mezus

I don't think Xylene is an oxidizer like N2O, It should just be very energy rich.

944-LT1

Youre absolutely correct (well except chemistry is math--without math chemistry cannot be). But you cant even use a chemical equation either. So its a perfectly acceptable equation for a crude-close estimate.

The reason is because gasoline is a complicated mixture of hundreds of different compounds with chemical formulas between C6H14 and C12H26 (the accepted "average" of the gasoline is C8H18). The problem with the equation I posted above is that the octane number he may see on the pump isnt even 100% correct.

Also check into toluene which may be cheaper and easier to obtain although note that toluene has been shown to cause cancer in lab rats ......so keep your lab rats away from the toluene.

FRporscheman

Race gas isn't that hard to find and it takes all the work out of calculating final octane. It's expensive but I'm sure it's still cheaper than using an equivalent amount of xylene/91.

DarylJ

Race gas is not even close be being cheaper when you buy Xylene in 3 or 5 gallon pails from a paint supply store rather than a gallon or less from Home Depot.

smlporsche

I feel sorry for you poor guys who can't buy 93 octane for $1.70/gal...
Why can't you go to your local Advance Auto and get a container of octane boost additive?
Xylene has other properties that I'm not sure are conducive to your car's fuel system in large quantities...

DarylJ

Those are just overpriced Tolunene or Xylene in very tiny containers. At that point, it IS worth finding somewhere to get race gas.

krystar

and those small 100ml bottles will increase octane by 0.1 per tank


mix e85! or denatured alcohol from hardware store

V2Rocket

after i get my SC on there i'll experiment with this a bit.

FRporscheman

Xylene is about $17 per gallon last time I saw it at Ace. If it's 1 gallon of xylene per 10 gallons of fuel at $2 per gallon here in the bay area, then that's $37 for 11 gallons of fuel at 93.4 octane. To make 93.25 octane using 100 octane race gas and 91 octane premium, it's 3 gallons of 91 with 1 gallon of 100, and the 100 costs something like $4 per gallon. For this 4 gallons, the cost is $10. So to have 11 gallons in the tank, you spend about $28.

Plus, with race gas, you know it's OK for your car. And you won't spill it on your fender trying to pour it into a funnel.

Xylene became available at Home Depot only recently here in the bay area so I always had to really search around for it. I did use some a couple times but I think I'll just stick with race gas if I need high octane.

PRICES MAY VARY! We all know everything is more expensive in the Bay area. I almost misspelled bay.

V2Rocket

xylene/toluene are higher octane than 100..

Fluidplay

has anyone used xylene for extented periods...and has done some, if any testing on at what percent of xylene to pump gas (91 or 93) achieves a certain octane rating? It would be interesting to know...Isn't race gas 103?
Home Depot $13
The differance was noticable.

kevincnc

From everything I've read, raising octane should not increase performance, just make it less likely to knock. In fact I believe that it should theoretically produce a little less power at the same boost level as was already stated. The advantage is that you can run higher boost to get more power. Maybe it can help spool, I don't see how though. Maybe someone else can explain it,

My car feels like it runs better after I wash it too..

FRporscheman

For cars with automatic timing retard, high octane can increase performance if the computer was running on retarded timing beforehand.

Xylene has the equivalent of 117 octane like 944-LT1 already posted. That's why you only need much less of it than race fuel to achieve the same thing. Race gas is available in different octanes, but at the station I go to, it's 100. I've also seen 95 and leaded 110.

944-LT1

That’s an excellent idea. Does a higher octane rating produce more power? To compare, I decided to use ethanol which has an octane rating of ~116 vs. gasoline which is ~90
Gasolines formula is 2(C8H18) or C16H36. Using the ratio of fuel to air the complete combustion of gas is:
2C8H18 + 25 O2 ----> 16CO2 + 18H20 + Heat/energy.

The total energy given off from this reaction is -2.5X10^3 (-2,500.00) mega joules. That negative sign just means its an exothermic reaction or simply....it gives off energy to do work.

Ethanols formula is 2(C2H5OH) or C4H12O2 (but its really the first structure to retain the -OH group…after all, it is an alcohol like pouring in Everclear or some backwoods fire-water into your tank).The complete combustion of ethanol is:
2C2H5OH + 6O2 ----> 4CO2 +6H2O + Heat/energy.

The total energy given off from this reaction is -1.8X10^3 (-1,775.50) mega joules. Again exothermic.
Both give off energy to do work....but heres the problem and stick with me here.... Assume a 150 HP engine and assume a twenty (20) gallon fuel tank. Also assume the same speed, vehicle weight blah blah blah…

1 HP = 745.7 watts so for 150 HP that’s 111,855 watts.
Watts (power) = Energy (joules)/ Time (seconds).

Gasoline puts out a respectable -2525.14 MJ or 2.53×10^9 joules so:
111,855 watts = X= 22,575.12 seconds or 6.27 hours until the tank is empty.

Ethanol puts out -1775.50 MJ or 1.8×10^9 joules
111,855 watts = X = 16,092.3 seconds or 4.47 hours until tank is empty assuming you don’t drink some on the way.

Again, gasoline puts out 2525 mega joules of energy while ethanol, with a higher octane rating, puts out only 1775 mega joules. So there it is.

Heres some octane ratings:
E10 gasoline 87-93
E85 gasoline 105
Methane 107
Ethane 108
Methanol 113
Toluene 114
Ethanol 116
Xylene 117

kevincnc

Aren't we talking about a 944 N/A here? If so what is gained by increasing octane?