DaveHam

What's the best over the counter octane booster? I want to make sure the 93 octane gas in the tank is still 93 when I launch the boat in April. I did add Sta-Bil to the tank last fall.

DaveHam

gmhdfan

With the gas they make now adays. I would pump it out and run it in your car this spring. The only way you are going to be sure you have 93 octane in spring is if you put 93 in before you start the season. If your motor needs 93 it will not be cheap to find out your gas went bad. Good Luck.

Gearhead99

I agree with gmhdfan, the only way to be sure you have the octane you require is to fill it before you go out.

There are alot of octane boosters out there. Are any of them all that good???? Don't know. When ever I've used them in the past, [motorcycles,boats,cars], the problem was how much and how do you get it to mix. Then it settles to the bottom of the tank and you end up fowling the plugs from too much additive. The other extreme, not enough additive, is even worse. If the compression is high and you don't have the numbers for it, well you get that "death rattle". And on an offshore boat with open exhaust and the wind and all........you may not hear it, and the damage is done. $$$

gmhdfan

Dave, Thanks for going into more detail for me. I just don't have the time to write a book sometimes. Octane boosters are a joke. At the very best I don't think they could raise octane more han a 1/2 % of 1 octane point. (.5) The best additive I would see using is something with LEAD in it if you were running an old muscle car. Just so you wouldn't BEAT out the seats as fast. But that is just pissing in the wind anyway. If you run an older motor you just need to have hardened seats put in for less than $200.00. To tell you the truth with the way gas prices are going I think you are going to find racing fuel to not look so bad to us. They don't tax racing fuel like they do fuel on our roads. If you really ran the numbers it would be cheaper to mix racing fuel to your gas than octane boosters. And the smell of racing fuel is "sweet".

eliminator219

I agree on the racing fuel, I have 55 gals of 110 sitting in my shop and they even have a sheet to show you how to mix it with the reg gas to get what octqne you need to keep away from detonation,any time Im a little worried about the gas(93 octane??) that I put in the boat I add 5 to 10 gal of 110 and go about my business
eliminator219

D_Casten

The easiest is to add Toluol (paint thinner you can get at hardware store, also called toluene). A safe mix is 10%; that will raise 92 to 93.5. (I believe this is what Whipple recommends too) The folks that gave me that said you can go as high as 30% to bring the fuel to around 98 but I’ve neither seen or heard of anyone actually doing that.

If you’d like to stick to the off the shelf products …
100 oz of toulene for octane boost
25 oz of mineral spirits (cleaning agent)
3 oz of transmission fluid (lubricating agent) should = 1 gallon.

paradigm shift

You might check out this link if you are in to home brews. (octane) I think I have some others if I can find them.

http://www.gnttype.org/techarea/misc/octanebooster.html

Bazooka

Take a look at batterystuff (it's a .com website) but I can't post URL's yet.

David Stotz

105MPH-38-2003, How do you calculate octane? Based on your post I would calculate your octane at just under 96.