Speedworks

Anybody has any recommendations with regards to altering the spark plugs on the Renesis engine?

Stock:
Leading: RE8A-L+
Trailing: RE9B-T

Option would be to have colder ones in there due to spark plugs which are worn after a few thousant miles.

pistonsuk

Correct me if I'm wrong but I dont think the heat range of a plug has anything to do with the rate at which it wears.

The only reason you would want to change the heat range is to:

1) Reduce hotspots in the combustion chamber by going with a colder plug. This is only necassary if you are running a lot higher massflow rates than a stock engine.

2) Reduce fouling due to under-heated plugs. Plugs must maintain 300-400C inorder to self clean enough to not foul. Too cold of a plug will not due this without adaquate heat input from high massflow rate of combustion gas.

Justin

Speedworks

Correct, but the heat indicator for the spark plugs does affect the point where it melts.

Difficult to explain, but many of us with blown engines have found melted spark plugsin their motor which in theior turn caused the engine to detonate (igniting the mixture because the spark plug was redhot.

A friend is destroying his RX8 spark plugs in an abnormal way and lots of solutions have been tried already so we though colder plugs could be a next way to go

Speedworks

*edit*

crispeed

[QUOTE=Speedworks

A friend is destroying his RX8 spark plugs in an abnormal way and lots of solutions have been tried already so we though colder plugs could be a next way to go[/QUOTE]

Is he destroying them on a NA RX-8 motor? Also is he melting the leading or trailing plugs?
There are some major differences in the design of the rx-8 plugs between the leading and trailing in regards to length. The leading are at traditional length but the trailing are shorter at about the same length as the NGK's 'EV' and 'IX' series. On the earlier motors the EV/IX plugs would leave some threads open on the rotor housings due to them being shorter. I have not check the RX-8 housings as of yet but Mazda might have designed the trailing holes to accomodate for the shorter plugs. If that is the case you'll have to be carefull if you're going to try the NGK R6725 series of cold plugs that were designed to be used in the earlier rotary motors. The '6725' series are available in various heat ranges from 10.5 to 11.5.
I will have to check the RX-8 rotor housings to varify the dept of the trailing holes.
BTW. On our NA PP 13B motor we made the best power with the NGK '6725' series of plugs. We lost 10 to 15 rwhp using the RX-8 plugs.

Speedworks

Hello, Yes the engine is NA and stock (even weirder). I'll check with him what plugs were damaged the most (can't remember right now)

Thanks

SureShot

Maybe think outside the box on this one.
Different / better fuel.
Water/alcohol injection.

j9fd3s

iTrader: (3)

wtf are you doing to a stock car to melt plugs? is it running at 9000rpms all day or something?

KeloidJonesJr.

iTrader: (8)

Needs more denser air?

mono4lamar

iTrader: (32)

what is the part number for the ngk 10.5's i cannot find it... and wheres the cheapest place to get them. please give me more than sparkplugs.com