my uncle said he has been running a higher octane fuel then the unleaded. he has a power commander and flowmasters with an aircharger. will he really notice a gain in power? if so how much?

 

....No gains in power.
....Look at it from a science point of view.
....What makes more power?
....It's the BTU content of the fuel.
....Higher Octane fuel is not very much BTU related but actually flame speed retarded.
....The Octane rating is mostly for higher compression engines to prevent ignition ping and spark knock if the motor needs it..
....The higher octane fuel actually burns slower to prevent the ping and knock asociated with higher compression.
....Ping, and knock an advanced form of ping, is the pressure in the cylinder that 'peaks' too early when the piston is too near the top of the cylinder such that the piston and rod are too much in a straight lineup to move very fast until about 12 to 15 degrees past top center when the rod angle becomes a better lever to put better pressure on the crank throw.
....This ping/knock is what you hear when that flame speed is to fast in a high compression motor or the ignition timng is to far advanced in any motor.
....So you can see from this that he has little chance to see any real benifit to power except maybe some percieved smoothness.
....I know it a lot of words but too many try to associate high octane with more power and that's not the way it works from just changing fuels in the same engine.
....Actually in a Ford and likely in other makes as well, the PCM just readjusts the fuel and ignition tables due to the crank sensor measuring a sleight difference in overall crank revolution time periods per cylinder and all 8 tables get the same adjusted change..
....Play along with him for awhile and see what he says.
....If he says he got more power; ask how so and hear the answer as related to what you read here.
....Only way to get more power is use an oxygen rich fuel like Nitro or Laughing gas the same thing used by the racers in a little tank in the trunk under high pressure.
....When you do 'this', extra 'gas' has to be added or the motor burns pistons from the huge increase of heat (BTU) content of combustion but you really fly on it while it lasts.
Good luck.

 

he also uses some stuff that he dumps in his gas tank
??

 

What is "some stuff"?

 

snake oil.

 

He did say a Power Commander was being used. If that's like a SCT tuner then he may be forced to use premium fuel by the program. Probably gets a little more hp in upper rpms but whether it's feelable in a big heavy truck ???????

 

the blood of his enemies!

 

If you asked that?
You may not be in a position to know if in fact that's all he has.
I can't remember howany times I have told kids I have a stock motor in my car.lol.
That's a classic tho.
Exhaust and intake.lol

 

If you run a tuner, then yes, you can use a higher octane fuel for slight power gains. But that is a lot of expensive for very minor gains.

 

To make the most power you can out of any engine, you want to run the lowest possible octane you can safley run.

Safley run means that your exhaust temp is in check, and the engine isnt Pinging/knocking. If you start to add higher octane past the point of what you need to run safe, your are just paying more and getting less.

 

To respectfully offer a correction, exhaust temperature is not 'directly' related to fuel octane except on a 'secondary basis' through pre-ignition or spark knock that should not happen in an engineered application.
Exhaust temperature is normally based on air to fuel ratios.
The normal ratios provide some 'excess' fuel.
This is what keeps the engine from overheating by utilizing the effects of vaporization of the excess fuel that has not combusted.
To relate another way;
In an alcohol burning engine, the fuel does have a very high cooling rate but just let the A/F drop at high rpm and you get piston crown softing and melting very quickly.
As good as alcohol is for cooling is also can cause very fast distruction if the A/F ratio goes lean for just an instant.
To relate alcohol to octane, alky has an octane rating in the 115+/- range and cools very well but is much more sensitive to leanness that causes overheating not from the octane rating but from it's very fast rate of vaporization.
Using higher octane gas formulations in a standard engine changes the rate of flame travel so becomes ignition advance sensitive to get the most power. This is were the use of a tuner comes in.
Switching to a higher octane in a stock engine usually does not cause an issue but it does not help anything but empty the wallet a bit more and faster.
Good luck.

 

Actually is does often cause or contribute to issues. Since the mixture burns more slowly, unless you run enough timing advance, you will not get as much complete combustion inside the cylinders as you should. Any unburned mixture that enters the exhaust is not only that much less energy being used to drive the piston, but it contains unused oxygen. The O2 sensor does not measure fuel to air ratios, it only measures oxygen. If you have unused oxygen, the computer will interpret that you are running slightly leaner, and will add more fuel to compensate. So the end result is that you will run slightly rich. This rich operation contributes to carbon deposits, which can cause all sorts of issues.

So in other words you will be spending more money to make your engine run worse.

So you should use the octane rating recommended by the manufacturer.