There is a place about an hour from my house that sells Sunoco Racing Fuel. Supposedly a choice of 95/99/110 octane.
Is there any reason(s) to put some in my base 2014 Stingray?
more importantly,
is there any reason(s) NOT to put it in?

thx

 

There's no reason to use race fuel. Your Stingray doesn't need the extra octane (some debate using 87 rather than 91!)..Save the money for something else. Generally, the outlets selling race fuel also sell ethanol-free 91. That's what I choose to use. A tad better mileage and easier on your fuel lines and internals.

 

Short answer. There is no benefit to running fuel with an octane rating higher than what the owners manual calls for.


Longer answer. The octane rating in fuel is just telling you how stable the fuel is. By this I mean how resistant it is to premature ignition. When you increase cylinder pressure through higher boost, more compression, or more timing advance the fuel needs to be stable enough to not self ignite. When this happens we call this knock.

Luckily our cars are smart enough to hear this through knock sensors and can pull power to safely run lower octane fuel. Though I obviously don't suggest running regular in your corvette especially not a boosted one. Unfortunately this only goes one way with the factory ecu and tune.

So unless you're suffering from knock running race fuel will not benefit you in anyway over a quality premium fuel from the pump.


Now you can have your car tuned for race fuel and it will make more power. Especially if it's modified.

This is also why people have their cars tuned for Ethanol fuel like E85. As the Ethanol is effectively an octane booster and also burns cooler compared to normal gas.

 

If you use higher octane fuel than your car "needs", it will actually deliver less power. Higher octane fuel has less power in it. The reason you need high octane fuel is to stop detonation, high octane fuel is less volatile so it doesn't explode in the cylinder rather than burn.
The gas company want you to purchase the highest octane fuel they have,,,,,,, super dooper fuel. SUPER expensive fuel.

 

Money and/or catalytic converter. The 110 is usually leaded, so it can cause issues with your cats if they are still installed. 95 and 100 are non-leaded, but just cost more money. You'll have more knock protection using higher octane, but if you don't race the car on track you probably would be wasting money.

I run 110 on track for the knock protection. It's relatively cheap insurance.

 

thank you to the forum members.
all good info.

 

I get that octane is the ability to resist PREMATURE detonation. What I don't see is how the energy content of the gasoline is affected by the octane. I think summer blend of fuel is made less volatile and winter blend is more volatile for ignition purposes but I don't think it changes whether it explodes or burns in a cylinder.

 

Octane is a rating number,,, it isn't an additive. Has nothing to do with summer/winter fuel.

 

It doesn't. I was thinking about the blend affecting volatility of the fuel.

 

No need to run gas that is a higher octane rating than that recommended in the owner’s manual. Just more expensive.

 

Wouldn't the best thing be to stress the engine with WOT runs and read knock counter via the ECM to make a decision?

 

From my experience, leaded fuel is hard on O2 sensors as well.

 

Yep, but I still prefer replacing sensors to engines.

 

Does it even detonate at 100 octane?

 

All depends on heat, tune and mods. Like you mentioned someone would have to do some analysis to determine octane. Even then you cannot account for all scenarios that could lead to detonation.

TLDR; Detonation is a non-zero risk.


Price wise. The jump from unleaded 100 to leaded 110 is the same. My car is happy on leaded, so that's what I run.

 

I would THINK that you do a few WOT runs and read the datalog. If it knocks, it would be only the start of knocking before the ECM pulls timing away. At least that's what I saw rhe tuner do on my C4 when it was on the dyno. Timing and fuel, I believe. Obviously, he was a pro so he should know how far he can push it and give the appropriate cushion.

 

Dyno heat is not the same as road racing heat. Dyno has less air moving over the car, but isn't seeing the same level of repeated thrashing. It also depends on ambient temperatures. There isn't a magic octane.

tldr: more octane = more protection

 

Forgetting ethanol or not, simply a higher octane could benefit a Stingray I think. Several posts above mention the ecu pulling timing to prevent detonation. OK great no detonation, but how about power loss from less timing? Think about how we drive these cars generally in an rpm range that back in the day would have been considered 'lugging' the engine. What happens when you're driving around in 6th at 1500 and need to go up a hill. Put your foot down, or the cruise does it for you, think maybe it knocks a bit and the ecu pulls timing? I am old enough to have messed around w/ cars w/ distributers and no ecus. Spent plenty of time trying a little extra timing to see if I could get more power and used 1500-2500 rpm full accel to see if I got any knocking. So basically, if I could get a gas identical to my normal 91 that had all the same qualities but was also higher octane, I'd love to try it.

 

leaded fuel also eats catalytic converters for breakfast.

 

Correct, all gasoline engines detonate, thats why we have knock sensors. They are just tuned to start making noise above a certain amount of detonation.