Spark Plugs - Wow, what a difference!

[wozzlegummich]

Just threw at set of spark plugs at the Rangovery (Classic RR with DII mechanicals - Thor) and I can't believe the difference. It had platinum NGK's in it which I replaced with DENSO IK20 Iridium.

It runs injected gas (LPG) and had started to pop (backfire) when lugging at low engine RPM.

It not only now pulls smoothly away from idle in 1st but has appreciably more power throughout the rev range. Can't wait to check the fuel consumption.

I've owned many rover V8's over the years but have never had this sort of gain in performance from just a spark plug change!! The old ones didn't even look that bad.

I guess the power had dwindled away over time and i just hadn't noticed it.

[bee utey]

Yup, 90% of gas running problems are fixed by fitting suitable spark plugs. Keeps me in business.:)

[Pedro_The_Swift]

Where from and how much Wozzle?

[wozzlegummich]

Fleabay - DENSO IRIDIUM POWER Spark Plug IK20 x 4 RACING PLUG | eBay (http://tinyurl.com/88ua7hc)

$140 for 8 inc postage.

Hurts me paying that much for spark plugs!!!!

[Pedro_The_Swift]

at the risk of starting WW3:p
around $60 plus freight from USA

[wozzlegummich]

at the risk of starting WW3:p
around $60 plus freight from USA

Yeah, I saw them but I am going on the Tour T'Adelaide (http://tourtadelaide.blogspot.com.au/) rally this weekend and needed them quickly. Only 2 days from Brisbane to Melb.

It's the price I pay for not planning ahead!! At least the $$$ stayed in OZ.

[Pedro_The_Swift]

looks like fun,,
its good to see all maps read north at the top:angel::p;):D


oh and remember!!!
:rulez:

[wozzlegummich]

I'm on the dark side of participants (an Official).

Unfortunately we have to remind competitors that north is at the top of the map. Even the experienced navigators sometimes get geographically embarrassed.

[Cannon]

what did you set the gap to?

[wozzlegummich]

Funny you mention that. After doing research on what the gap should be when running on gas I was totally confused.

Some used to say the gap should be opened up for gas but current thinking is to close them up from standard. There are a heap of "experts" out there on the web but no one could give me a valid technical reason as to their recommendation.

I believe factory Landrover for petrol is 1.1MM .043".

The plugs came pre-gapped at .040" or 1.0MM so I left them at that. Seems to have worked OK now but I'll have to see how I go.

[bee utey]

Funny you mention that. After doing research on what the gap should be when running on gas I was totally confused.

Some used to say the gap should be opened up for gas but current thinking is to close them up from standard. There are a heap of "experts" out there on the web but no one could give me a valid technical reason as to their recommendation.

I believe factory Landrover for petrol is 1.1MM .043".

The plugs came pre-gapped at .040" or 1.0MM so I left them at that. Seems to have worked OK now but I'll have to see how I go.

Bosch LPG specific plugs are supplied out of the box gapped at 0.7mm or 0.9mm depending on application, I use 0.6-0.7mm on the Thor, 0.7 to 0.8 on the older engines. Most of your improvement will be from the geometry of the electrodes. Even stock standard plugs with sharp edged new electrodes would have had a similar effect, at least for a few weeks until the edges round off. Your Iridiums will be fine although I can get good results from plugs that cost $5 each. It's mainly about the gap.

[400HPONGAS]

Apart from what Beeutey has said , the main thing that dictates the gap is what is your intended purpose. The gap chosen will allways be a compromise of Starting/light throttle,cruise and WIde open (your dymamic comp ratio should dictate the "Heat range".I wonder if the plugs that replaced the originals were of the same heat range ? It is the density of the charge (idle very dense , and LPG is more dense again ) and the gap that dictates the energy required to jump the spark .So its a matter of doing many plug chops to optimise the gap .More Gap more ignition power required .Unless youve a got MSD (Multiple SPark discharge ) (ie Crane HI-6)(not to be confused with MSD the brand name for a certain group of Products)or a Maggy or uprated coil packs ,Iridium,titanium , unobtainum,whatever , just sales gimmicks !!!
The standard NGK or Bosch pug of the right Heatrange is just as good .!!

[wozzlegummich]

Unobtainium - Love It :lol2:

Main reason I used iridium was for longevity.

Many, many moons ago I was a lowly apprentice motor mechanic working to get off the shop floor in a Mitsubishi franchise. When the TE Magna came out around 1996 the inlet manifold had to be removed to replace the three rear spark plugs on the V6 models. (Great design - NOT).

In an effort to reduce servicing costs (and therefore making the car more attractive to fleet buyers) they fitted platinum plugs only to the three rear cylinders and mandated that they only needed changing at 90,000K's, as opposed to the front three which needed doing every 45,000K's.

I know that spark plugs being used on LPG get a hard time, and me being a lazy bugger was just trying to prolong the time when I have to change them again.

That was my train of thought.

[bee utey]

Unobtainium - Love It :lol2:

Main reason I used iridium was for longevity.

Many, many moons ago I was a lowly apprentice motor mechanic working to get off the shop floor in a Mitsubishi franchise. When the TE Magna came out around 1996 the inlet manifold had to be removed to replace the three rear spark plugs on the V6 models. (Great design - NOT).

In an effort to reduce servicing costs (and therefore making the car more attractive to fleet buyers) they fitted platinum plugs only to the three rear cylinders and mandated that they only needed changing at 90,000K's, as opposed to the front three which needed doing every 45,000K's.

I know that spark plugs being used on LPG get a hard time, and me being a lazy bugger was just trying to prolong the time when I have to change them again.

That was my train of thought.

I cross-referenced your plugs, the heat range should be ideal for gas. The main thing (apart from wear) that kills correct heat range plugs is combustion/oil deposits. A clean engine should be able to see 60,000km easily out of iridium plugs, if not 100,000. Make sure you repost on this thread when they are next due for replacement!

[wozzlegummich]

A clean engine should be able to see 60,000km easily out of iridium plugs, if not 100,000.

Funny, the old NGK platinums were as clean as a whistle with a slight brown/pink tinge on the insulator. Sure, the centre electrode was a bit rounded but nothing that I thought would of warranted changing them.

Still, those old plugs made the engine buck like a raging bull at low revs in the first three gears (it's a manual). The regained power is sure welcomed but it's the new found driveability (is that a word?) that I'm enjoying most.