Highest Octane to run in viper- Pump Gas 110 octane

SneakyPete

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A local Sunacco gas station at the beach is getting all new pumps and ****** mart upgrade. With the new pumps, they will be selling 110 octane unleaded racing gas.

Has anyone run this type of gas in a viper? can you run it straight? or do you mix it with 93 octane? How much more of a performance difference would there be?
 

Bugeater

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You wont get any performance gain. Unless your car is modified with high compression, tuned to run some advanced timing or running forced induction (turbo...S/C) its really a waste of money.
 

Vic

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That's what I heard. The computer is "mapped" with certain parameters, and unless the computer is programed to change fuel flow, spark advance, it doesn't "see" the increased octane. Thats what I've been told, any way.

Now my old C4 Vette, it really came to life on 112 octane. Of course, I had an aftermarket chip in it, so maybe that allowed it to adjust for the increased octane. Sure was fun for a tank full, at least.
 

Paul Hawker

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At a ViperDays event several members filled up with racing fuel at the track. All complained of REDUCED performance. Hi Octane fuel burns more slowly, perhaps that is why it did not work well in our cars. Stick to normal premium fuel. Get the best you can find.
Track cars easily go through a tank a day, making racing fuel (+$5.00 gal) an expensive proposition.
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jp

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In a non modifed Viper...don't do it, waste of money.
I Use VP:s 103 Motorsport when running my 10 sec times with Nitrous. On the street I'm on Pump gas.
 

racetech

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Yep, you guys are right on the money. Octane or Octane Number Rating (ONR) reflects the antiknock characteristics of the fuel and is NOT synonymous with power.

About four or five years ago, one major oil company ran a (I thought) misleading TV advertisement. It showed a Vette accelerating with "normal" octane fuel, then they ran it again on their "super premium" fuel. It ran quicker on the higher octane fuel.

What they didn't tell you is that the Vette (at least then) had a knock sensor. The comptuer was programmed to "listen" for knocks. If none were heard, it would advance the spark timing 2°, then listen again. Since it was in effect tuning to the fuel *increased spark advance*, there was a performance improvement.

As you correctly pointed out, the blend of fuels and/or additives necessary to increase octane cause the fuel to contain less heat energy. I'm fairly sure that this accounts for the loss of performance many of you experienced with the higher octane fuel.

Gasolines tend to exhibit different anti-knock characteristics when run under load in the engine than they do at cruise. RON (Research Octane Number) is the result of a steady-state cruise test. Another octane rating, called MON (Motor Octane Number), is tested under high speed and high temperature conditions.

The octane number test was developed in the 1920’s and is still used today. A particular fuel that is to be rated is run in a CFR (Cooperative Fuel Research) engine. This special one-cylinder engine, also called a “knock engine”, has an adjustable combustion chamber so that most any fuel can be squeezed until it detonates. Fuels are tested and compared to ISO-octane, that has been assigned an AKI (anti-knock index) of 100.

In the late 1960’s, the US Congress standardized an octane number rating (ONR) system for passenger car motor fuels that is an average of the RON and MON (thus the R+M/2 displayed on the pump).

In racing, we are less concerned about the performance of the engine at cruise. For this reason, racing fuels are usually listed by their slightly lower MON rating. This means we may have an "apples & oranges" problem here on the quoted ONR's of these fuels.

110 Octane is a really high rating--and if true, it could handle extremely high dynamic engine compression ratios. However, if you don't plan on changing pistons or combustion chamber sizes to put the squeeze on the fuel/air mixture (or supercharging), you'll be better off running pump super premium.

For what it's worth, the street racers around here seem to prefer the Amoco Super Premium and it's what I run in my Viper.
 

Vreracing

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The Porsche 993TT I had would only boost to .6 with 90 octane gas. It would boost up to .8 with 104 octane gas. It made a big difference. In that case the car was turbo charged and the computer was programmed probably through a knock sensor to detect what gas you were using. It was pretty much of a digital effect. Either it ran with the faster program, or it ran with the slower program. Not much gradiation between.

I bet the Viper doesn't have such program. I noted zero difference when I put the race gas in the Viper. The only difference with race gas, is that "supposedly" there are other things in it that will allow the gas to burn better. Nothing to do with octane in our case.
 
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