Sorry, but premium has little if any difference in density nor in much additives. It does have components like toluene that raise octane levels and also the energy content when burned. If you take it to the track where mostly WOT will be used it will yield a trifle more power but thats all.
And we ran timing tests here with pretty sophisicated test equipment and didn't find ignition advance more than 1 degree difference between premium and regular on runs made under precisely identical conditions on a dyno. Couldn't find any part of the FIT ECU that programmed increasing advance until knocking is detected and backing up slightly. The ignition map is pretty complicated itself though.

 

You're going to have to cite your sources.

API gravity is a function of specific gravity. The higher the specific gravity the more dense the liquid compared to water that has a specific gravity of 1.000.

The specific gravity of octane (the, um, high octane component of premium gasoline) is 0.701 (other compounds are substituted for octane: it used to be lead.)

Heptane, found in greater concentrations in regular fuel is 0.681.

Ethanol is 0.787.

If we accept that ethanol has less energy than gasoline (see my previous post), then the relationship between denser fuels and power doesn't exist, ethanol is much more dense than either component of gasoline.

The energy in gasoline comes from chemical bonds. Specific gravity is not an indicator of this. No reference I've found indicates the energy content of premium gasoline is different than regular. The properties of the fuel, its ability to ignite at lower temperatures are different: premium fuel requires higher temps/compression to ignite.

Oh and you'll have worse mileage but potentially better performance (in a high performance engine due to the higher octane rating of ethanol), not better mileage when using blends of ethanol.

specific gravity of various fluids

API gravity explained.

 

Gasolines are composed of many components from C5 to c!5 tanes. The ratio of the various components density, or specific gravity, not API gravity, isn't great enough to yield a 10% change in density for commercially available gasoline. If it were it would drive fuel management systems completely off course. Not to mention the greater cost.
true ethanol is a poor fuel because it has a low combustion yield in Btu per pound but that's all. it does burn cleaner than gasoline compounds.

API gravity is given by the formula (141.5/SpG at 60 to 70F)-131.5. you may notice the difficulty in comparing the API between two liquids. Which is why labs use density.
The density of virtually all gasolines runs between .68 and .73 and that range covers both premium and regular gasolines from many refineries, all of which are working on formulations derived from the crude stock being used at the time. That means gasoline isn't a tightly fixed formulation any more than crude is all the same. The range in both naphthene based and paraffin based crudes is very variable. I've seen regular gasolines with higher densities than premium but almost always lower heats of combustion. Its not density that makes gasoline better but components with higher heats of combustion compromised by octane requirements.

PS octane is merely the standard compound to define octane rating = 100 and so certainly not the best octane rating. Toluene for example is about 110 if memory serves.
Ethanol has a heating value of about 13,000 Btu per pound, gasolines 15,000 to 20,000 btu per pound although the drive is on to reduce the cost of gasoline components by shifting formulations toward the lower end so that higher gasoline yields are gotten from each barrel of crude (currently in the 20 to 22 gallon per barrel, depending on the crude).

The only reason to use premium is if you knew that particular one had a higher heat of combustion and you needed it to maximize power. otherwise, not of any value beyond the octane rating to avoid knock.

 

You are right but there is a lot more to gasoline than octane, volatility and vehicle age has more to do with running higher octane. I never got below 35 miles per gallon in mix driving with a high of 42 mpg in summer with premium gasoline. Higher octane will give you better acceleration and more mpg esp as the car ages. Turbo cars will have a higher duration cams to bleed off pressure so you don't blow the head off your engine plus add 20 percent more fuel is need to keep engine cooler. Also there are a lot of posts saying they get 28-32 mpg, they should be getting more miles per gallon even with auto trans. As your car ages it leaves deposits on the pistons which raise the octane requirement increase. I did not say that your car will not run on regular but I will not use it esp. with ethanol in the gas. Most cars will run fine on regular but might run better on premium, Regular gas will contain 10 percent ethanol and premium 5-7 percent, coming soon 20 percent ethanol in gasoline. The maximum brake torque is at an fuel air mix of 13.2-13.8, Honda is very efficient at 13.8 at full throttle. The oxygen sensor are calibrated to 14.7 a complete burn for gasoline period. The computer adds and removes fuel to keep it at 14.7 most of the time (closed loop). The theory is that when you let off the gas the car goes lean 16.1 air fuel but when you accelerate the car adds 10 percent or more fuel to get to 14.7. I notice when I run regular gas I have to press the pedal more compared to premium.


I am not trying to argue but a car in the 60-70 with 10.4 compression ran 100 octane gasoline. and premium know is like premium of the 70s minus lead

 

Self-delusion is the most powerful free drug available.

 

sorry to cherry-pick your statements, but this is the only one that came close to making sense. I'd qualify this with the statement "most cars will not benefit from running premium" and put the Fit in that category.

 

Don't know if you have ethanol in your gas yet but when you do you will notice a drop in mileage and a hotter running engine and poor throttle response then you will know what I am trying to say. There is a difference between brands. Honda adjust fuel trim all the time and sometimes timing but engine timing is mostly fix by engine design until you change parts and will correct up to 15 percent before check engine lite comes on. Look in owners manual, also look at fuel recommended 87 or higher. Honda like all car mfg has to make there cars compatible to run on 87 but that does not mean 93 wont run better and get better mileage. There are several different blends across America so what you use down there is not the same up hear. Ethanol been up here since the 70s and reformulated gasoline since the 90s. Premium gas was the only alternative to e10 gas that had no ethanol until recently. Premium gas still is better but not as good as it was.

 

Did the dyno yield any difference in hp? Could a premium tune be created? O lol this the gd side. I'm thinking of the ge with its stil untouchable
ecu.

 

I am just guessing but the car tested must have been equipped with automatic transmission which unless the torque converter is locked will not give accurate dyno results..... The real life driving performance and fuel mileage increase from high octane fuel is felt when the car is under load and the timing will maintain a more advanced position as the throttle position is increased to accelerate or maintain speed on grades without down shifting.... On a car with automatic transmission that isn't possible to do because even if it doesn't down shift there will be slippage in the torque converter .... In the old days on the cars that I grew up with and first worked on, the cars used used weights and springs in a distributor that allowed the ignition timing to advance as the RPM would increase and a vacuum actuated advancing mechanism that worked independently to increase the timing advance even more at cruising speeds or other times when the engine was under light load and the manifold vacuum was high..... Sports cars like the Austin Healey 3000 weighed 2500 to 2700 lbs, made 50 BHP per liter, ran 0 to 60 in 9.5 seconds, had a compression ratio of 9.0 to 1 and required premium fuel for optimum performance but had a vernier adjustment on the distributor to change the timing as needed by the owner.... The fit weighs 2500 lbs, develops 78 BHP per liter, runs 0 to 60 in 9.5 seconds, has a compression ratio of 10.4 to 1 and is able to run on fuel with a minimum octane rating of 87 but has a very complex engine management system that will automatically adjust the timing to not ping with fuel of octane as low as 87 by reducing the advance from what it would be if using higher octane fuel instead the old weights, springs, vacuum diaphragm and driver adjustment by advancing until ping is heard and reducing advance until ping isn't detected by ear.... In most countries the lowest octane fuel available is rated at 95 which would still be 91 if the same system of rating as used in the U.S. was used.

 

The dyno showed 2 to 3 hp gain on engines rated at 115-125 hp (hondas). Did need 3-4 degrees more static ignition advance tho.
And yes, you can formulate gas that will yield 5-6 hp gains by adding about 5% by volume of pure toluene, for example. (thats a gallon in 20)There are other organics that can boost it even more (icluding higher concentrations of toluene) but the problem with many of those is the problem with detonation and burned pistons. And in every case breathing masks and gloves are needed to handle them.
Was that done? yeah, I'd be very surprised if it wasn't.

 

What is going on with 15 percent ethanol, I heard that we might have it as soon as mid 2010. I know that bp is working on butanol and is supposed to be 16 percent in there gas this summer. Butanol is something between ethanol and mtbe in energy and could be use 100 percent in car with little or no modification. Isnt bp ultimate ethanol free? I know that there is 10 mandatory ethanol states in the usa but illinois isnt one of them. Every one say that premium burns slower but how can that be true because toluene burns 20 percent faster than isooctane and isoctane runs 20 percent leaner than toluene?

 

I believe upo to 15% ethanol is already legal and many states require 10% as you say thanks to the agriculture lobbies.

Don't see any advantage to butanol over ethanol and ethanol is relatively cheap and somewhat plentiful, tho a drag on food prices.
The problem with ethanol or most alcohols is the much lower heat of combustion, and thus lower mpg.

 

Does ethanol content depend on the grade of gas? For instance, is premium ethanol free while regular has at least 10%?

 

That is what I though too. Supermarket gas will have at least 10 percent, but bp might only have 7 percent in their regular. My problem using regular is ethanol will seperate out of the gas and you will have lower octane than 87. Everywhere I look fuel engineers say that a 9 to 1 compression engine should run 95 ron gas. So the 9.4 static compression Fit should run 98 ron at least. I know that the Honda fit has a knock sensor and is a small bore and dont rev that high so you can run regular, but when carbon deposits build the damage to the engine already happened. There is a test in au. that ran e10, regular and premium, the e10 used 9.8liters the regular used 9.4, and premium used 9.0 l. No performance gain was noted but they use 3 different cars but the same type. So running regular saved money and e10 and premium cost the same except that you had 10 percent less gas being burned in the premium car.