What grade fuel do you use?

[gjrock]

I have a pretty built 302 and run regular.What does everyone run?I used to run premium but I dont notice a difference.

 

[daddyg]

Mine is mildly built and I run regular with no problems.

 

[Apogee]

Healthy 351W in my EB runs regular just fine...the 429 in my pickup requires 92 octane or else it detonates. Just about kills me everytime I have to fill up both tanks. Note to self: early heads and high compression ratios are overrated.

 

[4x4babygirl]

Regular, which is 87 octane in my state. I find it works better with my 170 that was made to run leaded fuel.

 

[77BroncoWag]

I have a pretty built 302 and run regular.What does everyone run?I used to run premium but I dont notice a difference.

you would only need to run premium if you have a knocking problem

 

[Madgyver]

When I build my motors the main focus is to run regular pump gas... hence the max 10.5 - 10.8 compression ratio and a matching cam... So far I've hit my mark but not so lucky with my racing C..

 

[bmc69]

I'm stuck running Sunoco 280 or Cam2 if I'm running straight gas...otherwise 93 pump gas with two $8 bottles of Lucas booster per 15 gallon fillup. Ouch, either way.

 

[BamaBlue'67]

Interesting...
I have been running 93, but on my next fill up will probably try a lower octane and see how she stomachs it.
I just assumed that given the age the higher octane would perform better and we all know what they say about assumptions.;D

 

[bradj1964]

I run premium gas in my 351 stroker motor, if I dont I get spark knock, and when I shut the engine off it has "run on" like a dieseling knock,engine wants to keep on running

 

[73stallion]

i have to run premium. it rejects low or mid grade, it starts pinging on me. just paid $3.46 a few minutes ago.

 

[6677ebman]

Have always put plus in my '68 (289 4V) and in my '74 (302HO), but my '71 ('71 stock 351C 2V) runs better on regular, which was a pleasant surprise

 

[bmc69]

Interesting...
I have been running 93, but on my next fill up will probably try a lower octane and see how she stomachs it.
I just assumed that given the age the higher octane would perform better and we all know what they say about assumptions.;D

If you are running higher octane than just what is required to avoid pinging with a good timing advnace range..it is money wasted. That said, the later-model EFIs with knock sensor will run low-grade fule without pinging but the mileage goes down (as does the oomph) due to the ECM not allowing as much ignition advance...so in that case, yr not really saving money. Found that out quickly with my Expedition and since have always run 89 vice 87 because of it. But for an engine without timing controlled by ECM...just enough octane to avoid pinging is all ya need....more does little or nothing for performance.

'Octane' refers to the propensity of a fuel to ignite due to pressurization and also its combustion velocity after it does. Burn rate modifiers, like lead octoate in the good ole days, Copper salicyclate, lead beta-resorcylate, toluene, etc produce kinks and even plateaus in the fuel pressure-ignition curve, said curve heads quickly upward with increasing combustion pressure. Early 19th century gasoline with no burn rate modifiers would self-detonate at CRs in the range of 5 or 6:1! Note that none of that 'stuff' affects or increases the amount of energy in a gram of fuel...it only affects the pressure at which it wants to kick off on its own, without a spark to ignite it (detonation/predetonation) or if its burn explosion velocity is too high after it does ignite (pinging or 'spark knock').

Ok..got carried away. Class over for today.;D

 

[fwilder]

i have to run premium. it rejects low or mid grade, it starts pinging on me. just paid $3.46 a few minutes ago.

Just be glad you aren't paying 3.70 for regular like we are in Sol Cal.

 

[needabronco]

I built a hot little street Karmann Ghia in high school, small displacement huge heads, lumpy cam, dual 40mm carbs..., it wouldn't run on anything lower than about 110 octane, I used to have to mix racing fuel with premium, otherwise it wouldn't even run. I sure learned my lesson there. Now I do my best to stay with the cheap unleaded if I can.

 

[bmc69]

I built a hot little street Karmann Ghia in high school, small displacement huge heads, lumpy cam, dual 40mm carbs..., it wouldn't run on anything lower than about 110 octane, I used to have to mix racing fuel with premium, otherwise it wouldn't even run. I sure learned my lesson there. Now I do my best to stay with the cheap unleaded if I can.

LOL..sounds familiar. Had a '57 Chebby BelAir with a bone stock '67 327-365HP Vette engine in it when I was a young lad in HS (70s...%). It was supposed to ('supposed to' as in right from the vette owner's manual) run 104 minimum octane. They were not kidding..if I was poor (often) and had to pinch my pennies and run 'only' 98 leaded so I could save my last $5 to impress my date, it barely managed to git down the road a bucking and a kicking and generally running like doo doo. ahh..the good ole days..when Hess 104 or Sunoco 280 was an outrageous 85 cents/gallon at the neighborhood gas station and they all had it.

 

[73stallion]

Just be glad you aren't paying 3.70 for regular like we are in Sol Cal.

ya, but that was for premium. i usually pay closer to $3.38 for my premium, but gas gauge had been flashing 00 for a while already. low grade is about $3.26 locally.

 

[joser]

My 351W (I know nothing about its internals) with a TA carb wants premium, otherwise it pings a bit.

In cooler months, here in Phoenix, AZ, I try mid grade and can sometimes get away with it.

In my 1986 Bronco with the 351W (that I foolishly sold many moons ago), as with my V10 Excursion, if I am towing in warmer months, they want premium or they ping.

 

[77BroncoWag]

ha! Diesel is 4.19-4.30 up here

 

[Broncobowsher]

If you are running higher octane than just what is required to avoid pinging with a good timing advnace range..it is money wasted. That said, the later-model EFIs with knock sensor will run low-grade fule without pinging but the mileage goes down (as does the oomph) due to the ECM not allowing as much ignition advance...so in that case, yr not really saving money. Found that out quickly with my Expedition and since have always run 89 vice 87 because of it. But for an engine without timing controlled by ECM...just enough octane to avoid pinging is all ya need....more does little or nothing for performance.

'Octane' refers to the propensity of a fuel to ignite due to pressurization and also its combustion velocity after it does. Burn rate modifiers, like lead octoate in the good ole days, Copper salicyclate, lead beta-resorcylate, toluene, etc produce kinks and even plateaus in the fuel pressure-ignition curve, said curve heads quickly upward with increasing combustion pressure. Early 19th century gasoline with no burn rate modifiers would self-detonate at CRs in the range of 5 or 6:1! Note that none of that 'stuff' affects or increases the amount of energy in a gram of fuel...it only affects the pressure at which it wants to kick off on its own, without a spark to ignite it (detonation/predetonation) or if its burn explosion velocity is too high after it does ignite (pinging or 'spark knock').

Ok..got carried away. Class over for today.;D

Thank you, someone who understands gasoline.

a few more things. Run the lowest octane fuel you can. Pump gas has a slightly lower BTU (energy value) as octane increases. Also the difference in pump gas tends to result in changes in flame speed. Higher octanes tend to have a slower flame speed (which helps with detonation. Now these can go out the windo when dealing with specially blended race fuel.

For reference my 9.1:1 iron headed 330" stroker was set up and runds just fine on cheap 87 octane.
My 11:1 aluminum headed 351 needs every bit of the 91 octane it can get, and a little more would probably be a good idea. On a warm restart it will do a rattle start, actually detonate while starting. The rest of the time it does good but when the water temp starts climbing past 215 on hot days it will start rattling at highway speeds. I just have to take temperary action and unhook the vacuum advance at that time.
My boat has under 7:1 compression and was built in the days of 80 octane. I managed to find 80 octane at the airport once and I will tell you it ran better on that tank of low octane gas then it has ever ran in it's life.

So more is not better. Using the right level as per the engines demands is better.

 

[HotWheels]

Is everyone using ethanol now? I have noticed a decrease in mpg ever since they started...anyone else?