pressure between the turbo compressor and the t'body, the pressure regulator/convertor will simply behave as if it were operating in a (very deep ) mineshaft.

Ignition timing changes will need to be made within the ECM, as they would be for a turbo engine on petrol.

[vn6pwr]

I've actually heard of gas injection setups, like fuel injection. Whether or not they retain the factory computer im not sure but they would be far better IMO.

[VN_Luke]

i need to correct you sorry :P

Jason's Ghiller's 4.0-litre turbocharged XE Falcon going 9.97 at 132mph. This is the first car in Australia to run a 9-second pass on LP Gas fuel.

fair enough! I swear last time i read about it (2 years ago?), it was running 11's on a stock bottom end? turboed, on gas?

Regardless, TOP EFFORT by the owner!

[xlr8_87]

i might have to go into Gas Research and talk to them, will posting a pic of my current engine/LPG setup help in answering?

thanks for the help so far

[Doctor Bob]

A mate of mine has a 1948 Anglia with a 1GG toyota turbo engine in it straight gas & ran 12.4 at the nostalgia drags the other week.
the LPG needs extra time to tune but its ok.

Rob

[Cheap6]

Originally Posted by vn6pwr

I've actually heard of gas injection setups, like fuel injection. Whether or not they retain the factory computer im not sure but they would be far better IMO.

Most gas injection systems use a stand alone computer for the gas side. Better? Yes. They are significantly more expensive than the carb. or gas ring systems though.

Originally Posted by xlr8_87

Regarding injection of LPG, would it still be injected into the intake pipe, in the attached pic would it be after the BOV?

Sorry, negelected to answer this. Yes, the gas will need to be introduced downstream of the BOV. Not doing so will result in venting of a fuel/air mix into the atmosphere (which will require the local fire station on speed dial on your mobile) and an excessively rich mixture as well if fed back into the compressor inlet.

In non injected LPG systems, it is desirable to locate the mixer or gas ring close to the throttle body to allow better control over fuel mixture anyway. Not doing so is one reason for backfires in poorly thought out gas systems.

Originally Posted by xlr8_87

i might have to go into Gas Research and talk to them, will posting a pic of my current engine/LPG setup help in answering?

A pic and/or short description won't hurt .

[xlr8_87]

cant describe it as i have noooo idea about them, but here's a pic of the engine bay/setup

[Cheap6]

This is an Impco system.

To get it to work under boost, the atmospheric vent from the Fuel Control Valve (FCV) needs to be connected to the inlet duct, in a position where it 'sees' static pressure, not a reduced venturi pressure generated by flow in the duct - at the end of an elbow is good, where there is a change of flow direction - and leave everything else where it is (see below for components). The FCV is the solenoid valve located on top of the LH strut tower.

The vacuum switch on the manifold, which responds to mixer venturi vacuum and cuts LPG supply with the engine off, will be difficult to reference to boost pressure, so it will need to be replaced with a frequency switch that detects engine rpm set to about 500 rpm (25Hz). I am using a Jaycar kit, but there are others around.


For an explanation:

The LPG, as a liquid, goes into the convertor/pressure regulator, mounted just in front of the LH strut tower. In two stages, the LPG is reduced in pressure and allowed to evaporate. The heat energy for evaporation is provided by the hoses hooked into the heater pipes. The final gas pressure out of the convertor is referenced to atmospheric pressure via the ~1/2" hose leading out of the top of the convertor to the FCV and the vent that is attached to the FCV.

In an open loop system the hose would be simply left open to the atmosphere at all times. In a closed loop system, it is normally open to the atmosphere but venturi vacuum is applied when the FCV is actuated, reducing the pressure above the diaphram and the gas pressure out.

The convertor functions similarly to the fuel pressure regulator in a petrol EFI system, using a counteracting spring and a diaphram referenced to the fluid pressures to operate a bleed valve. The difference is that, with the FCV closed, it is referenced to atmospheric pressure rather than manifold pressure. It therefore supplies a constant gas pressure to the mixer for a given pressure above the diaphram which will be atmospheric in open loop operation, less when venturi vacuum is applied via the FCV.

This is, as it should be, a system operating with closed loop mixture control. When actuated, the FCV bleeds venturi pressure (vacuum) from the mixer to above the convertor/pressure regulator diaphram, hence reducing the gas delivery pressure to the mixer and leaning off the mixture. In a boosted system the venturi pressure relative to the atmosphere will be higher than no-boost but still low relative to the pressure in the intake duct, which is what matters when that is what is also applied to the convertor diaphram.

As stated, the convertor diaphram, via the vent off the FCV, will have to be referenced to pressure in the intake duct prior to the t'body. Under non-boost conditions, this will be close to atmospheric pressure anyway and operate as it does now. Under boosted conditions it will 'see' the same pressure as the mixer, (not necessarily the engine, which will be throttled) and automatically increase the LP gas pressure to the mixer. Since the mixer draws in a constant volume of gas relative to the volume of air passing through it, the increased pressures and densities balance out.

The FCV is pulsed with a duty cycle by the gas computer operating in closed loop with the O2 sensor voltage as feedback. The gas computer is not obvious in the photo, but the simplest ones are about 1/2 the size of cigarette packet, the more complex ones, with self learning, a bit smaller than the size of an old VHS tape.

The gas carb - mixer - is the item mounted close to the t'body. This where the baseline fuel mixture is determined. It works like a petrol constant downdraught carb. but with a bullet shaped plug ~20mm dia., instead of a needle, connected to the piston. This fits into the open end of a short pipe connected to the gas supplied from the convertor, inside the mixer. The connection to the gas supply from the convertor is via the hose leading under the intake duct/pipe from the convertor.

The (bullet) shape of the plug alters the size of the hole opened as it moves out of the end of the short pipe in the mixer in response to venturi vacuum above the piston. This determines the fuel mixture relative to the position of the piston and gives mid range fuel mixtures.

The screw on top of the mixer is an air bypass and is used to adjust idle mixtures.

The large screw on the mixer where the gas enters, determines maximum gas flow and is used to adjust max power mixture.

Global mixture changes are made by the FCV and fuel computer. Baseline mixtures need to be set with the FCV unplugged from the computer.

All of that may seem somewhat complicated and assumes some prior knowledge but in order to design/modify and troubleshoot something it helps to understand it.

Any Qs and I'll post back.

[xlr8_87]

cheers for that info dude
got a bit confusing at times but i think i got it all...