[Subscribe to Daily Digest] |
Members do not see ads below this line. - Help Keep This Site Online - Signup
Octane:
Toluene 114
Xylene 120
Source: most paint stores
These two hydrocarbons are aromatics and are a significant portion of normal pump gas. (25 - 45 %)
A while ago there was a post asking about using toluene injection. This would create on boost enrichment and enhance the octane of the AF mixture. This would require an auxilary fuel tank, pump, pipes, FPR and controls. This would work, so would bigger injectors. Only a few application would merit entertainment of that idea.
There are posts on the net concerning adding these to pump gast to get improved octane and power. Some claims are for greatly improved power. In these cases the subject vehicles were getting higher boost and the ECU and knock control functions had been holding things back becuase of lack of sufficient octane in pump gas.
Octane averaging calculations:
C = tank capacity
X = volume of octane enhancer to add
Op = octane of pump gas
Oa = octane of addative
Ot = octane target
( (C-X)xOp + XxOa ) /C = Ot
moving the terms around yields:
X = Cx(Ot-Op) / (Oa - Op)
for 92 octane pump gas, a target of 94 octane, a 50:50 mix of toluene and zylene for a Oa of 117 and a 17 gallon tank
X = 17X(94-92) / 117-92 = 1.36
So for 1 17 gallon tank, adding a 1.36 gallon 50:50 mix of toluene and xylene will produce an estimated octane of 94. The concentration of 1.36:17 is not very high! Obviously adding any oil as a lubricant is not warranted for low concentrations.
You can see why those weeny cans of octane increaser in the store shelf are ineffective. When those state that they increase octane by 4 points, they are talking about 4 10ths of of one octane level. They really don't explain that to they? And those off the shelf addatives can contain oxygenates and ?MBTE? that fake out trionic systems that use spark plug knock sensing and you may actually get less power and boost!
You will probably end up spending $15 for that increase of two octane numbers. You cannot afford to do this as a permanent solution to any problem.
What could you expect to gain? By increasing the octane you can evaluate if there are any improvements with higher octane or problems that go away. Spending $20 on these addatives is certainly a definative way of making such an evaluation. Compare this cost to shop time at the dealer to chase down a vague running problem. Compare to a large bottle of Techron Concentrate at $10. Certainly one should first use Tecchron Concentrate to deal with any acquired octane demand from deposits and such.
With a Trionic system you probably are not going to see massive increases in boost and power as these are already limited by the ECU. But hesistation, bogging down, a loss of boost or perhaps things like a part throttle increasing power over that of full throttle may respond to higher octane. If they do not, you can conclude that such problems are not octane related or not responsive to the octane increase that you created.
If an octane fortified tank of fuel does produce some obvious running benefits, I don't see a good permanent solution other that water/alchohol injection.
For those at lower altitudes, 93 and 94 octane fuels are available. For those in California or higher altitudes, many turbo applications can suffer. With the Trionics, the boost target against the absolute pressure sensor reading. And with the 9-5 Aero, and Viggen as well as boost modified systems, there may not be any pump gas available that will allow things to run as they should. So there is a good method to evaluate if higher octane will improve things.
I am not suggesting that everyone should do this. But a few will, and if they post their observations, we can all learn by that.
2003 9-5 Wagon, 24K
SMBC, TurboXS BPV (corked and backwards), EBC pads on four corners, 92 octane pump gas :(
posted by 208.24.17...
, Sat, 30 Aug 2003 19:37:08
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
