Lets talk race gas

[Elganja]

90% of my experience comes from cars, mainly mustangs... so please forgive my ignorance.

When it came to cars there was usually one major thing that was different between a race gas tune and a pump gas tune.... Timing. With my 03 cobra on pump gas I could run around 17deg safely, but when I used VP103 I could bump the timing up to 23deg or so depending on the mix.

From what I have researched so far, bikes are completely different. People tend to use VP MR9 or U4. This race gas seems completely different then the race gas for a car.

I'll try to clarify my confusion (lol), it seems that a car's race gas is basically just a higher octane gas while a motorcycle's race gas is not. I'm a little confused why this is the case and was hoping someone could elaborate on why? and does a higher octane gas, VP103 (assuming you up the timing) make more power? Can you run higher timing on U4/MR9? I know some of these questions are loaded, thanks in advance.

My application is drag racing not track racing if that matters.

 

[Hot Rod Harv]

On the dyno, I will make about 3% more hp with the race gas, with no changes in the timing.

 

[Dweezel]

On the dyno, I will make about 3% more hp with the race gas, with no changes in the timing.

Do these bikes have knock sensors that are possibly pulling timing on pump fuel? I'm not really new to riding, but the electronics of them for sure. I know cars have knock sensors and there are tricks to get around them to solve/determine "false" knock, does this trick exist in the motorcycle community?

I also read that PC3's just let you add/remove fuel, nothing with timing. Would you need an aftermarket computer to alter timing?

I don't plan on doing anything to the bike, just always like to know, call me nosey

 

[Elganja]

On the dyno, I will make about 3% more hp with the race gas, with no changes in the timing.

Do these bikes have knock sensors that are possibly pulling timing on pump fuel? I'm not really new to riding, but the electronics of them for sure. I know cars have knock sensors and there are tricks to get around them to solve/determine "false" knock, does this trick exist in the motorcycle community?

I also read that PC3's just let you add/remove fuel, nothing with timing. Would you need an aftermarket computer to alter timing?

I don't plan on doing anything to the bike, just always like to know, call me nosey

aye you need the ignition module which I do have. Greg @ GPW will be tuning my bike early next week. He is going to do both a race gas tune and pump gas tune. I should of asked him all these questions when I dropped off my bike, he is at an event in Texas currently

Hopefully he will chime in on this thread!

 

[Professor]

I started to give a quick reply. However these threads quickly become a bunch of misinformation and crap slinging of people who do not have a clue. (not in this thread"¦yet) So here is a small book version. I'm no expert but feel I have a bit more experience in the matter than the average guy. Just because someone claims to have used something and it worked for them, does not mean it is the best choice. There is a very good reason the VP makes over 50 different racing fuels. You have to choose for the application.


VP103 (I'm assuming you are talking about motorsport 103) should make about the same power as pump gas. The specific gravity of the fuel is the same so there should be very little change in the jetting between it and pump gas. It is an oxygenated fuel but so is pump gas and about the same amount. If StreetBlaze 100 is available it should be fine for your application as well.

The older bikes like 87 octane pump better than 91. 87 was all that was needed. There is much confusion about octane numbers. Octane is a measurement of resistance to detonation, not horsepower production. To further confuse it you have motor and research and then the way pump gas is measure motor + research divided by 2. Add to this pump gas and race gas use different methods of obtaining octane numbers. When they raise the octane on pump gas they may be using methods that actually reduce power when used in applications that only require lower octane fuel. (see first line of this paragraph). Race fuel may or may not be custom blended gasoline stocks. It very much depends on the manufacturer and the fuel. You might be surprised to see that some "race gas"￾ has very little "gasoline"￾ in them. Race gase is usually referred to by its octane number. There is much more to it than that.

The combustion chamber in the Hayabusa (and most late 4 valve bikes) will run much lower octane for a given compression ratio than most automotive design heads. Aluminum heads have shown to run a full point higher compression on the same fuel as well.

Then there is oxygenated vs non-oxygenated fuel. The EPA requires pump gas to be oxygenated in certain areas and on certain times of the year. Levels are usually in the 2.5-3% if I remember correctly. They usually use ethanol or MTBE to do this. I think by now all fuel in the US may be. Race Fuel is available the follows this lead like the Street blaze and MotorSport fuels VP makes. Sunoco has a few as well. I know Sunoco's unleaded are based on gasoline base stocks and suspect VPs SB and MS fuels are as well. The U4 and MR9 are what I would call exotics. They have much more oxygen content than the pumpgas blends and are likely more chemical base than gasoline base. They also can not be left in the fuel system like the others mentioned. They carry much more oxygen than the others. Combined with this and chemicals that produce more BTUs per pound,, they make more power"¦.. at a much higher cost.

Specific gravity comes into the picture another way. You will see unleaded race fuels in the .700 to .800 area. Pump gas is about .740-.745. The target air/fuel ratios are based on the blend by weight. However we blend the two mechanically by volume. So if you change fuel from one with a .717 specific gravity to a .800 you are now putting in 11.5% more fuel in to the mix. (hmm something to consider if maxing out injectors while spraying! Topic for another thread) You have just changed your air fuel mix


Personally I didn't think the exotics were worth it for my application. I bracket race so I want consistency and predictability in my fuel. Not having to drain it is a factor. Cost is another factor. I'm willing to spend $6-6.50 a gallon for my goal. Being able to swap to pump gas on the street with out tuning "¦. another. I'm not willing to spend $20 per gallon for MR9. If I needed it to make an index or was racing heads up class, it would be another story.

Also be advised some of the exotics could damage the factory O2 sensor. You do not have the ability to correct for this like some aftermarket wideband loggers do.

Disclaimer, don't take my word for any of this. I'm no expert by any means but I have had a few conversations on the subject with some very knowledgeable people in the field over the last 25 years or so. Do some research on fuels that are available in your area. Make sure the guy selling it knows what he is talking about. In my experience few do, you need to be talking to the manufacturers tech support. It has been harder to contact VP tech reps in the last several years. But with time you can still put together info. I don't think you are going to gain a lot by advancing the timing in an all motor 08 busa. If you are running the wrong fuel, it might help correct for it. If you are going to spray N2O, it is a whole new ball game.



I hope to be testing mine with 91 octane pump gas and a Sunoco race fuel in the next two weeks.

 

[Elganja]

Professor,

I was hoping you would chime in, thanks for the detailed response!

I now understand the difference between u4/mr9 and VP103 (motorsport, your assumption was correct).

Octane is a measurement of resistance to detonation, not horsepower production.

I agree 100%. I was hoping to use 103 and up the timing a bit but I guess it won't make that much of a difference. I am not a fan of 20 bucks a gallon for u4/mr9 or having to drain the tank. I'm 100% I will never use either of those fuels due to the price and inconvenience.

I'll have to give Greg a call, but for now I am thinking of doing something like this (via multifunction HUB):

Tune 1: 93 Octane
Tune 2: 103 Octane via VP Motorsport 103

 

[Professor]

I've got more compression than a stock 08. I was leaning toward the MS103 myself. My call to VP confirmed my choice. However my local distributor (VP and TrackTek dealer) changed from Chevron/Phillips TrackTek 101 (Specific Gravity .743) to Motorsport 101 (SG .800) as their bulk unleaded fuel. This kind of confirms my previous statement about the dealer may not know enough about their product/target customers. In my opinion, MS103 would have better filled the needs of those using the fuel. (SG .743)

It is for that reason, I'm now going to try Sunoco 260 GT-Plus. SG .748 with 4.8% Oxygen. This combination should cause my bike to lean out slightly on the pump gas as well. It is readily available here at the distributor and at the track which is a big plus over me having to order in the MS103!

 

[mymaster]

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[mymaster]

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[Mr Bogus]

looks like the gas stations around the Parker Strip

 

[mymaster]

looks like the gas stations around the Parker Strip

http://www.infineonraceway.com/

 

[roadthing]

Kind of off the subject,but when somebody says RACE fuel, I get to thinking about MSD and adjustable spark curves.

Man do I love the smell of race fuel, and the sound of finely-tuned engines!

I think I need to go for a ride.

 

[Hot Rod Harv]

...

I sure wish we had some of those pumps here.

I have to go to the speed shops or, my personal favorite, the Airport, for 100 octane low lead.
I like it because it is so consist for each "brew".

If you want a little extra umph, in each tank, add one ounce of NOS's 104 "race" octane booster to the airplane gas.(+ 7 points)

Oh yeah, it smell good too.

I don't know much about the chemistry, but it FEELS better and even sounds different.

I will probably catch He** about how I am doing it wrong, but this combo has worked for a lot of years in many different things for me.

 

[Elganja]

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1352001[/ATTACH] AM]
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I sure wish we had some of those pumps here.

I have to go to the speed shops or, my personal favorite, the Airport, for 100 octane low lead.
I like it because it is so consist for each "brew".

If you want a little extra umph, in each tank, add one ounce of NOS's 104 "race" octane booster to the airplane gas.(+ 7 points)

Oh yeah, it smell good too.

I don't know much about the chemistry, but it FEELS better and even sounds different.

I will probably catch He** about how I am doing it wrong, but this combo has worked for a lot of years in many different things for me.

fyi, octane boosters aren't all that great at boosting octane

 

[Professor]

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1352176[/ATTACH] AM]
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I sure wish we had some of those pumps here.

 
I have to go to the speed shops or, my personal favorite, the Airport, for 100 octane low lead.
I like it because it is so consist for each "brew".

If you want a little extra umph, in each tank, add one ounce of NOS's 104 "race" octane booster to the airplane gas.(+ 7 points)  

Oh yeah, it smell good too.

I don't know much about the chemistry, but it FEELS better and even sounds different.

I will probably catch He** about how I am doing it wrong, but this combo has worked for a lot of years in many different things for me.

This is pretty common and I also feel it is a pretty common mistake. Even though I nave done the same thing in the distant past. My mixes included plenty of banned/dangerous chemicals. It is a good thing we had to start using Methanol the rules were easier to enforce

1st 104+ will hurt the performance unless you are suffering from detonation. The properties that raise the octane also slow the flame travel. If it is not detonating, it will impair the performance.

Yes, av gas is very consistent. However it is made for higher altitudes. Made to prevent deicing, vapor lock and engines that run less than 3000 rpm. It burns slow. The specific gravity is much less than automotive pump gas. You have likely heard stories about it buring so hot it burt up the engine"¦.. we actually it leaned out the engine because the weight of the fule was incorrect. Remember we meter the fuel by volume but the air fuel mixture is determined by the weight of the fuel. An aircraft engine is also more of a steady state constant rpm engine. The av gas is tuned to this and detonation can occur under heavy loads and rapid acceleration in automotive and bike use.

Do yourself a favor and try some racing fuel for your application. You may be surprised and it will be cheaper than trying to doctor up pump and av gas.

 

[Busanova]

Interesting thread.

Hat's off to you Professor. Certainly can't argue with with your screen name or your presentation!

 

[Hot Rod Harv]

Thanks Professor,
I always wanted to get the "skinny" on this and you have put it right out there.

 

[99'busa]

 

[Jaddie]

Dear Rick & Friends

It's information like this that causes me to be an Internet forum junkie!

I appreciate it.

The information isn't vital for my use as a novice 'Busa street rider, but I still find it interesting. If there were some sort of secret base brand/additive combination that's optimal for my bike and use, I'd definitely want to know all about it.

--Jaddie