Ya me too. As Sparky's engine has been waiting at the dyno for 2 months. I think Dyno Room should comment
I wasn't going to get involved but I guess I can give my opinion, & remember, you get what you pay for here.
I have tested my engines on ERC, VP, Union 76, Trick, Sunoco, & Cam2. At least these are the ones I recall. None of the info here is derived from proper A B A test so it's just my observations.
All of the above vendors make or for those who are no longer around made a 110 octane race gasoline. So my input is related to these fuels.
I think it's important to mention here that most "hard chargers" running at Bonneville are using a compression ratio that the 110 octane fuel would not be appropriate, conversely, using 118 octane on a 13.0:1 engine on the salt is likely a waste of performance potential along with a corresponding loss of dollars.
First, if you tune on the engine or chassis dyno to make the absolute best power you can then load it in the box & head to the salt you are likely in for disappointment. This is assuming carbureted, as EFI will help compensate for the density & altitude. That being said, the ERC 110 I've tested didn't lose any power to the VP or Union on the same engine +\- 3 hp on a 800 hp engine. This is within the area of error on an engine at this power level. If I had to choose the Union fuel had a bit of an advantage. But since everyone who runs the gasoline class MUST run the same fuel vendor I would tune to rich best power, then go to the salt and tune from there. Most guy forget that a 10 second pass on the engine dyno is not the same a a 1 minute 20 second pass at wide open throttle on the salt. And for those who say just pull the handle & count to 90 I say go ahead. You will likely find the weak link in your cooling tower or boil the water in the brake. What I mean to say is sure, test your stuff before you go the the event but don't show up on kill. I have tested on Cam2 & gone to the salt due to time issues and after a pass to the 3 with a conservative tune running the event fuel the customer set the record in his class... even got into the 200 MPH club.
So while I would prefer to tune on the fuel we must run on the salt you can get very close with a high quality fuel vendor.
I would add the oxygenated fuels (racing unleaded) can add a few percent to the power output but my experience has shown a much more narrow tuning window.
Now that I have gone way out of my comfort zone I hope Harold & Fordboy will tell us all where I'm wrong...
Well . . . . OK then. My experience with fuels varies, and I am NOT a chemist or a fuel/gasoline engineer. BUT, I do have a lot of dyno test experience, some of which included A vs B vs A fuel testing. Disclaimer, this is my opinion, based on my experience. Feel free to add your experiential 2¢ or better yet, your data . . . . . . Feel free also to correct my terminology with respect to fuels and/or fuel chemistry
Fuels brands I have tested and used: VP, Sunoco, Cam2, ERC, Union 76. I tend to recommend the use of what is regionally available. In the "midwest", VP. On the east coast, Sunoco. I don't do much on the west coast anymore. Of course I use ERC at Bonneville.
Some random thoughts:A/ Octane rating is the basis for "knock resistance" compared to other fuel mixtures. But it is not the only important fuel rating . . . . .
2/ Caloric value, ie specific heat released, since heat is work,
d/ Specific gravity,
q/ Burn rate, ie burn speed,
z/ Oxygen content, if any.
■ It is important to recognize that when the comparison parameters vary widely, you have performed an "apples Vs oranges" test . . . . . For instance, substituting an "oxygenated fuel" for a similar, but non-oxygen bearing fuel probably would show an "improvement".
■ In the testing I have done, when the fuels "match up" closely, there have been very small differences in power production. Say, less than 1%. These differences can usually be explained as variations, errors, OR, differences in
tune-up required. In a close match, precise "tune-up" makes more difference, say 1% to 2% or so.
■ Higher octane rating does not equal more bhp at the flywheel. Using higher octane than required is just a waste of finances.
■ Also, using a higher octane fuel than required temporarily,
usually will not damage an engine. Using too low an octane rating
definitely will damage an engine. Especially one tuned into the
"kill" zone.
■ Some engines need a LOT of knock resistance. Others do not.
■ Knock resistance varies with operating temperature. The speed of chemical reactions speeds up with increasing temperature. And it might increase with increasing pressure . . . . . . . This is going to affect your tune.
■ I agree that the tuning window is smaller with oxygenated fuel. This does create a degree of peril for the inexperienced . . . . .
■ Spark plug types affect the length of the "spark path". This changes the ignition timing required. Ignore this at your own risk . . . . . This affects octane required.
■ We tried to get ERC fuel for dyno testing the "Grenade" during the Milwaukee Midget project. It was prohibitively expensive, so I made the decision to test using a close match from VP. Things worked out fine, due to experience.
■ I agree that a 10 second pull on the dyno does not replicate conditions during a 90 second 3 mile run. As Mike has pointed out, very few dyno installations can accommodate high bhp extended run testing. The typical facility
does not have the heat extraction capacity. This is
expensive. Tune accordingly . . . . .
■ In spite of what folks might think, I am somewhat conservative about tune-up, for the very reasons Mike mentioned. It is also important to note that someone with a
LOT of tuning experience, like Dynoroom, for
instance, would have a different skill level of tuning than someone else. Guys like that can "slice the cheese" pretty thinly and their idea of 2 steps away from "kill" might vary. I know mine does.
■ As a practical consideration, tuning "slightly" on the soft side tends to preserve parts and allows continued racing. "Stepping over the line", well, not so much . . . . .
■ And finally, as an example: The "Grenade" for the Milwaukee Midget was tested on the dyno to find the "kill zone". I crept up toward it with 90 second slow acceleration pulls. (Remember that it only made 100 bhp . . . ) It was
then backed off 2 steps. We went to Bonneville and corrected for density altitude, because it was carburated. I didn't guess right, I had enough experience to know which direction to go.
My thinking is that if you are looking to find power by changing the fuel hose from one jug to another, you are probably not doing all your "homework". You can probably find "something" by carefully tailoring your tune to what the engine really needs.
I submit this data for your perusal . . . . .This is all "tuning". What the engine wanted, Vs the owner's "seat of the pants" track tuning. Fuel is VP 110
A "more extreme" example. Again, ALL TUNING. Owner/builder's seat of the pants tune Vs what the engine wanted.
30+ bhp Stupidy Vs Science. Never bet against science . . . . . Fuel is VP 110
Same engine as above, port color check after dyno session. Safe mixture strength.
You don't check port color? Why not? It's a tuning parameter.
My advice:A/ Do ALL your homework with regard to engine octane requirements. This includes talking to fuel engineers about the SPECIFICS of your engine . . . . .
2/ Dyno test thoroughly, and APPROPRIATELY!! Test various "tune-ups"!! TEST, don't guess.
d/ Learn to tune! OR, pay a good tuner to get your stuff worked out.
Yeah, I know that nobody wants to hear this, BUT, . . . . It's Complicated . . . . . It'sComplicatedboy