I just had my motor rebuilt a few months back and the guy that did it installed new spark plugs. He put in the stock plug type - NGK BUR7EQ leading, BUR9EQ trailing. Ive got a street ported N/A with a staight exhaust setup (mods below), and I think I should probobly use hotter plugs. Racing Beat reccomends B9EIX plugs for my setup, but is there some reason why I should use non-resistor plugs? Thanks for the input.

 

as long as the engine runs smooth you might just want to keep them in until the wear out. if they end up scorched and worn after only a few thousand miles you'll know to move up to the other plugs. otherwise you could save money on just ussing the oem ones. $6 a plug is hard enough to handle, let alone the $10-$15 the colder plugs go for. however even my stock port s5 with similar exhaust muches plugs so id guess bur9eq all around would be a good idea.

 

Yeah, Im pretty sure Im gonna go ahead and get them sometime fairly soon. Once I get the engine fully broken in and I find an exhaust backpresure tube (that runs the aux ports) its going to see higher RPMs more, as well as some road racing and auto-x.

 

good luck with the backpressure aux port rig. ive been trying to figure it out for a while on my s5 as a meens of ditching the airpump without going to an electric but i cant get it to work for the life of me. its supposed to work in theory but it just doesnt oh well. lmk if you figure it out

 

Im pretty sure that s5's use the air pump as the sole means of opening the aux ports. In the s4's, like mine, its just used for the initial opening of the ports, and has little or no actual effect. Im pretty sure theres a thread near the top of the archive about how to make something to open the ports, if you end up doing that. Good luck.

 

really, the s4 cars still use the airpump to fully open the aux valves i thought the backpressure did all of it.

 

Why do you WANT to run hotter spark plugs?
Everyone else wants to run colder spark plugs.
I think you're confused on the role of what the spark plug is supposed to do in and engine.
Higher number = COLDER range

Why do you insist on running a non-resistor spark plug?
Are you running a race car?
Are you running no other electronics in the car other than the ignition system?
The resistor is built into the spark plug to supress RFI.  Non-resistor spark plugs can emit RFI which WILL cause interference with almost every other piece of electronics in the vehicle.



-Ted

 

Sorry, my bad. I meant colder plugs, not hotter. And no, I don't insist on running non-resistor plugs. In fact, I don't want to. Racing Beat reccomended the use of B9EIX (non-resistor) plugs for a street-ported motor, and I was asking if there was a reason why they listed those, and not the BR9EIX (resistor) plugs.

 

Cause they are cheaper?


-Ted

 

That, or a typo. Just making sure there wasn't some reason to use non-resistor plugs. Thanks for clearing it up.

 

This might help: http://www.mazdatrix.com/ign-2.htm