Outer Limits 4x4 Board

I have an '89 Patrol on straight LPG. Has anyone tried iridium plugs or the LPG iridium plugs? Is it worth using iridium plugs at all?

NGK BPR5EIX or NGK BPR6EIX-LPG

X 2

I replaced mine only last night. However, i just used the NGK bp4..? ones instead of the BP6...? ones. I also replaced the leads with 9mm ones and a K&N air filter. it made a noticable difference.

However, not sure which part made the most difference. Maybee it doesnt run any different at all from the plugs, maybee its because of the Air filter or leads?

Let us know if you change them and what you find. Even if i replace my new ones, they were only $3 each. so not like i've wasted much.

IMO, unless your running 100% petrol or 100% gas - dont waste your time/money on the flash iridium plugs.

Instead, get the "standard" plugs, and gap them to suit you preffered fuel. It would probably pay to google it for a better idea, but generally the plug manufacturers can tell you what the gap should be.

Smaller gap for LPG, Bigger gap for petrol.

For the price of the expensive plugs (usually around 4 times as much), you're better off changing stock plugs that have been gapped correctly at shorter intervals (20,000km max).

My 2c.

Coxy

hi wot bout if your running straight gas on a TB42 Turbo on 12psi???
any idea's keep going throu plugs?

Best plug i ever used for Dual Fuel was Denso WPU16-11U. They are Resistorless plug, standard type but i could tell the difference, they lasted longer, and gave more power on gas

coxy321 wrote:IMO, unless your running 100% petrol or 100% gas - dont waste your time/money on the flash iridium plugs.

Instead, get the "standard" plugs, and gap them to suit you preffered fuel. It would probably pay to google it for a better idea, but generally the plug manufacturers can tell you what the gap should be.

Smaller gap for LPG, Bigger gap for petrol.

For the price of the expensive plugs (usually around 4 times as much), you're better off changing stock plugs that have been gapped correctly at shorter intervals (20,000km max).

My 2c.

Coxy

if you car has LPG, you are generally 99% LPG use.

So one range colder plugs, not standard ones.

JEs

Just did my plugs on the weekend NGK 1 step colder, I also changed airfilter but took off the steel part for cold starts and didn't run through the collector on the front.

Hadn't changed plugs or air filter in 3 years. The difference in performance was quite noticable.

Mine is a street driven car any other air filters worth trying to suit LPG carby ?

(quote)I replaced mine only last night. However, i just used the NGK bp4..? ones instead of the BP6...?(unquote)

im not %100 sure but i think the higher the number the colder the plug, i think you went to a hotter plug. Lpg like a colder plug.

henry wrote:(quote)I replaced mine only last night. However, i just used the NGK bp4..? ones instead of the BP6...?(unquote)

im not %100 sure but i think the higher the number the colder the plug, i think you went to a hotter plug. Lpg like a colder plug.

xacery! you need to run a colder plug on LPG/modified. So if you have a BPR6es you need to run a BPR7es or colder, not hotter.

With modified engines (those engines that have increased their compression) more heat is a by-product of the added power that normally comes with increased compression. In short, select one heat range colder for every 75-100 hp you add, or when you significantly raise compression. Also remember to retard the timing a little and to increase fuel enrichment and octane. These tips are critical when adding forced induction (turbos, superchargers or nitrous kits), and failure to address ALL of these areas will virtually guarantee engine damage.

I have used NGK plugs for a long time without issue, and have always gone one heat range colder (for the hotter combustion temperature and low carbon content), I have always used non-resistored plugs as (LPG has a lower carbon content and is harder to ignite or ionize the gap due to carbon being the semiconductor in the A/F mixture). Using non resistored plugs often allows you to run standard gaps, except where manufacturers specify over 1.5mm gaps which I would set at 1.2-1.3mm. A turbo engine has higher cylinder pressure and greater turbulance requiring a smaller plug gap, depending on the application .2mm smaller is usually enough.

Cheers

Joel

PGS 4WD wrote:I have used NGK plugs for a long time without issue, and have always gone one heat range colder (for the hotter combustion temperature and low carbon content), I have always used non-resistored plugs as (LPG has a lower carbon content and is harder to ignite or ionize the gap due to carbon being the semiconductor in the A/F mixture). Using non resistored plugs often allows you to run standard gaps, except where manufacturers specify over 1.5mm gaps which I would set at 1.2-1.3mm. A turbo engine has higher cylinder pressure and greater turbulance requiring a smaller plug gap, depending on the application .2mm smaller is usually enough.

Cheers

Joel

Went to mechanic, asked for gas plugs. He looked up his book, and said that tb42s uses the NGK BP6..., so you need to go COLDER for gas, therefor use NGK BP4...

Now i am confused. everyone agrees that you have to go colder, but not sure whether to go up or down in number. since you seem to have used NGK should i be taking them back? It does run better than before but whether that has anything to do with the plugs i dont know?

hi, the NGK's numbering system to plugs are backwards so the higher the number the colder the plug.

TEAMRPM wrote:In short, select one heat range colder for every 75-100 hp you add, or when you significantly raise compression.

So that must mean my 180B plugs need to be about FOUR heat ranges colder (i wish)

TEAMRPM wrote:Also remember to retard the timing a little and to increase fuel enrichment and octane.

Not being a smart @rse, but i didn't know gas came in different octanes. Is there something i'm missing?

Coxy

Ultimate plug temp can be established based on plug life, fouling and so on.

Joel

Rang the place i got the plugs from this morning, and they were not sure who gave me the plugs, but they were happy to let me come in, and they will swap them for the right ones, even if i have already killed them.

Thats customer service right there.