Spark plugs for a GU Nissan Patrol that runs on LPG

Submitted: Friday, May 13, 2016 at 07:26
ThreadID: 132394 Views:3661 Replies:3 FollowUps:2
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Help please.
I need to replace the spark plugs in my 2001 Patrol. Several websites indicated that spark plugs that run colder are needed. Whatever that means.
The bloke that is going to change them for me suggested I buy Iridium Spark Plugs (at $25+ each). Repco said their computer doesn't show them to be suitable for LPG.
Has anybody any thoughts on this?
Regards
PeteM Qld
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Reply By: Robin Miller - Friday, May 13, 2016 at 08:02

Friday, May 13, 2016 at 08:02
Don't waste the money Peter.

We have always used the much cheaper ($9) platinum ones in our several 4800 petrol patrols , one of which was on gas. change them every 100,000km.

A 2001 gu could be 45 or 48 hundred , you don't say , but your owners manual should list the numbers for you - mine does.
Robin Miller

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Follow Up By: Member - Peter M (QLD) - Friday, May 13, 2016 at 09:52

Friday, May 13, 2016 at 09:52
OOPS! Didn't think of the Manual. Do you think that might be a man thing?
I will follow your advice. Our Patrol is a 4.5 ltr (4500) petrol/LPG
Many thanks Robin
PeteM Qld
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Reply By: Ron N - Friday, May 13, 2016 at 13:29

Friday, May 13, 2016 at 13:29
Peter, Denso manufacture a special Iridium LPG spark plug, it's called Iridium Plus (some sites say Iridium Tough, there's a bit of confusion there).

The Denso LPG plug is manufactured from tougher ceramic materials in the electrode insulator, to resist fracture when used in the higher temperature LPG applications.

For LPG you need a colder plug, as LPG combusts at a higher temperature than petrol. The higher the heat code number on the plug, the colder the plug.

The Denso LPG plug is identified by a "T" in the plug number. Denso make 4 varieties of Iridium plug - Iridium Power, Iridium Tough, Iridium Plus, and Iridium Racing.

Your standard Denso plug for the 4.5L Patrol is W16EPR-U11 - the Iridium Power is IW16 - the Iridium Plus is VW16 - and the Iridium Plus LPG is VW20T (20 is the higher heat code number [colder plug], as compared to the regular 16 heat code number).

These plugs are costly and a little difficult to source. You can buy them online from eBay, and other sites, and other countries - but they are going to cost $25 each, regardless.

Whether this money is justified or not, is a moot point. Denso reckons it is - only use and experience will prove it.
They make claims that the LPG plug is designed for long life under the harsher LPG operating conditions.

Denso Plug specifications

Denso - Nissan fitment chart

Denso - Iridium Plus features

Cheers, Ron.
AnswerID: 599975

Reply By: Erad - Sunday, May 15, 2016 at 09:58

Sunday, May 15, 2016 at 09:58
Champion used to recommend that you closed the gap in the plug by 0.1 mm to compensate for the higher resistance of the LPG mixture. This also helps with the erosion of the plug electrodes, keeping the gap closer to design levels and importantly reducing the risk of backfire or misfire due to the spark jumping to earth.
AnswerID: 600072

Follow Up By: Ron N - Sunday, May 15, 2016 at 10:28

Sunday, May 15, 2016 at 10:28
Yeah, well, if anyone knows anything about sparks plugs, they'd know that Champion plugs are a joke, and known as the worst plugs you can buy. Vintage tractor owners know this particularly well.

I've no doubt Champion plugs suffered from major spark erosion as soon as they were installed, they were built so cheaply.

This is where the Jap spark plugs shine - NGK or Denso - you get the benefit of the Japs fastidious and relentless study into why a plug is not performing satisfactorily, and how it can be constructed with better design and better materials.

So today we have iridium and platinum to resist erosion and heat, and very thin electrodes to intensify spark, and dual straps to assist in plug longevity.
In the bad old days, we would change plugs every 10,000-15,000kms and see a noticeable difference with new, top-of-the-wozza KLG plugs.

I've only just pulled the original platinum dual strap factory Denso plugs from the missus' old 2001 Camry and they've done 140,000kms, and they were still performing quite satisfactorily.
There wasn't a lot of deposit buildup, nor was there any serious amount of strap or electrode wear. It says a lot for the Japs use of quality materials and good design.

Cheers, Ron.
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