Question on mixing race gas and premium fuel

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Hey Guys,

I have a new engine for a street car that's sporting 11.25:1 compression. It's a iron headed 440 with stock intake and exhaust manifolds, running a pure stock cheater cam and 800 avs edelbrock carb. Stock reproduction coil and factory dual point converted with pertronix ignition kit. Total timing set at 38.

On initial break-in we mixed 110 octane with 93 so it wouldn't ping. I was wondering if any of you guys have had experience mixing race gas with premium. Someone told me the stock coil doesn't put out enough voltage to properly burn the race gas and I should try and run it on 93 if possible, stating that with alcohol added it is more like 96 octane. I'm not up on that stuff, so not sure what is a old myth or real. I would appreciate any input from guys that have experience mixing this stuff.

I don't mind adding race fuel if needed for it not to ping. I want to understand better how they act when mixed and if the stock coil is a limiting factor.

Thanks !

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Stock coil doesn't have enough voltage to burn race gas Another urban myth The coil(any coil) will produce enough voltage to jump the gap, regardless of pump swill or race gas being in the motor Your pushing the limits on compression with the iron heads and exhaust sytem and total timing What spark plug brand and heat range(part #) are you running? The cheater cam may help a tiny bit as far as the compression but I would be very careful on detonation, if it starts pinging(when it gets hot outside)lift up the throttle and get some better fuel I have treid mixing race gas and pump swill years ago, the race gas is a different specific gravity than the pump swill so they ended up seperating when the car sat overnight, I think Try getting a clear gas jar, as big as possible, and mix the two fuels together % like your going to use, shake them up and let the jar sit for a while, at least two hours or more. If the two fuels seperate in the jar you know it will seperate in the car Let us know if you test it and what it does

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38 total seem a bit much. I'v always had luck with 35 total.

How much do you drive it? Around here, there's a handful of places that sell 100 octane unleaded at the pump for $7.25 a gallon. One place is even open 24hours. You could put a 1/4 tank of that and top off with pump premium. I run straight 100 unleaded, but I have almost 13 to 1. My car loves the stuff!

For longer road trips, I plan on fitting a small 10 or 15 gallon fuel cell filled with leaded 110 that's plumbed to be partially drained into my custom main tank.

I figure I can add 5 gallons of the good stuff just before I fill up with premium unleaded and with the fuel cell, be able to mix up 2 or 3 batches of decent fuel out on the road.

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Wow is all that worth running a little extra compression. If you got rid of the extra weight it would probly be just as fast with a little less compression and 13.1 on 100 octane doesnt seem like much. Most people on here told me to run 110 octane with 12.5 to 1 on my 499 unless maybe just idleing around town.

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38 total seem a bit much. I'v always had luck with 35 total.

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Quote:

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Hey Guys,

I have a new engine for a street car that's sporting 11.25:1 compression. It's a iron headed 440 with stock intake and exhaust manifolds, running a pure stock cheater cam and 800 avs edelbrock carb. Stock reproduction coil and factory dual point converted with pertronix ignition kit. Total timing set at 38.

On initial break-in we mixed 110 octane with 93 so it wouldn't ping. I was wondering if any of you guys have had experience mixing race gas with premium. Someone told me the stock coil doesn't put out enough voltage to properly burn the race gas and I should try and run it on 93 if possible, stating that with alcohol added it is more like 96 octane. I'm not up on that stuff, so not sure what is a old myth or real. I would appreciate any input from guys that have experience mixing this stuff.

I don't mind adding race fuel if needed for it not to ping. I want to understand better how they act when mixed and if the stock coil is a limiting factor.

Thanks !

---

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Quote:

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38 total seem a bit much. I'v always had luck with 35 total.

How much do you drive it? Around here, there's a handful of places that sell 100 octane unleaded at the pump for $7.25 a gallon. One place is even open 24hours. You could put a 1/4 tank of that and top off with pump premium. I run straight 100 unleaded, but I have almost 13 to 1. My car loves the stuff!

For longer road trips, I plan on fitting a small 10 or 15 gallon fuel cell filled with leaded 110 that's plumbed to be partially drained into my custom main tank.

I figure I can add 5 gallons of the good stuff just before I fill up with premium unleaded and with the fuel cell, be able to mix up 2 or 3 batches of decent fuel out on the road.

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Wow is all that worth running a little extra compression. If you got rid of the extra weight it would probly be just as fast with a little less compression and 13.1 on 100 octane doesnt seem like much. Most people on here told me to run 110 octane with 12.5 to 1 on my 499 unless maybe just idleing around town.

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Quote:

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Hey Guys,

I have a new engine for a street car that's sporting 11.25:1 compression. It's a iron headed 440 with stock intake and exhaust manifolds, running a pure stock cheater cam and 800 avs edelbrock carb. Stock reproduction coil and factory dual point converted with pertronix ignition kit. Total timing set at 38.

On initial break-in we mixed 110 octane with 93 so it wouldn't ping. I was wondering if any of you guys have had experience mixing race gas with premium. Someone told me the stock coil doesn't put out enough voltage to properly burn the race gas and I should try and run it on 93 if possible, stating that with alcohol added it is more like 96 octane. I'm not up on that stuff, so not sure what is a old myth or real. I would appreciate any input from guys that have experience mixing this stuff.

I don't mind adding race fuel if needed for it not to ping. I want to understand better how they act when mixed and if the stock coil is a limiting factor.

Thanks !

---

Stock coil doesn't have enough voltage to burn race gas Another urban myth The coil(any coil) will produce enough voltage to jump the gap, regardless of pump swill or race gas being in the motor Your pushing the limits on compression with the iron heads and exhaust sytem and total timing What spark plug brand and heat range(part #) are you running? The cheater cam may help a tiny bit as far as the compression but I would be very careful on detonation, if it starts pinging(when it gets hot outside)lift up the throttle and get some better fuel I have treid mixing race gas and pump swill years ago, the race gas is a different specific gravity than the pump swill so they ended up seperating when the car sat overnight, I think Try getting a clear gas jar, as big as possible, and mix the two fuels together % like your going to use, shake them up and let the jar sit for a while, at least two hours or more. If the two fuels seperate in the jar you know it will seperate in the car Let us know if you test it and what it does

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