93 octane question

[johnymac]

This could be a stupid question but here goes.

I like to run Sunoco 94 octane in my truck ZZ4 create motor, only calls for 92 or 93 I think.

There are no real close Sunoco stations near the house so I have to take a ride to the nearest staion, not to mention these stations are much more expensive than any others I have filled up at when out of time.

I am thinking of just running a high quality 93 octane.
Close by I have Citgo, Mobil, and Irving close by the house.

I there much difference in the gasolines? I am thinking not, but figured someone out here might be able to set me stright on the best gasoline to buy?

Or is there another station that I haven't listeded that has a better 93 octone.

Thanks guys!

[Longhorn Man]

If your engine does not need the extra octain, you are literally burning your $$ away.
The higher the octain, the slower the burn. This is why it doesn't pre-detonate like 86 octain.
As the octain level goes up, so does all the additives. High grade fuel will soot up[ yur engine a little. Not enough to harm, but none the less, deposits that you don't need to put on your exhaust valves and pipes.
Run what they till you, I would even try a 1/2 tank of a lesser grade just to see if it'll work. If it doesn't, then just top it off with your 94, and then try the mid level.
There are many factors to figure on what grade of fuel. If you live in denver, you can run 86 in just about everything. But if you tried that in the Florida peninsula, you'll be getting detonation like crazy.
When the good general said run this type of fuel, it is an average. Some areas need higher octain, some lower.

[Project1970]

I'm sure that engine would be fine with 91. A lot of stations here have 91 instead of 92...and I don't recall seeing a 93 octane pump around here, ever. Yet I know at least one person with a ZZ4, and it runs great.

My Vortec motor is making about as much compression, too - 10.0:1 thanks to a stock bottom end with flattop heads - and it's very, very happy on 91.

[MikeB]

That ZZ4 has very good heads that promote efficient combustion and reduce detonation. I would try regular first, then move up as required. If it doesn't detonate, there's no benefit to using higher octane. Make sure your total mechanical advance + initial advance is no more than 35 degrees. With those heads, you may not even need that much.

[71402BB]

Ya I don't see a problem with you running 93 or even 91 octane! Andy- I don't see how you could be burning your money away by using a higher octane fuel! I know "they" (whoever they is) say that the higher octane gas is suppose to have more detergents in it whice would = a cleaner better burn! I I'm running 94 right now in my burb with a very stock lame 350 and have not noticed a damn bit of difference with fuel milage or power! But for some reason my friends fuek injected stock 4.3 seems to like the 93-94 octane! Not sure why? He says that it has made a big difference in his fuel economy (was getting 13 around town with 87 octane and is now getting 18 around town running supper)! So I'm not sure what to think! LOL My carb engines don't seem to care what I run in them but with fuel injection it seems to make a big difference??? COuld someone please explain this to me? LOL

[540 Stroker]

You can call the shops that sell GM Performance Parts crate engines to verify this if you want, but I believe all GM crate engines are designed to put out max power/torque using pump gas. For the vast majority of us, that's 91-93 octane. If you've got the time and some extra cash on your hands and are feeling curious, you can fill up on whatever Sunoco you want, rear wheel dyno it, fill up with pump gas from the local station, rear wheel dyno it. See which one puts more ponies to the pavement and make your own decision. That's just what I'd do.

[MikeB]

I'm not Mr. Wizard, but here goes. Octane rating is a measure of gasoline's resistance to detonation. Higher octane = less detonation -- NOTHING MORE! Sure, premium gasoline once had detergents, whereas regular did not. But now they all have detergents to keep injectors clean.

Here's where higher octane CAN help an engine that runs fine on regular: Newer engines have knock sensors. They "listen" for detonation and the computer retards the timing before the human ear can hear the knock. But, less advance = less power and lower gas mileage, so premium CAN MAKE A DIFFERENCE with a newer engine. As an example, I read that a new Corvette would not knock on regular gas, but would make 10% - 15% less horsepower than on premium.

So, if you don't have a knock sensor and your engine is not pinging on regular, there is ABSOLUTELY NO REASON to use premium, old wives' tales notwithstanding.

[Longhorn Man]

My wife's 4.3 Vortec ('92 with CPI injection) runs like crap on '93 octain, but runs like a raped ape on 87 juice.
If you get worse MPG on a computer car with lower grade fuel, then the computer is probably reducing the timeing from hints of detonation by the knock sensor.
Try this, it is pretty cool. put the timing lite on the new car, and watch the timing mark as you tap the side of the block with a hammer. The computr will think that the hammer is detonation and take out all the timing.
All fuels have more detergents then yesteryear. If you want to ensure you are keeping your system clean, run a cleaner in the tank once a month, you'll still come out ahead, and polute less.
I say plute less becouse if your fuel does not ignite when it should (remembering that the flash point is a higher temp on higher octain rating) then you are not getting 100% burn, onless your engine is optimized for that grade of fuel.

[71402BB]

Cool! So thats how that works! LOL thats some good info to know! Thanks for all of that "tech help" hehe. I guess I will just run the cheapest gas in my low compression lame @ss 350 from now on since anything higher doesn't do a darn bit of good! LOL