dispensing of premium fuel

[Fallon]

The higher the octane gas has, the harder it is to ignite & the less chemical energy it has per gallon.High compression engines need that hard to ignite aspect to prevent pre-ignition (a.k.a. pinging) when things explode on their own rather than the properly timed burning triggered by the spark. In forced induction engine (turbocharged/supercharged) the added air & compression more than makes up for the slightly less chemical energy in the gas with higher efficency & stuff.

Paying for premium gas when it needs regular is just a waste of $$$ & will not increase performance. In thoery it might decrease performance by an inperceptable amount due to less chemical energy per gallon.

However as we all know that ethanol sucks. If you can get overpriced premium with slightly less chemical energy per gallon that is ethanol free i'd personaly go for it. Its only an extra buck or 2 & means fewer carb problems from that dam ethanol. Personally I use that way overpriced canned fuel to get away from ethanol for the few gallons a year I need for my 2 strokes. I'd consider ethanol free premium if there were any around in my area.

 

[Texasmark]

Interesting. Pump has to contain the valve since each pump has to distribute per the customer's requirements. Say a 10' hose is 120 inches. 1" ID would be pi x .5" exp 2 = 0.78" x 120" =94 cu in......quantity of fuel in the hose. With a gallon being 231 cu in. looks like about 0.4 gallons would be your loss.

So .4/2 gal for a 2 gallon lawnmower tank = 20% of an 87 octane added to 80% of 93 works out to 91.4 octane average for the 2 gallon tank.......not worth fooling with as I see it since I fill up 4ea 2 gallon and 3ea 5 gallon when I fill up.

But thanks for the heads up.

 

[CalG]

Interesting. Pump has to contain the valve since each pump has to distribute per the customer's requirements. Say a 10' hose is 120 inches. 1" ID would be pi x .5" exp 2 = 0.78" x 120" =94 cu in......quantity of fuel in the hose. With a gallon being 231 cu in. looks like about 0.4 gallons would be your loss.

So .4/2 gal for a 2 gallon lawnmower tank = 20% of an 87 octane added to 80% of 93 works out to 91.4 octane average for the 2 gallon tank.......not worth fooling with as I see it since I fill up 4ea 2 gallon and 3ea 5 gallon when I fill up.

But thanks for the heads up.

If only fuel math could be so calculated.

Hybrid has proven to be "a tough show". The mix might be better than anyone could design.

;-)

 

[Texasmark]

On using or not using premium, I've converted over to it long enough now to know for sure. It works much better for me in engine performance including easier starting expecially hot. I'll stick with it.

On storage, not a rocket scientist, but if premium has more volatile elements to control pre ignition and those elements are what's lost in storage, especially with non-sealed containers, it seems that premium would have more of such so it would take longer to lose such so it would store longer.....dunno, just seems logical. We'll see over the winter if there is any truth to that assumption based on a SWAG....S for Scientific. Ha!

 

[clemsonfor]

you can run high octane in your engines, its a waste and they make less power but you can do it. You should be rotating your fuel anyway and not have any that is old enough for octane degradation.

For info I run 87 octane NO E gas in my 2 strokes. They make more power on it and get more complete burns when your running over 10,000 rpms, there is no time for detonation at that speed. I have stihl and Chinese and husky stuff, yes I know what the manual says. I am not alone doing it, and I choose to do it on purpose, I can also buy premium no E fuel but I buy the 87 as you make more power with it.

 

[hawkeye08]

I know of one station in the entire Spokane, WA area that has ethanol free gas and its regular. CDIH when I'm going to make a 60 mile round trip just for a five gallon Jerry can of ethanol free gas. Everything I own runs just fine of 10% ethanol gas or it goes back to the dealer on warrantee.

When we bought our new weed wacker at ACE hardware, the sales rep told us Cenex near North 40 in Mead had ethanol free... yes it does! He told us there are more, but not well known.

 

[CincyFlyer]

The higher the octane gas has, the harder it is to ignite & the less chemical energy it has per gallon.High compression engines need that hard to ignite aspect to prevent pre-ignition (a.k.a. pinging) when things explode on their own rather than the properly timed burning triggered by the spark. In forced induction engine (turbocharged/supercharged) the added air & compression more than makes up for the slightly less chemical energy in the gas with higher efficency & stuff.

Paying for premium gas when it needs regular is just a waste of $$$ & will not increase performance. In thoery it might decrease performance by an inperceptable amount due to less chemical energy per gallon.

However as we all know that ethanol sucks. If you can get overpriced premium with slightly less chemical energy per gallon that is ethanol free i'd personaly go for it. Its only an extra buck or 2 & means fewer carb problems from that dam ethanol. Personally I use that way overpriced canned fuel to get away from ethanol for the few gallons a year I need for my 2 strokes. I'd consider ethanol free premium if there were any around in my area.

The high octane is to prevent detonation (instead of the normal deflagration) which causes the flame front to spread at supersonic speed. It normally occurs after the ignition event (usually a spark). Pre-ignition can cause detonation, but is an entirely separate thing (a "hot spot" in the combustion chamber can cause pre-ignition). This occurs, by definition, prior to the planned ignition event.