The higher the octane the higher the resistance to starting fire. This is why high octane is used to avoid detonation.

Are you running more retarded ignition timing as well?

 

The higher the octane the higher the resistance to starting fire. This is why high octane is used to avoid detonation.

Not true. Octane (RON or MON) is a measure of a fuel's resistance to detonation. The air/gasoline mixture should burn very quickly in the combustion chamber, not explode or detonate.

RVP or Reid Vapor Pressure, is a measure of the HC vapors generated from a given fuel at a standard temp and pressure. We blend RVP for summer gasoline and a winter. The winter RVP is higher so there is more light ends like butane or propane to generate vapors at a lower atmospheric temp to ignite on cold start. Summer gasoline has a lower RVP, like 3/4 psi, winter 6/7 psi.

For an example, propane has a high octane number and a very high RVP. (Propane is a vapor @70°F, 0 psig).

If your having cold starting problems with this fuel versus pump gasoline, its either a RVP problem (not enough vapors generated to ignite) or a radical air/fuel mixture problem at cranking idle. But given the lower ambient air temps right now I'd venture to say its a RVP problem.

How does the engine start if you shut it off hot and restart it with the race fuel?

 

Yup, an RVP problem. The 110 fuel doesn't generate enough vapors for the given ambient temps, cold start. You could blend it with winter season 93 pump fuel like 60% pump/40% race and it would probably cold start ok.

 

I'll give it a try, thank you very much :thumb:

 

Not a problem Greg, good luck with it.

 

Thanks Pat, and this would be cheaper too.

 

How long before gas loses it's "edge"- I know some of the racers around here will not buy any extra gas to carry over from week to week.
My only thought is, especially with the race gas, is that it is probably the same batch sitting in the tank at the station since I'm sure it doesn't move too fast...

Guess I'm not clear on what really is "fresh" gas? How long after making it, shipping it, sitting at a station or just sitiing in a 5 gallon container? What in it breaks down or what happens? I would assume just from vapors evaporating is where some of the change comes from?

 

How long before gas loses it's "edge"- I know some of the racers around here will not buy any extra gas to carry over from week to week.
My only thought is, especially with the race gas, is that it is probably the same batch sitting in the tank at the station since I'm sure it doesn't move too fast...

Guess I'm not clear on what really is "fresh" gas? How long after making it, shipping it, sitting at a station or just sitiing in a 5 gallon container? What in it breaks down or what happens? I would assume just from vapors evaporating is where some of the change comes from?

:them: I would like to know the answer to this also.

 

I think its the oxygenated fuel that looses it bite after setting.

 

thats some good stuff to know.

 

One of the racing schools talked about not using last weeks gas- I'll try and see what they were refering to, I think they did a study by using gas from last week to a fresh fill and it took so much off each lap.

That's good to know because I wouldn't buy like 5 gallons of the race gas and keep it for mixing since I never knew how soon I would use it.

Thanks for the info!

 

One big thing in this area w/ storing gas,is too not let it sit on a concrete floor.Keep it off the floor by setting it on some 2x4's.

Where have you found race fuel?Everyone on my side off town who carried,has now switched to Kerosene for the winter months.

 

You got it.....:thumb:

 

Am I to understand that gas stored in airtight 5 gallon plastic jugs will last indefinitely. So there is no need to add stabill (seafoam) or any other additive to airtight stored gasoline.

I only need to use additives in fuel left in the bike, mower, boat, etc. for extended periods of time.

Sorry if I am beating a dead horse here, I just want to be absolutely clear on this matter. I keep several cans of gas around and could save a few $$ on additives if I don't need them.

 

I guess I'm a little off topic here. I am refering to 91 or 93 octane pump gas.

 

If the containers are indeed air tight and are filled to say 90% capacity (you must leave some vapor space for thermal expansion) and not opened frequently and kept in a cool secure location, then there is no need to add Stabill. When your ready to use the fuel, agitate the gasoline a bit before opening, then open slowly with caution (pressure/vapor release). I use Stabil in fuel over the winter months kept in my lawnmower, weedeater, or blower. Or a vehicle your not going to start or run in over 2 or 3 months or longer.

 

Thanks!!! That clears it all up for me.