What gas to run

[luke]

Hey all I was wondering what octane fuel you are running in your boats I am currently running 91 witch is the best you can get at the pump and runs about 5 bucks a gallon in my neck of the woods so I was thinking maybe I could get away with running either 89 or 87 octane to save some money and I have the pcm343 what are your thoughts ?

[boatwakes]

They're set up for 89 so go with that. The older merc 315 should only have 87 or the soot gets bad on the transom and all the 6.0 PCM's are set up for 89.

[boardman74]

I ran just regular pump 87 in my RZR with the 303 and it ran fine. That met the requirements per the manual. You will have to check the manual for the 343 to see if it has a minimum octane requirement. I run ethanol free in my sleds, 4 wheelers and other small engines but the boat just burns way to much fuel to be paying a $1 plus extra per gallon. I ,however, don't recommend fuel with ethanol if you are storing for long periods due to the phase separation.

[luke]

The manual states 87 or greater and that the motor can sense the octane level so I guess I'm wondering if it makes a big enough difference to justify paying the extra money my lake is at 7200 feet and that 343 could use all the help it can get with big ballast but do you think it makes that much difference?

[chpthril]

Luke,

87 oct and 91 oct have the same BTU's p/oz. So once ignited, they expel the same energy. There is no performance gain with higher octane fuel, its all about controlling pre-ignition. So run what is recommended or higher if thats what is available on the water.

[luke]

Cool thank you that's the answer I was looking for that should save me 50 bucks a fill up which means more surf money

[IDBoating]

I buy whatever grade is 100% non-ethanol and run it in all of my marine (inboard, outboard, jetskis) and "occasional use" engines (lawn mower, weed whacker, ATV's, etc.). I work hard to keep that hydrophilic garbage out of my fuel systems.

[luke]

It all has ethanol out here in Cali I have to run an additive to remove it that has been the case in my snowmobiles people's sleds where seizing up when they first started adding it to our fuel now people have wised up and run the additive but I thought it was mainly a problem with two strokes should I be running the ethanol remover in my boat

[boardman74]

No need to run it in the boat. Unless the % is super high.

[chpthril]

The problem with ethanol blended fuel is not whether the engine is 2 or 4 stroke, but the length of time the ethanol-blended fuel is in the tank and how long the engine sits between uses. This is where is not a bad idea to use an additive that slows the onset of phase separation. Ethanol blended is also corrosive to older fuel systems that where not designed for it and no additive will help here. This is where the yard implements and toys like sleds and 4-wheelers come into play. They where slow to redesign the fuel systems with ethanol resistant components.

[luke]

Ok that makes sense good info is this the same concept as fuel stabilizer witch is put in the boat for winter storage?

[rensink]

The manual states that it can take up to 10% ethanol however I avoid it straight 91 non-ethanol here thats what all the marinas on the water and most gas stations in our area have it available. I see you unfortunately do not get that lovely option...what snowmobile do you have and what are you running to remove the ethanol I have ran some Torco before in my sled to bump the octane up before.

[luke]

05 900 rmk 2011 m8 sno pro both mountain sleds I'm running star tron enzyme fuel treatment