I have been told yes and no what is the real deal???

 

i would run at least 108 cam purple 2.

 

I run 11.1 compression piston in my 416. I fill up an 5 gallon jug then i'll add a half bottle of octane booster to the 5 gallons. No problems.

 

I have a 11:1 Wiseco and have never ran anything but 93 octane pump premium and have NEVER had any problems. If you are still not sure go to www.gthunder.com and click on the catalog and go to pg.15 there it lists octane requirements for the 400ex with aftermarket pistons.

Clint

 

Octane requirements vary from day to day. Cool heavy air might need more octane. Altitude also plays a huge part as does jetting when in doubt a little boost and a larger jet wont hurt.

 

My 416 has 11:1 JE piston and is fine with 93 octane and some octane booster once and a while.

 

I have an 11:1 piston and when I run 93, it pings under a hard load in mid rpm range (exiting corner, climbing hill, etc.). I run a mix of VP C12 and 93 octane (50/50) and it comes out to 100 octane and my pinging is gone. I am not running a timming advancer, but this would allow you to also advance a couple degrees.