Just trying to find some answers fo the best out right now..
thanks
I am running a 12:1 piston and a stage 1 cam with porting ...what is the best deal ,ultimate -4 is good but scared of the leaness it might cause,had to replace a piston after i burned a hole in it from running 91 pump gas and the ult-4 is 92 octane,so i was told to go to VP red but read alot about the Ultimate-4 and it sems good but expensive as heck..

 

Sam. Since you went 12:1 your gonna have to go with the 76 100 octane and run it strait or a mixture of others to get you around 100 octane to be safe. I'd run no less than 100 octane, no need probably to go much higher. jmo

 

U-4 all the way
although it only carries a value of 92octane it is leaded and oxygenated...its gnarley
Instant power just putting it in...you will need to up at least 2 jet sizes on your main
its totaly worth it...even at $10 a gallon

 

Your making me scared for T-day 03 [img]i/expressions/face-icon-small-sad.gif[/img] 686 with 12:1, I dont know if I can hang, mind taking it easy on me? I've used 110 leaded mixed 50/50 with 89 octane with good results, should bring you right around the 100 range, you might be able to get more power out of something lower like 98 or 97 octane, but I understand you'll play it safe. I have 11:1 and I try to run right at 94.

 

I run 100 octane unleaded 76 straight in my 12:1 686 with good results. I 've seen unleaded fuel make more HP than an equal octane leaded fuel. I've seen results on a dyno, granted it was a GXSR 1000.[img]i/expressions/face-icon-small-wink.gif[/img][img]i/expressions/face-icon-small-smile.gif[/img]

 

lower octane burns hotter and faster making more heat etc...remember peak hp is typically to lean for a motor and could lead to problems..a little rich never hurt anyone

 

True, true![img]i/expressions/face-icon-small-smile.gif[/img]

 

What about av-gas? It's 100 octane and a heck of alot cheaper than VP

 

yea they have av gas up in palmdale near me at the airport..,i may have to try that..I e-mailed the VP re and he reccomended the MRX-01 straight and that is a 98 octane,and he also told me i could mix ultimate-4 and som c-12 50/50 for a good mix

 

Sunoco GT100...$3.99 a gal.
If ou really want some HP go with Nutec...