Excuse my ignorance- but I just found a source of this gas-normally $4.68 a gallon and I can get for $2.10 (which now-a-days is not too much more than premium would it be bad to use it>?

 

Is it 100LL?

 

If this in UNLEADED racing fuel it would run the same as 91 , if it has lead in it it would slowly begin to run worse as your catalytic converter deteriorates.

 

i was thinking the same thing

 

just stick with 94 ultra

 

Leaded will also destroy the front O2S almost immediately.

 

It is unleaded "street legal" racing gas, 100 octane- someone said stick with the 94, however, 91 is the highest we can get here Would I maybe benefit from mixing to try and get a medium

 

you won't benefit from it at all right now...unless you have done some significant engine mods...like FI...other wise you'll waste your money...if you want to see what it does go buy some Xylene at a paint store and run a mix...

 

If it won't do anything I won't bother- I got screwed buying some crap gas once cause I was on the interstate in the middle of nowhere and all they had was 87 octane-(So I only got five bucks to get me to the next gas exit) I could SURE TELL a major difference between that and the 91 octane I always usually buy- just thought a few extra octane might make a difference- thanx for the honest answers and for not patronizing my ignorance when it comes to fuel

 

Kain -- it's not the octane it's the energy content of the gas that affected your performance. If you were running CZ Stage 3 and had tuned for max power (pushed the edge) then the racing fuel would be necessary. Fuel with the same octane can have very different power content. Cheap (poor) gas usually has additives that increase octane but are poor for power. High quality (Shell, BP, etc.) usually has a good energy content as well. That's why people sometimes add Xylene -- high power content (and also increases the octane) -- but you can increase octane without increasing the power content of the fuel.

 

Why would 100+ octane not have any affect over 87-94? ECU? Just curious. I used to occassionally run 102 Octane (I think) from Gas City in my CBR600 and ZX7 and it made a very noticable difference.

 

RXHUSTER YOU MENTION SOME GAS COMPANY (Shell, BP, etc.) I LIVE IN TEXAS AND ALL TEXACO WHERE BOUGHT BY SHELL....I PUT EXXON IS THAT A GOOD GAS COMPANY

 

anyone have sunoco in there area
all i have used is sunoco 94 ultra
i notice the difference in my s4
especially when i turn up the boost

 

didn't someone had a discussion that lower grade fuel is more beneficial for naturally aspirated rotary compared to super grade fuel ie 91? I personally use 91 thinkin about switching to 87 because of that discussion.

 

I'll try to participate to that thread but you first apologize for my bad english which is not my first language, and for technical things, I'm not sure that I'm able to explain correctly. Anyway, let's try.

First octane has something to deal with timing (do we say that?), you know when your engine starts to overheat, the timing is not good, gaz explose before that the spark lights it up. It's really not good for the engine. Higher the octane is, later this problem will appear. To be clear, higher the octane is and longer and later the gaz will explose by itself, under pressure and heat.

With your car, you've been told to use fro example 91 or 95 or 98 octane gaz. Several cars accept 95 to 98 (In europe). Then it depends on how the ECU was tuned originally. All modern engines are able to modify the timing in a limited range, so that they can adapt to different octane ratings. But if it's specified that you can use from 91 to 98, it will not make any difference if you use more than 98, because the ECU and your engine is not built for that. However, if you use 91, may be the ECU will detect timing, and adapt it, reducing fuel injection and may be you'll lose some HP. Again, if you use octane under than 91, may be your ECU will not be able to handle the timing, and therefore will use the "save default mode" of your engine, or your engine will blow!

Using higher octane is useful when you have a very modified engine. Because the gaz has a better resistance to heat and pressure, you'll be able to increase the comp. ratio whithout modifying anything else. It's bad. Well, it's not bad, but ther's no point to do that. If you need more power, you can add a suprecharger, or use a bigger engine. Using higher octane agz is usefull when you reached to all other possibilieis on your engine, and when you're not allowed to increase the engine because you particape in racing with a limited engine size. In that case, when you're not able to increase the rpm of the engine, you can using higher compression cylibders and put higher octoane gaz also, it will work. This is for racing cars, no point to do that on a road car. What would you do in middle of nowhere, if your engine is made to be used whith 100 octane gaz and if you only find 91? The engine would blow, for sure.
Again, no tuner will ask you to use higher octane gaz, except the one you normally find in stations, or except if he has reached the possibilities of the engine.

I'm not sure it helps, may be my exlanation is a bit confused?

NTTY

 

Hi, do not use lower grade, there's no point to do that, except if the price is lower for the 87 and if the manufacturer allows it for your engine.

As I said, higher grade will better resist to heat and pressure, and avoid "auto-ignition". If you live in a "hot" state or country, this will better save your engine.

NTTY