Race Fuels, Additives, and Octane Booste? What's real, what's BS, what to use?

[FL SAAC]

I don't want to sidetrack this excellent thread but want to offer a differing opinion.  Keeping your tank filled will minimize condensation. Water is the enemy.  Also, I can attest that 93 non-ETHANOL treated with STABIL as directed can last up to 2 years and still perform as intended.

look out for separation or phasing when blending

[propayne]

Very very useful info, thanks to all of the contributors for taking the time to post.

- Phillip

[Vernon Estes]

Awesome thread dudes! Some really great info! Thanks to all who have posted!

Kind regards,
Vern

[gt350hr]

  Detonation is better described as uncontrolled combustion. It has more causes than the simple compression reason Doug mentioned. Compression "squeezes" the air and fuel mixture which adds heat because of friction between the molecules. In a "perfect world" the air fuel ratio , compression , and octane rating are all in balance and the spark makes it all explode. Other things besides the mechanical compression Doug mentioned that can cause detonation are and uncontrolled ignition source. This could be carbon build up on the top of the piston that is still glowing from the exhaust stroke. Another potential source is the compression ring for the same reason. It is also important to know that detonation is often described as the "silent killer" What you hear most often is "pre ignition" and is more closely associated with timing and octane.  Pre ignition is just that ignition before the spark plug. Detonation can happen before or during normal combustion.

    With respect to aluminum heads my experience is far different than Doug's. That alone doesn't mean Doug is wrong.
  Aluminum heads do have the potential to reduce detonation over an iron head. The first is the "physics" part. Aluminum absorbs and dissipates heat far better than does iron as most of us already know. Heat is a product of combustion and is normally referred to as BTUs ( British Thermal Units). A higher percentage of this heat is "lost" in the aluminum head through the absorption I mentioned. Next is less "latent" ( or stored ) heat in the combustion area does reduce the "possibility" of detonation. IF all things were equal this reduction in heat would also REDUCE horsepower output when using an aluminum head! Another lesser known change is the aluminum head "pulls" heat out of the spark plug to the point where a step hotter plug is necessary to eliminate potential fouling. That can also deduce the possibility of detonation. The final factor in an aluminum head reducing detonation is they are a "modern design" where the latest technology is employed for improved combustion quality over a 50+ year old design .  Combustion chamber shapes are now designed specifically to enhance "swirl " which is important in eliminating dead areas and hot spots that can cause detonation.Those improvements are also why they end up making more power along with "modern" port designs and volumes.  Adding a point in compression is an accepted number by our industry when using aluminum heads.
      Randy

[shelbydoug]

I agree with Randy for the most part but the difference that he saw in performance between using a "Regular" pump gas, at about 87 octane and a "Premium" at 92 or 93 AND seeing a decrease in performance in the 1/4 mile IS the difference in the heat calories generated by the different octanes.

The 1.1 aluminum = 1.0 iron is not a linear graph. The higher you go, the less significant it is. An engine in iron at 10.9 would be about an aluminum at 11.1 but an iron 9.2 would be around 10.0:1 in aluminum. It's not a straight line graph. Kind of a tangent curve.

That ratio was much more significant in the old drag cars running 14 or 15 to 1 cr's.



The Regular burns hotter, therefore supplies more heat calories and the difference was 1mph faster then the Premium could do and a little less the a .1 sec faster then the Premium.

Academically, that is correct but that is a very similar proportion to iron vs. aluminum PRESUMING that the two are identical other then the materials, which frankly, is very unlikely.

Pick up a set of 4v 289 or 302 heads from '67 or '68 and look at the combustion chambers. See the little wall near the spark plug, between the valves? That's Ford's high swirl design. Nothing new there.

That design is STILL in many of the current aftermarket small block heads. Manufacturers tinker with that still.

THAT Ford designed combustion chamber is no doubt a large factor in the sensitivity or more correctly the lack of sensativity of the SB Ford to fuel octane? I'd speculate that anyway. 



Another thing that affects cylinder pressure is cam timing. Not being a cam designer myself, I'll use the term of dynamic compression, and leave it to everyone to go do a Google on that themselves. As I understand it though, it's kind of an art form of blowing out some of the pressure created by the static compression, through the exhaust. An art form to get the exact timing right.

I tried that on my Cleveland and all I can say is I was VERY disappointed. There wasn't enough of a change and the results of detonation were still present. Maybe even worse?

Then I went to the aluminum A3 heads. Same deal. Not enough.


MY point is that it is static compression that accounts for the vast majority of detonation.  Ignition advance is involved in that but what happens is that ignition advance creates more cylinder pressure. So this is all a balancing act between all of these factors and if everyone else is like me, I'm always on the ragged edge anyway.

From what I have experienced, the ignition advance both initial and the rate are the same as for an iron head. I can't speak for others on that though.


I do agree on the spark plug heat range with aluminum heads. If for instance you were fine at a BF32 with the iron head, presuming you could use that plug type with the aluminum head, I have found I had to go hotter, up to a BF42 to keep it clean. That is absolutely gospel as far as my results are concerned. However you can sort of throw that reasoning out the window with some induction changes.

Webers for instance, even with an iron head, would like you to go hotter one step. They also defy logic with what is thought to be perfect a/f ratios. Webers don't agree with those at all and use a much heavier a/f ratio.

For the sake of discussion I have NGK BP6ES plugs in my Pantera. The heat ranges aren't exactly the same as Motorcrafts but have a little wider heat range. These are right around what a BF42 would be heat wise, or a Champion F11y. Incidentally I think Champions have a wider heat range then the Motorcrafts do and the Autolites don't even enter into the discussion. Their heat range is narrower then the Motorcrafts.


At the performance levels we are talking about, static compression is the most SIGNIFICANT factor. It isn't the only factor though as Randy points out. Carbon buildup for instance will not only glow hot but closes up the chambers and raises the CR.



...and as far as me disagreeing with Randy, that's ok. That's why there are grudge matches at the strip?  Grrrrrr!

Now there is a saying that I remember, "age and cunning will beat youthful exuberance every time". In other words, us old guys cheat. Now considering Randy is 65 and I'm 69, who's got the edge?  As a matter of fact, we have about the same amount of grey hair? BUT WE GOT HAIR! Huh? Go figure!


"Best" everyone! 

[Side-Oilers]

I am envious of those of you with Sunoco stations in your area.  The best super unleaded that I can find in my part of SoCal is 91 octane. 

[shelbydoug]

$3.79 a gallon. Still envious?

[Side-Oilers]

Well yeah...I just paid $3.69/gal for 91 super unleaded this afternoon...the lowest price in my neighborhood.

[Don Johnston]

Oh, boo-hoo.  Lowest in my area for 91 E10 is $3.99.  E-free 89 is now $4.19.

But the cars still roll.  Lithium replacements cost lots more on those other things!

[Side-Oilers]

It's my goal to personally use up as much gasoline as possible in my time on the planet.  I don't fret the price...I just wanted to mention what it is in my area...and I've seen up to $5/gal in areas like Beverly Hills and Newport Beach.

IMHO: The best use of dead dinosaurs is in a thirsty Ford V8.

I posted earlier that I run $9/gallon 110 leaded VP Race Fuel in my two side-oilers.   

Party on.

[69mach351w]

93 octane, non ethanol fuel without any issues and no additives.

Ditto!!

Also where I'm at in WNC, our regular unleaded 87 is $2.71.
and our Ethanol Free 93 is $3.45

[FL SAAC]

we like your views, remember more electric and fuel efficient vehicles only means much more fuels for us to use !

yours truly,
Mr 8 MPG

It's my goal to personally use up as much gasoline as possible in my time on the planet.  I don't fret the price...I just wanted to mention what it is in my area...and I've seen up to $5/gal in areas like Beverly Hills and Newport Beach.

IMHO: The best use of dead dinosaurs is in a thirsty Ford V8.

I posted earlier that I run $9/gallon 110 leaded VP Race Fuel in my two side-oilers.   

Party on.

[Side-Oilers]

That's great, Tony. The next time some guy in an electric car gives me the stink eye, I'll tell him that!

[shelbydoug]

It's my goal to personally use up as much gasoline as possible in my time on the planet.  I don't fret the price...I just wanted to mention what it is in my area...and I've seen up to $5/gal in areas like Beverly Hills and Newport Beach.

IMHO: The best use of dead dinosaurs is in a thirsty Ford V8.

I posted earlier that I run $9/gallon 110 leaded VP Race Fuel in my two side-oilers.   

Party on.

Cam II unleaded racing gas in the pumps at a couple of SUNOCO stations here. $7 something a gallon. Problem is you use 1/2 a tank of gas going to get it.

[Side-Oilers]

Hopefully that half tank used is at WOT.