i seriously doubt that the amount a spark plug gap extends into the combustion chamber can be accurately determined by a manufacturer (i'm surprised they even attempt to publish such figures) given that heads and combustion chamber profiles on various engines designs aren't exactly an SAE standard, or even close to it. they can measure distance from the shoulder of their plug to the gap and from the end of the threads to the gap, but that's about it, IMO.

 

Update:

A few weeks ago I changed the spark plugs, installed Champion iridium 9801 plugs (RC8WYPB3), which I got for $20 from Amazon (maybe the seller had excess stock they needed to get rid of). They don't come gapped correctly, so I had to use my plug gapping tool to get them to .038.

Install went smoothly (except for the one closest to the firewall on the driver side, which was a PITA to torque) and I've put almost 500 miles on the car since. It feels the same as it did with the stock plugs, which were in surprisingly good condition for a car with 49k miles on the clock.

I haven't put it on a dyno yet, but I'm confident in saying these plugs are just as good as OEM.

 

I put the same in mine a few weeks back with similar results, running good.

 

I rescue this thread, buying now in England, right now, is very expensive, realize that now the English must pay for each product that enters their islands and that makes the pieces more expensive, from Spain I see how buying something from the English means paying 62% more than in Spain
it is unsustainable......
Prices from a Spanish accessories website: good prices here 10w60 castrol edge
https://www.recambium.com/bujias-coc...10-97105-.html
prices from england
https://es.gsparkplug.com/ngk-ifr7n1...g-iridium.html

 

Gracias Spainconnection pero 58 euros por bujia??

 

Hello, the translation was wrong, I wanted to say that buying ---DO NOT BUY-- BUY NOW IN ENGLAND, IT IS VERY EXPENSIVE, apart from the possible duplication of costs, which you never really know if they are charging you twice, everything that is going outside your region must be with very serious entities. I do not pay 58 pounds or euros or dollars for a spark plug ... when do you know that it is a robbery?

 

Yes I agree! Thank you for the clarification. I would never pay 58 euros for a spark plug unless it was solid gold😂

 

Hello all, i matched the Ifr7n10 to a NGK # prf5g-11 2647 all the same except the factory gap being 1.1 instead of 1mm

much cheaper and easier to find too - https://www.ebay.com.au/itm/27319386...gMrMTbuVVCCaTc

 

Nice find, thanks for sharing

 

About PartsHawkAbout PartsHawk https://share.google/BmffeLh1Ttq7t2Zsg

Found them here as well, fyi

 

you guys are all over the place with the heat range on your "equivalents". no shade intended but better stick with the factory value if driving hard

 

Thanks for the headsup but please tell us why the equivalents wouldn't be correct?. I almost bought those listed above. I know the code numbers on the plug tell the story but not sure how? TiA

 

you can get a fine explanation with Google search
https://ngksparkplugs.com/en/resourc...lug-heat-range
https://www.championautoparts.com/Te...eat-range.html

it seems 7 is the AM spec for NGK if the information in the 1st post is correct.
i also use 7 on my turbocharged Esprit. 6 would be normal for the Esprit but I run higher boost which = mucho heat.
5 in Corsa's post would be too hot and the plugs would likely experience reduced useful life
8 in the Champion brand is 6 NGK (each brand is different, google will provide a xref chart) which will probably be fine if not driven at high rpm often
you may find that the electrode protrusion distance is determined by the heat range

anyway, do your own research and make informed choices
cheers

 

Thanks for the information, I did read this info a while back along with Aston 1936 video on the db9. I just wanted to know if there was anything new was out there about these equivalent plugs. Having been on this forum for over 5 years, this forum for the most part, is a great place where owners share information generously to help each other with caring for our cars!

 

Spark plug thread was great.:
Don't want to hijack this thread, but what about the spark plug coils? Any suggestions on what to use and where to buy???