Maintenance for fun.
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From: Up, Planet Earth
Hi David,
You obviously have advanced knowledge of automotive mechanics, so what I've been hoping to gain from all my questions is the theory, mathematical formulae, or other means of calculating spark plug gap based on engine compression, cylinder design, plug choice and any other factors you have mentioned in your posts; and since you are using a spark plug that does not show up in any of the Jaguar documentation I have in my library or have been able to find online, I simply wanted to know on what basis you made your choice. You stated that "many in the dealer network use also 5464" et al., yet provide no supporting documentation, and I have not been able to confirm this by searching two of the Jaguar dealer databases available online.
If your plug and gap choices are based on your extensive personal experience as a trained professional mechanic, that's great, but please say so, so others who don't have your knowledge and experience can factor this into their own choices. For the rest of us, including those members who are only beginning to undertake their own auto maintenance, it would be helpful to understand the theory, calculations and knowledge on which you've based your choices.
Regarding your latest post about all those platinum part numbers having been cross references before the introduction of iridium, given that NGK introduced iridium plugs in 1994 and, as far as I have been able to deterimine, Jaguar specified iridium plugs in the X350 from its very introduction in 2003, I struggle to understand the relevance of any pre-iridium plug cross references.
I am truly not doubting or criticizing you. I simply want to understand the underlying knowledge and theory behind your choices and assertions so that I and other members can evaluate their applicability to our own vehicles and driving styles. Without the knowledge you possess, the rest of us have to either take a leap of faith or remain unconvinced.
With your knowledge and experience, you are in a position to help the rest of us to better understand our Jags and the pros and cons of potential part upgrades. I'm simply looking for more supportive detail before I use or recommend a spark plug other than the one specified by both Jaguar and NGK.
Cheers,
Don
You obviously have advanced knowledge of automotive mechanics, so what I've been hoping to gain from all my questions is the theory, mathematical formulae, or other means of calculating spark plug gap based on engine compression, cylinder design, plug choice and any other factors you have mentioned in your posts; and since you are using a spark plug that does not show up in any of the Jaguar documentation I have in my library or have been able to find online, I simply wanted to know on what basis you made your choice. You stated that "many in the dealer network use also 5464" et al., yet provide no supporting documentation, and I have not been able to confirm this by searching two of the Jaguar dealer databases available online.
If your plug and gap choices are based on your extensive personal experience as a trained professional mechanic, that's great, but please say so, so others who don't have your knowledge and experience can factor this into their own choices. For the rest of us, including those members who are only beginning to undertake their own auto maintenance, it would be helpful to understand the theory, calculations and knowledge on which you've based your choices.
Regarding your latest post about all those platinum part numbers having been cross references before the introduction of iridium, given that NGK introduced iridium plugs in 1994 and, as far as I have been able to deterimine, Jaguar specified iridium plugs in the X350 from its very introduction in 2003, I struggle to understand the relevance of any pre-iridium plug cross references.
I am truly not doubting or criticizing you. I simply want to understand the underlying knowledge and theory behind your choices and assertions so that I and other members can evaluate their applicability to our own vehicles and driving styles. Without the knowledge you possess, the rest of us have to either take a leap of faith or remain unconvinced.
With your knowledge and experience, you are in a position to help the rest of us to better understand our Jags and the pros and cons of potential part upgrades. I'm simply looking for more supportive detail before I use or recommend a spark plug other than the one specified by both Jaguar and NGK.
Cheers,
Don
NGK Automotive OE Replacement Parts on NGK.com
Last edited by Box; Jul 15, 2015 at 03:14 PM.
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Joined: Jul 2013
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From: Northern Virginia and Hong Kong
Anyone yet ask them how it can have 'better durability' and NOT have 'better lifespan'?
Joined: Feb 2014
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From: Crossroads of America
Thermite,
I think David just misspoke about the durability - it appears NGK gives both the 7866 and 5464 a durability rating of 3.5. But David is correct that the 5464 is rated higher in performance and fuel efficiency and NGK does recommend reducing the gap to 1.0mm for use in the X350. Both plugs have a Heat Range rating of 5.
David,
Thanks for the link to the NGK vehicle-specific listings. Very helpful!
I'd still like to see an official Jaguar recommendation of the 5464 for peace of mind in passing along the recommendation to others.
Cheers,
Don
Last edited by Don B; Jul 16, 2015 at 12:03 AM.
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From: on-the-edge
according to Ford, or so he says ...
the discussion was centered around sparkplug applications
for supercharged FORD engines. Not Jaguar, but the basic
principles still apply.
for supercharged FORD engines. Not Jaguar, but the basic
principles still apply.
O.K. as promised I can give you the following information I got from a source at Ford. I was told he is one of Ford's in-house spark plug guru's. Anyhow I asked the following questions and he gave the the corresponding answers.
What are the benefits and/or problems with substituting a motorcraft AWSF-22C plug with a AGSF-12FM1 plug? Are they in the same heat range?
A. The 22C plugs are cheaper. B. the 12FM1 spark plug run cooler (lower heat range by one grade). This is not important to you because you run without heat issues using a 2 heat range (AWSF22C, first number is the heat range, 1 is colder than 2) C. Length of thread is different but both are acceptable in your application.
D. The C means no precious metal enhancement; F is finewire platinum. M means nickel plated shell and 1 indicates copper cored ground electrode that also runs cooler than normal. The F and the 1 are robust for durability and cost more. This plug should last the rest of the car's life, however the 22C should have given you 50,000 miles unless you are operating a delivery service, ie; many starts, short drives and long idles.
How does coil-on-plug verses coil thru distributor design affect plug selection?
No affect whatever.
Is there any good published information available?
Most catalogs (found in dealers and parts stores) give a decent general explanation.
PS. Finewire is used on many supercharged apps throughout the world. You can use an
A(GorW)SF22F(anything) also.
The one question I have left would be about cylinder pressures and the plug gap. As cylinder pressure rises(increased boost/compression) you should close the gap up to prevent the spark from "blowing out", yes? Are there any "rules of thumb" to determine spark plug gaps?
#1. It is generally all right to blow out the spark. Ignition occurs sooner than the spark is extinguished. We don't have any corporate history that makes us pay attention to that phenomenon, probably because we run with excess energy and fairly small gaps.
#2. The effect of high pressure is increased required firing voltage. That coupled with 5000+ rpm can result in a critical intersection of coil charge time (limiting the available KiloVolts) and required volts. We don't see it and you won't either if you keep your plug gap less than .065".
What are the benefits and/or problems with substituting a motorcraft AWSF-22C plug with a AGSF-12FM1 plug? Are they in the same heat range?
A. The 22C plugs are cheaper. B. the 12FM1 spark plug run cooler (lower heat range by one grade). This is not important to you because you run without heat issues using a 2 heat range (AWSF22C, first number is the heat range, 1 is colder than 2) C. Length of thread is different but both are acceptable in your application.
D. The C means no precious metal enhancement; F is finewire platinum. M means nickel plated shell and 1 indicates copper cored ground electrode that also runs cooler than normal. The F and the 1 are robust for durability and cost more. This plug should last the rest of the car's life, however the 22C should have given you 50,000 miles unless you are operating a delivery service, ie; many starts, short drives and long idles.
How does coil-on-plug verses coil thru distributor design affect plug selection?
No affect whatever.
Is there any good published information available?
Most catalogs (found in dealers and parts stores) give a decent general explanation.
PS. Finewire is used on many supercharged apps throughout the world. You can use an
A(GorW)SF22F(anything) also.
The one question I have left would be about cylinder pressures and the plug gap. As cylinder pressure rises(increased boost/compression) you should close the gap up to prevent the spark from "blowing out", yes? Are there any "rules of thumb" to determine spark plug gaps?
#1. It is generally all right to blow out the spark. Ignition occurs sooner than the spark is extinguished. We don't have any corporate history that makes us pay attention to that phenomenon, probably because we run with excess energy and fairly small gaps.
#2. The effect of high pressure is increased required firing voltage. That coupled with 5000+ rpm can result in a critical intersection of coil charge time (limiting the available KiloVolts) and required volts. We don't see it and you won't either if you keep your plug gap less than .065".
Last edited by plums; Jul 15, 2015 at 10:40 PM.
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From: on-the-edge
more supercharged Ford application information
A good general discussion,
SPARKPLUGS 101
and an excellent nugget on using a colder heat range
which would also apply to naturally aspirated engines:
SPARKPLUGS 101
and an excellent nugget on using a colder heat range
which would also apply to naturally aspirated engines:
Now, the 32V Mark VIII (DOHC) engines have knock sensors from the factory. The EEC essentially listens to the engine for harmful knock. Since the onset of knock is lower than a human can ear, the sensor pulls timing out before you even know anything is happening. So as a very wise man once told us, these engines are already knock constrained from the factory and are pulling timing even with premium gasolines with higher octane ratings. So switching to an AGSF-12FM1 or an AWSFA-12C plug reduces the chances of knock, therefore the EEC doesn't get a chance to pull spark out. The result is you gain back lost power and a good amount of it. The plug itself is not responsible for more power, the spark advance is. Most of the 4.6L SOHC 2V engines do not have knock sensors so this doesn't apply.
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From: on-the-edge
And 200+ pages on the spark mechanism delving into esoterica
such as plasma chemistry
http://www.lib.utexas.edu/etd/d/2003.../seersp039.pdf
such as plasma chemistry
http://www.lib.utexas.edu/etd/d/2003.../seersp039.pdf
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From: Up, Planet Earth
Hi David,
You obviously have advanced knowledge of automotive mechanics, so what I've been hoping to gain from all my questions is the theory, mathematical formulae, or other means of calculating spark plug gap based on engine compression, cylinder design, plug choice and any other factors you have mentioned in your posts; and since you are using a spark plug that does not show up in any of the Jaguar documentation I have in my library or have been able to find online, I simply wanted to know on what basis you made your choice. You stated that "many in the dealer network use also 5464" et al., yet provide no supporting documentation, and I have not been able to confirm this by searching two of the Jaguar dealer databases available online.
If your plug and gap choices are based on your extensive personal experience as a trained professional mechanic, that's great, but please say so, so others who don't have your knowledge and experience can factor this into their own choices. For the rest of us, including those members who are only beginning to undertake their own auto maintenance, it would be helpful to understand the theory, calculations, knowledge and/or references on which you've based your choices.
Regarding your latest post about all those platinum part numbers having been cross references before the introduction of iridium, given that NGK introduced iridium plugs in 1994 and, as far as I have been able to deterimine, Jaguar specified iridium plugs in the X350 from its very introduction in 2003, I struggle to understand the relevance of any pre-iridium cross references.
I am truly not doubting or criticizing you. I simply want to understand the underlying knowledge and theory behind your assertions and choices so that I and other members can evaluate their applicability to our own vehicles and driving styles. Without the knowledge you possess, the rest of us have to either take a leap of faith or remain unconvinced.
With your knowledge and experience, you are in a position to help the rest of us to better understand our Jags and the pros and cons of alternate and upgraded parts. I'm simply looking for more supportive detail and verifiable facts before I use or recommend a spark plug other than the one specified by both Jaguar and NGK.
Cheers,
Don
You obviously have advanced knowledge of automotive mechanics, so what I've been hoping to gain from all my questions is the theory, mathematical formulae, or other means of calculating spark plug gap based on engine compression, cylinder design, plug choice and any other factors you have mentioned in your posts; and since you are using a spark plug that does not show up in any of the Jaguar documentation I have in my library or have been able to find online, I simply wanted to know on what basis you made your choice. You stated that "many in the dealer network use also 5464" et al., yet provide no supporting documentation, and I have not been able to confirm this by searching two of the Jaguar dealer databases available online.
If your plug and gap choices are based on your extensive personal experience as a trained professional mechanic, that's great, but please say so, so others who don't have your knowledge and experience can factor this into their own choices. For the rest of us, including those members who are only beginning to undertake their own auto maintenance, it would be helpful to understand the theory, calculations, knowledge and/or references on which you've based your choices.
Regarding your latest post about all those platinum part numbers having been cross references before the introduction of iridium, given that NGK introduced iridium plugs in 1994 and, as far as I have been able to deterimine, Jaguar specified iridium plugs in the X350 from its very introduction in 2003, I struggle to understand the relevance of any pre-iridium cross references.
I am truly not doubting or criticizing you. I simply want to understand the underlying knowledge and theory behind your assertions and choices so that I and other members can evaluate their applicability to our own vehicles and driving styles. Without the knowledge you possess, the rest of us have to either take a leap of faith or remain unconvinced.
With your knowledge and experience, you are in a position to help the rest of us to better understand our Jags and the pros and cons of alternate and upgraded parts. I'm simply looking for more supportive detail and verifiable facts before I use or recommend a spark plug other than the one specified by both Jaguar and NGK.
Cheers,
Don
In the end though Don, both of the plugs we are talking about are in actually, the very same plug. It's built on the same line with the exact same ceramic, same iridium tip, same resistor mix, same processes for which both undergo, with the exception of identification, the body is the exact same, even sharing the exact same ground electrode, until the portion where one gets a Platinum disk, or is trimmed by a press to create the v-shaped tip before being folded over. But because Jaguar specifies such a long service interval, it precludes not using the platinum, if you do run the full service interval. But even NGK states the non-Platinum is a better performer. My plugs won't see more than 2 years service before the current ones will be changed. The sparkplug is a 19th century technology...they have been around a while. Hope you have a great day, and again, thanks.
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From: Crossroads of America
Cheers,
Don
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Should we read "precludes not" as simply "precludes" ??
Last edited by Thermite; Jul 17, 2015 at 04:04 AM.
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From: Northern Virginia and Hong Kong
My assumption is that the higher resistivity of platinum compared to nickel must be the reason NGK recommends a smaller gap for the 7866. Can you think of any other reason why two nearly identical plugs would be gapped differently? (I'm referring to NGK's standard recommended gap - as you noted, they recommend reducing the gap to 1.0mm for use in the X350).
Cheers,
Don
Cheers,
Don
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From: Up, Planet Earth
My assumption is that the higher resistivity of platinum compared to nickel must be the reason NGK recommends a smaller gap for the 7866. Can you think of any other reason why two nearly identical plugs would be gapped differently? (I'm referring to NGK's standard recommended gap - as you noted, they recommend reducing the gap to 1.0mm for use in the X350).
Cheers,
Don
Cheers,
Don
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From: Toronto,Canada
My brain hurts! I use NGK BKR5EIX-11 in both my Jaguars and also in our 2008 Subaru Outbacks mostly because NGK recommend them.
The interesting thing is that my 2012 Subaru Legacy came with NGK SIFR6A 11 plugs and a recommendation to change them 60K kms earlier than the Outback!! So now I have to stock two types of plug instead of one.
The interesting thing is that my 2012 Subaru Legacy came with NGK SIFR6A 11 plugs and a recommendation to change them 60K kms earlier than the Outback!! So now I have to stock two types of plug instead of one.
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From: Northern Virginia and Hong Kong
I've yet to have both of the one-lung lawn-mowers that take the same plug, let alone commonality among the stable of 4, 6, and 8 cylinder critters..
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