Yellow Bullet Forums banner

1 - 15 of 15 Posts

·
Registered
Joined
·
43 Posts
Discussion Starter #1
Just wanted to ask some of the more experienced people in here. I have a 14.1 comp 408 windsor and the car seemed to slow with the C16 versus the C12. Is it possible that the higher octane rating would slow a car and can you explain why? Just wanted to add that this is N/A motor. Thanks for any help.
 

·
Registered
Joined
·
19,969 Posts
yep..its all about burn rate and timming
 

·
FE Ford Specialists
Joined
·
3,953 Posts
Interdependant variables.
Talk to your fuel supplier.
As noted, burn rate and BTU content are not directly proportional to octane (self ignition/detonation resistance).
Sometimes they need to "lose" on a given characteristic in orer to optimize/improve on another.
 

·
Registered
Joined
·
1,365 Posts
That is the problem. You WILL lose power and slow down running c16 n/a from the c12. I actually like c14 for this, but if the tuneup is right, I guess the c12 is fine. Two completely different fuels and burn rates and specific gravity, etc..It is not just about octane.
 

·
Registered
Joined
·
4,906 Posts
Ok gentlemen, on a average, a 112 octane fuel, R+M/2 is good to 15 to 1. I never run 112 with a higher compression engine but it is capable of handling without issue, a 116 octane, R+M/2, is good over that and really will work all the way up to 18 to 1. If you run a fuel like 116 in a 13 to 1 motor, you will experience a rich condition, slower burning fuel, higher octane, that equals less performance than if you used the 112. The inportant aspect of choosing fuel is the R+M/2 equation. Research octane + Motor Ocrane divided by 2. You need to use that and research you fuel to get what you need......
 

·
Registered
Joined
·
3,814 Posts
Click here http://www.vpracingfuels.com/page469659.html to learn the 4 key properties to selecting the right fuel.

VP C-16 is misused a lot in selecting the right fuel. C-16 is really designed as a blower fuel primarily and in naturaly aspirated applications it's not the best choice. It's designed to handle much higher intake air temps than you will see in a non-blower application.

Blessings...............Ron.
 

·
EFI/N2O JUNKIE
Joined
·
17,046 Posts
It all depends on the combo. I ran back to back passes using C-16 and C-12 one day with my 14.8:1 SBC and there was NO difference. I did not touch timing of fuel curve and the weather was identical, passes were within 1/2 hour of each other, and yes, all the fuel was pumped-out and a fresh 5 gallons was put in the cell so there was no mixing. Those are my results, I have seen others slow-down between different fuels though.
 

·
Registered
Joined
·
43 Posts
Discussion Starter #14
Thanks guys for all the helpful information. I am gonna run the C12 this weekend to see if it puts me back to where we were running. Am I correct in understanding that the C12 has 108 octane? With cost not being a variable, what would be the best fuel for my combination? Would it run better with the oxygenated 113?
 

·
Registered
Joined
·
19,969 Posts
from above......

Would it run better with the oxygenated 113?

yes, if you jet for it...
 
1 - 15 of 15 Posts
Top