Spark plugs

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i860
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Spark plugs

#1 Post by i860 » Sat May 25, 2019 10:58 am

I am sure this has been discussed but I want to share my personal experience.
So far in 6 years ( 4 cars converted on lpg ) i only used NGK spark plugs double platinum 0.8mm 3mm spark
One month ago i was looking to renw my spark plug and saw that bosch double iridium 0242140515 0.7mm and 4mm spark.
I went for the bosch and I am glad I did, acceleration now is much better ( on ngk i had a small lag while accelerating hard from low rev ), also the consumption is better now ( i change my spark plugs every year, so the ngk are not too old ).
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Gilbertd
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Re: Spark plugs

#2 Post by Gilbertd » Sat May 25, 2019 5:02 pm

A lot of cars don't like Platinum plugs at all when running on LPG but run fine on Iridium. It might just have been the change of electrode material that made the difference. Do NGK make an Iridium for your car?
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i860
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Re: Spark plugs

#3 Post by i860 » Sun May 26, 2019 10:26 am

No, for my engine they do only platinum, but they mention reducing the gap. I was afraid of doing that.

LPGC
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Re: Spark plugs

#4 Post by LPGC » Tue May 28, 2019 11:36 am

What car / engine is this?

An old rule of thumb is that NGK nickle single electrode plugs usually give good results on LPG with some exceptions such as on certain Vauxhall engines (where the standard fit Bosch twin electrode plugs work best). On most modern engines the manufacturer original fit plugs (usually platinum) give good results and will last longer than nickle plugs despite old claims of platinum only lasting as long as nickle in LPG engines (something about platinum acting as a catalyst in the LPG burn process). Iridium plugs last longer than platinum which last longer than nickle in any engine on either fuel, none will last quite as long on LPG as on petrol, so iridium (which lasts longest) can be a good choice on engines where spark plugs are difficult to access/change to extend plug service life/interval but only if a compatible iridium plug is made for the engine and is found to work well on LPG - There are good rules of thumb but going from a plug type that is known to work well on LPG (usually the manufacturer fitted type these days) to a different plug is always on a proof is in the pudding basis, exceptions to all the rules of thumb. If an owner has found standard platinum plugs worked well on LPG and plugs are difficult to access they might want to try switching to iridium to extent service life, or might think that if the iridium plugs don't give quite so good results they'd then have wasted money on iridium plugs and have to swap the difficult to change plugs again.
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SubaruFan
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Re: Spark plugs

#5 Post by SubaruFan » Wed May 29, 2019 4:47 pm

Talking of difficult to access plugs - try a Subaru H6. You do n/s rear from underneath! The working space is whatever the thickness of your hand is, minus about 5mm.

NGK Iridium plugs for me.
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Re: Spark plugs

#6 Post by LPGC » Fri May 31, 2019 4:47 pm

SubaruFan wrote:
Wed May 29, 2019 4:47 pm
Talking of difficult to access plugs - try a Subaru H6. You do n/s rear from underneath! The working space is whatever the thickness of your hand is, minus about 5mm.

NGK Iridium plugs for me.
Yes I've done the plugs on Subaru H6's... And I rebuilt a H6 engine after dropping a bolt into it's inlet manifold :-(

What I was getting at is that if plugs are really difficult to access it would be even more unfortunate than if plugs were easy to access to replace already fitted type of plugs (which the engine is known to run well on) with a different type of plugs (perhaps iridium) only to find that the engine didn't like running with the new type of plugs so it'd be necessary to remove the new type of plugs (no refunds on used plugs) and fit the type that's known to work well (immediately have to buy more plugs and do all that difficult work again).
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i860
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Re: Spark plugs

#7 Post by i860 » Sun Jun 02, 2019 12:57 pm

Hi
Mine is a mercedes slk 350 m272 engine, I am lucky that the spark plugs are very easy to access.
This April I change the spark plugs on my wife car c280 same m272 engine with ngk 4288. After changing mine with bosch double iridium 0242140515 and saw the improvement, I change them as well a few days ago, now I have 6 spare ngk's.

raeturbo
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Re: Spark plugs

#8 Post by raeturbo » Mon Jul 08, 2019 10:54 pm

I know this is an old thread but I use cheap as chips ngk racing plugs in my Astra for well under a tenner and they are fine. Don't waste your money!

i860
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Re: Spark plugs

#9 Post by i860 » Fri Jul 19, 2019 11:03 am

I paid £8.80 for one bosch double iridium 0242140515

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