Proper octane level for lo206?

Double E Ranch

New member
Since our move from clone to an unrestricted LO206 I was wondering what the proper octane should be run for optimal performance? Does anyone run VP Racing fuel?
 

alvin l nunley

Site Supporter
Do you know how many CC’s are in the combustion chamber? Knowing what the compression ratio is would be a big help in determine what octane you need. If the compression ratio is anything like a clone, you would most likely run best with the lowest octane you can find.
Octane is not a measure of the power you will get out of the fuel; it’s a measure of the fuels ability to resist detonation. Low compression ratio engines run best with low octane fuel. If you raise the compression you might need higher octane fuel, but it’s the higher compression that will give you more power, not the higher octane fuel. The higher the compression, the better chance you have of getting detonation, and this means you need higher octane.
If you can run low octane fuel, without detonation, you’ll get more power from it.
A lower octane fuel may need a change in mixture ratio, so keep an eye on that.
Now I see where someone said they use 91 octane for best performance, so I think either the compression ratio is higher than I thought, or they didn’t have the mixture right when they tested the lower octane fuel. I can think of multiple reasons why they got the results they did.
 

Kart43

Member
If you are running according to Briggs Rules it is specified. No they do not need race fuel and they usually specify High test fuel.
 

GoFastHP

Member
87 Octane is just fine. Any high octane really is a waste of money. Finding a gasoline without ethanol would be preferred as well. We have had numerous issues lately with ethanol messing things up. I think it depends on the gas station supplier as well the ethanol percentages per gallon.

-Shannon
 

rainman

Site Supporter
With the clones in completely stock stage or midly built on Cl1 cam testing at same tracj same day under same conditions best performance came on non ethanol low octane gas. Higher octane gas showed even lower lap times than regular ethanol gas. What's WKA rules on gas for 2O6? What issues have yiu seen running regular ethanol gas? If nothing change definitely moving to 206 for 4 cycle asphalt classes, specially Road Racing.
 

alvin l nunley

Site Supporter
I find it strange that the ethanol fuel was slower. We use to add alky, in small quantities, in our Macs to go faster. And of course there was the water test for detecting alky in the KT. And I'm sure everybody knows, that the WB3 would not pass much. And now I'm hearing that adding alky slows you down. That's strange.
 

Kart43

Member
Follow Briggs rules it works:

10. Engine Fuel
Premium Gasoline no greater than 94 octane sold at normal roadside fuel
stations open to the public. The addition of fuel additives in any manner is not
permitted. Fuel dispensing location may be specified in Event Supplementary
Regulations.
 
Just for general info. At the 4 Cycle Super Showdown in Phoenix last month we spec'ed our normal club race spec fuel, VP MS98. Mostly to make tech a little simpler. The race was strictly World Formulas and LO206's. No complaints, no issues.
By the way, the race was a complete success and will be bigger and better next year. If you race sprint karts with the above engines keep your calender open for the first weekend in November 2014!!
 

Dr.T

New member
Ethanol and Methanol have RON & MON ratings for octane. Both are close in octane between 108 and 115 depending on a couple things. I agree that it should make more HP but tuning is the most important factor. Can't for the life of me figure out why WKA wants to go back to gas with 4 strokes. Pump gas is all over the place. Methanol is easier to tech and control.
I grew up in a time when gas smelled good.......not now. That stuff stinks!
 

alvin l nunley

Site Supporter
Just for general info. At the 4 Cycle Super Showdown in Phoenix last month we spec'ed our normal club race spec fuel, VP MS98. Mostly to make tech a little simpler. The race was strictly World Formulas and LO206's. No complaints, no issues.
The San Diego club has someone bring in, I think about 103 octane, fuel to each race. Everybody runs the same fuel, no problems. But that doesn’t mean it’s the best fuel you can use for peak performance on all engine. Sure it was great for the TT 75, but probably not the best choice for the KTs.
I can see no problem with clubs doing things like that. It makes tech easy and has no bad effects on any engine.
Comments compliments criticisms and questions always welcome.
If the data does not support the theory, get a new theory.
Tuning is tough! (Al Nunley)
 

clonedog

New member
hey dr-T we like pump gas in this clone dont change now. when we ran flat hd years ago it was a pain in the butt with methonal its funny why most racing uses gas like nascar, motorcycles, etc............. the list is long. if methonal was so good why is almost all limited to kart racing? hmmmmm........ somebody trying to make some money...............????
 

Dr.T

New member
Gas is for your tow vehicle. Methonal is for racing! Nascar has Gas sponcers, of course there going to use gas. Sprint cars ALL run alky and make some big HP. Late models, alky drag cars and bikes. So.....it is always about the money and I would rather support the shop at the track selling race shine then Opec and their rollercoaster pricing. Besides.....if you want to learn how to really tune a engine, learn on alky.
 

spud majic

New member
I will take alcohol over gas in most every intstance except classes like this. it doesnt hurt the engine even though it runs a bit hotter, and you get less of it in the oil which means you can go longer between changes. not having to purge a carb at the end of the day makes for a reduction of work. in the old f200 class, when you had it running right you didnt get any carbon buildup on the head either.
 

BrendanFitz #73

New member
I don't get this. The man asked a question about what octane to run in his 206 and one person says somethin about Methanol and then the whole thread is derailed.
 

alvin l nunley

Site Supporter
It’s a real shame isn’t it, here we have F1 and CIK using gas and not understanding how much better things would be if they used alky.
Comments compliments criticisms and questions always welcome.
If the data does not support the theory, get a new theory.
 
Do you know how many CC’s are in the combustion chamber? Knowing what the compression ratio is would be a big help in determine what octane you need. If the compression ratio is anything like a clone, you would most likely run best with the lowest octane you can find.
Octane is not a measure of the power you will get out of the fuel; it’s a measure of the fuels ability to resist detonation. Low compression ratio engines run best with low octane fuel. If you raise the compression you might need higher octane fuel, but it’s the higher compression that will give you more power, not the higher octane fuel. The higher the compression, the better chance you have of getting detonation, and this means you need higher octane.
If you can run low octane fuel, without detonation, you’ll get more power from it.

That's well said, and why I run 87 without ethanol if I can find it, which is not easy in this part of the state to find. 91 is easy to find. One problem we have had with ethanol in a different motor is fuel pump related with the ethanol. We also know someone that dynos regularly, everything from high end drag race engines to his son's Honda & Clone, and has had no success with running VP.
 
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