Hypermilling on LPG

[Rambenz]

Hi everyone,

I'm new on ecomodder and proud to be part of the community ! I just read this thread and have already two questions :
- Is it best to have a cold or warm air intake with LPG ?
- For the spark plugs, do you use the OEM recommended gap or a little bit narrower like few people advise ?

Thank you for your replies !!

[niky]

Colder plugs, narrower gap.

LPG burns plenty warm already. Don't know how advisable it is to run a WAI.

[pmiulian]

For me, the WAI would sometimes choke the engine.
Keeping the IAT moderate ( summer-like temperature ) works best.
For my short trips, the WAI helps me warm-up the engine faster, but for the long trips, the power loss is noticeable.

I still use the standard plugs and they work fine.

[DocT]

Hi all,
I have a 1.3 Yaris 2007 too converted to LPG, with a STAG QBox, STEFANELLI vaporiser and OMVL FAST injectors, which is the second Yaris I've had converted but this time with no noticeable loss of power on gas. £15 for 30L LPG tends to produce a constant 265 miles mostly urban driving, which is less than half the price of petrol here in the UK.

That said I've put in iridium plugs which are widely available now - given this is an older (yet still very interesting) thread - designed specifically for LPG - NGK were first, [part number: BKR6EIX-LPG, stock number 3356] and Denso followed shortly after, which are reportedly good for 60k miles.
sparkplugs.co.uk/ngk-iridium-spark-plug-bkr6eix-lpg

Basically the LPG plugs have a wider gap with a stronger core to give a bigger spark to ignite LPG while drawing less electrical power to fire. They also have a more heavy duty insulation around the central electrode.

[cRiPpLe_rOoStEr]

Makes me wonder if some sort of intake manifold heating would be useful, like it had been in some Brazilian dedicated-ethanol cars.

[Instigater]

Originally Posted by pmiulian

I`ve noticed something interesting when running on lpg.
It seems that I get better FE going 100 to 110 km/h than going 80 or 90.
I think that it is because the lpg ecu has some problems in the lower rpm. At 105 km/h the engine stays at about 3000 rpm. That is the peak torque rpm - so it seems that the lpg gets along better with the overall car configuration at that rpm.
If I run on gasoline, I get better FE at about 85-90 km/h.

Reviving dead thread. I'm also LPG converted car driver. I have read a lot about properties of petrol and LPG. You are observing this phenomenon because LPG is burning slower on low to mid rpms compared to petrol and it needs more timing advance as high as additional 12 degrees. Otherwise flame front in cylinder never catches piston head. I also feel that my car revives around 4000 rpms on LPG. There are special devices to correct timing advance on LPG for nineties cars called Timing advance processors on Google. Unfortunately my BMW is newer and the only way to get correct timng is to make custom ECU remap. 7 years ago I eas driving Swedish brick 740 with dumb 2.3 liter petrol engine also converted to LPG basic system. I optimized it to run extra lean on light loads and normal on full load and advanced timing around 8 degrees. The effect was 2 liters per 100 kilometers less LPG consumption than petrol. There was no signs of premature engine wea.

Search on Google "lpg timing advance processor". You will also get graph of optimized timing.

[cRiPpLe_rOoStEr]

It seems like the electronic hardware is pretty much similar from a CNG conversion to an LPG conversion, despite the fact that CNG doesn't require any pre-heating in order to vaporize as LPG seems to do.

[herbivor]

Originally Posted by Rambenz

Hi everyone,

I'm new on ecomodder and proud to be part of the community ! I just read this thread and have already two questions :
- Is it best to have a cold or warm air intake with LPG ?
- For the spark plugs, do you use the OEM recommended gap or a little bit narrower like few people advise ?

Thank you for your replies !!

Ok, bit late for a reply and I am sure you have it well sorted out by now, but for anyone else wondering the best LPG set-up, heres my advice.
LPG is a little bit more dense then petrol, hence a smaller spark plug gap. Also, its recommended to run with (hope I have got this the right way round) cooler plugs as LPG runs hotter. All this being said, I kept my current car OEM on the plugs with no adverse effects.
As for a hotter intake system-NO WAY. Hot air losses energy for the engine as it contains less oxygen per given volume. A lot of LPG systems require you start on petrol to get you up to temp because
1)ECU still may be booting up and may not like the LPG gas just yet
2)Keeps the petrol injectors from blocking up so its worth using them at least once per journey
3)LPG sucks heat from the cooling system. On a very cold morning and without starting with any heat in the water, there is a risk of freezing the pipes
4)as mentioned, LPG is more difficult to ignite, so using the stuff on a warm engine will ensure no miss-fires.

[Eek!]

Hello from Romania, I'm the owner of the second car on LPG.

First car was a small Daewoo Matiz, 0.8l 3 cylinder car, 2005/Euro3 engine. Mileage was around 6.5 - 7 l/100km on LPG, driving 90 km/h, not a noticeable big increase in fuel for city driving, maybe going 8l/100km. I had a Tomasetto-Achille sequential LPG injection, the car started on petrol and when the coolant would reach 30C will switch automatically on LPG. The car ran fine from 2010 to 2016, bought it second hand in 2010 for about 1500 Euros, made around 60.000 km with me, no problem, then this year was scrapped (rust started to eat the car, brakes starting to fail, strange sounds from clutch) because the cost of fix the car was higher than the car itself. The engine ran very fine till the end, just eating some extra oil. Switching from petrol to LPG was only a beep, no change in engine sound, no change in speed or power.

I bought last year an Opel Corsa B 1.4i 1997/Euro2 for about 1000 Euros. Older but much serious car, i fit it with LPG right away. The instalation is Tomasetto classic, due to single injector petrol injection. Switching on LPG will begin over 2000 rpm, no matter about coolant temperature. Best technique is to let the engine warm a little before start driving, even in summer. If i start the car in the middle of the summer, switch on LPG then drive 1 km, next time the engine will start poorly. This car have 7.5 - 8 l/100km mileage driving 90-100 km/h, going to 9l/100 km city driving or highway 130km/h.

The old Daewoo Matiz was a slow car, max speed was 125 km/h on GPS, so sometimes I used to stay behind a big truck, drafting. Big trucks almost never brake without reasons and they run 90 km/l limit, but i was afraid to close-in too much because of the ****ty brakes of the Matiz. This car type is known sometimes as "the suppository", but my "suppo" was a great car for running the city streets and finding a parking spot. The little engine was not a very good fuel-saver, having a 0.8l 3 cyl. 50 hp on 800 kg car, but was reliable and never broke down.

[cRiPpLe_rOoStEr]

It's still somewhat surprising to me that you don't just start it up on LPG like it's done in forklifts.