Why are some cars able to start cold on lpg?
Do they have a heating element in the converter so they dont need hot coolant?

nop they are just tuned for cold start

and there no choke

I have a V8 Holden WB that is on straight gas and it starts first time , hot or cold.
I am pretty certain that my machanic said that is has a cold start curcuit.
Without a cold start curcuit it would be nearly impossible to tune for both a hot and cold start.

I understand what your saying, but im not asking about a choke system on lpg. What im talking about is how is the converter suppose to work without hot coolant flowing through it?

I got 100kms with no coolant, the converter then froze up but it doesnt freeze instantly.

Ascension, liquid LPG is minus a-lot-of-degrees while coolant, even with a cold engine, will be over zero. The secret is the DIFFERENCE in temperature, not just the temperature of the "heating" part of the heat exchanger. This same theory is why air conditioners still work when it's 40 degrees outside.

At the same time, I have heard of a bloke who had a 308 Holden ute on LPG. Every winter morning after a night shift in the Wollongong mines, he'd start the ute and BLAST OFF down the road. And nearly every winter morning, he'd be seen at the front gate of the mine with a frozen converter!

Yeah I understand that, the lpg is under high pressure, the second it comes out of that pressure it will turn into gas just because of the difference of boiling points under different pressures. The hot coolant is just there to stop the thing from freezing over.

But every dual fuel setup i have seen, if the engine is cold and you try to start it on LPG you have to sit there cranking the motor and pressing the pedal for a while then it still runs like **** till it warms up a bit. (maybe this is just the few systems ive had expereince with are old)
But a mates VH which was on straight gas, when you'd start it, doesnt matter how cold it was, it would start straight away like a normal petrol car.

So this is still just a matter of tuning?

if the fuel mixture is richer it will make a easy start

some convertor can have a eletronic primer or a button type

last car i had on lpg if it didnt start id have to pop the bonnet and press the primer and then it would start straight away

the anti freeze in the motor helps stop the convertor freezing the gas goes down to about -40deg but with a thermostate in the motor the water will quickly warm up and stop the convertor icing up

My car starts cold on LPG just as fast as it starts on petrol. And as far as I know, I don't have petrol start.
I believe it is the positioning of the gas convertor.

On my TR, the gas convertor was on one side of the engine bay with a long tube running across the engine bay to the intake, you had to crank it a fair bit in the mornings.

On my TL, the convertor is positioned right where the gas goes into the mixer, my theory being that the gas gets into the engine much faster. Engine starts cold on gas straight away!