Does anyone use this stuff in their quad? Does it really work? Is it a waste of money? Thanks.
Clint

 

This is a good question. Many people think that the octane level is a measure of power in the fuel. Not true, despite what advertisers encourage us to believe. The Octane number is simply a measure of knock resistance and doesn't necessarily mean more power. For example, the heating content (or "power") of regular gasoline is about 20,200 BTU/pound. Very high octane aviation fuel may have 20,300 BTU/pound. But it's often harder to get this fuel to fully burn and you lose that extra little benefit and then some. The higher the octane the less likely the fuel is to pre-detonate from pressure and temperature in the cylinder. If the fuel you're using is within the manufacturer's requirements for octane level and you have no pinging or knocking, then you're better off not using it. If you have pinging then go with a higher octane first. If that still gives knocking, then try the additives. However, note that high octane levels have been known to cause some damage to certian high RPM engines (due to depsoits left behind). With that said, the additive you refer to is usually a mixture based on Isooctane (C8H18),or similar chemical, and only keeps the fuel from predetonating. Save your money.

 

Your understanding of the operational effects of octane ratings parallel mine, RichardB. However, some disagree; they think higher octane gas produces more power from ANY engine, from a 6:1 compression ratio lawnmower's mill to a 12:1 dragster's. This topic may receive posts with that claim.

Higher octane permits higher compression ratios and greater ignition timing advance without pre-detonation or pinging. In my view, unless an engine can take advantage of these properties, higher octane fuel provides no benefit. No authority, I welcome contrary information.

Diogenes

 

You're exactly correct, Diogenes. I'm not a mechanic, but I am an engineer.

I base my opinion on simple combustion cycle engineering and can provide a number of references to support my conclusion. Gasoline is actually a mixture of hydrocarbons and it's BTU or "energy" content varies very slightly with composition. In most cases less than +/- 1.5% total. That's only the BTU content of the fuel that varies, don't expect to get another 1.5% out of your engine. It's more like only 0.3 or 0.4 percent more HP and that's at the engine, not the wheels and ONLY then if ALL that extra BTU is burned. Remember that higher octane fuels may not burn as completely as lower octane fuels. Especially if you don't have excessive compression (i.e. knocking) already to help that fuel combust. Actually, you might just end up turning that fuel into deposits in your engine and exhaust, not power. As such, it's possible to get less useful power out of higher octane fuels even though the engine may run a tad smoother. But you'd have to REALLY be perceptive to notice any difference in most examples unless there's something else going on.

The octane number is nothing more than a measure of knock resistance and should never be considered a measure of the "energy" a fuel contains. Higher octane fuels require higher temperatures to vaporize. As such, they aren't as prone to detonation in a hot high compression environment (note that compressing a vapor will raise it's temperature). It's that simple. Unless you have knocking or pinging from predetonation, stay away from the additives and even then, first try a higher octane fuel, it's usually cheaper and safer. If anyone is interested in exactly how the octane rating is determined for specific fuel (i.e. hydrocarbon) mixtures, I'd be happy to post a description.

 

I doubt many Forum readers' interests extend into the finite detail you offer, RichardB; however, I have no reason for doubting you can provide that information.

Upon reading your post, I wondered if I communicated adequately in mine: I AGREED with your premise. I mentioned that others have posted their belief, that increased octane ratings increase the power output of any and all engines, a supposition for which I find no convincing supporting evidence. Yet, open-minded, I'll examine any evidence offered.

Your perception of the significance of octane ratings corroborates my own.

Diogenes

 

Well now let me ask you this. If you install a lets say a 12.5:1 piston. This type of compression obviously requires a higher octane level that just plain premium pump gas (93 pump octane) cant provide. Could octane boost in premium pump gas provide enough octane, or do you have to run race gas? I ask this because I would like to run a 12.5:1 piston in my bike, but there are many times when I am out on the trail, that I am miles from my truck or camp, and premium pump gas is all that is to be had. If octane boost would suffice I would just keep some with me and add it to the 93 oct on fill-up. Thanks again.

Clint

 

Clint,

I would think that octane boost would suffice. I haven't used any in a very long time and I'm not very sure on just how much of a boost you get with the stuff, or the proper ratios of mixture to obtain a specific octane level. My preference would be to use a fuel already formulated for a specific octane level, but if none is available, you gotta' do what ya' gotta' do.

I'm not sure what race fuel costs, but as a side note, 100LL (100 octane, low lead) aviation fuel is available at most airports especially the smaller "General Aviation" fields. The prices are usually between $2 and $2.75 a gallon depending on where you are and what the competition is. Note that the "low lead" designator is a bit misleading. It still has more lead in it than unleaded car gas and is formulated for air cooled high compression engines. I haven't done any research on what effect the extra lead has on an engine designed for unleaded fuel, though. My thought is that the lead would "lubricate" things a bit better and possibly reduce some wear, but again, I'm not sure. Someone else may be able to answer that one. Oh, if you do try that fuel, it has a blue dye added for identification and safety. The dye has no affect on the engine or performance.

 

As long as were on the subject of octane and octane boosting... I have heard of using fuel stabalizers during long periods of storage, Although I do not use them, as I simply dump the fuel and start with fresh fuel, Would it be possible to use a octane booster (the reasoning I heard for fuel stabilizers is that fuel looses octane over extended period of time) to be able to use the fuel in low-octane sensative motors? I would rather pay $5 to use the fuel I have than to pay another $10 to buy new fuel for my lawnmower..

Here are a couple more questions if you dont mind... Does octane rating affect operating temperature? Does lower octane fuel burn at a hotter temperature? Is there anything you can add to [pump] gas that will make it burn cooler? I know that acetone "feels" cold because of the fast vaporization rate, Would it help cool a motor to mix in a 1 or 2% acetone (maybe 0.5% ether?) in the fuel? It is a well known fact that a cooler running motor will run and work better than a slightly hot one will.

 

AdrenalinFreak,

I think it's good to have an understanding of why things work the way they do. However, I've been accused of providing too much detail and just don't want to offend anyone else here by doing that again. So here are the simplist of answers. Note that there are many variables that impact the answers to the questions you've asked. Octane rating is among the least of them.

Higher octane fuels have additives that make it harder to burn. Other than that, nothing else changes. Octane boost just makes the fuel harder to burn. Use too much and it's a bad thing.

Fuel stabilizer doesn't hurt, it helps. But there are a few "ifs" associated with this.

Acetone is a bad thing for engines.

Cooler is better, (to a point) but temperatures are MUCH more affected by engine design, how you ride, environmental temperatures and fuel air mixture than the type of gasoline you use. All gasolines generate nearly the same temperatures when they burn and octane ratings have no impact on this.

If you or anyone else would like an explaination of WHY these thigs are so, e-mail me and I'll provide the detail.

Rich