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The mkiv Supra Owners Club

My Spark Plugs


Markie

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Hi all..

 

Just found out what plugs are in my car at the moment.

 

Anyone know how good these are: HKS SUPERFIRE PLUGS S40i

 

 

 

 

Also, any good way to clean plugs like these for the supras, as from the invoice it looks like they were new last April.

 

Thanks,

 

Marcus.

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So these plugs are good shit??

 

How can I clean them without causing damage to them?

 

The HKS iridium plugs are some of the most expensive plugs you can buy, whether this makes them better than others is debatable. I always use HKS plugs as I can get them a lot cheaper here and rate them highly.

 

The S40i is the middle grade of the 3 plugs that can be used on the Supra. The S35i is okay for a stock car, the S40i would be fine for intermediate mods and then the cooler grade S45i if running higher boost. I use S45i on stock turbos running 1.25bar (430hp.)

 

You do NOT need to clean/gap them and if you do you may well damage the very fine electrode. Provided the car is running well and not missing at high boost then leave them well alone.

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I have been using a set of s40i for over a year now boosting at 1.2bar (295hp on the stock twins and now 480hp with the single)

I found I was getting a slight mis at high boost using S40i's which was why I switched to the S45i. Probably as a result of the higher summer temperatures here and running high boost on stock twins. I guess your single will run cooler egt's than the stock twins?

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