2012 QP Sport GTS Spark Plugs

[WestBP]

G’day everyone,

Has anyone fitted Denso IU24 plugs in lieu of the factory NGK PMR8C-H?

They’re different lengths on the electrode side and it didn’t fill me with enough confidence to pop them in.

My thinking was Iridium “should” last longer considering how much a of a pain the back ones are to get to.

Interested to hear your experience.

 

[dunnah01]

I fitted IU24 plugs to my grunt 06 QPV 4.2 but they were exactly the same size as the plugs that came out - I'll need to dig out the old plugs to see what model they were.
IU24s have worked perfectly for the 3k I've done so far with them

 

[WestBP]

Hmm, interesting.

The NGK and Denso websites both list the same plug for the 4.7 variants. I assume the extra hp on the Sport GTS is a software not hardware change so they should be the same.

I’ll dig a bit deeper

 

[dunnah01]

Probably just confusing things further but the plugs that came out were NGK-R: PMR-8B

 

[voicey]

The dry sump and wet sump engines use different plugs. If you put those shorter plugs in you'll have trouble building a suitable flame front to ensure complete combustion.

 

[WestBP]

Thanks for the replies.

dunnah01 - are you saying the factory plugs were the 8B? The plugs in it at the moment are the NGK R PMR8C-H.

voicey - agreed on the combustion issue. What’s got me guessing is why the Denso reference might be wrong as I thought all the 4.7’s were wet sump = 1 less variable...maybe

This will teach me for trying something different

 

[dunnah01]

Thanks for the replies.

dunnah01 - are you saying the factory plugs were the 8B? The plugs in it at the moment are the NGK R PMR8C-H.

My car has done 50k so the 8B plugs were probably factory although I can't be sure. I did a service about 3 months ago and it made sense to change the plugs whilst I was there, which is when I installed the IU24 plugs. I made sure to compare them beforehand just to make sure that they were the same size (which they were). Mine's a dry sump 4.2 so I'll happily take Voicey's advice that the wet sump 4.7 use the longer 8C-H plug

 

[WestBP]

Ahh got it now, I missed that yours was the 4.2.

Thanks all for the info