Hypermilling on LPG

[Phantom]

I believe that LPG should have an AFR of ~15.7.

[pmiulian]

I went today for a tune-up. So the diagnose / calibration software showed that the system and the car are in very good shape and everything is ok.
The guy from the shop said that it might have to do with the plugs. I will change them as soon as I can and see if there is any difference.
Except for that it seems that the only problem with the low FE is the driver ( me ).

[niky]

Yup. Go one step colder, at least.

The rest will be up to your driving style.

If you want to look at improving performance, check how your vaporizer is connected... sometimes the car's standard thermostat blocks off the coolant bypass route that takes hot coolant to the vaporizer. You'll want to check that out. If you can keep vaporizer temperature as warm as possible, that will improve LPG stability.

[pmiulian]

The car has 2 coolant circuits. The small one, is connected all the time to the engine block and to the heater core. The large circuit, is opened by the thermostat only when the coolant from the small circuit heats up too much. The vaporizer is connected on the small circuit. So there isn't much room for improvement there.
I do get the impression that a CAI would help. The outside temperature dropped a little these days and the engine seems to be running a little better.
Also, there is a dramatic improvement when I start with the engine already warmed up.
I have to investigate a series of mods to keep the engine warm for a longer time and to make it warm-up faster.

[Peter7307]

pmiulian,
I have LPG on my car and also have a slight drop with LPG when I run on that.
The difference is around 10% (around 8.0 or so on unleaded and around 9.0 or so on LPG).

One thing to check is the spark plug leads as well as the plugs.
ANY weakness in the ignition side will usually show up as an erratic idle or slight miss with the car at idle.

Welcome to the place as well by the way.

Peter.

[pmiulian]

Well, I did the computer diagnose and everything seemed fine. The spark plugs are new and the idle is fine.

I think it has to do with the engine temperature also.

[pmiulian]

Here`s an ideea I had for keeping the engine warm when not running. Since building an automatic grill block is complicated, what if I mounted some engine bay insulation with a trap door ( in the back of the grill ), so that the trap door would be opened/closed by pulling the parking brake ? So when pulling the parking brake, the door would close.
Just an ideea.

[D.O.G.]

Originally Posted by pmiulian

Here`s an ideea I had for keeping the engine warm when not running. Since building an automatic grill block is complicated, what if I mounted some engine bay insulation with a trap door ( in the back of the grill ), so that the trap door would be opened/closed by pulling the parking brake ? So when pulling the parking brake, the door would close.
Just an ideea.

Maybe use a bicycle brake cable (or similar) from the trap door to a knob mounted near the bonnet/hood release?
That way you have the option of leaving it open in summer.

[niky]

Be careful. Some LPG injector systems have electronics that aren't quite as robust as OEM gasoline equipment, so if you let it get too hot, you might fry something (not literally...).

Why not a block heater? Just throwing it out there.

Also, even if the LPG installer has tuned the engine for best economy, it's not tuned for best power. If you can get to a shop with a dynamometer and bring the installer's laptop, they can tune to give you a bit of extra power. Power by itself doesn't make for better economy, but having a little more kick gets you up to cruising speed quicker, which does.

[pmiulian]

@D.O.G. - I was thinking the same, about using some bicycle parts. Actually I tried making an automatic system - I bought a thermostat which I would use to open the grill block. Unfortunately the thermostat that I bought I meant for 89 degrees C and my coolant has a temp of about 82.
And the summer wouldn't be a problem since the grill block would close only when the engine is stopped.

@Nicky I can't use a block heater, I don't live in a house - I live in a flat, and the parking space is about 100 m away. Also, I don't really like the idea of a block heater - is like cheating .

After the tune-up I did a refill and the FE for urban driving is about 7.8 l / 100km - that is about 30 mpg. Which is pretty good - it's above the factory rating.