Topic: High Octane Fuel, Anyone??
in Forum: C3 Fuel, Emission Control, and Exhaust Systems
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Former Member
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DOWNINGTOWN, PA - USA
Joined: 11/24/2001
Posts: 962
Vette(s): 1969 Monza Red Black Conv / Black Vinal hardtop
454/480 Tremec 5 Speed 308 Posi.Black Leather Interior, PS, PW, Air cond., tilt/tele,AM/FM Cass.-5 Pack CD, Hurst Shifter, side pipes
2004 Yellow convertible with black top and black interior
Tom,
Have you tried lower octane gas? I think that engine has 9.5:1 pistons in it. You might be able to get away with 89, but for sure 93. I just got 93 for $1.69 a gallon last night.
Have you tried lower octane gas? I think that engine has 9.5:1 pistons in it. You might be able to get away with 89, but for sure 93. I just got 93 for $1.69 a gallon last night.
If I run 93 octane my vette pings like crazy. I have taken it to 2 corvette places and they can not get ride of it. I run 50/50 of Sunoco Racing Fuel. It is 110 octane plus it is leaded. I buy it from Kelly Racing fuels. They are about 10 minutes from Allentown PA. They sell gas at most of the reace tracks around here. It runs great. The only problem is I buy it 5 gallons at a time and it costs 25 dollars each time. I went on vacation once and took the car. By the time I got to the third tank the pinging came back. I have a 300/350 and the compression is 10.25:1. I talked to many people and they think it has engine work done to it. One of these years I am going to have it Dynoed at Carlisle.
Have you ever checked your timing 70vette ? I thought a 350/300 would run on 93? but of course i don't know nothin. I have changed many vehicles timings and made a big difference. Just thought I would ask
By the way I LOVE the color of that 70 


I have a 81 4 speed with a similar built engine and mine won't run on anything less than 100 octane. I used to live where I could buy racing gas at a local station, but not where I live now. I buy my gas now at the local airport. It's aviation fuel, 100 plus octane and "low lead". It cost much less than the pump gas. Downside is I have to take 5 gallon cans in the airport in my truck to get it because the nozzel won't go in the vette tank.
Good luck
Keith
Good luck
Keith
No, additives actually raise your octane content. I read a good treatment of gasoline chemistry and additive chemistry somewhere, but I can't seem to locate it. You can actually make your own additives from commonly available chemicals if you know the ratios.
I'm thrilled to see that we have this much discussion.
From talking to my local perfomance engine builders (pronounced 'gearheads') the consensus seems to be that 10:1 compression is about the limit for 93 octane. Glenn, you're probably just squeeking by on 93 in that big block, but then you've got so much torque that you probably don't miss that advanced timing. Tom, I'm sure your '71 will run on the 93 octane fuel, but its kind of nice to advance the timing with few concerns over pinging. I do believe in '71 they lowered the compression to 9.5:1 like Glenn said.
In regards to Larry with his "70vette", I'm wondering too if your engine hasn't had a little work done to it. If it has the need for 102 octane (after mixing) then it is probably closer to 400hp than 300hp. My bet though is that you could decrease the amount of racing to 60/40 or even 65/35 to save a few bucks (it's $3.95 here) and still not ping. I usually pour in 5 gallons of 110 when the tank is as low as I'll go and then head for the gas station for some cheap 93.
As for the octane booster angle, I may be wrong in that it may boost octane after all, but there is NO way that it hits 104!! (at 99 octane the engine runs sweet and powerful, with 93 and the additive it ran lousy and pinged) Plus I know I read about the compression chamber coating somewhere. It only took 3 tankfulls to completely foul a set of plugs to the point it tried to stall if I gave it gas too quickly. I've never seen plugs that looked that bad before and they were less than a year old.
I'm very interested in the aviation fuel though, anyone else out there with input??
"Ya gotta pay to play!!"
|UPDATED|4/16/2003 11:40:15 PM|/UPDATED|
From talking to my local perfomance engine builders (pronounced 'gearheads') the consensus seems to be that 10:1 compression is about the limit for 93 octane. Glenn, you're probably just squeeking by on 93 in that big block, but then you've got so much torque that you probably don't miss that advanced timing. Tom, I'm sure your '71 will run on the 93 octane fuel, but its kind of nice to advance the timing with few concerns over pinging. I do believe in '71 they lowered the compression to 9.5:1 like Glenn said.
In regards to Larry with his "70vette", I'm wondering too if your engine hasn't had a little work done to it. If it has the need for 102 octane (after mixing) then it is probably closer to 400hp than 300hp. My bet though is that you could decrease the amount of racing to 60/40 or even 65/35 to save a few bucks (it's $3.95 here) and still not ping. I usually pour in 5 gallons of 110 when the tank is as low as I'll go and then head for the gas station for some cheap 93.
As for the octane booster angle, I may be wrong in that it may boost octane after all, but there is NO way that it hits 104!! (at 99 octane the engine runs sweet and powerful, with 93 and the additive it ran lousy and pinged) Plus I know I read about the compression chamber coating somewhere. It only took 3 tankfulls to completely foul a set of plugs to the point it tried to stall if I gave it gas too quickly. I've never seen plugs that looked that bad before and they were less than a year old.
I'm very interested in the aviation fuel though, anyone else out there with input??



"Ya gotta pay to play!!"
|UPDATED|4/16/2003 11:40:15 PM|/UPDATED|
'69 350/350 conv.
I also think I might be able to get away with less. The person who told me to try racing fuel gave me the 5 gallon number. The only thing is I am afraid to go to low and ruin something. As for the timing it was check by two Corvette places. Thanks about the color Smokin. I get many comments about it.
I've got a '69 435 hp car that has the 11:1 compression it came with. To make it run the best I mix 2-3 gallons of 110 race gas to a tank of prem. unleaded. When I take a trip that will require two tankfuls, I fill up with 3/4 tank of race gas, then refill when at about 1/4 tank so I still get some extra octane.If longer then that I take some octane booster along,don't like it,it runs a little dirty but gets rid of the pinging. As for your small block,If you have the 11:1 pistons you should be able to run just Prem. unleaded just fine. If not you need to check timing and/or your plugs might be to hot. Set your dist. up for mech. advance only,and run around 10degress initial with 36-38 degrees total. Then you can play with the curve with a sping kit to get the best results. Good luck!
Former Member
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Wayne, NJ - USA
Joined: 5/31/2002
Posts: 973
Vette(s): White 1975 L48 Stingray 129,000 Miles, daily driver.
Sounds like I got the cheap end of owning a classic Corvette
My 75 run perfectly on 87 octane. Its pretty slow, but I'd've blown something up by now if it were faster and I had to worry more than I do! Its my daily driver anyway, so I'm better off ;)
Scot

Scot
in Forum: C3 Fuel, Emission Control, and Exhaust Systems
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