I have a audi S6 4.2 V8 running fantastically on lpgtech and I'm due to change the spark plugs. it has the original equipment specified bosch super 4s which I've had in the last 2 and a half years. from previous searches I have decided to fit some NGK Iridium plugs for it, but a quick look on eBay popped up some bosch lpg specific plugs, but the ads a bit shady with no part numbers or anything listed.

here's the ones I was going for

http://www.ebay.co.uk/itm/152024204428


but these are the ones that caught my eye

http://www.ebay.co.uk/itm/371781026975



opinions please?

stick with the originals if they've gave no issue

I'd go for the former (assuming it's the ANK or AQJ engine) as that is the recommended NGK plug for your engine. Numerous people have had problems with 'special' LPG plugs, although not Bosch admittedly, but at the price is it worth the gamble?

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One of the supercharged Rangerovers I converted years ago came back for sorting recently, the owner said he'd been messing with the calibration and had accidentally cocked it up, brought it back for re-calibration when he couldn't calibrate it right himself. First thing I noticed when I opened the bonnet was a big sticker for Brisk spark plugs, so my immediate thought was the plugs might be the biggest issue. Luckily though in this case the Brisks seemed to work fine, the problem really was a simple case of him messing up calibration. But special plugs not recommended by the vehicle manufacturer are the cause of a lot of problems, Brisk no different. Best part of an hour re-calibrating and it ran fine, but I might not have expected that.

I'd be equally happy to fit those that worked well in the past or the NGK ones, I wouldn't go out on a limb for plugs that were not OEM recommended or hadn't already proven to work well, expensive gamble.

Simon

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There has been reports of some of the off brand ones falling apart in the past (the electrode falling out if I remember correctly).

thanks for the advise

Anyone finding this on Google, Do not use bosch super 4s for LPG, use NGK iridium!

I installed the LPG system 18k ago and fitted the bosch super 4 spark plugs as that what Audi fits. there has always been a delay with the throttle response when you stamp on the pedal. a second delay lag then it picked up and went. I put it down to the lpgtech being a piggy back system off the petrol injectors so it was just a natural processing delay. it's only when stamps on the pedal and surprised it.

I fitted the NGK iridium plugs today and recalibrated and WOW what a difference. the delay has gone, throttle response is instant, and defiantly feels stronger higher up the rev range. I am amazed at the difference and can't believe I just made do and accepted the delay for the last 2 years!

It seems to be a mixed bag - more often than not a multiprong plug in theory should be better, but in practice it doesn't always work out that way. I'd suspect the potential for several weak sparks rather than one strong one would have a lot to do with that. At least you know what to use in future now.

totaly agree..............the bosch plugs were an option for my van and what a mistake, poor economy, judder on change over to lpg and lousy throttle response on both petrol and lpg......a return to single electrode ngk cheapos changed at 5k intervals and im back in lpg heaven ...........see no need for iridium unless they are a pain too replace