Which fuel ?

[boatless]

I have an RTP-1 engine. I have been using 87 gas, just look at the onwer manual and it said to use 89. Which fuel did you guy use ?

Thanks,

boatless.

[3event]

I've got the "Predator" 310 in my 02 - I don't know what if any changes were related to the name change to RTP. Dealer recommended 89 octane, and have run it since day 1. No probs.

There is another lengthy thread on this topic here somewhere - search and ye shall find.

[east tx skier]

Indmar recommends 89 because boat gas tends to sit a little longer than auto gas for example. That is, people tend to use boats less frequently than cars. So if you get 89, and its octane rating decreases to 87 over time, no worries. As Engine Nut once said, 87 is okay; 85 is not.

If you had a carb'd boat, I'd say go ahead and start running 89. But with fuel injection, you'll probably be fine. Worst case scenario, the engine timing will be retarded to avoid predetonation. When timing is retarded to avoid the knock, performance will not be optimal. So any money you save by putting 87 in the boat could theoretically result in using more fuel to accomplish the same thing on the water.

The difference in price between 87 and 89 is roughly $3.00 per tank.

[OhioX14]

Both my MCX and the GT40 I had in my Nautique before that called for 89 and that is the minimum I've ever run. Sometimes when at large lakes on vacation the marina's only offer 93 so I'll run that occassionally as well.

That said, I own an Acura which calls for 93, the dealer said 89 was fine, but when gas hit $3.29 last year I started running 87 and it hasn't seen anything better since. There is no valve knocking, no decrease in fuel economy, etc. just fewer $$ coming out of my wallet.

I guess I just like to baby the Mastercraft but could care less for the car as long as it runs. :D :D

[boatless]

Thanks guy,

It will be 89 going into the boat.

boatless.

[Maristar210]

Boatless,

I just filled up my boat with 89 at $3.13 a gallon. How does $138.00 sound? :rolleyes:

S

[endl]

Boatless,

I just filled up my boat with 89 at $3.13 a gallon. How does $138.00 sound? :rolleyes:

S
I had a quarter tank put in 175.00 and did not hit full.....hurts bad....

[Sodar]

Ouch!!! I am glad my little boat only hold 30 gallons, still though, $100 bucks to fill up!!

[rstitson]

We run 87 / regular in a new x-15. I will have to double check manuals; but was told no since to run anything higher... Run hightest in my vette. Fuel gets used up pretty regularly. Have been told to use a fuel conditioner ocassionly to keep the water out of the injectors.

[2QWICK]

I guess i think gas is part of the game. I have and always will run 93 in everything I have. Maybe its the racer in me that grew up on Cam 2 but every vehicle I have had was always JUST a bit quicker than the next guy... must have been the fuel.

My vote is 93!

[mallees]

You guys get it easy, In Australia we are paying between $1.30 and $1.40 a litre for regular unleaded, which works out to about $5 gallon.:mad:

[TJsAudio]

Torco 100 unleaded! YEA BABY cheap stuff only $5.00+ a gallon

[JDK]

I guess i think gas is part of the game. I have and always will run 93 in everything I have. Maybe its the racer in me that grew up on Cam 2 but every vehicle I have had was always JUST a bit quicker than the next guy... must have been the fuel.

My vote is 93!

You may be quicker than everyone else.......but it ain't due to the fuel. Burning 93 in an engine that only calls for 87 or 89 actually slows you down, and the price difference is going out the window.
(higher octane doesn't have more energy than reg., and it actually burns slower).
http://www.state.mn.us/mn/externalDocs/Commerce/Gasoline_Octane_Facts_102902052227_OctaneFacts.pdf

[JimN]

For those who apparently don't know, 100 octane is a waste of money. 87 octane is potentially a waste of an engine if it's run hard and the air is hot and dry. With the amount of noise generated by the motor and exhaust, knock isn't going to be easy to hear in all cases. Lower octane burns faster and if the timing is advanced too much, the valves are likely to burn. The higher octane burning slower makes for a smoother combustion cycle, better power transfer and longer life if the motor is designed to be run on that kind of gas. If it's a low compression, normal performance motor, use what the motor is made for.

Running 87 when the manufacturer calls for 89, 91 or 93 is taking a chance. The cam and compression are what determine the need for particular octane and when someone other than the manufacturer says it's a waste, think about that when the valves go away or a piston burns.

Does anyone remember that octane drops when gas sits for long periods and stabilizer doesn't help that very much?

[Jerseydave]

JDK and JimN are correct................if your engine calls for 89, putting 93 in it is a waste of $$.

If it's only $3-$5 more per tankful for 89, your crazy for using 87.

Boats are not cars, they are under a constant load with NO COASTING! It's like driving your car up Mount Washington for its entire life!
That's why you need to change your oil every 50 hours, which would only be roughly 1,000 miles in a car. You wouldn't think of changing your cars oil every 1,000 miles, but in a boat it vital. (Plus the fact it's always around moisture which does get into your oil through condensation, etc.)

Sorry, got a little off the subject.

[Jesus_Freak]

For those who apparently don't know, 100 octane is a waste of money. 87 octane is potentially a waste of an engine if it's run hard and the air is hot and dry. With the amount of noise generated by the motor and exhaust, knock isn't going to be easy to hear in all cases. Lower octane burns faster and if the timing is advanced too much, the valves are likely to burn. The higher octane burning slower makes for a smoother combustion cycle, better power transfer and longer life if the motor is designed to be run on that kind of gas. If it's a low compression, normal performance motor, use what the motor is made for.

Running 87 when the manufacturer calls for 89, 91 or 93 is taking a chance. The cam and compression are what determine the need for particular octane and when someone other than the manufacturer says it's a waste, think about that when the valves go away or a piston burns.

Does anyone remember that octane drops when gas sits for long periods and stabilizer doesn't help that very much?

Agreed. I actually have read (dont know for sure) that 87 actually has a higher energy content (heat released per mass consumed).

Question for you: Although your engine is "noisy", doesn't detonation occur within an estimated range of sound signatures (freq and mag) that the knock sensor is looking for?

[JimN]

It does have a definite signature but what is the cause- low octane, too much timing advance, hot/dry air coupled with all of the above or ?

[TX.X-30 fan]

It does have a definite signature but what is the cause- low octane, too much timing advance, hot/dry air coupled with all of the above or ?



If its hot air keep that motor away from this site. 8p