Kawasaki ZX-10R Forum banner

1 - 12 of 12 Posts

·
Hillbillie Mod
Joined
·
20,155 Posts
Discussion Starter #1 (Edited)
I got these articles from www.motorcycle.com



Editor's Note--This is the first in a series of "Wrenching with Rob" articles, in which Vintage Editor Robin Tuluie will discuss, in depth, technical and theoretical topics that make motorcycles function.

In many high-performance situation, riders clamor for higher octane fuels, thinking this will give them additional horsepower and, thus, an advantage over the competition. But this is not the case--adding higher-octane race fuel to your motorcycle may actually produce less horsepower. Here's why: Octane, an arbitrary number which is calculated as the average of the Research Octane Number (RON) and the Motor Octane Number (MON), and is only an indic ation of a fuel's sensitivity to knock, which is typically pressure-induced self-ignition. (Of these two ratings, MON is more applicable to racing fuels as it is measured under high load and high speed conditions.)

Octane, as you can see, is not a measure of how much power--or, more correctly, specific energy--is contained in a fuel. And remember that leaded high-octane race fuels burn slower than most unleaded fuels, and may reduce performance in stock or lightly modified motorcycles. A high octane rating itself, however, does not mean that the fuel is slow burning. Hence, it has no direct bearing on the power characteristics of the fuel.

The knock tendency (and hence, the Octane rating) of a fuel is a function of the amount of free radicals present in the fuel prior to ignition and can be reduced by the addition of tetra ethyl lead, aromatics and other additives.

Although some racing organizations still use maximum octane number as the discriminating factor for fuel legality, it is really not appropriate for racing purposes.

Instead one should look at the amount of energy (heat) released in the burning of a particular fuel. This is described by the specific energy of the fuel. This quantity describes the amount of power one can obtain from the fuel much more accurately. The specific energy of the fuel is the product of the lower heating value (LHV) of the fuel and molecular weight of air (MW) divided by the air-fuel ratio (AF):

Specific Energy = LHV*MW/AF

For example, for gasoline LHV= 43 MJ/kg and AF=14.6, while for methanol LHV= 21.1MJ/kg (less "heat" than gasoline) and AF=6.46 (much richer jetting than gasoline). Using the above formula we see that methanol only has a 10% higher specific energy than g asoline! This means that the power increase obtained by running methanol, with no other changes except jetting, is only 10%. Comparing the specific energy of racing and premium pump gas you can see that there is not much, if any, difference. Only alcohol s (such as methanol or ethanol) have a slightly higher specific energy than racing or pump gas.

Other oxygen-bearing fuels, besides the alcohols and nitromethanes, such as the new ELF fuel, will also produce slightly more power once the bike is rejetted. However, at $15.00 to $20.00 at gallon for the fuel the reportedly minor (1% - 2%) improvement is hardly worth the cost for the average racer.

The real advantage of racing gasolines comes from the fact that they will tolerate higher compression ratios (due to their higher octane rating) and thus indirectly will produce more power since you can now build an engine with a higher compression rati o. Also, alcohols burn cooler than gasoline, meaning even higher compression ratios are possible with them, for even more power.

The bottom line here is that, in a given engine, a fuel that doesn't knock will produce the same power as most expensive racing gasolines.

However, it sometimes happens that when you use another fuel, the engine suddenly seems to run better. The reasons for this are indirect: First, the jetting may be more closely matched to the new fuel. Secondly, the new fuel may improve the volumetric e fficiency (that is, the "breathing") of the motor. This happens as follows: Basically a fuel that quickly evaporates upon contact with the hot cylinder wall and piston crown will create additional pressure inside the cylinder, which will reduce the amount of fresh air/fuel mix taken in. This important--but often overlooked--factor is described by the amount of heat required to vaporize the fuel, described by the 'enthalpy of vaporization' (H), or 'heat of vaporization' of the fuel.

A high value of H will improve engine breathing, but the catch is that it leads to a different operating temperature within the engine. This is most important with two-strokes, which rely on the incoming fuel/air mix to do much of the cooling--even mode rn water-cooled two-strokes rely on incoming charge to cool the piston. For two-strokes a fuel that vaporizes, drawing a maximum amount of heat from the engine, is essential--the small variations in horsepower produced by different fuels is only of second ary concern.

Also important is the flame speed: Power is maximized the faster the fuel burns because the combustion pressure rises more quickly and can do more useful work on the piston. Flame speed is typically between 35 and 50 cm/sec. This is rather low compared to the speed of sound, at which pressure waves travel, or even the average piston speed. It is important to note that the flame propagation is greatly enhanced by turbulence (as in a motor with a squish band combustion chamber).

The most amazing thing about all this is that you can get the relevant information from most racing gasoline manufacturers. Then, just look at the specification sheet to see what fuel suits you best: Hot running motors and 2-strokes should use fuels wit h a value of "H" that improves their cooling, while more power (and more heat) is obtained from fuels with a high specific energy. By the way, pump gas has specific energies which are no better or worse than most racing gasolines. The power obtained from pump gas is therefore often identical to that of racing fuels, and the only reason to run racing fuels would be detonation probl ems, or, since racing fuels are often more consistent than pump gas--which racers call "chemical soup"--a consistent reading of the spark plugs and exhaust pipe.
 

·
Hillbillie Mod
Joined
·
20,155 Posts
Discussion Starter #2 (Edited)
FIG 1



FIG 2




Editor's Note--This is part of a "Wrenching with Rob" series, in which Vintage Editor and Technical Writer Robin Tuluie will discuss, in depth, technical and theoretical topics that make motorcycles function.

Since the previous Wrenching With Rob, Chemical Soup: The Meaning of Gasoline we've been besieged with questions and comments regarding the combustion process occurring in an engine. In particular, the discussion focused on the problem of detonation, commonly referred to as "knock," which is a very serious and detrimental problem when it occurs - usually the pressures exerted onto the piston top during detonation are much larger (but of a shorter duration, like a pressure spike) than the mean combustion pressure. Nevertheless they are very detrimental to engine life, as the continual high shock loading of the piston, rod, crankshaft and bearings is quite destructive.

Detonation is the result of an amplification of pressure waves, such as sound waves, occurring during the combustion process when the piston is near top dead center (TDC). The actual "knocking" or "ringing" sound of detonation is due to these pressure waves pounding against the insides of the combustion chamber and the piston top, and is not due to 'colliding flame fronts' or 'flame fronts hitting the piston or combustion chamber walls.'

Let's look in some detail at how detonation can occur during the combustion process: First, a pressure wave, which is generated during the initial ignition at the plug tip, races through the unburned air-fuel mix ahead of the flame front. Typical flame front speeds for a gasoline/air mixture are on the order of 40 to 50 cm/s (centimeters per second), which is very slow compared to the speed of sound, which is on the order of 300 m/s. In actuality, the true speed of the outwards propagating flame front is considerably higher due to the turbulence of the mixture. Basically, the "flame" is carried outwards by all the little eddies, swirls and flow patterns of the turbulence resident in the air-fuel mix. This model of combustion is called the "eddy burning model" (Blizzard & Keck, 1974).

Additionally, the genus of the flame front surface - that is the degree of 'wrinkling' - which usually has a fractal nature (you know, those weird, seemingly random yet oddly patterned computer drawings), is increased greatly by turbulence, which leads to an increased surface area of the flame front. This increase in surface area is then able to burn more mixture since more mixture is exposed to the larger flame front surface. This model of combustion is called the "fractal burning model" (Goudin, F.C. et al. 1987, Abraham et al. 1985). The effects of this are observed in so-called "Schlieren pictures," which are high-speed photographs taken though a quartz window of a specially modified combustion chamber (Fig. 1, above).

Schlieren pictures show the various stages of the combustion process, in particular the highly wrinkled and turbulent nature of the flame front propagation (initially called the flame 'kernel'). A higher degree of turbulence, and hence a higher "effective" flame front propagation velocity can be achieved with a so-called squish band combustion chamber design. Sometimes a swirl-type of induction process, in which the incoming mixture is rotating quickly, will achieve the same goal of increasing the burn rate of the mixture.

As a general rule-of-thumb the pressure rise in the combustion chamber during the combustion phase is typically 20-30 PSI per degree of crankshaft rotation. Once the pressure rises faster than about 35 PSI/degree, the engine will run very roughly due to the mechanical vibration of the engine components caused by too great of a pressure rise. Sometimes, the pressure wave can be strong enough to cause a self ignition of the fuel, where free radicals (e.g. hydroxyl or other molecules with similar open O-H chains) in the fuel promote this self ignition by the pressure wave. However, this can still occur even without the presence of free radicals; it just won't be quite as likely to happen. This is why high octane fuels, with fewer of these active radicals, can resist detonation better. However, even high octane fuel can detonate - not because of too many free radicals - but because the drastic increase in cylinder pressure has increased the local temperature (and molecular speed) so high that it has reached the ignition temperature of the fuel. This ignition temperature is actually somewhat lower than that of the main hydrocarbon chain of the fuel itself because of the creation of additional radicals resulting from the break-up of the fuel's hydrocarbon chains in intermolecular collisions.

Detonation usually happens first at the pressure wave's points of amplification, such as at the edges of the piston crown where reflecting pressure waves from the piston or combustion chamber walls can constructively recombine - this is called constructive interference to yield a very high local pressure. If the speed at which this pressure build-up to detonation occurs is greater than the speed at which the mixture burns, the pressure waves from both the initial ignition at the plug and the pressure waves coming from the problem spots (e.g. the edges of the piston crown, etc.) will set off immediate explosions, rather than combustion, of the mixture across the combustion chamber, leading to further pressure waves and even more havoc. Whenever these colliding pressure fronts meet, their destructive power is unleashed on the engine parts, often leading to a mechanical destruction of the motor. The pinging sound of detonation is just these pressure waves pounding against the insides of the combustion chamber and piston top. Piston tops, ring lands and rod bearings are especially exposed to damage from detonation. In addition, these pressure fronts (or shock waves) can sweep away the unburned boundary layer (see figure 2 above) of air-fuel mix near the metal surfaces in the combustion chamber.

The boundary layer is a thin layer of fuel-air mix just above the metal surfaces of the combustion chamber (see figure 2, above). Physical principles (aptly called boundary conditions) require that under normal circumstances (i.e. equilibrium combustion, which means "nice, slow and thermally well transmitted") this boundary layer stays close to the metal surfaces. It usually is quite thin, maybe a fraction of a millimeter to a millimeter thick. This boundary layer will not burn even when reached by the flame front because it is in thermal contact with the cool metal, whose temperature is always well below the ignition temperature of the fuel-air mix.

Only under the extreme conditions of detonation can this boundary layer be "swept away" by the high-pressure shock front that occurs during detonation. In that case, during these "far from equilibrium" process of the pressure-induced shock wave entering the boundary layer, the physical principles allured to above (the boundary conditions) will be effectively violated. The degree of violation will depend on (a) the pressure fluctuation caused by the shock front and (b) the adhesive and cohesive strength of the boundary layer. These boundary layers of air-fuel mix remain unburned during the normal combustion process due to their close proximity to the cool metal surfaces and act as an insulating layer and prevent a direct exposure of metal to the flame. Since pressure waves created during detonation can sweep away these unburned boundary layers of air-fuel mix, they leave parts of the piston top and combustion chamber exposed to the flame front. This, in turn, causes an immediate rise in the temperature of these parts, often leading to direct failure or at least to engine overheating.

Scientists and engineers have recently begun to understand combustion in much greater detail thanks to very ambitious computer simulations that model every detail of the combustion process (Chin et al. 1990). Basically, a complete computer model includes a solution to the thermodynamical problem, that is a solution to the conservation equations and equation of state, as well as a mass burning rate and heat transfer model. In addition, a separate code (called a chemical kinetics code) models the chemical processes which occur during combustion and sometimes juggles several thousand different chemical species, some in vanishingly small concentrations! Needless to say these codes require huge amounts of memory and CPU time that only the largest supercomputers in the world can provide. They are far beyond the reach of the private individual and usually only employed by large research institutions or major car manufactures.
 

·
Hillbillie Mod
Joined
·
20,155 Posts
Discussion Starter #3
--------------------------------------------------------------------------------



Here's a brief recital of the question we received:



Someone asked:

Rob, I read your "Chemical Soup: The Meaning of Gasoline." Quick question if you have the time... You mentioned that "flame propagation is greatly enhanced by turbulence." Should this be a consideration when an engine is ported? Can turbulence be enhanced by porting without losing the intake flow?



Unless the ports are specifically designed for a strong swirl-type induction process, the turbulence created during the intake process is not very affected by porting. This is true as long as one sticks with the same general port layout. However, drastic porting changes may increase or decrease the turbulence in the combustion chamber, but it is quite difficult to say anything definite. I think that any improvement gained by porting the engine is likely to be far greater than any possibly detrimental effect the porting may have had on turbulence.

As far as I know there is only one motorcycle engine that uses a highly turbulent intake process of the swirl type. It's a "homebuild" single cylinder racing engine from Switzerland that uses cross-scavenging and has two pairs of diagonally opposed intake and exhaust valves. Most conventional ports do induce a very small amount of swirl, but this is not important as far as generating much turbulence. Rather, the biggest benefit is obtained by reducing the squish band to it's safe minimum (about 0.020-0.040 in, depending on the particular engine used). This will have a far greater effect on increasing the turbulence in the combustion chamber than any other modification.





Mike Meagher ([email protected]) wondered about the effects of the squish band.



It is important to realize the two important functions of reducing the squish band clearance: (a) to enhance turbulence due to rapid ingestion of gas into the combustion chamber, hence increasing the burning rate of the mixture and (b) to reduce the volume of the unburned gas in the boundary layer of cool gas near the piston top and cylinder head surfaces. Typically, gas trapped in the squish area doesn't burn, even if the squish band clearance is relatively large. The cooling effects of the large surface-area-to-volume ratio of this region will prevent any ignition of the fuel-air mix therein, even if the squish band clearance is rather large. Hence any gas caught in the squish band will not be burned near TDC when it does the most good, but later during the combustion process when one cannot extract as much work from the late-burning gases. The amount of gas trapped in the squish band can actually be a substantially greater amount than just the relative volume of the squish band because the pressure wave from the ignition process literally crams a lot of the unburned gas into crevice areas like the squish band. Reducing the squish band clearance will decrease the amount of unburned gas substantially, leading to more complete and faster combustion, lower emissions and improved power. It is one of the few "all gain with no pain" modifications one can carry out on racing or even street motorcycles.

--------------------------------------------------------------------------------





Someone wondered: Is the extra cooling of the squish band less than the added heat?



Basically the mixture in the squish region is in thermal contact with the cylinder wall and piston top and at roughly the same temperature, which is quite lower than the burn temperature. Reducing squish will decrease the amount of the cool gas in the squish region and increase the amount of hot gas in the burn region. A reduced squish clearance will increase temperatures a little even if the compression ratio is held constant. There is no "extra cooling" mechanism if you reduce the squish band clearance. The cooling rate of the gas in the squish zone depends on the thermal conductivity of the gas-metal interface, on the total surface area of this interface and the temperature difference between gas and metal. Note that these factors are all essentially constant at TDC and don't depend on the squish clearance. Hence the cooling rate is the same for large squish clearances and for small squish clearances. Thus there is no "extra cooling" mechanism if you reduce squish band clearance.

--------------------------------------------------------------------------------





David Goodenough ([email protected]) asked:

Suppose I mix one gallon of 87 octane pump gas, and one gallon of 92 octane pump gas. Are you telling me that instead of two gallons of 89.5 octane gas I have something closer to 92 (like between 90 and 91)?



The mixed gas' octane rating will in general not be a linear function of the original constituents' octane ratings. Neither will it be a simple function in most cases. Rather, the octane rating becomes a quite complicated, non-linear function of some very small amounts of free radicals, such as hydroxyl and hydroxen peroxide, in the fuel. Essentially, there is no simple analytic way to predict the final octane rating of a fuel; rather, extensive tests with a calibrated engine are necessary (see MON and RON explanations in the last article).



David also asked:

While I'm at it, how does the energy per ounce of mixture react?



As mentioned before, the "energy per ounce" (more exactly the Specific Energy for an stoichometric [an ideal] mixture) does not vary much at all between different kinds of pump gasoline or even racing gasoline.



Ramon Hontiveros ([email protected]) wrote:

Ok, I got the article and read it, now some questions: Isn't the fuel already in gaseous form due to carburation?



Ramon, the air fuel mix as it flows into the combustion chamber is not perfectly atomized, that is the fuel vapor droplets consist of larger droplets of fuel molecules surrounded by air. It takes additional energy to further atomize this vapor, that is to break the hydrostatic forces (the surface tension of the fuel droplet). This additional energy can be taken from a hot surface (such as the piston crown, etc.), which then leads to a cooling of the piston. The additional energy can also be imparted via large turbulences and pressure waves, as in a squish band-type motor, which will help to further atomize the fuel. Note that the term "atomize" is actually misleading since the molecules are still left intact, that is the hydrocarbon chains (and oxygen bonds for alcohols) are not broken.



Ramon also wondered:

does carburation just "spray" the gas into the air flow as tiny droplets which are thus still in liquified form?



Yes.



Ramon also asks:

Also, if the fuel does evaporate quickly and creates additional pressure - thus reducing the amount of fresh charge - then the engine will produce less horsepower, right?



Correct. The horsepower will depend on the volumetric efficiency of the engine which is a function of the pressure difference between ambient air and cylinder pressures. If additional fuel is vaporized inside the combustion chamber the pressure in the cylinder will rise, and, while the valves/ports are still open, reduce the volumetric efficiency, and thus the power output.



So 2-strokes would benefit from using fuel that has a _lower_ heat of vaporisation rating?



Correct. A fuel with a lower heat of vaporisation will "atomize" easier and thus improve engine cooling, but decrease power somewhat.



So which type of fuel has a lower heat of vaporisation? Leaded or unleaded?

A fuel's heat of vaporisation does not depend on the it's lead content. Rather, it depends on the fuel's main hydrocarbon chains; iso-octane verses n-heptane, for example. Since pump gas can consist of up to 20 different components with a wide range of individual boiling points (We were serious when we called it "chemical soup!") one should look at the specifications sheet for each fuel separately. For racing fuels these are available from the manufacturer.





Lastly, I gather from the article that it's okay if you end up mixing some leaded fuel with the remaining unleaded fuel in the tank?



Most fuels, pump or racing, will give about the same energy release, so when switching from pump to racing fuel (in general) do not expect a drastic increase in power. Mixing leaded fuel with the remaining unleaded fuel in the tank has no advantage and will give inconsistent plug readings; hence I wouldn't do it on a race bike.



--------------------------------------------------------------------------------



REFERENCES

Abraham, J. et al., 1985, "A Discussion of Turbulent Flame Structure in Premixed Charges", SAE paper 850345



Blizzard, N.C. and Keck, J.C., 1974, "Exp. and Theo. Investigation of Turbulent Burning Model for Internal Combustion Engines", SAE paper 740191



Chin et al., 1990, "Diagnostics and Modeling of Combustion in Internal Combustion Engines," JSME, Tokyo, p. 81-86



Goudin, et al., 1987, "An Application of Fractals to Modeling of Premixed Turbulent Flames", Combustion and Flame 68, p.249-266
 

·
Registered
Joined
·
34,537 Posts
Stick & move per Mr Hillcountry. :thumbsup:

BD
 

·
Supercharged Mod
Joined
·
4,392 Posts
Good articles.

Alex - For the user of a production 4-stroke engine (as opposed to the engine designer), the nutshell summary is that there is no point to use fuel of higher octane than required to prevent detonation, and there is no point to using "racing" fuels unless the engine was built to require this fuel in the first place.

My race bike (Yamaha FZR400) has an engine originally produced in 1986, before a lot of this theory was as well understood as it is today. It has old-fashioned crowned pistons - too much surface area, not enough squish band, and the shape of the crown blocks the turbulence from what squish bands that it has. The slow-burn combustion chamber - as evidenced by the 35 to 48 degrees BTDC ignition timing at higher revs - needs that much timing advance to compensate for the slow burn. Engine runs hot, uses too much fuel for what it is, and I'm sure it has high exhaust emissions. I wish it were possible to fit nice flat-top or dished pistons and make it work, but the compression ratio would be too low if you did that ...

The ZX10R has nice flat-top pistons, by the way.
 

·
Registered
Joined
·
1,213 Posts
GoFaster said:
Good articles.

Alex - For the user of a production 4-stroke engine (as opposed to the engine designer), the nutshell summary is that there is no point to use fuel of higher octane than required to prevent detonation, and there is no point to using "racing" fuels unless the engine was built to require this fuel in the first place.

My race bike (Yamaha FZR400) has an engine originally produced in 1986, before a lot of this theory was as well understood as it is today. It has old-fashioned crowned pistons - too much surface area, not enough squish band, and the shape of the crown blocks the turbulence from what squish bands that it has. The slow-burn combustion chamber - as evidenced by the 35 to 48 degrees BTDC ignition timing at higher revs - needs that much timing advance to compensate for the slow burn. Engine runs hot, uses too much fuel for what it is, and I'm sure it has high exhaust emissions. I wish it were possible to fit nice flat-top or dished pistons and make it work, but the compression ratio would be too low if you did that ...

The ZX10R has nice flat-top pistons, by the way.
Hi Gofaster,

Thanks for the summary. Fyi, I also rode a FZR400, but it has a lot electrical issue....:rolleyes:
 

·
Registered
Joined
·
181 Posts
I think I got something is easier for reading here:

http://www.nsxprime.com/FAQ/Miscellaneous/FuelAdditives.htm[/url]

Can Someone Tell Me About Gasoline?
[AWN] You DO all know that all the gas companies fill their tanker trucks from the same refineries, and that the only difference between one brand and another is the additive package... Right? Ok. With that out of the way...

Chevron's "Techron" additive and Texaco's "System 3" additive are basically the same thing: They're detergent packages that help to keep deposits from forming on the backs of your intake valves and in your fuel-injectors, etc.

However... There's not enough detergent in EITHER brand (or any of the others) to keep your valves PERFECTLY clean, so if you care about that sort of thing, you should periodically run a bottle of valve/injector cleaner through your fuel system.

Any Chevron station will sell you a bottle of Techron; it's pretty cheap and is recommended (by name) by Porsche, BMW, and maybe a couple other manufacturers.

Personally, I prefer Redline SI-1 or SI-2 (same stuff, different bottle sizes). It costs just about the same, but may be harder to find.

The recommended dosage for prophylactic purposes is one bottle every few thousand miles. For curative purposes -- like if your car's running poorly and you suspect clogged injectors -- the dosage is two bottles in a tankful of gas followed by one bottle in each of the next two tankfuls.

Be aware, if you've never poured a bottle of Techron or SI-1 into your tank before, that it may loosen deposits that have formed in the system ahead of the fuel filter. Those deposits will break free and be captured by the filter, potentially clogging it and necessitating its replacement.

I use only Unocal gasoline in my cars, mostly because my local Unocal station has newer underground tanks than all the other stations in my area AND I know when they fill the tanks.



[REM] My cousin drives gasoline tanker trucks for a living. All brands of gasoline get their gas from the same refineries.
The only difference in an 8000 gallon load is the 1 QUART can of additives they dump in separately!


What Does "High Octane" Mean?
[AWN] Higher-octane fuel isn't harder to ignite in the usual way (that is, with a spark); the octane rating just indicates how easily the fuel can SPONTANEOUSLY ignite before the flame-front reaches it. "Spontaneous pre-ignition" is just another phrase for "detonation" or "knock"; higher-octane fuels resist knocking better than low-octane fuels.



[EN] There are two types of octane numbers for gasoline, the Motor Octane Number (MON) and the Research Octane Number (RON). The ASTM methods for MON and RON use the same test engine, but operate under different
conditions. MON is a measure of performance of the fuel at high speeds or under heavy loads, while RON repersents the performance during low speed conditions. The octane number displayed at the pump is the average of these two values ([R+M]/2).



Which Fuel Additives Are Recommended?
[Merritt Wikle, Auto Enthusiast & Chevron Lubricants Employee - 2000/10/20] The formulations of all manufacturers aftermarket products is very proprietary. So it is unlikely anyone knows Chevron or BG's formulations. Chevron sometimes tests/analyzes selected products a part of competitive analysis. I do know BG44K is a fine product. Further, Techron Concentrate is not just "4% active ingredient", with "filler" for the balance. [BTW filler in gas additives is typically some type of solvent.]

The active ingredient in Techron Concentrate is engineered and manufactured by Chevron. Though we do contract the actual bottling of the "juice" to others; it is Chevron that originally invented, made, and patented PEA (polyetheramine) fuel additive technology in the 80's.

In short, Techron Concentrate is the "original", and still unbeatable fuel system treatment.

In fact, the automakers use Chevron gasoline with Techron for EPA testing, even though we do not market gasolines in the Midwest (they haul from Louisville KY).

While I cannot comment on any specific Chevron Chemical customers I might know of (I'm not in Chevron Chemical group), Chevron Oronite Chemical Division sells very good PEA fuel system additives (not Techron Concentrate, though) to many well-known customers both as aftermarket chemicals, and for use in bulk gasolines. Typically these customers package and market these chemicals, or use them in bulk gasoline.



[GM] BEWARE! The 44K can is perhaps the worst designed product on the market. A large opening means much will spill down the side of your NSX. At $15 a can you are wasting part of the product, but worse it left marks in my paint! I had to polish the area several times to remove them, then re-wax of course. Luckily I was minutes from home when this happened. I don't know if it gets worse if left on the paint for longer times.



What Are The Specs On Gasoline?
[BZ] Gasoline: Mobil Super+ unleaded, 92 octane (min). Color: yellow-green. Gasoline Density: 0.75 grams/mL. Air Temp: 16 to 18 deg C. Date of test: January 1992. 1 gallon = 3.785 liters = 3785 mL = 2838.75 grams = 6.25 pounds.
 

·
Registered
Joined
·
181 Posts
http://www.nsxprime.com/FAQ/Miscellaneous/FuelAdditives.htm

Petroleum Proof, High-Performance Gasolines

Popular Hot Rodding Magazine, January 1998
By Scott Parkhurst
Octane is a measurement of a fuel's resistance to ignition. Ideally, the air/fuel mixture will ignite at the proper time and burn smoothly through the power stroke. The idea is that one powerful combustion of the air/fuel mixture is better than several randomly-ignited small flame fronts. When you can precisely control the point at which the fuel will ignite, maximum performance of the engine can be achieved, and power-robbing knock and ping will be eliminated. Knock and ping are a result of abnormal ignition, or multiple flame fronts colliding within the combustion chamber during the compression stroke.

All reputable fuel manufacturers determine the octane rating of their gasoline in the research lab using a special, dedicated single cylinder engine. Comparing the gasoline to a series of standard reference fuels in the test engine results in either a research octane number (RON) or a motor octane number (MON) depending on a set of operating conditions. The RON is determined with the test engine operating at 600 rpm, at standard barometric pressure, and the intake air temperature set at 125 degrees Fahrenheit. RON is primarily used to address part-throttle knock and ping problems. The MON addresses wide open throttle operation and is determined with the test engine spinning at 900 rpm, also at standard barometric pressure, and the intake air temperature pumped up to 300 degrees.

The best predictor of a fuel's performance in a street/strip machine is the Anti-Knock index (AKI). This is simply the average of the RON and MON numbers, or (RON + MON) / 2. Most all octane ratings posted at the pumps are determined by this AKI formula, and are the minimum values you could expect to see. The minimum octane requirement
of your engine is determined by several variables besides the compression ratio. The engine and cylinder head configuration, air/fuel mixture, timing, coolant temperature, atmospheric pressure, relative humidity, and ambient air temperature will also affect the octane required to make your mill produce maximum power.

The burn rate of a fuel is a measurement of the time required for complete combustion of the air/fuel mixture. The notion that octane ratings affect the burn rate of fuel is about 180-degrees from reality; burn rate is a function of several variables, and the two are completely independent, although there is generally a correlation between octane ratings and burn rates.

To give you a good example of this, we contacted Jim Wurth from Sunoco Race Fuels. He explains, "A perfect example is Sunoco Maximal, which is our fastest burning fuel, and coincidentally one of Sunoco's highest octane fuels at 116 (R+M) / 2. A lot of Pro Stock teams rely on Maximal for those sub-seven second runs. When they are turning 9,000 rpm or more, the fuel has to burn pretty quickly to achieve complete combustion".

Octane boosters offer little help in the quest for higher octane. Most popular street-legal octane boosters claim increases in octane ratings up to five points, and those boosters intended for off-road use only claim up to seven points. That's a lot of octane to hope for simply by pouring an additive in a tank. Sunoco told us that before they launched their GT-100 Unleaded retail pilot program, they wanted to be sure that a 100 (R+M) / 2 octane street legal fuel would be of value, and that enthusiasts would not be able to get the same (or better) results using an octane booster. Nine of the most popular retail octane boosters were put through a series of tests to determine where the consumer could get the most bang for the buck. The test results were verified by an independent testing facility, using several brands of regular unleaded and premium gasolines, just to make sure everything was legit.

According to Mark Borosky, Vehicle Test Engineer for Sunoco,"Of the nine octane boosters tested, none showed a significant increase, and one actually lowered the octane number of the test gasolines."Testing repeatedly showed a maximum increase in octane of 3.5 points by only two of the six street legal octane boosters when the recommended treatment rate was blended with lower base 87 octane gasoline. The best the remaining four products could muster was less than a one point increase. "While clearly no one would actually use an octane booster in a low base octane fuel, we wanted to give the manufacturers the benefit of the doubt relative to their claims of five-to-seven point increases," explained Borosky.

When tests were performed using 93 and 94 octane fuel, even the two best products from the previous tests produced a disappointing 1.5 to 2 point maximum increase. The remaining four street-legal octane boosters showed less than a .5 point increase. Those products designated for offroad use only didn't fare any better than the street-legal products. Subsequent tests where the dosage of octane booster was doubled, tripled, and even quadrupled produced only minimal improvements in octane, regardless of the base octane number of the test gas. In fact, quadrupling the treatment rate of the most powerful additive produced only a 3.5 point increase in octane when added to 93 premium, resulting in a cost of $3.25 a gallon.

An alternative path to octane euphoria is to blend gasolines of different octane levels yourself. It's easier than you may think, safe, and the results are predictable. The formula for mixing gasolines of the same type is pretty straightforward. When you mix a 50/50 blend of two unleaded fuels, simply average the two octane ratings to determine what's in the tank If you mix 94 and 100, you get 97. The same generally holds true for leaded gasolines, assuming the lead content is
nearly equal.

Blending a leaded fuel with unleaded, however, pushes the octane up a bit more than the math would suggest, due to the effect of the lead. Just a gram or two of lead blended into the unleaded fuel will raise the octane number significantly. Commercial leaded racing fuels contain anywhere from a trace to six grams of lead per gallon. If you were to mix 50 percent 110 octane leaded fuel with 100 octane unleaded, you would actually end up with an octane number around 106 to 107. Keep in mind that even the smallest amount of lead or leaded gas line with unleaded, could spell the end of your catalytic converter or oxygen sensor. The same holds true for using octane boosters intended for off-road use only. A word to the wise, check for any lead content in all the additives you might mix with your unleaded gasoline. And check with your state emissions regulations for street use.

We asked Sunoco's Wurth about using aviation fuel in an automobile engine. He was emphatic when he said, "Don't do it. Even though Sunoco is a major producer of aviation fuel, this fuel is specifically blended for aircraft engines. Aircraft operate under very different conditions than automobiles, and the fuel requirements are quite different as well. Aircraft engines generally.... run within a very narrow rpm range. There's no need for transient throttle response in an airplane because after the pilot does the initial engine run-up, the throttle is set in one position and the rpm doesn't normally change until landing. Also, airplanes fly where the air is cold and thin, and the atmospheric pressure is low. These are not even close to the conditions your street machine will see on the ground. Also, since most piston-driven aircraft cruise at 3,000 rpm or so, the burn rate of aviation gas is much too slow for any high performance automotive applications."
 

·
Registered
Joined
·
181 Posts
http://www.nsxprime.com/FAQ/Miscellaneous/FuelAdditives.htm

What is it that makes race gas so different? What's it made of? Sunoco tells us their GT PLUS 104 octane unleaded race gas is only 15-20 percent traditional gasoline, and about 85 percent additives! Actually there are about 120 different chemicals in GT PLUS. One reason it isn't street legal is the high oxygen content. The EPA requires that the oxygen content of a street legal fuel cannot exceed 2.9 percent. GT PLUS is about 3.5 percent oxygen. This fuel is light in weight at only 6.14 lbs-per-gallon. The high oxygen content improves the octane, and when the induction system is properly calibrated, this fuel will help make additional horsepower. The high oxygen content has a supercharging effect, since 3.5 percent oxygen is the equivalent to about 17 percent more air. Different fuels can actually alter horsepower 5-to-10 percent or more.

We wanted to to know more about the different types of race gas Sunoco had, and didn't realize there were five different types of racing fuel alone.

GT-100 Unleaded, is a clear fuel with a pump octane of 100, and will handle compression ratios of up to 12:1, and is street legal in all 50 states.

GT PLUS, is also unleaded, and is rated at 104 octane. It is suitable for compression ratios up to 14:1 and is colored light blue. It will not harm oxygen sensors or knock sensors in computer controlled engines. It is not street legal.

STANDARD, is a leaded fuel rated at 110 octane, is colored purple, and is intended for drag racing, road racing, and race boats.

SUPREME, is also a leaded fuel and is dark blue. It was developed to help resist vapor lock and meet the demands of sportsman, modifieds, offshore powerboats, and endurance racing where engines regularly run in excess of 7000 rpm.

MAXIMAL, we mentioned earlier, is colored red, has 116 octane, and is leaded. It is intended for exceptionally high performance applications like Pro Stock where extremely high cylinder pressures are common. Its extremely fast burn rate is satisfactory where rpm exceeds 10,000.

Now that you're an expert on gasolines, you probably would like to know where to buy and store the stuff. If you are fortunate enough to live in the mid-Atlantic states, you can take advantage of Sunoco's GT-100 Unleaded retail pilot program and get 100 octane race fuel at pumps located at select Sunoco stations. The rest of us have to purchase from local speed shops, at race tracks, or directly from Sunoco distributors.

When you plan on buying fuel in quantity, say a 55-gallon drum, you'll be happy to know that racing fuel has a shelf life of about a year, if you store it properly. The container must conform to all safety standards, and should be made from metal or polymer. Make sure the container is opaque and solid in color. The white plastic jugs we see at the track should be used for short-term storage only. They let in sunlight, which will affect the fuel. The lead in leaded fuel and other chemicals in unleaded fuel are photosensitive, and will dissipate if they am exposed to the sun. Keep any container tightly sealed to prevent evaporation.
 
1 - 12 of 12 Posts
Top