C12 vs C16

[turbovanman²]

They don't list R+M numbers but C12 is 108 Motor Octane, C16 is 117 MO, so what does that aprox translate to in pump gas terms?

I find C16 seems to slows me down but then I never adjust the timing curves, so does C16 really take a lot more timing?

C12, I used once and didn't have to change anything but wanting to go over 30 psi, and they don't list C12 for boosted engines?

Thanks.

[contraption22]

Pump gas octane is an average of research and motor octane numbers.

If R is 90, and M is 92, than the pump gas octane rating is 91. It says that right on the pumps in the US.

C16 is for boosted and nitrous applications.
C12 is for high compression, N/A applications.

I would imagine that given the same cylinder pressure, more detonation resistance is required on a boosted engine vs a N/A engine because the combustion chamber temps would be higher. Guessing. Somebody smart correct me.

[turbovanman²]

I am just going to use the C16 and jack up the timing. Looks like Friday is my last kick at the can.

[zin]

The C16 is the better choice, but it will burn a bit slower and have a higher specific gravity, which means it will want more timing just to put it back where it ought to be and will probably need to be leaned out a bit compared to pump gas or even "Pro Stock" type fuels, which incidentally aren't a good choice for nitrous or high boost...

Mike

[turbovanman²]

Thanks guys.

[BadAssPerformance]

Are you running pure C16 or a mix like you have in the past? Mix = ???

[turbovanman²]

Are you running pure C16 or a mix like you have in the past? Mix = ???

I usually have a couple gallons of 94 in the tank, and put 5 gallons in, so its diluted a bit.

[bakes]

Simon what about Q16 ........

[turbovanman²]

Simon what about Q16 ........

That is better stuff but can't find it, and its only for this Friday, weather is holding out,

[R/Tony]

That is better stuff but can't find it, and its only for this Friday, weather is holding out,

Why is better the Q16 ? .... isnt that too much for our cars?

[bakes]

Why is better the Q16 ? .... isn't that too much for our cars?

because it is oxygenated . so if you add more fuel to the cal , the higher Cly pressure you can make. Simon and i both know someone who made 40whp more on it over c16.

[turbovanman²]

Why is better the Q16 ? .... isnt that too much for our cars?

Too much? Bite your tongue,

[BadAssPerformance]

I usually have a couple gallons of 94 in the tank, and put 5 gallons in, so its diluted a bit.

Ahhhh, OK, so you are running C1946

[turbovanman²]

Ahhhh, OK, so you are running C1946

Funny guy, lol.

[johnl]

or, is it C9416?

[zin]

I feel compelled to share some of what I've learned in the last 17years providing tech for NOS, etc (dear God, that long?!!), and this really only applies to maximum effort cases, though DD and others that are tuning their cars would benefit too.

Consistency.

A simple concept but you'd be surprised how many "professional" racers/teams don't follow it.

As it applies to fuel, not following it can cause everything from a "blowed-up" engine to a migraines due to chasing your tail while tuning.

The problem arises from the different fuels designed for different applications. Some are made to burn really fast, but still be resistant to detonation in some ways, such as Pro Stock style fuels. These guys run high compression and very high RPMs, they need that sh!t to burn fast, as they only have milliseconds to get the work done.

A heavy user of nitrous or high boost forced induction (esp roots blowers) need a fuel that will deal effectively with high cylinder pressures that occur at lower RPMs and, in the case of nitrous especially, a slower burn, as the extra oxygen in the nitrous does the job of speeding it back up and then some! The higher percentage of oxygen (in the case of nitrous) and the longer "saturation time" (heat soak) of the mixture tend to destabilize the mixture and make it more prone to detonate or pre-ignite, it's one of the reasons why "lugging" an engine will make it ping/detonate.

That all said (there's more, but I don't want to bore folks with details and exceptions to the rules), mixing fuels, especially in an inconsistent manner on a highly tuned engine is asking for trouble, don't do it unless you have to, and when you do, do it the same way, with the same fuels (hard to do with pump gas due to winter/summer blends..).

Another .02 into the either!

Mike

["Top Fuel" Bender]

Here's a nice comparison chart I came across awhile back


http://www.smithtex.com/racing/fuelcomp.html

[R/Tony]

Too much? Bite your tongue,

haha well... I know we always want the best fuel we can get, but I thought this "oxigenated" fuel was not really worth it since it is quite more expensive than the C16

[turbovanman²]

haha well... I know we always want the best fuel we can get, but I thought this "oxigenated" fuel was not really worth it since it is quite more expensive than the C16

I had a mag or saw a test online, and Q16 made more power than C16.

[BadAssPerformance]

or, is it C9416?

Depends on if it is shaken or stirred

Consistency.

You had me at consistency Mike Damn, you been there that long? *counts on fingers* yep, guess you were... I remember talking to someone in ~'98 about jets and they were like, "oh, we got a guy with a shelby"