gas

This is bad information:

quote:
"...leaded, oxygenated..."

pretty useless information:
lead IS actually the oxygenate...a damn good one too. but the clean air act forced the use of mtbe...solved the emmissions problem but created a bigger groundwater problem.

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This is a little better:

tetra-ethyl lead was used to boost octane levels and stave off pre-ignition but it does not oxygenate the fuel. Oxygenating is adding an oxygenating substrate to fuel and lead does not do this. Tetra-ethyl lead has no oxygen in it's molecule: (CH3CH2)4Pb . MTBE and Ethanol are compounds that contain oxygen and are added to reduce the amount of unburned gas and carbon monoxide. They do not significanlty increase the octane rating.

In racing fuels Lead is required to get to octane levels above 101 - there are currently no other additives that work as well and are as commercially available as lead.

Lead is also used to prevent erosion in the valve seals and seats.



Edited by - geeto67 on Oct 18 2006 10:38:59 AM

New Laws prohibit people from AVGAS from being sold for automotive applications. If you get busted it isn't just a fine it's a few days in the pokey to boot.

My father is a pilot and I used to work the flightline at Republic airport and Montauk Airport as a kid (no gas at MTP), so the stuff has always been accessible to me. Een now I can still get cans of it. I used to run it in my GTO before I rebuilt the engine because it was one of the few places I could get leaded gas. When I rebuilt the engine I lowered the compression to 9:1 (from stock 10.5:1) and installed hardened valve seats. The car runs like a champ and is as fast as she ever was. In the old days avgas went all the way to 115 octaine, today it is all 100 octaine low lead.

A note about running it in your bike. Unless you have 9.5:1 compression or higher, big cams, etc...Avgas or racing fuel will not help you. It is a common misconception that high octane fuel is a power adder - it is not at all. All it does is allow engines with massive squeeze or high lift /high duration cams to run their optimal by preventing preignition and detonation (pretty much the same thing and can rob power in the same way hitting an upward moving piston with a sledge hammer can rob power). Cam2 lead free 100 octaine is a much better fuel and costs about the same, if I had the choice I would take the cam2.

If you have a bone stock 1970's street bike you should not even think about running premium (92 or 93 octaine), let alone race fuel. Even the vaunted high performance superbikes of the 70's like the cb750 , z1, and gs750 run off of regular. As long as you are tuned up good Reuglar will give you the best performance.

That being said I run premium in my cb750 during the summer months only and here is why: 1) Premium is less likely to contain higher concentrations of ethanol, and 2) I ride in a lot of heavy traffic and a cb750 will begin to detonate when she starts to overheat (sounds like rocks in a coffee can). By running premium the engine can get a little hotter in traffic without detonating. It won't totally prevent it but it buys me a few extra minutes while I figure out my next lane splitting line.

oxygenated fuels pack a substrate containing oxygen into the fuel. This is not a performance enhancing measure but rather it is done to reduce the amount of carbon monoxide put out by an engine. I think there must be some performance benefit since nitrous oxide, methanol injection, and other chemical power adders (ahem.....hydrozine....ahem) all work of the principle of jamming more oxygen into the combustion chamber - but the real use is so that there are free oxygen molecules to bond with the carbon monoxide molecules post combustion.

On a standard engine the air fuel mixture creates a thin layer on the crown of the piston called the barrier layer which keeps the heat of combustion from destroying the piston. With detonation an uneven flame front is created with lateral explosion forces as well as vertical, and the barrier layer is consumed as part of the initial combustion process(instead of forming a carbon deposit on the crown from incomplete combsution - BTW this is also how a lean condition casuses a hole in the piston). Nowadays there are pistons which have a thermal barrier coating which make racing engines more resistant to detonation effects. This is formula 1 style technology although some trickle down is starting to happen (mahle and a few other piston suppliers have begun to make coated pistons).

Finally 94 octane or higher no lead gasoline isn't going to do much harm to a perfectly tuned stock engine, but it wont do much good for it either (there are some bikes that lose power running on higher octane). If the engine is out of tune, espically with regard to ignition timing that is a different story. That being said I wonder if there isn't some small benefit in running 94 in a roadrace engine which tends to see more high rpm low speed abuse than a street bike. Sure the back straight cools the engine down but I wonder what kind of heat builds in a roadrace engine through chicanes and other twsty sections of the track. For now I am going to chalk it up to all in your head but it would be worth investigating on a dyno.

quote:
I can assure you VP doesn't oxgenate fuels to reduce emmissions. They all but promise a 6% power increase with their oxygenated fuels. And as most racers will tell you...VP knows their stuff.

When you spend 30 or 40 hours in the seat of the same race bike you get a pretty educated butt when it comes to how the engine is running. I can without a doubt tell you after a race if the bike had pump gas, race gas (Sunoco) or VP in the tank. Probably half of the street bikes I've owned responded very noticably to race fuels like CAM2....I don't claim the difference was due to octane though. The other half would run the same...or worse.

Presently I plan on switching from VP C12 to VP U4 specifically to get a lower octane. In the case of my race engine with only about 10:1 compression I'm probably giving up some power running 108 octane VP C12. The U4 is around 94 octane.

The major difference I've seen between pump fuels and race fuels is that in almost every case the race fuels will see more complete combustion during a race...almost always indicated by a plug that begins to run more lean. Race fuels often require jetting up a size for the plug to read the same as with pump gas.
JohnnyB

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Branson, not doubting anyone's butt dyno - I'm sure y'all get very good at telling what makes a difference in the bike. I do however know some very expirenced pilots who when they fly over water they think their engine suddenly runs rough, so it is possible through fear or desire for a very expirenced person to fool themselves into thinking there is an effect or the effect is greater than it is.

After some thought about it I think the biggest gain is by using bottled race fuel over pum gas is that bottled fuel is very clean where as pump gas is contaminated. Most pump gas contains at least trace amounts of water, plus silt from the tanks, some gas that has gone bad sitting in the tank, and god knows what else. Bottled race fuels usually just contain fuel - that probably accounts for the biggest difference in power.

As for why VP oxygenates their fuel, they claim both power and emissions on their website:

"Oxygenated with ethanol, this CARB-legal fuel is well-suited for high-performance street cars. It's environmentally friendly and street legal throughout the U.S. Dyno tests with a turbocharged application proved StreetBlaze 100 generates 14% more horsepower compared to premium grade 91 octane unleaded gasoline."

"Motorsport 100 is oxygenated with ethanol. It meets California Air Resource Board (CARB) requirements and is street legal throughout the U.S. Generates substantial power increases over premium grade 92 octane unleaded gasoline."

They also state several times that their oxygenated fuel makes 6% more hp over non-oxygenated fuels, but are vague as to whether it is the oxygenation (is that a word?) or because of other things (like selling 100 octane as a replacement for 91 and 92 octane)

They also have a lousy FAQ section (ok none at all) and don't really talk about oxygenation or why it is important to the fuel.

quote:
All I can say is....if a person needs an opinion on race fuel....they should talk to a racer. If they want an opinion on street fuel...talk to a street rider.
I'm not much for theory when experience is available. And to be honest...I have the experience when it comes to racing the same engine, at the same track, in the same conditions, with different fuels. I've also got about 50 dyno runs on this engine...but while none of them were done to specifically test one fuel to another. I am pretty good and comparing my seat of the pants dyno to actual dyno readings.
You can ask any of the guys here I race with, they will tell you I am not one to believe in untested theory, rumor or conjecture. I am rabidly anal about actual and real performance and my results on the track show it.
In most instances reading or guessing about how fuel might work in a particular instance is no replacement for the actual experience of running 100's of laps on various fuels and noting the differences.

You've quoted a couple of sentences off the VP site discussing particular fuels...VP makes about 50 different fuels. Oxygenating leaded race fuel is not done to reduce emissions, whether that is a by product of the process or not. Leaded race fuels are not known for being friendly to the environment. The two fuels you mention are both unleaded street legal fuels that far from the same as the specialty leaded race fuels we are discussing.

While I'm no chemist....I CAN tell someone how a particular fuel will most likely perform in their race motorcycle. Not by guessing, but based on my experience with these fuels.

And while mentally unstable pilots may have fantasies about their engines. I assure you I didn't build what is probably the fastest Honda 175 race bike in the country based on my imagination
JohnnyB

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Dude...chill the fuck out. It wasn't meant to be an attak on your personally. Years of race expirence absolutely have some credibility when it comes to racing. All I am saying is nothing is set in stone when it comes to an educated guess (that is a guess based on past epxirence without hard numbers to back it up) and there are still falibilities when it comes educated guesses in the absence of hard numbers.

As for this:

quote:And while mentally unstable pilots may have fantasies about their engines. I assure you I didn't build what is probably the fastest Honda 175 race bike in the country based on my imagination

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hopes and dreams, or wishes, or butterfly wing dust didn't build yout 175. You built it out of trial and error, and logical problem solving, and expirementation, and frankly just straight out thinking about it. While you may call it your imagination it is still very scientific in nature. Sure you used feel as well as hard numbers in homebrewing your race bike and I commend you for the feat. However I find yout take on a well known and documented phenomenon that affect everybody (not just pilots) and the expirenced and inexpirenced alike just plain ignorant.

You are right about what I quoted from VP is for street fuels. Frankly their website doesn't make any claims as to power adding or emissions concerning oxygenated when it comes to their race fuels at all. All I am saying is that the fuel companies are intentionally vague when it comes to what ethanol or MTBE or any oxygenating compound actually does. The only information I can find about oxygented fuel relates to emissions (although the federal government also makes the claim that it enhances combustion without explaining how: http://www.epa.gov/otaq/oxygenate.htm ). Most oxygenating power additives contain some other catalyst that is the power adder (nitromenthane for example).

You say that vp doesn't add oxygenating compounds to their LEADED race fuels to reduce emissions - then why do they do it? The lead is the octane catalyst they need, why add the oxygenating catalyst as well? My only point is they don't make any solid non-vague power claims as to the oxygenating compound when it comes to race fuels.


I don't like alcohols as a fuel in general because they have a greater density than gasoline, require more fuel make only slighly more power. In drag racing alcohol is popular not because it makes more power but it's cooling properties make engines more reliable. There are top alcohol and top funny car drivers who can run whole races on the same engine where as their nitro counterparts have a tear down and rebuild between each run.