120 octane unleaded ?
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From: Troy, AL
Re: 120 octane unleaded ? The highest octane unleaded that I am aware of is VP's HTG. It's 106 motor octane (motor octane is what you need to be looking at.) CSP is only 96.6 motor octane by comparison.
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Re: 120 octane unleaded ? HTG has higher octane but is not designed for my application. I have had extensive discussions with VP on this topic and they say CSP is best for my unleaded application (blown/sprayed). The detonation properties and burn rate of CSP are best I have found so far. I was hoping someone knew of better fuel.
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Re: 120 octane unleaded ? Yes, still using stock PCM and stock O2 sensors, along with a wide band O2 sensor. Can't go to leaded fuel w/o going to a different engine management system, such as FAST.
Re: 120 octane unleaded ? just out of curiosity....why havent you tuned it for open loop? thats what i have done since i am going to a direct port on the stock bottom end to run c116
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From: Troy, AL
Re: 120 octane unleaded ? Stealth, you just asked for a higher octane. 
Wonder why they said it would be better for you when HTG and Motorsport 103 both have a higher octane?
"The detonation properties and burn rate of CSP are best I have found so far."
How do the detonation properties and burn rate differ than HTG? I'm curious since HTG has a far higher octane.
I found it very strange that the guy I spoke with at VP recommended C46 for a 15:1 9000 RPM engine. It has a motor octane of only 98.6.
Wonder why they said it would be better for you when HTG and Motorsport 103 both have a higher octane?
"The detonation properties and burn rate of CSP are best I have found so far."
How do the detonation properties and burn rate differ than HTG? I'm curious since HTG has a far higher octane.
I found it very strange that the guy I spoke with at VP recommended C46 for a 15:1 9000 RPM engine. It has a motor octane of only 98.6.
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Re: 120 octane unleaded ? I stand corrected, HTG is an unleaded fuel that is not recommended for my application. As I understand it, the octane rating is a formula and general reference point, but higher octane may or may not identify the best fuel for your setup. I also agree that VP does not provide consistent info on their fuels.
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From: Troy, AL
Re: 120 octane unleaded ? Oxygenated fuel adds power but I don't know what it does for detonation. I wish VP's site had more detailed information. There are ALOT of different fuels but it seems to be a real guessing game to figure out which one is best for a particular application.
As far as the unleadeds go, I've tried CSP, C10, and Motorsport 103. If I had to guess, Motorsport 103 may have worked best for my 422.
As far as the unleadeds go, I've tried CSP, C10, and Motorsport 103. If I had to guess, Motorsport 103 may have worked best for my 422.
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Re: 120 octane unleaded ? Colonel, I agree and the same can be said for oils. I've been using Mobil 1 15W50, but now I find that there are much better racing oils out there, such as VP RT 1060 or VP RS 1540. Of course they are much more expensive ($10/quart), but protect bearings better and have to be changed less often.
Reher Morrison did some testing and concluded that Mobil 1 did not protect high hp motors very well
PS - Are you racing at the Southern Shootout?
Reher Morrison did some testing and concluded that Mobil 1 did not protect high hp motors very well
PS - Are you racing at the Southern Shootout?
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From: Troy, AL
Re: 120 octane unleaded ? Interesting find about the oils. That's something else I need to learn more about.
I hope to run at the Southern Shootout. At this point, I can't make any promises but I think I should be ready by then.
I hope to run at the Southern Shootout. At this point, I can't make any promises but I think I should be ready by then.
Re: 120 octane unleaded ? Colonel I am not a fuel specialist but I do know that on a 400ci motor that has 15.3 to 1 compression and we shift at 9400rpm we used to run VP C-16. My VP dealer told me to try C-46. The car normally runs 9.30s with the C-16. We tried the fuel but we had to take 4 degrees of timing out and added 2% fuel and we ran 9.15. I cant explain the octane rating but I was impressed with the fuel and the power we made.
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Re: 120 octane unleaded ? Yea, there's an example of lower octane producing higher hp or better times. We would be a chemical engineer or chemist to understand this issue.
Colonel, I share your uncertainty. This season has been one big experiment that has eliminated accurate predictions. This week alone we are installing 9/16" head studs, 8740 main studs, a new coated bearing, new cam, new valve springs, new retainers and have changed engine clearances. We too are PLANNING to be in Baton Rouge!
Colonel, I share your uncertainty. This season has been one big experiment that has eliminated accurate predictions. This week alone we are installing 9/16" head studs, 8740 main studs, a new coated bearing, new cam, new valve springs, new retainers and have changed engine clearances. We too are PLANNING to be in Baton Rouge!
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From: College Station, Tx
Re: 120 octane unleaded ? The octane rating is just a measure of the amount of energy it takes to initiate oxidation (start the fuel burning) - the higher the octane rating the more energy it takes. The spark has much more energy than required, but by raising the threshold to ignite you can prevent other factors (hot spotting, free radicals, etc.) from starting the burn process early.
As soon as the fuel starts burning the octane rating is pretty much irrelevant - at that point you are worried about the flame speed and probably the energy content of the fuel. The energy content isn't as big of a deal as it may sound since your fuel is not the limiting reagent - air is. You can always spray in more fuel - so you just spray in as much as you can react with the air.
The flame speed is probably the basis for alot of VP's recommendations - you will more than likely want a slower flame speed on a FI car due to the dense charge mixture - you would really need something like a cylinder pressure gauge and to correlate that with crankshaft degrees (and remember, the amount of force transmitted to the crank depends on the geometry of the rotating assembly at that moment). You have to balance the flame speed so it doesn't burn to fast - so you get a tremendous instantaneous release (which would be pretty hard on parts and not to efficient) - but if you wait to long you either loose part of the burn, or you get so far down in the stroke that most of the pressure is wasted due to the r/s angle.
As soon as the fuel starts burning the octane rating is pretty much irrelevant - at that point you are worried about the flame speed and probably the energy content of the fuel. The energy content isn't as big of a deal as it may sound since your fuel is not the limiting reagent - air is. You can always spray in more fuel - so you just spray in as much as you can react with the air.
The flame speed is probably the basis for alot of VP's recommendations - you will more than likely want a slower flame speed on a FI car due to the dense charge mixture - you would really need something like a cylinder pressure gauge and to correlate that with crankshaft degrees (and remember, the amount of force transmitted to the crank depends on the geometry of the rotating assembly at that moment). You have to balance the flame speed so it doesn't burn to fast - so you get a tremendous instantaneous release (which would be pretty hard on parts and not to efficient) - but if you wait to long you either loose part of the burn, or you get so far down in the stroke that most of the pressure is wasted due to the r/s angle.
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From: Boostingham, AL
Re: 120 octane unleaded ? Phillips B42 is pretty popular. (shown as TT105 in the link below)
http://www.cpchem.com/fuels/products/racingfuels.asp
http://www.cpchem.com/fuels/products/racingfuels.asp
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From: Troy, AL
Re: 120 octane unleaded ? SSpilot, better put some money aside for new O2 sensors about once a weak...seriously, don't do that. "Low" lead gas isn't as low as you want to think. It also has a lower specific gravity (gonna throw your tune of I would think.)