10:1 or 11:1

[400exnac]

Im going to go ahead and make my 400 into a 416. Its already jetted and I have a full white brothers on it. Cant forget about the K&N. What do I want to run....10:1 or 11:1?

[Silverfox@C&DRacing]

most 416 kits come in a 10.8:1 which will run on good pump fuel or you can get a thinner gasket kit to get you to 11-11.2:1 and then you are looking at running a mix of race fuel and good pump fuel.

[400exnac]

Really? Some of the web sites are giving me the option of a 10:1 or 11:1.

[Silverfox@C&DRacing]

must be for a wiesco piston then

[nosliw]

go for the 11:1. you can run 93.

[PHIL_B54]

i got a 11:1 wiseco pretty cheap, so thats what i went with. then i just used stock thickness gaskets, so i figure i lost .1-.2, so that puts me at the 10.8 range. i mix 50/50 race gas/93 oct. in the summer, and straight 93 when it gets cooler out. i might not even need the race gas at all, but ive never tried

[250EXking]

my buddy runs 11.1 with over sized valves and port and polish. standard bore on the piston. He runs 94 with a splash of octane booster. Runs good.

[QuAdEr 317]

so 11:1 you cant run pump gas??

[250EXking]

Originally posted by QuAdEr 317
so 11:1 you cant run pump gas??


you can, he has a slight knocking. so he just adds a splash of octane booster and no problems.

[400exrider707]

I've heard from people on this site that they run 93 with 12:1. I just ordered my 11:1 and will run 93 with octane boost to be on the safe side.

[250EXking]

Originally posted by 400exrider707
I've heard from people on this site that they run 93 with 12:1. I just ordered my 11:1 and will run 93 with octane boost to be on the safe side.

sounds good. thats what my buddy does and it runs great.

[400exnac]

when you all talk about octane boost or a splash of it how much do you mean. For example how much would you put in a 5 gallon gas can?

[markk]

id go JE 10.8 to 1 or 11 to one! im running 11.1 and never had a sparknock problem ever!!! 93octain Amaco fuels!

[Fast350ex]

What ratio compresion runs with 93 or C12?

[nosliw]

i think i remember reading on here that octane booster is a big no-no for our quads

:scary:

[Kansas T]

Originally posted by nosliw
i think i remember reading on here that octane booster is a big no-no for our quads

:scary:

I've done testing with octane booster in my car and I'll never use it again. Most claim it can raise octane by 8 points, but the fine print actually reads 8 tenths of a point. It also discolors the plug and in some cases left nasty deposits on it. I've found its cheaper and more effective to buy several gallons of race fuel and mix it with premium. When calculating octane, it works on a 1 to 1 ratio. One gallon of 100 octane mixed with one gallon of 90 octane equals two gallons of 95 octane fuel.

[TC426EX]

go 11:1.... It still runs on premium pump fuel like the 10:1 but you get a higher compression ratio so whats to lose?

[Dave400ex]

I say stick with the 10.8:1 to stay on the safe side. No problems out of mine on pump fuel.

[400exnac]

If I went with an 11:1 but used a stock size gasket then it would be close to 10.8:1 if Im correct?

[cals400ex]

from what i read, a 10.8:1 with thin gaskets isn't even a true 10.8:1. however, every brand of piston is different and the only way to know for sure is to check it out. i run a 11:1 piston with no base gasket and a thin cosmetic head gasket. i always run it on 93 octane. i have tried race fuel and notice no difference in power when drag racing. i can't tell it runs cooler with the leaded race fuel either.