Really dumb fuel question....

[cophotoguy]

I think the gauges on my Spyder 97 are not stock, but they do say Premium fuel on them.

Does this car require premium fuel, and what would happen if I accidentally put regular in?

Thanks,
Tim

 

[DSMnoobsause]

Your gas door should say something on the inside if it is required. If you do require premium and you put regular in. Fear not. Just go to a parts store and pick up some octane booster.

 

[cophotoguy]

Whats the difference between the two. Just cleaner?

 

[bryanwheat]

Whats the difference between the two. Just cleaner?

No, higher octane fuel has a higher knock threshold.

 

[DSMnoobsause]

HowStuffWorks "What does octane mean?"

 

[DSM1G90]

Regular fuel is cleaner and hotter since it ignites quicker due to the lower octane level and additives.

91 plus octane has more additives to increase octane that it's actually considered, a 'dirty' fuel.

Why a lot of owners are using E85 due to the high 100 plus octane level, but it burns cooler due to the high alcohol content.

Your GS setup is designed for 91 plus octane fuels for top performance out of the factory.

 

[BLOHS7844]

DSM1G90, you have no clue what you are talking about. Don't be trying to explain things that you don't know. Premium is more refined and technically less dirty.

Regular fuel does NOT burn quicker. If it burned quicker technically that would raise the octane. Knock always occurs after the fuel has been ignited to some degree but hasn't finished burning.

Regular gas has more heptane, which is just a long chain of carbon and hydrogen. Premium has more 2,2,4 trimethylpentane, which is carbon and hydrogen bunched together. Heptane doesn't burn quicker, it just has more degrees of rotational freedom in its bonds so it can ignite before the flame gets there, which is what knock is.

If you use regular, you will potentially reduce your power and gas mileage by delaying the ignition timing.

 

[jtmcinder]

I think that his or her first sentence was trying to say that regular fuel BURNS cleaner and hotter, but that doesn't stop most of those claims about gas from being nonsense. (For example, whether hotter and cleaner go hand-in-hand kind of depends on which by-products of combustion are the most worrisome to you.) The idea that having more trimethylpentane (aka iso-octane) somehow makes the fuel "dirty" is very silly.

 

[WES_393]

For what it's worth, I have ran 85, 87, and 91 in my bone stock Spyder GS with very VERY little difference between all three. I still like to fill up with 87 just for the peace of mind that I'm not pumping the cheap stuff into my tank. Like you said, your gauges are not stock (I have NEVER seen a stock Spyder GS say "Premium Only" like the turbo models) and the Spyder GS is not nearly as dependent on higher octane fuel as a turbocharged engine.

So bottom line: It's about what you want to pay at the pump. The butt-dyno may notice a very slight increase with higher octane fuel, but the lower octanes aren't going to hurt at all.

 

[3kgt2nv]

you should always use what is manufacturer recommended for octane. if you are recommended to use premium and use 87 you will get worse gas mileage and performance and may experience knocking. if you are rated for 87 and you move up for no reason there will be no difference as the car is not going to take advantage of the higher fuel octane. all fuel is required to have cleaning agents nowadays so its not like it will run cleaner or clean the engine. its all what the car is designed for and timed / tuned for.

as far as it being dirty with the higher octane that is an epic fail on the posters part as higher octane fuel goes thru extra steps in refining since they can no longer use additives like lead to boost octane.

some basics on fuel octane
The Low-Down on High Octane Gasoline

by the way i work in a fueling based industry and go to qc seminars yearly about this kind of stuff. mainly i deal with avgas which is 100 octane leaded fuel specifically for aircraft but we also cover regular car fuel also(mogas)