Will C16 race fuel help any?
Thread Starter
Registered User
Joined: Nov 2000
Posts: 101
From: Cary/Mooresville, NC USA
Will C16 race fuel help any?
I have a stock internal, no power adder LT1, so i don't see how it would benefit me much. But i read an article where a turbo buick went from 280hp with pump gas, to 320hp with C16. What do i stand to gain with this stuff? Also, some guy at the track told me to run some brand name of paint thinner is my tank. He said Hot Rod magazine did an aritcle on it, and that it really helped. Is this just BS, or does it work? I'm trying my best to bust 12's bolt on.
Registered User
Joined: Aug 2001
Posts: 1,983
From: Jacksonville,fla
Re: Will C16 race fuel help any?
Originally posted by matt104a
I have a stock internal, no power adder LT1, so i don't see how it would benefit me much. But i read an article where a turbo buick went from 280hp with pump gas, to 320hp with C16. What do i stand to gain with this stuff? Also, some guy at the track told me to run some brand name of paint thinner is my tank. He said Hot Rod magazine did an aritcle on it, and that it really helped. Is this just BS, or does it work? I'm trying my best to bust 12's bolt on.
I have a stock internal, no power adder LT1, so i don't see how it would benefit me much. But i read an article where a turbo buick went from 280hp with pump gas, to 320hp with C16. What do i stand to gain with this stuff? Also, some guy at the track told me to run some brand name of paint thinner is my tank. He said Hot Rod magazine did an aritcle on it, and that it really helped. Is this just BS, or does it work? I'm trying my best to bust 12's bolt on.
Registered User
Joined: Apr 1999
Posts: 2,784
From: Rochester Hills, MI
First of all the stuff is extremely expensive and you will not gain anything by going to C16. Also you then have to worry about messing up your 02 sensors since you will be running leaded fuel.
Administrator
Joined: Nov 1998
Posts: 71,094
From: Hell was full so they sent me to NJ
I ran my setup NA on the engine dyno and it made 480HP on Sunoco 94. With no other changes, we re-baselined it with C16 for the nitrous tuning, and it made 486HP. The difference is probably accounted for by the changes in "specific energy content".... or BTU/gallon, and nothing else.
C16 is $7/gallon and has 6 grams/gallon of lead. It is not friendly to O2 sensors or catalytic convertors.
C16 is $7/gallon and has 6 grams/gallon of lead. It is not friendly to O2 sensors or catalytic convertors.
Registered User
Joined: Apr 1999
Posts: 2,784
From: Rochester Hills, MI
Originally posted by Injuneer
I ran my setup NA on the engine dyno and it made 480HP on Sunoco 94. With no other changes, we re-baselined it with C16 for the nitrous tuning, and it made 486HP. The difference is probably accounted for by the changes in "specific energy content".... or BTU/gallon, and nothing else.
C16 is $7/gallon and has 6 grams/gallon of lead. It is not friendly to O2 sensors or catalytic convertors.
I ran my setup NA on the engine dyno and it made 480HP on Sunoco 94. With no other changes, we re-baselined it with C16 for the nitrous tuning, and it made 486HP. The difference is probably accounted for by the changes in "specific energy content".... or BTU/gallon, and nothing else.
C16 is $7/gallon and has 6 grams/gallon of lead. It is not friendly to O2 sensors or catalytic convertors.
Administrator
Joined: Nov 1998
Posts: 71,094
From: Hell was full so they sent me to NJ
Originally posted by IDOXLR8
Around here C-16 sells for $10.00 A gallon
Around here C-16 sells for $10.00 A gallon
I haven't bought a drum since last year, so maybe it has gone up a bit.
Registered User
Joined: Mar 2000
Posts: 2,037
From: 51°N 114°W, 3500' elevation
There's no more BTU energy in C12, C14 or C16 than there is in 87, 89 or 92 pump gas. The main difference is the rate at which the fuel burns. The higher octane fuels burn slower which will reduce detonation in high compression, boosted or NOS engines. If you can hook a scanner onto the engine to watch the knock counts, you can determine the amount of octane required. Increase the octane levels just enough to eliminate any knock. Any more increase in octane will just lighten you wallet. If the engine doesn't knock with 89 then it won't run any better with 92. If you see a big performance increase from running a higher octane fuel then the computer was probably retarding the timing trying to compensate for a lower octane before which will reduce power.
As mentioned above, stay away from the leaded fuels when using a knock sensor. VP Fuels sells different versions of unleaded fuel for EFI cars.
Buying Xylene or Toulene to increase the octane level of pump gas isn't cheap. By the time you add enough Toulene to 92 pump gas to increase it to 100 octane, it will be cheaper to just buy 100 octane race gas.
http://www.gnttype.org/techarea/misc/octanebooster.html
When looking at these formulas, look at the percentage requirements to raise the octain up. A 10% mixture of Toulene means 9 gallons of premium fuel plus a gallon of toulene. 30% means 7 gallons of premium and 3 gallons of Toulene. Unless you can get Toulene or Xylene for next to nothing, mixing your own home brews gets very expensive. Plus just how accurate will each batch you mix be?
I'm glad I've switched to alcohol (Methanol). I couldn't afford to buy C14
As mentioned above, stay away from the leaded fuels when using a knock sensor. VP Fuels sells different versions of unleaded fuel for EFI cars.
Buying Xylene or Toulene to increase the octane level of pump gas isn't cheap. By the time you add enough Toulene to 92 pump gas to increase it to 100 octane, it will be cheaper to just buy 100 octane race gas.
http://www.gnttype.org/techarea/misc/octanebooster.html
When looking at these formulas, look at the percentage requirements to raise the octain up. A 10% mixture of Toulene means 9 gallons of premium fuel plus a gallon of toulene. 30% means 7 gallons of premium and 3 gallons of Toulene. Unless you can get Toulene or Xylene for next to nothing, mixing your own home brews gets very expensive. Plus just how accurate will each batch you mix be?
I'm glad I've switched to alcohol (Methanol). I couldn't afford to buy C14
Last edited by Stephen 87 IROC; Jun 26, 2003 at 12:53 AM.
Administrator
Joined: Nov 1998
Posts: 71,094
From: Hell was full so they sent me to NJ
Originally posted by Stephen 87 IROC
There's no more BTU energy in C12, C14 or C16 than there is in 87, 89 or 92 pump gas. The main difference is the rate at which the fuel burns. The higher octane fuels burn slower.....
There's no more BTU energy in C12, C14 or C16 than there is in 87, 89 or 92 pump gas. The main difference is the rate at which the fuel burns. The higher octane fuels burn slower.....
If you are pointing out that octane has a NO direct correlation to energy content, I'll agree. But you can not simply state that the energy content is the same... it isn't.
You also have to look at the means by which fuel is delivered. It is volume based. If you use a less dense fuel, you will deliver less pounds of fuel, so the energy content of the mass of fuel delivered can change. In a carb system, or in an open loop FI system, you better correct for this. That is why you need to look at "specific energy content".... BTU/volume, rather than BTU/#. And this number is differnet for each specific fuel blend. And still, there is NO correlation between octane and "specific energy content".
It can also be demonstrated that burn speed is not the key criterion for resistance to knock. It can also be demonstrated very easilly that burn speed does not correlate directly to octane level. It is a matter of what chemical compounds form under the pressure and temperature conditions in the combustion chamber, and whether they are compounds that will auto-ignite. It is not about burn speed.... although burn speed can play a part in whether detonation occurs. I've seen some interesting tricks played with VP Air Race fuel in nitrous applications.... $9.50 a gallon in 5-gallon containers.
I hate to keep posting this link , but it is one of the most reliable reference sources I have found on gasoline. In particular:
6.3 What fuel property does the Octane Rating measure?
The fuel property the octane ratings measure is the ability of the unburnt end gases to spontaneously ignite under the specified test conditions. Within the chemical structure of the fuel is the ability to withstand pre-flame conditions without decomposing into species that will autoignite before the flame-front arrives. Different reaction mechanisms, occurring at various stages of the pre-flame compression stroke, are responsible for the undesirable, easily-autoignitable, end gases.
During the oxidation of a hydrocarbon fuel, the hydrogen atoms are removed one at a time from the molecule by reactions with small radical species (such as OH and HO2), and O and H atoms. The strength of carbon-hydrogen bonds depends on what the carbon is connected to. Straight chain HCs such as normal heptane have secondary C-H bonds that are significantly weaker than the primary C-H bonds present in branched chain HCs like iso-octane [21,22].
The octane rating of hydrocarbons is determined by the structure of the molecule, with long, straight hydrocarbon chains producing large amounts of easily-autoignitable pre-flame decomposition species, while branched and aromatic hydrocarbons are more resistant. This also explains why the octane ratings of paraffins consistently decrease with carbon number. In real life, the unburnt "end gases" ahead of the flame front encounter temperatures up to about 700C due to compression and radiant and conductive heating, and commence a series of pre-flame reactions. These reactions occur at different thermal stages, with the initial stage ( below 400C ) commencing with the addition of molecular oxygen to alkyl radicals, followed by the internal
transfer of hydrogen atoms within the new radical to form an unsaturated, oxygen-containing species. These new species are susceptible to chain branching involving the HO2 radical during the intermediate temperature stage (400-600C), mainly through the production of OH radicals. Above 600C, the most important reaction that produces chain branching is the reaction of one hydrogen atom radical with molecular oxygen to form O and OH radicals.
...........
The antiknock ability is related to the "autoignition temperature" of the hydrocarbons. Antiknock ability is _not_ substantially related to:
1. The energy content of fuel, this should be obvious, as oxygenates have lower energy contents, but high octanes.
2. The flame speed of the conventionally ignited mixture, this should be evident from the similarities of the two reference hydrocarbons. Although flame speed does play a minor part, there are many other factors that are far more important. ( such as compression ratio, stoichiometry, combustion chamber shape, chemical structure of the fuel, presence of antiknock additives, number and position of spark plugs, turbulence etc.)
Flame speed does not correlate with octane.
The fuel property the octane ratings measure is the ability of the unburnt end gases to spontaneously ignite under the specified test conditions. Within the chemical structure of the fuel is the ability to withstand pre-flame conditions without decomposing into species that will autoignite before the flame-front arrives. Different reaction mechanisms, occurring at various stages of the pre-flame compression stroke, are responsible for the undesirable, easily-autoignitable, end gases.
During the oxidation of a hydrocarbon fuel, the hydrogen atoms are removed one at a time from the molecule by reactions with small radical species (such as OH and HO2), and O and H atoms. The strength of carbon-hydrogen bonds depends on what the carbon is connected to. Straight chain HCs such as normal heptane have secondary C-H bonds that are significantly weaker than the primary C-H bonds present in branched chain HCs like iso-octane [21,22].
The octane rating of hydrocarbons is determined by the structure of the molecule, with long, straight hydrocarbon chains producing large amounts of easily-autoignitable pre-flame decomposition species, while branched and aromatic hydrocarbons are more resistant. This also explains why the octane ratings of paraffins consistently decrease with carbon number. In real life, the unburnt "end gases" ahead of the flame front encounter temperatures up to about 700C due to compression and radiant and conductive heating, and commence a series of pre-flame reactions. These reactions occur at different thermal stages, with the initial stage ( below 400C ) commencing with the addition of molecular oxygen to alkyl radicals, followed by the internal
transfer of hydrogen atoms within the new radical to form an unsaturated, oxygen-containing species. These new species are susceptible to chain branching involving the HO2 radical during the intermediate temperature stage (400-600C), mainly through the production of OH radicals. Above 600C, the most important reaction that produces chain branching is the reaction of one hydrogen atom radical with molecular oxygen to form O and OH radicals.
...........
The antiknock ability is related to the "autoignition temperature" of the hydrocarbons. Antiknock ability is _not_ substantially related to:
1. The energy content of fuel, this should be obvious, as oxygenates have lower energy contents, but high octanes.
2. The flame speed of the conventionally ignited mixture, this should be evident from the similarities of the two reference hydrocarbons. Although flame speed does play a minor part, there are many other factors that are far more important. ( such as compression ratio, stoichiometry, combustion chamber shape, chemical structure of the fuel, presence of antiknock additives, number and position of spark plugs, turbulence etc.)
Flame speed does not correlate with octane.
Last edited by Injuneer; Jun 26, 2003 at 11:50 AM.
Registered User
Joined: Feb 2000
Posts: 1,445
From: Seattle, WA
I agree with Fred. There is no appreciable difference in flame speed between different octane gasolines as the composition of the base fuel is relatively unchanged, and the combustion reaction does not change in its nature. There are some additional double-bonds involved, to alter BTU's by less than 1%, but the effect is not responsible for any reduction in flame speed propagation (which has MUCH more to do with pressure and base fuel composition). And if it DID... the higher octane fuel would have LESS hp.
Glad to see someone stills remembers that Gasoline FAQ... I've never found any glaring issues with it (and yes I've read the whole thing... us Bio-Chem car-guys live for topics like this).
One thing that hasn't been mentioned here is that Toluene, Benzene, and other aromatics are KNOWN carcinogens... and they are volatile. Mixing drums of this stuff is a OSHA nightmare and I honestly think you'd be retarded to try this without a respirator. Not a surgical mask, not a charcoal filter... a respirator. Anyone whose been in a lab doing benzene extractions outside of a fume hood will testify to the splitting headaches you develop over an hour of exposure. Toluene is less volatile I believe... but it's just as cancerous.
There's a reason Organic-Chemists had an average life span of 50 years in the 70's... mostly the aromatics.
Buy the octane you need and keep the brake cleaner to small jobs and well-ventilated areas.
Glad to see someone stills remembers that Gasoline FAQ... I've never found any glaring issues with it (and yes I've read the whole thing... us Bio-Chem car-guys live for topics like this
).One thing that hasn't been mentioned here is that Toluene, Benzene, and other aromatics are KNOWN carcinogens... and they are volatile. Mixing drums of this stuff is a OSHA nightmare and I honestly think you'd be retarded to try this without a respirator. Not a surgical mask, not a charcoal filter... a respirator. Anyone whose been in a lab doing benzene extractions outside of a fume hood will testify to the splitting headaches you develop over an hour of exposure. Toluene is less volatile I believe... but it's just as cancerous.
There's a reason Organic-Chemists had an average life span of 50 years in the 70's... mostly the aromatics.
Buy the octane you need and keep the brake cleaner to small jobs and well-ventilated areas.
Last edited by Steve in Seattle; Feb 10, 2004 at 12:46 AM.
Registered User
Joined: Mar 1999
Posts: 659
From: Chicago, IL
C16 is a lazy fuel, and it's about 117 MOTOR octane.
If you were blown and were running say over 17:1 total compression it would be almost an necessity.
If you were to play with advancing timing and wanted to run a higher octane like 100-104 unleaded you might find a gain.
I'm making over 700rwhp with my blown setup and I am using C12 which is 108 motor octane. I'm around 15:1 total compression.
If you were blown and were running say over 17:1 total compression it would be almost an necessity.
If you were to play with advancing timing and wanted to run a higher octane like 100-104 unleaded you might find a gain.
I'm making over 700rwhp with my blown setup and I am using C12 which is 108 motor octane. I'm around 15:1 total compression.
Moderator
Joined: Dec 1969
Posts: 10,745
From: Buffalo, New York
Fred's post was very informative, as usual. I will just add something really simple. The specific gravity of fuels can vary quite a bit. Even if all else is essentially equal, a denser fuel will have more energy per unit volume (which is what you get with a given tune) in direct proportion to the density. Look at http://www.vpracingfuels.com/vp_01_f...639D8E2#leaded and you can see specific gravities between 0.7865 and 0.690. That's a difference of ~14%, a HUGE difference.
Rich Krause
Rich Krause
Administrator
Joined: Mar 1999
Posts: 3,664
From: Brunswick, Maine 04011
The common sense rule of thumb is if there is no knock, you don't need higher octane. I mix some high octane unleaded with Sunoco 94 for a blend of 95.5 octane. Any more than that is a waste on my car.