RaceGas

[V10 MOJO]

typically ive got 93 octane in my car. since ive heads/cam/nitrous, is it worth running racegas on the track?? if so, what ratio/amount and what octane

 

[PRVT JET]

Mojo, is your car at stock compression? if yes, on motor you won't need higher octane. with spray, I would do half/half. 100-104 should be good, you won't need anything higher.

 

[V10 MOJO]

compression was incresed to 10:1

 

[V10 MOJO]

I was also wondering; since i wont be making any additional VEC2 adjustments (such as timing) would increasing the octane even benefit at all?? isnt the reason for adding higher octane is to allow for timing changes to benefit the car? so, if i add race gas, toluene/xylene, whatever, i assume i also need to alter my current vec2 settings right??

 

[joe117]

The engine has no way of knowing if it is knocking. I believe that the engine will have no way of changing the timing on its own to take advantage of higher octane.

If you have control of the timing, you may be able to advance it more than you could with 93.

 

[Warren S]

Some info on race gas and octane, click here >>> http://www.osbornauto.com/racing/dragster.htm

 

[joe117]

If you don't raise the compression or advance the timing, you will not gain anything from higher octane.

And, if you have your cats still on, the lead in it it will ruin them but I'm not sure if one tank full would do it.

 

[CHAD]

Leaded race gas will burn up the O2 sensors quickly as well.

A couple gallons of race gas (3 gallons or about 20%) will just make racing a little safer by holding off detonation.

It is a cheap insurance policy for your engine.

Chad

 

[PRVT JET]

I thought not all racing gas was leaded, 100-104 are unleaded.

 

[HARDVIPER]

We only get 91 Octane here, is this going to hurt my car in the long run?

 

[FE 065]

If your extensive dyno testing with 93 octane has everything where you want it, then why change? Any limitations of the 93 octane would have shown up on the dyno wouldn't they? You're probably way rich for the nitrous anyway.

 

[J DAWG]

higher octane is harder to ignite, therefore you can advance the timing and get a little more power.


probable won't make a noticeable difference, but one never knows until one tries.

 

[FE 065]

One theory about that is,that the rate of combustion in relation to the piston position during the expansion stroke contributes to combustion temperatures.  

The higher octanes produce peak combustion temperatures/pressures slightly later during the expansion stroke than the lower octanes, leading credibility to the the notion that octane fuels resist detonation, are harder to ignite, and once ignited have a slightly longer burn duration.

MOJO is you're going to be using the nitrous and the rich mixture it requires on all your runs you're probably best with what the dyno runs tell you.

If you're going to use gas only for some runs, and haven't done alot of recent dyno time w/o the nitrous to document horsepower readings vs timing, you might consider the higher octane gas just in case there's some detonation.


On the street it might not be worth the expense but since you're looking for max hp at the strip, it's one of those cover-all-your-bases things.

 

[NCVCA]

We've been racing open wheel cars and fuel is a 'hot' topic. We've most recently been running and are very please with AVGAS 110LL. It's aviation fuel (color is blue) 110 octane. The benefits are that it's MUCH less than race gas (here about $2.80 a gallon) and has thermal and stability properties that blow auto fuel regulations away. The 'LL' stands for low lead, but thats a relative term. AVGAS LL has much more lead than the leaded gasolines we bought in the 70's so no lubrication issues arise from it's use.

Might be worth a try, but remember with such a change you must adjust tuning to get the benefit. This will require dyno time.

Lastly, if fuel isn't 'free' in the series your running (meaning not restricted by rules) this is a waste of time because EVERY fuel test will detect aviation fuel...

AND as a point of pure curiosity did you know that there are legal fuels available to Formula racers in SCCA that cost over $30 a gallon? Yeah, like a fillup in a small car costs $210!!

They say at the national level you have to run it to be competitive...

Jeff

 

[Tom F&L GoR]

Lead levels:

115/145 Avgas 1.28g/L
100/130 Avgas 0.85g/L
110LL Avgas 0.56g/L
pre-1985 leaded automotive gasoline 0.29g/L
1985 leaded automotive gasoline 0.13g/L
1986-1994 leaded automotive gasoline 0.026g/L
after 1995 no leaded gasoline

Some (all?) states have road taxes; if you aren't filling up an airplane, there may be some paperwork to get you to pay the added tax. You can see how much this would be by looking at the sign on the gas pump next time you visit a gas station- it should show gasoline price+tax=final price.

Avgas also has a unique distillation curve so that the fuel will burn adequately and safely at higher altitudes (less barometric pressure and colder temperatures.) This may make the engine a little difficult to start, something I witnessed with a Viper (just keep playing with the pedal until it idles on it's own) but as long as you know that's what it is (and not an engine problem) it's OK.

Plug deposits and combustion chamber deposits will look a lot different. Racing and aviation applications have high fuel flow rates that will keep intake runners and valves clean by literal washing of parts; because Avgas doesn't have detergents, it could form engine deposits if used in street applications.

As Jeff points out, more lead in 100LL than ever was in auto gas. It will quickly poison the catalyst and soon thereafter, the O2 sensors.