Spark plugs

[zak_62]

Sorry~ Sorta not lotus related~

The required plugs for the esprit is BPR7ES, that is a resistored plug. We have another car at home using BP6ES plug, that is not resistored plugs. From my previous understanding, the resistors are added into the plugs for stablizing the sparks.
Can I use a resistored plug for the motor that calls for a non-resistored?

[lotusguy]

zak_62 said:

Sorry~ Sorta not lotus related~ The required plugs for the esprit is BPR7ES, that is a resistored plug. We have another car at home using BP6ES plug, that is not resistored plugs. From my previous understanding, the resistors are added into the plugs for stablizing the sparks. Can I use a resistored plug for the motor that calls for a non-resistored?

Zak,

You can actually use either plug in either application. They will both make the car go.

The problem with using a non-resister plug in an application which calls for a reistor plug is that it may interfere with the alternator and/or the ignition timing.

About that BP7 plug for the Esprit, are you sure? What make/model/year? On NGK plugs, the temp rating drops as the number increases ie. a BP5 is a 'hotter' plug than a BP6, which is 'hotter' than a BP7 etc.

This doesn't mean the plug makes a hotter spark, rather a hotter plug has a greater length of the electrode insulated with porcelain. This allows it to retain more heat. A colder plug has a smaller insulator allowing it to shed more heat.

Use too hot a plug, and it will degrade quickly as well as contribute to detonation. Use too cold a plug, and it will foul easily. Either case results in poor engine performance.

I am using the BP7 plug in my carb'd turbo which calls for a BP6, because I am running increased boost (10PSI v. 7.5PSI stock), as well as having increased the CR when I replaced the stock pistons for the Forged JE ones (8.5:1 v. 7.5:1 stock). While I didn't detect any detonation w/ the 6's, the engine seems to run smoother with the colder BP7 plug. Before the engine rebuild, I once tried the BP7's and the engine ran like crap, switched back to 6's and everything smoothed right out, but of course, that was before the engine upgrades were performed. Happy Motoring! Jim'85TE

[zak_62]

I am running BPR6 on my HC that calls for BPR7 because I can't find 7 anywhere in Taiwan unless it is a iradium plug. I did get the iradium (BPR7EIX) in my box now, but I still have some carb issue I want to deal with before I plug those expensive metals into the motor.

Another car we have at home is calling for a BP6ES, which I am thinking about giving it the BPR6ES after I am through with them on my HC.

[maigret]

You are probably better off with the Iridium plug as they have a wider heat range. The auto supply place should have details on comparison with std plugs.

[solar]

anyone know the NGK's that go in my S4S??

[kmaier]

Matt, according to the service notes, the S4s uses a NGK BPR6EKN plug. Monarch Products is a large supplier for NGK and other bits... here's a link for plugs that fit your S4s:

www.monarchproductsinc.com/results_app.asp?AAIA=1189133&mfid=1

Regards, KM
2000 V8

[solar]

cheers KM!