oxygenated or not

[steve_o78]

alright i am wondering what kind of race fuel i should get, i can get sunoco GT100 which is unleaded and oxygenated from a pump. or from a local race shop sunoco leaded standard 110 non oxygenated. i am going for a fuel that will offer crisper throttle response. they are about the same price. any suggestions?

 

[steve_o78]

fuel q for rich

i know rich knows about all this fuel stuff so come on rich help me out here?

 

[Rich Rohrich]

Steve - Assuming the fuel is fresh the oxygenated fuel should show better response and a bit more power if the jetting is corrected for it.

 

[steve_o78]

sweet

thanks man i can get the gt100 for $3.50, i'll try em both see which i like better i dont mind messin with the jetting if i can get it runnin awesome.

 

[nephron]

Even though $3.50 is a good price, if it's from a pump, you're wasting your money. Also, it looks like that fuel has a low RVP, high 10% and DEP. Looks like a car fuel, and they don't tell you how it's 'oxygenated'. But then again, for $3.50....only a dollar more than slag, might not be a bad deal??

 

[Rich Rohrich]

it looks like that fuel has a low RVP, high 10%

neph - In the area of 150F for a 10% point and RVP in the 6.5-7 range is fine for his purposes. But like you pointed out, if it's coming from a ground tank there is no telling what the spec REALLY is once it comes out of the pump. :ohmy:


Getting the 10% point too low on a two-stroke can lead to pre-ignition. You have to carefully balance response the threat of favorable pre-ignition conditions in two-stroke tuning. :cool:

 

[nephron]

LOL! It's because I'm 'spoiled' by U4 and Pro-MX with those 120 10% points (Rich, my bike really does run better on U4 than C12, even though it's jetted lean down low...and absolutely without detonation). Have you tested Sunoco MO2X?

 

[Rich Rohrich]

Neph - I don't have consistent access to Sunoco stuff so I've olny fiddled with the lower end stuff.

 

[steve_o78]

yeah i was lookin at the mo2x, i'll go ask the dude at the race shop if he can get some. but does it look like a good fuel?

Specific Gravity .717
Antiknock Index (R+M)/2 112.0
RON, Research Octane
115.0+
MON, Motor Octane 109.0
Reid Vapor Pressure, psi 9.8
Distillation, 0 F

Initial Boiling Point
90
10% Evaporation
120
50% Evaporation
190
90% Evaporation
230
Final Boiling Point
255
Leaded
Yes
For Off-road Use Only
Color Green
Oxygen, Wt.%
2.7%

 

[Rich Rohrich]

It's looks like a good fuel for a 250F but not your YZ125.

 

[steve_o78]

so what would you do just stick with the gt 100 or use the fresher non oxygenated std 110? i just want a good consistent fuel that will run good for a decent price

 

[nephron]

Why is that not a good fuel for a 125? Is the DEP too low? Forgive my ignorance.