10.5:1 compared to 11:1 piston

[91250x]

I was wondering if the difference is highly noticeable, I have a 250x and want to use that engine instead of a 350x conversion. Powroll says the 11:1 piston requires race gas and the 10.5:1 can run on pump. I just want to know if there would be a drastic difference in performance between the two. Also what your input would be. Thanks! Would it be worth it to have to get race gas, or just use pump on the other one.

[cals400ex]

the difference won't be all that much. i would run the 10.5 so you don't need to mix race gas.

[91250x]

thanks!

[ZSK]

Actually an 11:1 is fine on pump gas. My 400 on 11.2:1 does fine with 93 or 94 octane.

[nakomis0]

Originally posted by cleanshave300ex
Actually an 11:1 is fine on pump gas. My 400 on 11.2:1 does fine with 93 or 94 octane.

^^^ Same here. I run 94, from Sunoco. I'd say get the 11:1.

[cals400ex]

sparks says to not go over 10.5:1 on a 400ex without mixing race gas. however, i ran over that on 93. i should have my 426 together this week. it will be over 11:1 and will see how it does. i will run around 96-97 octane at first. if i don't need the race gas, i won't use it. if it helps, i will use it. i honestly don't think it will help one bit, but i will see. by the way, i said 10.5:1 so you know you would be safe for sure. the power difference can't be that much.

[nakomis0]

Cal you will be set with 93 octane. I ran 10.5:1 before and never had any worries. 11:1 and i have some more concerns.

Theres not alot of differance ... but compression is where the power is... dont forget that.

The only time that statement is wrong is when you have so much compression its effecting your top end because it takes alot of power to ignite and turn the high compression engine... but if your under 12:1 you dont have nuttin to worry about,

ps. sparks is a *****, they are better safe that sorry. Which aint bad, but ' you can do alot more than they suggest.