What Separates a Race Fuel from a Street Fuel?

wspohn said:

te72 wrote:

Shame that race fuel isn't available in more places, at the pump. Understandable, absolutely, but still unfortunate.

But why?  It burns more slowly, yes, but if you can't take advantage of thar because you don't have high enough compression to need it, nor a 'hunt forward' igniion timing set up, it won't do you any good.

We get good unleaded 94 octane with no ethanol here at the pump, and I can't imagine needing aything else.

 

 

All about your specific setup bud. I could easily crank out another couple hundred horse out of my setup with the right fuel. It's the difference between 20psi and 35psi. Trouble is, the only places I know of that sell it, sell it in cans or barrels. Most of where I do my playing are at tracks that are nowhere near local to me...

Basically what I'm getting at, is it would be fun to be able to travel, fill up on race gas near the track. I don't drag my car behind me, I drive it to where I want to play. Consequently, I'd have to stick a few cans of the stuff in the hatch in order to run a track session. Not exactly convenient. As a result, I make due with pump gas and just deal with the lower power output.

If you are running a turbo engine with two different programs, what bout ethanol containing gas? Have to check injector flow but that would allow you to run two different programs with two different fuels. I have seen people doing that with a base tune for pump premium and an override (Trfifecta switchable) tune for gasohol.

Either way, aren't you going to be mixing gas unless you manage to run out of pump as you cost into the gas station to add race fuel or ethanol containing fuel?

In reply to Knurled. :

Again, all good stuff, but not very relevant to the use of leaded gasoline in this century. Formula 1 does not use turbines or diesel engines and does not run on diesel fuel or anything like kerosene. F1 does use very highly stressed spark-ignition piston engines... without needing lead.

E85 also keeps things cool since you have to / can run a lot richer.

I'd say that the biggest difference though is that nobody is ever happy with the ethanol content of their pump gas if racing - its either too much or too little depending on which camp you're in :)

wspohn said:

te72 wrote:

Shame that race fuel isn't available in more places, at the pump. Understandable, absolutely, but still unfortunate.

But why?  It burns more slowly, yes, but if you can't take advantage of thar because you don't have high enough compression to need it, nor a 'hunt forward' igniion timing set up, it won't do you any good.

We get good unleaded 94 octane with no ethanol here at the pump, and I can't imagine needing aything else.

 

 

Why do people keep saying that?  Octane rating has no real bearing on flame speed, especially in a very turbulent flame area like in an engine's combustion chamber.

Octane is more a measure of the stability of the molecule before a flame front passes through it.  High octane means it can take a higher temp/ higher pressure/ longer time than low.  So it won't just come apart on it's own in a very sudden way (the sound you hear is sound waves bouncing off of surfaces due to flame speeds at Mach 1- which is not what you want).

alfadriver said:

wspohn said:

te72 wrote:

Shame that race fuel isn't available in more places, at the pump. Understandable, absolutely, but still unfortunate.

But why?  It burns more slowly, yes, but if you can't take advantage of thar because you don't have high enough compression to need it, nor a 'hunt forward' igniion timing set up, it won't do you any good.

We get good unleaded 94 octane with no ethanol here at the pump, and I can't imagine needing aything else.

 

 

Why do people keep saying that? 

Because they read it on the internet

In reply to Suprf1y :

Good point.

wspohn said:

If you are running a turbo engine with two different programs, what bout ethanol containing gas? Have to check injector flow but that would allow you to run two different programs with two different fuels. I have seen people doing that with a base tune for pump premium and an override (Trfifecta switchable) tune for gasohol.

Either way, aren't you going to be mixing gas unless you manage to run out of pump as you cost into the gas station to add race fuel or ethanol containing fuel?

Running an MS3 Pro on my Supra, all it would take for me to switch over to the dark side would be a flex fuel sensor and a visit to the tuner, so yeah, that's certainly an option, and in fact, an item on the long term list.

You're correct that in most cases you'd be mixing fuel, but it's fairly easy to drain a fuel cell into a gas can, if you carry one of those with you. I see your point though! =)

rjstanford said:

E85 also keeps things cool since you have to / can run a lot richer.

I'd say that the biggest difference though is that nobody is ever happy with the ethanol content of their pump gas if racing - its either too much or too little depending on which camp you're in :)

Hooray alcohol for lowering IAT's!

Ethanol really is one of those all or nothing things if you ask me. If you're going to bother running it at all, may as well use a high concentration of it, and tune to extract the power it can provide. If you don't want to use it, may as well use zero ethanol gasoline and extract the BTU's for the mileage it provides. All about the right tool for the right job, right? =)

So is it beneficial to put a few gallons of 100 octane in my tank and run it hard to help clean things out?

Interesting about the summer/winter blends. Does that mean a fill up in the summer that sits until winter might not run well, even if the gas isn't actually bad?

The summer gas in winter thing mostly affects starting, not so much running.  I've had times in the fall / spring where I had a full tank of summer blend and took the Jeep into the mountains and had it get pretty cold overnight (20 - 30* F).  Starting the next morning was a lot more eventful than normal (several seconds of cranking and it didn't just light off all at once, more like each cylinder started to fire over the course of about a second, but it ran fine once it started).  

I run seasonal gas in the wrong  seasons in my lawn/snow care machines without problem.

 Again,  the internet has exacerbated this.

I read once, written by someone who seemed to know his chemistry, that the energy density of ethanol is much less than that of ordinary gasoline, so when running pure ethanol your fuel mileage would suffer substantially, like 25 or 30 % less.  On the other hand, since ethanol has an oxygen molecule already built into it, it doesn't require as much oxygen (air) to burn it (convert it to carbon dioxide and water), so you can, and indeed must, run a much richer mixture.  In a piston engine, this means that you don't have to pump nearly as much air through the motor to burn ethanol.  Another way of saying this is that for the same amount of air you can burn more ethanol fuel so that in a properly set up motor you can usually generate more power on pure ethanol although at a stiff penalty in fuel mileage.  Any chemists out there who can verify this?

iceracer said:

I run seasonal gas in the wrong  seasons in my lawn/snow care machines without problem.

 Again,  the internet has exacerbated this.

Exacerbated, sure, but there is seasonal fuel around the country.  What sucks for car people are the handful of areas that put VERY summer fuels in pumps (as a non-attainment area patch), and it gets below 40F.  Cars are a bitch to start in those cases.  But that's pretty rare.

If I were the dictator,  really would specify a very tight package of fuels around the country, instead of having a huge variety of blends.  Terrible.  FE, emission, and driveability would get better if there were only a handful of blends.

one makes for the breakfast of champions. 

More octane than you need is not a good thing, it can cause incomplete combustion. In a low compression motor over time can cause combustion chamber deposits and lower mileage.

There are concerns besides just octane, Reid Vapor Pressure, specific gravity are a couple of the biggies.

Reid Vapor Pressure is why Av Gas is not recommended for the street.

The specific gravity changes the fueling requirements.

Off the shelf octane boosters are a joke, You can't significantly change 15 gal of gas by adding a quart of anything that is legal to distribute "over the counter".

In reply to bentwrench :

No, high octane fuel will not cause incomplete combustion.  Poor quality fuel will, but not octane.   That myth needs to end.

alfadriver said:

In reply to bentwrench :

No, high octane fuel will not cause incomplete combustion.  Poor quality fuel will, but not octane.   That myth needs to end.

Why then did dyno testing show higher than needed octane produced lower power levels?

Each type of fuel is blended according to its intended use.

AvGas has high octane, but most of its additives are to prevent high-altitude gas line freeze up and gum up... not to make added power.  Not a great choice for street or race cars.

E85 is cheap, makes power, but gives horrible fuel mileage... ask anyone who has tried it. 

Race fuel's high octane allows engine builders to use higher compression and tuners to advance timing further.  That's what makes more power. 

All ECU's can retard timing to prevent detonation (knock). Your modern car can make more power with race fuel IF your ECU also permits timing to advance when higher octane is present.  Many cars, and most all modern high performance cars will do this.

Race fuel costs more because (1) its additive package is more expensive, (2) its blended in much smaller quantities, and (3) its distributed in smaller quantities.

Where to buy? Use the fuel finder at sunocoracefuels.com

bentwrench said:

alfadriver said:

In reply to bentwrench :

No, high octane fuel will not cause incomplete combustion.  Poor quality fuel will, but not octane.   That myth needs to end.

Why then did dyno testing show higher than needed octane produced lower power levels?

Probably because it's a different fuel blend.   Octane, by itself, is not an indicator of how fast it burns, but an indicator of how stable the molecule is to spontaneous break down- the higher the better.  Once a flame front hits it, it will react like low a low octane blend of roughly the same thing.

Some of the cheap ways to get high octane don't have the same energy content as other fuels.

In reply to Torqued :

Not a chemist, but this is accurate in the experience of those I know who do use E85, E90, etc. Roughly a 30% penalty, but can make a fair amount more power.

Example, my 1jz Supra makes just shy of 500whp on 91 octane pump gas at approximately 20psi. My friend Albert's setup is largely similar as far as the items that affect power output. VERY similar turbos, he makes just shy of 750whp on approximately 39psi on E85.

Mileage isn't the motivating factor here.

alfadriver said:

In reply to bentwrench :

No, high octane fuel will not cause incomplete combustion.  Poor quality fuel will, but not octane.   That myth needs to end.

Like "engines overheat because the coolant is moving too fast", this is a myth that will last forever because there is no worthwhile science education in this country.

In reply to Knurled. :

Caterpillar calls their thermostats, "regulators" and I think that might be a more appropriate term. All I've ever seen happen when you remove your thermostat is that your coolant never warms up enough to enjoy your heater on cold days.

Brian_13 said:

In reply to Knurled. :

Again, all good stuff, but not very relevant to the use of leaded gasoline in this century. Formula 1 does not use turbines or diesel engines and does not run on diesel fuel or anything like kerosene. F1 does use very highly stressed spark-ignition piston engines... without needing lead.

They also don't have traction control or ABS, but that is not because it wont make them faster, it is because that is what the rules say. They used to run a toxic fuel but they changed the rules for safety and environmental concerns. just like they limit the amount of fuel they can burn in a race and the max flow, because they think that acting green will make people overlook the 100 jets that they use each week to transport all the cars, gear and crew to each race.

I used to race a 2-stroke 250c GP motorcycle that ran only leaded fuel. You could get head inerts that were made for unleaded, but you gave up a lot of HP and invited detonation. 

In reply to Rusnak_322 :

I get the point that F1 uses unleaded fuel in part because of the rules, rather than not wanting lead, but they still produce massive power from small heavily-boosted engines with the unleaded. Even where the rules allow lead, it isn't needed... unless you can think of an example of an auto racing class in which lead is allowed and engines produce more power (per displacement) for 90 minutes at a time than F1.

I'm sure that GP bike is a classic. Current MotoGP/Moto3/Moto2 bikes run on unleaded, but everything else about the engine rules is different, too. A reality of motorsports is that no series offers a fair comparison of engine designs or fuels; we'll never know if a modern engine in the same class would need lead.