Racing spark plugs

[max]

I’ve removed spark plugs on my 95 SVT cobra to inspect/clean them. They are autolite AR3932 spark plugs.
First thing I’ve noticed that the electrode is ground back on these. Does this produce cooler spark or what’s the reason behind this?

Topic

[Lorrin Barth]

If that indeed is the proper plug for that engine then it is what the engineers found worked best – probably by trial and error.

[max]

Is is the proper plug for my car, it has supercharger and whole list of other modifications, basically it’s race car.
Just wondering how race plugs are different, their spark is less hot vs traditional spark plug, etc?

[dan]

the grond back electrode is SUPPOSED too allow the spark too be more direct into the air fuel mixture, this is very popular with Autolite too have the cut back ground electrode and i think its also big with Nascar or something, if this is the plug your manufacturer recommends then use it.

all the spark plug manufacturers have there ways of making high performance plugs.

[EricTheCarGuy]

High performance stuff gets into the ‘black magic’ area of engineering. As for why the plug is designed that way, perhaps because of high compression, more likely to promote more complete combustion at higher RPM. Most performance engines spend a lot of time at higher RPM’s.

I just interviewed some oil experts on Monday to answer questions about oil. Perhaps it’s time I reach out to some spark plug manufacturers to see what they have to say about spark plug design.

[Lorrin Barth]

Good idea.

[Bill]

I did a little research on those plugs and they are racing plugs. Only problem is that they are non resistor so if your car messes up an important broadcast over the air and they trace it to you there could be repercussions. I wouldn’t say that is too likely however. Non resistor plugs for highway use is illegal.

[dan]

YES! do not, i say again DO NOT use non resistor plugs, they reduce electro magnetic pulses from your ignition system too prevent interference with things like your radio and other important electronics on your car, like your PCM!

stick with OEM plugs and you can’t go wrong.

[Brian]

Typically with forced induction we run one range colder than stock. But do your own homework on that with supercharging/turbocharging.

[dan]

ooh i am very aware of that and do my homework on that one, if you run enough boost like if i where too turbocharge my grand prix or do a top swap and a 3.4 pulley with large fuel injectors it is in that case customary too also install Autolite copper plugs of a cooler heat range too reduce spark knock!

but in the instance where there are only minor modifications even in the case where the car is subjected too forced induction it is recommended too stick with OEM AcDelco spark plugs, unless you are starting too run in the area of 12-14 or more PSI of boost, THEN when spark knock starts too become a issue because of boost levels run cooler plugs with lesser gap!

in my opinion unless he is having issues with spark knock and he is running lots of boost, stick with OEM, if he is having issues with spark knock then buy all means run heat range colder. going with some special E-3 garbage or running non resistor plugs will not remedy that issue, its silly and unessisary…

[Author]

Replies