NAVY

Hi i want to know what the best spark plug for my engine ( 408ci , 9.1 cr , 18 psi ) ???

TR6 = ?? gap
TR7 = ?? gap
TR8 = ?? gap

thanks
navy

HydroStream6

iTrader: (16)

TR7 at .024" here

NAVY

some people told me about .028" to .032 .

HydroStream6

iTrader: (16)

If you can get away with the larger gap then that's fine to run it at .028-.032. My plugs are kinda hard to change so I don't want to chance blowout.

NAVY

I understand now .024" better for me .

98Z28CobraKiller

iTrader: (17)

At that power level you will need a #8. NGK stock#7317's at .022-.024. More if you can get away with it but it wont make much difference IMO.

Phil99vette

iTrader: (11)

Autolite 3911s

veee8

iTrader: (40)

Yup, same here....

daws222000

iTrader: (6)

Would a tr6 with a 22-25 gap work?

98Z28CobraKiller

iTrader: (17)

Thats a #6. Way too hot IMO. I wouldn't go over 450 rwhp with those. That's what you put in a stock motor with a 100 shot.

Snyper

iTrader: (27)

...I run those at 700hp all day long...gapped at .032

NicD

iTrader: (7)

Just because you can get away with running a 6 heat range doesn't mean it's a good idea at that power level.

I would run an 8 heat range plug with the ops combo. I run the Autolite AR94s since it's still a tapered seat plug for the AFRs but they don't last long with the cut back strap. I believe the 3911s are gasket seat and not sure how well those will work with AFR/stock style heads.

98Z28CobraKiller

iTrader: (17)

I tried doing back to back passes on TR6 and the 7317 (#8's) when I was NA at about 520 rwhp and ran the same exact number. Why risk the hotter plug?

Snyper

iTrader: (27)

Maybe im just lucky..I changed them after 3k miles and they looked great.

98Z28CobraKiller

iTrader: (17)

I would try the colder plug and see if you notice any penalty. I bet you wont. You may have to tighten up your gap aswell with the colder plug or you may blow out your spark.

Quik

iTrader: (7)

ive ran TR6 at a dyno'd 700 rwhp with a pt88 and i also ran the Tr6 at 20 psi around 800 rwhp with no issues and 23* timing on 93 octane. no issues what so ever, this was on a 4.8



to the OP, what size turbo? what compression? what grade fuel, what motor size all play a role in plug choice

98Z28CobraKiller

iTrader: (17)

You are missing the point. We aren't talking about spending several thousands of dollars or paying thousands in labor to change them. We are talking $18 in plugs and 30 min. It's the cheapest insurance you can buy in this game. It's not like you'll lose any power. Why risk it?

droksformula

iTrader: (18)

Since a #8 plug is meant for higher cylinder pressure levels, is it ok to drive around town with them off boost ? Also what change intervals is recomended ?

daws222000

iTrader: (6)

I have tr6 gapped at 25 now and i was thinking about changing them to tr7. MY concern was if they were to cold they might foul out on normal street drivimg. I should be around 700 to 750rwhp but its a daily driver, i might see a track 4-5 times a year.

Boosted One

iTrader: (6)

I run a 9 heat range NGK gapped @ .024"in my car and drive it all over the place without fouling. 402ci @ 15psi. (but drive around at 8psi)