Need to find a source for Racing Fuel / 100 Octane

[TX69]

As others have stated you really shouldn't need to run 100oct. in a 10.5. Maybe fatten your tune a hair or pull a few degrees out up top. If its aluminum heads you definitely do not need it.

If its an original motor then it is probably not even 10.5 most motors were oversold.

Toulene will boost it, most oct. Boosters are toulene based or have it in there.

My guess is that over the years carbon build up has helped raise the compression some and it isn't far off from the state compression or even higher. I do have the motor at factory secs so I can back a few degrees of timing out of it but is that really going to take care of the pinging? Is Toulene going to have any negative affects on components? I have switched the rubber fuel line sections over to Gates Barrier, upgraded the fuel pump to accept corn gas and the original factory carb has been completely rebuilt to accept corn.

 

[Das Jared]

My guess is that over the years carbon build up has helped raise the compression some and it isn't far off from the state compression or even higher. I do have the motor at factory secs so I can back a few degrees of timing out of it but is that really going to take care of the pinging? Is Toulene going to have any negative affects on components? I have switched the rubber fuel line sections over to Gates Barrier, upgraded the fuel pump to accept corn gas and the original factory carb has been completely rebuilt to accept corn.

Really interesting. Have you swapped head gaskets at all? Those can play with compression. How are you running? Lea, rich?

Sent from my SPH-L720 using Tapatalk 2

 

[SR9TEX]

No speed shops carry VP 5 Gal steel cans of it? I know C16 was up around $75-80 last time I was looking at race fuel but 100Oct. Might be had cheaper. What kind of car/engine is it?

 

[SR9TEX]

I have a few friends running slightly higher compression, and are just running 93 pump gas. I think it might be more of a tune or jetting issue in the carb if its pinging up top. Do you have a wideband air/fuel gauge for it?

 

[Ole Cowboy]

My guess is that over the years carbon build up has helped raise the compression some and it isn't far off from the state compression or even higher. I do have the motor at factory secs so I can back a few degrees of timing out of it but is that really going to take care of the pinging? Is Toulene going to have any negative affects on components? I have switched the rubber fuel line sections over to Gates Barrier, upgraded the fuel pump to accept corn gas and the original factory carb has been completely rebuilt to accept corn.

If you are having pinging now but have not had it before in the past then there several ways you can approach the problem. If it were mine this is what I would do:

1) Clean out the carbon from inside the combustion chamber. This is easy since you are carb'd (I think). Engine at normal operating temp, remove air cleaner to you can see down the carb throat. About a 12 tab top can, rinsed and filled with water. Using the butterfly/accel lever on the carb to race your engine, slowly pour the can of water down the carb throat while revving the engine. Try not to let it die and when the engine stumbles due to the water hold and rev clearing the engine then start pouring again. This is called a 'poor man's' valve job. But in fact in shops many years ago it was often part of a major tune up and if you brought your car in for a valve job they would perform this prior to removing the heads. Have I done this? ALL MY LIFE. Live on a farm or ranch with tractors and trucks that see limited road or high-speed use and you will need to do it about every other year and anytime you did a tune up. This will get your your CR back to factory specs and get rid of any sharp edges of carbon that often lead to Pre Detonation (pinging)

2) Still pings? Or not as bad then you can put on a high flow air cleaner if you have not do so. You other option would be to to fab up a cold air package. Cold air is more dense and can reduce pre-det. This is far simpler than one may think and does not have to cost much more than a few dollars and some ingenuity.

3) Of course there is the old trick of backing off you timing. I put this last as when you do that you begin to lose performance. I would check my timing and insure is dead on factory spec and after all the above if you are still having issues you can back off 2 degrees at a time till it stops.

When I moved out to the Phoenix area several years ago I brought my Jeep with me which I had installed a supercharger. I arrived in mid winter and did not have any issues...then summer came on and in downtown rush hour traffic street temps of as high as 137 F were common. I had pre-det so bad I could not even drive on the freeway. I knew my issue was with incoming air temp so the first thing I did (after a lot of research and investigation) was to install a set of hood vents. WOW this almost solved the problem, but not quite and by this time (going into my second summer) I was determined to go back to 87 Oct rather than run the 91 stuff (I am an engineer and I think that way). Since the results was so good with the hood vents which kept the hot from pooling on top the engine, which is also where the SC sat, which had a oil line running to it and also gen'd up a lot of heat I knew if I could get the air temp down some more I could solve it...maybe. So I built a cold air system and not only did it solve pre-det but I picked up about 1-1.5 mpg and a noticeable boost in seat of the pants power.

Another addition I made was going from a 5 blade fan to a 7 blade and a HD fan clutch.

Hard off road use gens up a LOT of heat and in the Sonoran desert where I spent a lot of time and in Death Valley where I have wheeled for weeks on end in the Valley and Johnson Valley I never had any issues at all. I wheeled with my AC on and stayed cool while I watched guys overheat all the time. My fan, HD clutch, radiator were all OEM components, I ran 87 oct and at full boost I had issues with pre-det, I put over 80,000 miles on that rig, wheeling across the SW.

View attachment 24432

View attachment 24433

Cold Air Fab and Install Part I - II "Trash Air" CJ/YJ/TJ/XJ | SavageSun4x4 | SavageSun Engineering

Let us know who this works out for you...

 

[Eli]

Just retard the timing some. You can fatten up the mixture by changing jets, but it's a bit more effort.
Most old high-compression motors had enough cam to bleed off cylinder pressure at lower RPMs where detonation is an issue.
What's the vehicle/engine specs?

Eli

 

[drummingchevy]

I've always heard that av-gas had additives not good for automobile motors.

Lead and dye, that's it. It's 100 octane with those two things put in it. Regular 100 leaded Avgas: green, 100LL Avgas: blue.

 

[DFTR]

As long as the engine is original and states to use premium lead fuel, like my old 67 Cadillac did, use it. No sensors nor catalytic to mess up. If, rebuilt with hardened seats? You should just continue using the additive. Here's a link to local Sunoco dealers. Sunoco Race Fuels | Fuel Finder. I can't get the VP fuel link to work well. Might be my laptop? VP Racing Dealers, racing gas station.

 

[mosin]

My guess is that over the years carbon build up has helped raise the compression some and it isn't far off from the state compression or even higher. I do have the motor at factory secs so I can back a few degrees of timing out of it but is that really going to take care of the pinging? Is Toulene going to have any negative affects on components? I have switched the rubber fuel line sections over to Gates Barrier, upgraded the fuel pump to accept corn gas and the original factory carb has been completely rebuilt to accept corn.

If it is set up for e85 it should be running fat already, unless you are referring to just the gaskets and such and not rejetting the carb.

Generally speaking you run as much timing as you can without pinging, if you are pinging and you back it out you shouldn't really lose much power. I doubt you'd pull out enough to notice it without running down the track and seeing the numbers. If it just a small amount of ping and its nothing serious you are only taking up a very minor amount.

Toulene isn't going to hurt anything.

Next time you get the motor apart whenever/if ever that happens throw some hardened valve seats in the heads. The use of leaded gas vs. unleaded is more dependent on the valve seat than octane requirements. Lead was used as a lubricant, the move to unleaded brought in the hardened seats. It isn't that big of issue though and plenty of old cars are still putting around with original heads and unleaded gas.

 

[Rangerscott]

My motorcycle is 11.6 : 1 and runs on 87. LOL

Also what Das Jared said.