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11-13-2014, 12:57 PM | #1 |
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Fuel octane vs concistancy
I have made the jump from Super Stock to .90 and t/s class racing. I have always been limited to 112 octane for the combos i ran, but now with the new car and engine combo i am ready to freshen the engine and am wondering if i can expect more consistancy with the higher octane levels. the engine is currently @ 14:1 and requires C16 or an equivelant. I will look at options between dropping compression to run VP98 through to 16:1 compression.
Your thoughts are appreciated. Ian
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They say money can't buy happiness, it can buy race car parts, and that makes me happy Ian Hill GT/FA 1982 Camaro, F/CM 1968 Camaro |
11-13-2014, 05:26 PM | #2 |
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Re: Fuel octane vs concistancy
Once was told that the Q-16? (the oxygenated one) would make the car as consistent as a dragster on alky, would have to change to bigger jets obviously, He ran on Sunoco 16 and would switch to that VP stuff at big $ bracket races. I am just telling you what I was told, I never got around to trying it. Mine was pretty good on just Sunoco 116.
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11-14-2014, 06:01 PM | #3 |
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Re: Fuel octane vs concistancy
I run a Super Rod car on alcohol and it is Deadly using a Number 1 stop and a Rupert carb!
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11-15-2014, 01:39 PM | #4 |
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Re: Fuel octane vs concistancy
14.1 compression hardly requires C-16 fuel .
My Big Block combination has 15.9 to1 and runs perfectly on C-14 or, for the last 2 seasons on Sunoco Maximal Red. At 14 to1 , depending on the cam and ignition timing Sunoco Blue or VP C-12 should be more than adaquate for a throttle stop application. While oxygenated fuels such as Q 13 or Q16 have some benefits, there are many drawbacks to it , personal safety being my biggest concern . ....MTBE is nasty stuff, and the fuel requires more attention as far as storage in the fuel system. In the big picture , fuel cost $ per gallon from one grade or brand to the other is minimal. Run the higher compression, the car will be more consistant when heat and humidity go up than a low compression setup.
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11-17-2014, 02:10 PM | #5 |
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Re: Fuel octane vs concistancy
For a standard race fuel look for VP X16, NOT C16. Vaporization properties are better for a NA engine, and the price is better. VP113 is another option that is reasonably priced, lightly oxygenated but most engines just need around a couple sizes larger jets.
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12-18-2014, 11:54 AM | #6 | |
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Re: Fuel octane vs concistancy
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12-22-2014, 11:19 PM | #7 |
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Re: Fuel octane vs concistancy
Consistency has a lot more to do with the Lean/rich of the tune than the octane.
Get her to lean and the air goes up a couple of numbers she falls off. Get it too rich and the air goes down and she slows up because she is way too rich. There is a sweat spot in the tune. It is usually a "Window" and that is what you need to find at your track, the conditions you run in. The oxygenated fuels seem to have a little larger "Window".
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Adger Smith (Former SS) Last edited by Adger Smith; 12-22-2014 at 11:20 PM. Reason: SP |
05-24-2015, 10:28 PM | #8 |
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Re: Fuel octane vs concistancy
I prefer the VP Q-16 myself.
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05-25-2015, 06:50 AM | #9 |
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Re: Fuel octane vs concistancy
I ran my 565 on Renegade 116 and then VP X-16. Engine has just under 15 to 1 compression.
It ran very well on both and was generally very predictable. Tried Q-15 for a few races this year. Just jetted up 3 numbers. Q-15 is a 50-50 mix of Q-16 and C-15 I'm told. Results were more power but consistency due to dips in throttle stop rpm intermittently gave me fits... I have fought this t-stop issue for what seems like forever......and it occurs with an inline stop or a disc plate stop.... Switched back to Sunoco Maximal for my last 2 runs this past weekend and both runs were normal without t-stop rpm drops and this was using the disc stop. I did not like handling the Q fuel or the smell.....and from what I see and know.....you really need to have a carb done and tuned on the dyno for the fuel your using. The Oxygenated fuel was not for me....
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05-25-2015, 08:02 AM | #10 |
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Re: Fuel octane vs concistancy
Rich said " ..and from what I see and know.....you really need to have a carb done and tuned on the dyno for the fuel your using. "
I totally agree. You can zero in on the lean rich "window" & nail down the changes in power that occur when the "Air Changes". It helps your combination with consistency and predictability.
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