Does the gap change as you add HP?
Thread Starter
9 Second Club NA
iTrader: (180)
Joined: Mar 2003
Posts: 5,943
Likes: 1
From: Houston, TX
Does the gap change as you add HP? Just wondering if the gap needed to change because Ive added over 160hp to the motor. Im running the TR-55s right now...I think they have around 10k miles on them, should I take them out, clean them, regap them if needed, and put them back in, or buy new ones? Would you consider those a good performing plug for race use? Thanks.
Increasing HP means you must increase the
pre-spark cylinder pressure. The spark voltage
required to arc increases with pressure. At
some point you will have a problem striking
the arc (or it will find a weaker point to start
arcing, like through the wires or internally,
which is bad). Then you get misfires and maybe
some damaged coil packs. So you see the N2O
guys run smaller gaps. I'd say, rule of thumb,
{new gap}/0.055 = 350RWHP/{new RWHP}
though you might be able to push it out some.
Don't know exactly how far you can go (peak HP)
before standard gap begins to resist firing. If
you get a "good number" for that, substitute it
for the 350RWHP value.
pre-spark cylinder pressure. The spark voltage
required to arc increases with pressure. At
some point you will have a problem striking
the arc (or it will find a weaker point to start
arcing, like through the wires or internally,
which is bad). Then you get misfires and maybe
some damaged coil packs. So you see the N2O
guys run smaller gaps. I'd say, rule of thumb,
{new gap}/0.055 = 350RWHP/{new RWHP}
though you might be able to push it out some.
Don't know exactly how far you can go (peak HP)
before standard gap begins to resist firing. If
you get a "good number" for that, substitute it
for the 350RWHP value.
Thread Starter
9 Second Club NA
iTrader: (180)
Joined: Mar 2003
Posts: 5,943
Likes: 1
From: Houston, TX
I havent dynoed the car since I put the auto. in, however, when it was a 6 speed, it dynoed at 417rwhp/388rwtq. I believe thats around 485hp to the motor. What would you say I should gap my plugs at for that power? Thanks for your input.
