Freestyle wow amazing compression change.

[txsuperjetfreak96]

wow i live in the tx panhandle roughly 200' above sea level running 185 psi in each cylinder, i come to houston to work on a job decide to bring my ski, checked the compression today running 200 psi in each cylinder, now need to check what octane fuel im gonna have to run, will prob have to readjust my carbs, what do yall think.

thanx

 

[jetpilot36]

definately run at least 50/50 of race and 93 octane.aviation gas will do.its usually 100 octane.i wouldnt readjust the carbs unless it bogs or hesitates.u should be fine.

 

[Speedfreak]

On stock porting it should be fine at the 200 mark with 93 octane. I have ran 230 compression with stock porting and 93 octane. Just don't hold it WOT for more than 3 or 4 seconds and you'll be fine.

 

[Waternut]

Sounds funny...200 feet of elevation change shouldn't make a difference. Timing and porting will make a huge difference as to what fuel you need to run. Are both stock?

 

[txsuperjetfreak96]

yep its stock except bpipe, carbon tech reeds, ad racing head,

 

[txsuperjetfreak96]

my bad 2,000 ft above sea level

 

[Waternut]

Oh ok, that makes more sense. In that case, you should be fine with 93 unless you like to run WOT for extended periods of time. I'm running 200psi on a heavily ported engine with 93. If it makes you feel more comfortable, put some octane booster in as a temporary aid while you're there but you shouldn't need it.

 

[engineman44]

yeah av gas is 100 octane you have 100LL (low lead) and avgas 100 that is for airplanes i would research it and will ask tonight but i think its illegal to use in anything other than a plane and faa has some pretty hefty fines

 

[Waternut]

It's illegal to use it on the road. Off road use only has pretty lax laws.

 

[astandupguy]

av gas doesnt break down like pump gas either, years rather than months

 

[ryan]

im running 215 ported 701. w.o.t. all day long. 93

 

[JHD]

How does elevation change compression?

 

[icecoled007]

How does elevation change compression?

Higher elevation will lower it. 35cc domes will not give 180 it will be more like 170 ish. I know tons of guys that run 33cc to get 185-190ish

 

[suva]

How does elevation change compression?

Air is less dense at higher elevation.


http://www.npl.co.uk/reference/faqs/why-does-atmospheric-pressure-change-with-altitude-(faq-pressure)

 

[sjetrider]

I read the first post and was like NO FREAKN WAY 200 feet made that dif. So there is somewhere that has a lake 2000' above sea level in TX. HMMMM cool, didnt know that.