Legal Fuel

Can anyone help this mechanically challenged CSH boat racer understand how fuel rules work in Stock and Mod? I have read over the APBA Stock and Mod rules, but I might as well be reading another language.

Does octane such as 87, 89 or 92 change the readings? Does the type of oil such as Mecury, OMC, Yamaha or Red Line change the readings?

Is there really any performance difference between any type of gas or oil?

[Karl 9W]

The readings on the tests we use for stock & mod are affected by oxygen bearing compounds in the fuel. The gas itself does little to change the reading. Additives used in pump gas by different suppliers of fuels(Citgo, BP, Shell, etc.) can change the reading somewhat. Alcohol is one of the main components we look for & makes a big change in the reading on the meter. Water also makes the meter read go skyward. WHY?-- Alcohol & water both contain a bunch of oxygen molecules which the tests pick up very easily. So look at the pump you are getting your race gas from & be absolutley sure it is not reformulated gas. (Ethynol added) My personal experience is that you can use any pump gas(87 thru 110 octane) non-reformulated of course, & it has always metered fine. The oil you add also can cause the meter to read high for the same reason as the gas. If it has oxy-compounds in it, it will show up on the tests when you mix it with your gas. Bottom line information for you--- Keep it simple & consistant at the race. Do your testing of fuels with the meter in one hand & away from the race site so you don't make an error when the points count. Octane is the ability of the fuel to be detonated(ignited). The higher the octane the harder it is to ignite. Thats why your car engine doesn't "ping" or "knock" when you run the mid-grade or premium gas. We don't run enough compression in our stock or mod engines to require Hi-octane gas(Big time race fuel 108, 110, etc.) I use premium no-lead with Chevron 2-cycle oil. Most any brand name 2-cycle oil TCW-3 rated will work just fine.
I've used non-synthetic OMC oil, Merc synthetic, Merc non-synthetic, Yamalube, etc. etc. they all meter fine. Stay away from oils that specifically are made for power boosting. Thats that chemical thing again. The oil I'm using now seems to help in the power department but, it's more important job is lubrication & that is where I see it works well. When I tear down one of the motors, all the internals look nice & clean, no wear, & a light film of the blue oil/gas clinging to all the surfaces. My motors turn some pretty high rpm's too. I'm not at all gentle in the throttle. One other suggestion, once you come up with a gas/oil mix you prefer. ALWAYS TAKE THE GAS & OIL WITH YOU TO THE RACE!!!! Don't buy gas at the town you race at for your boat. You never know if a station has reformulated fuel until your standing at the pump & that's too late. Carry with you what you know works & is legal.

Hope this helps, Karl 9W.

[Bill Huson]

As explained ...

your basic stock engine doesn't need octane to run well. I used regular gas - 86 or 87 octane - for the OMC A motors, and high test for my Hot Rod 15 which compression tested at 195 psi.

Oil can kill you on the meter readings. If the oil smells like amonia beware, and pre-test the mix. I know OMC "GT" oil bumps the reading up, but the standard TCW-III is fine. Also, fuel seems to *cook* in the heat and jack up the meter. Solution, fresh gas and oil mix every day. I say "mix" cause the fuel doesn't cook unless it is mixed, at least not in my experience.

[elda nichols]

octane/oil

don't run maxima racing caster 924 it will pull in moister and that creates a lot of oxygen and it will blow a meter off the charts......with race fuel or pump gas.......and it will also make you pull that big prop that was just a liitle to big before.......it will not change your r.p.m. but it will create alot more power............but the bad news is it won't pass the gass test at the race....

[sam]

We don't run enough compression in our stock or mod engines to require Hi-octane gas(Big time race fuel 108, 110, etc.)

Speak for yourself

[DougMc]

Speak for yourself

Now Sam, how does that quote edumakate a mechanically challenged racer such as me on fuel?

[sam]

Some mod engines actually do need high octane fuel. My FE Merc's compression is so high that even with 110 octane gas I'm only running 5º to 10º ignition advance. It won't even start on 96 octane gas. (An old 55H runs 40º advance with the same bore and stroke.)

The motor is an old Lon Stevens alky Merc that I decreased the compression ratio on. Lon had the ratio up to about 18:1 (10cc's) .... just won't work on gas no matter when you start the spark. I increased the TDC cc clearance according to recommendations from O.F. Christner a few years back.

Karl's information on gas for Stocks and unaltered Mods is accurate

[Dave M]

I second that...

Find a local gas station in your home town where the fuel is safe. Always get gas from that station before you go. You don't have to mix it then, just get your cans filled. I never have any problems with the meter when I do that. It seems that local gas at the races always raises issues and the inspectors end up doing the fuel of the day readings.

I prefer to know what I am getting.

Another tip, don't fill up your gas tank on the engine until just before you race, it sits in the sun, and can affect readings. Sun heats it up, creating condensation inside your gas tank, it could affect your readings. Also, leave your gas cans in a shaded area, never in the sun. I always cover my engine with a towel to keep the sun off as well.

[elda nichols]

fuel/oil

don't run maxima racing caster 927 it will NOT pass test............

[DougMc]

Another tip, don't fill up your gas tank on the engine until just before you race, it sits in the sun, and can affect readings. Sun heats it up, creating condensation inside your gas tank, it could affect your readings. Also, leave your gas cans in a shaded area, never in the sun. I always cover my engine with a towel to keep the sun off as well.

Guilty as charged on this one. I opened my trailer yesterday and the 5 gallon can was as fat as a water mellon.

What does "cook" mean when the oil and gas is mixed?

[Fast Jack]

fuel for Sam-- Fuel for thaught

Better get that battery charged...fuel don't matter if it don't start. rrrrrrrr.

[sam]

Guilty as charged .... or discharged in this case.

My old charger died on me and a new one is on the way. I couldn't find one locally that matched the specs for recharging the funky Odyssey battery I use. I'm also thinking of rigging up a connector from the tow pig directly to the battery in the boat so it is charged during the trip each time.

[epugh66]

Simple, race a class where methanol is legal Er...at least own some BRAND new, raced only once equipment, in a class where methanol is legal.

[modFE]

speaking of methanol, why does an unrestricted fuel class, run high compression, when a small addition of nitro burns easier and doesn't require the extreme high compression ?

[sam]

because lots of nitro makes you go faster ... if you can afford pistons, rod and crankshafts. nitro used to be allowed and was used heavily; the nitro restriction reduces the cost of racing