Dag-dag - LPG injection

[Greg_S]

I use to have my old cavalier SRI 2.0 8V on LPG, was brilliant since I was doing about 35k a year at the time, was a basic carbeurtation system, again quite primitive but worked perfectly well.

I know what you mean, but it kind of defeats the purpose....

When I was working on fitting my own LPG kits, if the system switched to petrol on load there was a problem with the system, either electronically or the vaporiser was too small for the application.

LPG is the route for more power. Whilst it does have a lower calorific value to petrol, it buns colder..Thus great for turbo applications. Just the whole fueling parimeters that need to be sorted out under boost.

Once converted a 1.0 Polo Mk4 to LPG, and with Petrol and LPG tanks full you could do approx 700 miles on a run without filling up either tanks....Would only pull 90 mph on LPG though...But it was an open loop system, so very primative.

[bernsaudi]

All I can say :
To run lpg at the same power figures, you will use more than petrol, roughly 14%, and the timing has to be adjusted to suit.If you dont do the timing(ie leaving it at petrol setting) you will not get the same power compared even to 95 octane fuel. Its all about timing, said the tart to the vicar.
turbo engines dont run 'closed loop' when cold, or at full tilt(not strictly true, there is still lambda control but nowhere near as precise as normally aspirated).
I've been in and around the uk lpg industry since 1999, and turbos engin cars have always been awkward to do, because of the fact the engines manifold pressure is never static, unlike generators and such.
Single point injection is not inferior to multipoint, and multipoint only really exists because of all the sophisticated crap that had to be fitted to PETROL engines to comply with the emissions directives given over by california and europe. However you get what you pay for with gas hardware, irrespective of what you may be charged by an autogas installer to convert a vehicle.

One of the best solutions I found was a system called jehin, which never gained popularity due to the immense wiring job you had to do to fit it, but it used a mechanical main jet and a pwm injector to control 15-20% of the whole operation of carburration.

Euro4 engines basically consider each cylinder as an engine in itself, so fitting gas on one means you have to intercept each cylinders fuel trim behaviour and follow it to make sure the vehicles onboard systems dont notice.

If I can find time, i will gas my motor with what I think is the answer to the audi 20v.
my car is about 280hp, so I'm going to use a reg that will deliver that at about 70%duty. It will be 'twin point injection', with one very nice gas carb fitted inline, with a gas injector fitted to deal with fuel trim. This will have to be done on the negative pressure side of the air intake. Backfires can happen using this way,but only because something is wrong(air leak, high ignition kva due to timing or running lean, ignition system faliureetc.
A multipoint injector system , fitted close to the previous injector housings, will work fine, but its got to have a strong pressure to overcome the pressure residing within the manifold at full tilt, so 1.5 bar to overcome plus 1 bar to inject.
I run 4 range rover for my business, with high quality ignition systems, and they give more power than petrol.
I wish more people would get into gas, but car companies dont want that.
Anyway I'll do my best with the car, and get back to you all.
cheers

[diesel des]

I built my on lpg kit for my mrk2 tdi golf. Worked fine, but since removed and fitted 2 turbos, and a larger diesel fuel pump instead.

Also have fitted a lpg kit to my UR s4. Not setup yet but will be soon. Vapourisor will do 450hp. Also 10 gas injectors. Car has gt2871R, etc and expect 350-400hp on gas. Should be no problem.

[diesel des]

Oh there was a guy on here(forgot his name) from Poland i think. Has a lpg s6 with gt30 etc. Saw a graph of 460+bhp....