Inspired by another recent post on fuel I'd like to discuss the opposite side of the octane question...

After recently having my first engine mod done (CAMS only) I started thinking about the fuel that I use. Like most of you out there I have been tought that using premium is the only way to go. Now, while I do believe that running prem is the best thing for my bike...what are your thoughts about octane BOSTERS?

Do you, should you, how often, does it effect the long term health of the engine, does it create a hotter (tempature) engine, ect.?????????? For fear of falling into a marketing ploy by "Big-Octane", I'd like to see your thoughts on this.

Thanks.

 

I have never run the boosters, thought about it, but believe you are probably just wasting your money for street use. I have the 96 C.I., with stage-1 mods, thinking, that might be as far as I am going to go. I run preminum fuel only, if I can get it. I feel the V-twin, by design, is limited after about 100 ft-lbs of torque and a peaky 100 hp. Expecting crotch-rocket performance from a Harley twin is like wanting a steam engine train to do a 100 mph in a quarter. The engine was never conceived to be a high-performance motor as I see it. It is true, after-market-developers and enthusiasts, have done tremendious advances to this old-engine. Sorry, didn't mean to rant, at 70 yrs old, I am finally realizing why I own a Harley, it's about the ride, not the speed!

 

First thing one should know is; what does octane do?
A gasoline fuels "octane rating" is a numbering standard that refers to it's ability to withstand spontaneous combustion when it's compressed. The higher the octane number, the higher amount of compression it will withstand before it torches off on it's own without the spark from the spark plug.
The HD engines being air cooled, the cylinders get very hot, that combined with compression and BANG, pre-ignition or "ping". I am looking at running some sort of octane booster. On very hot days I start getting the ping and wonder if a little bit of help in the octane rating might eliminate it. I'm not falling for the snake oil on the label and expecting the bike to run better, I just want the ping to go away when the temps are in the upper 80's and beyond.

 

Is a waste of money to put in your bike, low octane actually burns hotter and combusts quicker, the reason for hi octane is a higher compression engine will pre detonate regular fuel before it is supposed to, hi octane fuel actually burns slower and cooler then regular fuel, what you want is to run the lowest octane fuel you can withut having ping wich is pre detonation. I went thru all of this with my race car, I actually mix my racing fuel with a little regular gas, on the dyno this increased hp a little. Is pointless to do on one the these HD engines, I would just stick to what they reccomend you use from the factory.

 

A Harley certified tech told me once that you can run the 91 octane up to about 10:25 compression safely, then you need to go up accordingly to different modifications done. But it never struck me till fwb35s post that you can over do it. Thanks !

 

Exactly.....it really is isn't it.......

 

Are you talking about adding octane booster to regular unleaded to get the numbers up to premium levels, or adding it to Premium to get the numbers over 91-93 found at gas stations?

When I tour remote areas I bring along a can because premium fuel isn't available all the time. I can't tell you conclusively that it works.

 

Snake Oil.

 

I usually carry some Sea Foam on trips, don't know if it raises the octane or not. I don't want to necessarily increase octane because of different gas required for different areas air density, but I'm hoping to reduce pre-detonation and carbon buildup if gas is poor. An ounce of prevention type thing.