Is it safe to just throw in 100 octane racing gas into car and let it mix with the 91 octane that is already in the tank, and just drive it like that? I wanna try useing 100 octane for fun, but I want to know will anything bad happen? or do I have to do somthing to the car before I pump in 100 octane.

 

I have heard that is may wear out your catalytic converters faster if you use 100 octane. I dont think the mixing it with 91 is going to be harmful. I am planing on buying 100 octane at least 1 time a month up here in Nor Cal, mostly I just want to feel the difference in octanes.

 

same here I want to try it out for fun =D

 

The the fuel is unleaded 100 octane fuel that is approved for road use, it will result in NO ill effects. If anything it is quite a bit safer than 91 on the same tune.

Except of course, you'll end up broke a lot faster.

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Is your car completely stock?

 

A tune would definitely help... A LOT

 

you can run 100 in your car & have no issues.

 

AHHAH but if u dont raise boost u will be losing horsepower from running too rich!

 

It should be perfectly fine. That said, there's no point in using it unless: 1. you're getting knock 2. you've tuned for it. However, if I'm going to go do a trackday, i'll put in some 100 octane mixed with 91 to have that extra safety margin when you're REALLY pushing the car to make absolutely sure I don't get knock.

 

You'll just be wasting money? Dont really need 100 unless your on the track..

 

100oct won't affect afr's much if any at all.

 

yes my car is completely stock, and I just wanna to try out 100 octane for fun to see how it feels. I think I am going to do a 50/50 of 91 and 100. But do I have to up the boost, or can I just run stock boost? Thanks for the help

 

R u sure about that! There was a thread going on this very factor and 2 tuners chimed in saying that it wont benefit him unless he has knock, otherwise he WILL MOST LIKELY LOSE POWER. (if he doesnt raise boost)

 

The reason you would run a higher octane fuel is so you can safely run higher boost. If your not going to raise the boost it's pointless. You said your car is stock and until you get a boost controller, you cant raise the boost. Your not going to notice anything. So, basically, don't waste your money.

 

A 50/50 mix of 91 & 100 oct will only yield 94-95 oct at best. This octane level will not raise the afr enough to reduce horsepower. It will provide a better margin of error and will eliminate any knock you may experience but it will not do much without a tune and an increase in boost.