C16 works fine for certain engines and certain purposes.

$23/gallon ($300 fill-ups) would be hard to swallow on a daily basis. Lol!

Craig

 

Hold on, C12 is not "better" than C16. They are 2 different fuels for different applications. You can in no way run the same boost pressure with C12 that you can run with C16. I have run 14-16 psi with static of 9-1 with C12 with no problems but have seen lots of melted pistons using C12 at high boost levels or heavy nos use. C16 is a great fuel for any short term blown application,I have even tuned a few to run 1/4 mile passes with as high as 30 psi. But thats really pushing it to the limit.

 

Thats my understanding as well. The "best" fuel depends on several considerations, beyond simply the highest octane. The "best" fuel for one car is not necessarily the best for another and, likewise, the best fuel for one application is not the best for another.

Craig

 

Its also my understanding Craig was running C16 all the time, C16 for races and occassional uses is great. Running it all the time is too much, C12 would be better to run all the time. Better yet a unleaded type of fuel is better for everyday use.

You guys should read up on Torco. Their 118 fuel is similiar to VP Import and it costs about 10 dollars a gallon.

 

Exactly. Thats why I am switching to C12.

Craig

 

Craig,
Have you heard anything good about ethanol? Reason I ask because in Hawaii gas must have at least 9 percent ethanol mixed in. Sorry for the change in subject.
Aloha

Byron

 

I have no clue Byron.

Craig

 

Great info Craig,hats off to you for taking the time to do the research!

 

We ran back to back dyno pulls with 100% ethanol and 100% methanol on a 575 inch injected BBC, 15.8-1 compression, dart big chief heads. Both fuels when tuned perfect produced almost the same power.
In my pro mod (526 inch KB) I run 10.5-1 static with 44-52 psi on 100% methanol with no problems,but it would be a horrible fuel for a street car for a great many reasons. (absorbes h2o,corrosive,1/2 the mpg of gas etc)

 

Thanks Craig and Derboost. Just was curious about ethanol because on the local news a mechanic said the mix of ethanol (Required for all gas) is causing premature damage on the cars he has worked on.

Aloha

Byron

 

here you go UNDERSTANDING SPECIFIC GRAVITY

Specific gravity is the ratio of the mass of a liquid to the mass of an equal volume of distilled water at 64° F which is represented by 1.000 Specific Gravity on a fuel chart. Most fuel suppliers can offer the specific gravity number of a fuel. Should the fuel not match the specifications supplied, it might be contaminated fuel which could cause poor performance.



Specific gravity MUST always be referenced to a particular temperature reading. The specific gravity of a liquid decreases with a rise in temperature or increases when its temperature is lowered. Testing the specific gravity of a liquid will not identify its contents. it is only the measure of the weight of the fuel vs. distilled water. Methanol is commonly contaminated by water – which is heavier than the fuel. Checking the specific gravity allows the purity of the fuel to be referenced. When contaminated with a lighter or heavier specific gravity element, the final specific gravity reading will be lighter or heavier than the originally tested weight depending on the contamination of the fuel and the temperature reading.



WHY CHECK THE FUEL?

Combustion engines perform best at only one air-fuel ratio, and the ratio is determined by the weight of the air/fuel mixture. Since all carburetors and fuel injection systems meter fuel by volume, a jetting change must be made if the specific gravity of the fuel changes for any reason. This change will adjust the volume to keep the weight of the fuel going to the engine consistent. For instance, if the specific gravity of the fuel increases by 4%, then the volume of fuel put through the carb/injector system must be decreased by 4% to keep the net weight going into the engine consistent.



Many racing facilities and sanctioning bodies use the VP/Kinsler Fuel Analyzer Kit (sold by any VP distributor) to ensure the legality/accuracy of the fuel per any fuel rules the body might have. Alternative methods are available, but they can be cost prohibitive and time consuming.



OCTANE

Octane is a unit of measurement used to rate a fuels ability to resist detonation. Detonation (spark knock or “ping) is the tendency of the fuel to explode violently in the engine rather than burn smoothly at the precise moment when combustion occurs in the cylinder of the motor. If the fuel detonates, the pressure in the combustion chamber rises so fast and high that it is like beating on the top of the piston with a hammer – this is the primary cause of piston, rod, and bearing failures. The higher the octane rating, the higher the resistance of the fuel to detonate. Racing fuel is blended to provide additional octane rating, not necessarily more energy. In fact, all grades of fuel have about the same amount of energy per pound. Increasing the octane can help produce more power since more compression or spark advance is necessary to achieve the optimum performance level with that fuel. Too much octane, however, can slow the burn rate of the fuel causing a loss of power.



FUEL COMPARISONS

There is a big difference in specific gravity between various brands and grades of fuel, often even between two batches of the same brand. The typical range of premium automotive pump gas is .730 - .760 specific gravity rating. Aviation fuel is .680 - .720. Some unleaded racing fuel is as heavy as .790. Many blends of pump gas can often contain as much as 10% ethanol – measuring in a much heavier specific gravity range.



For Example: Unocal 76 Unleaded Racing Fuel - .788 Specific Gravity @ 59° F.

Unocal 76 Leaded Racing Fuel - .728 Specific Gravity @ 59° F.



METHANOL (ALCOHOL)

The specific gravity of pure methanol is .792 @ 68° F. Methanol, methyl alcohol or wood alcohol (CH3OH), is usually made from natural gas. It was first discovered in 1823 by the method of condensing hot gases from the burning of wood. It has been the fuel for Indy Cars since 1965. Methanol has the ability to absorb water, even right of the atmosphere. Keeping your fuel sealed will help prevent contamination. Adding water to alcohol will increase the specific gravity reading of the fuel. High levels of water contamination will cause the alcohol to get a cloudy haze in it. Loss of engine performance will typically occur before the contamination reaches these levels. Fuel should be checked with a hydrometer before using the fuel, possibly as you get you fuel from your supplier, just to avoid any problems. Methanol is extremely corrosive to aluminum and magnesium, so, great care should be taken to keep this reaction to a minimum. The fuel system components should be constructed of materials that do not react with methanol (stainless steel, brass, etc) or they should have a protective coating. Methanol also crystallizes when it dries and this dried material does not readily dissolve. The fuel system will need constant attention in this instance. When the methanol-burning vehicle is not in use, the fuel should be drained from the fuel system. Flushing or “pickling� with regular gasoline is a common practice to flush the system.



ETHANOL

The specific gravity of ethanol is .815 @ 68° F. Ethanol, ethyl alcohol or grain alcohol (CH3CH2OH), is a liquid derived from corn or other grain, other agricultural products or agricultural waste. Because ethanol is corrosive (due to oxidation), the same preventative maintenance as methanol must be utilized to protect the fuel system components.



In the 1880’s, Henry Ford built one of his first automobiles – the Quadricycle – and it was fueled with ethanol. Early Ford Model T’s had a carburetor adjustment that could allow the vehicle to run ethanol fuel that was produced by local farmers. Ford’s vision was reportedly to build a vehicle that was affordable to the working family and powered by a fuel that would boost the rural form economy. However, in the past, due to various reasons, any alternative fuels other than standard gasoline were suppressed. Today, we are seeing the return of alternative fuel vehicles.



NITROMETHANE

The specific gravity of pure nitromethane – nicknamed “nitro� is 1.139 @ 60-70° F and is chemically CH3NO2. The specific gravity of pure alcohol is .792 @ 68° F is obviously quite different from nitro. It is simple to determine the percentage of nitro in alcohol by measuring the specific gravity of the mixture. Adding nitro to alcohol will increase its specific gravity. A chart can be set up to show the percentage of nitro vs. specific gravity (as supplied with the fuel testing kit available from VP Racing.)



The procedure is only slightly complicated by the fact that temperature affects the specific gravity, since any fluid expands as it is warmed, and therefore has a lower specific gravity when warming occurs. For example, a 60% mixture of nitro and alcohol heated, we know that the mixture is still 60%, yet the specific gravity is decreased when this happens.



Some brands of nitro hydrometer kits are sold without a temperature correction table. Errors of up to 5% can be common if not temperature correction is used. For best engine performance, the nitro percent mixture should be kept within one or two percent of what the engine was specifically tuned for.



NOTE: Mixing nitromethane fuel with alcohol creates a mild endothermic reaction which absorbs heat from the mixture, thus, cooling the mixture (opposite of most reactions, which usually give off heat). The maximum affect is with about 50% mixture, which cools approximately 15° F.
e you go

 

solid info. Who's gonna have the first 996 with a little snap, crackle, pop to it?

 

Very informative post Derboost...seems 6speed is really becoming quite technically astute lately...Thanks to some "newer" guys and the old standbys.

 

DERBOOST - Great post! Thanks.

 

Thanks, 20+ years of building Chevys had to be good for something....