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Fuel Question

18 posts in this topic

I did a quick search and couldn't find this topic.

I'm purchasing an 08 175 Verado. I'm wondering what people are running in them. I spoke with the service guy and he said you'll lose quite a bit of HP, economy and speed using 87, even w. an additive. What do you guys think and what do you run?

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well anywhere you go you will have at least on ethonal in your gas with 87 the highest i think it 10%. I have a 66 6 horse johnson. I run the good old non ox 92 and I never have had any problems but there is 42 years of differents betweens our rigs so the technolgly is just a bit different. lol but I would say run the high buck stuff because you will have less problems with your gas.

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i kinda find that hard to beleive that you could loose "quite a bit of HP" just because your using 87oc? maybe i guess im not completly sure. but i like to run premium gas in my boat and sleds. just what i feel comfortable doing.

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Locate the specification sticker on the outboard and you should find a manufacturer's fuel rating.

Bob

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I love these posts.

I did a quick search, found Mercury's site, clicked on Verado and selsected the 175. It has a 8.35:1 static compression ratio with electronic ECU and boost control for the supercharger. The fuel spec is 87 octane pump with a 10% ethanol tolerance.

The answer to the original question is there. Burning midrange or premium gas is simply throwing money away since the motor is designed for operation with 87 octane. Higher ocrtane fuel will do nothing for performance, mileage, longevity or economy. The only possible variable would be if the electronic boost control were designed to increase advance with boost until it detected detonation, resetting the curves to match the fuel quality, and with today's warranty liabilities it is very unlikely that Mercury would program that into the ECU.

Now tank up with 110 race gas, crack the ECU and reprogram to retard the spark and bump the boost and see what happens.....

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right on!

I love these posts.

I did a quick search, found Mercury's site, clicked on Verado and selsected the 175. It has a 8.35:1 static compression ratio with electronic ECU and boost control for the supercharger. The fuel spec is 87 octane pump with a 10% ethanol tolerance.

The answer to the original question is there. Burning midrange or premium gas is simply throwing money away since the motor is designed for operation with 87 octane. Higher ocrtane fuel will do nothing for performance, mileage, longevity or economy. The only possible variable would be if the electronic boost control were designed to increase advance with boost until it detected detonation, resetting the curves to match the fuel quality, and with today's warranty liabilities it is very unlikely that Mercury would program that into the ECU.

Now tank up with 110 race gas, crack the ECU and reprogram to retard the spark and bump the boost and see what happens.....

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Thanks for the posts. They did say something about the computer knowing what gas is going thru even if you mix. and something about pinging. And that there'll be maybe a $30 difference at the end of the year with fuel efficiency savings vs. pump savings. I figure if I can get near the same performance out of the thing, I'll see $30 per tank fill by using 87!!

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I would listen to your service guy, I'm sure he works with these motors all the time and knows how they preform on different types of fuel. I would run non oxy 92 if it were my new motor.

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I would follow your instructions on the motor sticker...for warranty issues alone.

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I'd stick with Mercury's recomendation.

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My Yamaha owner's manual clearly states to use 87 gas, and that any other gas WILL NOT improve performance. As a racer, I was paying $5.75/gallon for 110 octane fuel for the car, but the motor was setup for it, meaning timing, valve clearances, carb jetting, etc. Trust me, your motor isn't suffering a huge power loss because you use 87 octane.

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The only time that I run anything higher than 87 octane is at the end of the season when I'm getting ready to let a motor sit until the next year. Higher octane (I've been told) doesn't break down as easily.

I've never had a fuel-related problem because of running 87 octane. I look at it as drinking gatorade versus water. Sure everyone will tell you that you get more energy and performance when you drink gatorade, but it's just a substitute for water and your body was manufactured to run on water.

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I would listen to your service guy, I'm sure he works with these motors all the time and knows how they preform on different types of fuel.

Why and how would he know that by running it in a tank. Running an outboard inside a tank on a stand is hardly the same as putting it on a real load on the water. They can only get so close in the tank.

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Quote:
The only time that I run anything higher than 87 octane is at the end of the season when I'm getting ready to let a motor sit until the next year. Higher octane (I've been told) doesn't break down as easily.

I think that may only apply if the higher octane fuel contains no ethanol. This is not always the case. I believe the addition of ethanol in itself might raise the octane.

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I think I'd still go with the engineers at Merc. Run what they recomend and use a fuel stabilizer

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The reason I would say go with the service guy is because he sees them coming in and out of the shop, he talks to the guys running them day in and day out and see the problems as they happen (because he has to fix them). I wouldn't believe a motor just running in a tank for real results as you mentioned, but seeing them in the shop and fixing them is a true test.

My service guy is really good, and I trust what he tells me. If he gives me bad info down the road, then I will think twice about what he tells me if it goes against specs, but for now he has been very good for the past 10 years.

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I emailed Mercury today and they got back to me right away. Here's what they said (copied from the email)

Thank you for your email, we appreciate the opportunity to respond.

The recommended fuel for your engine is 87 octane. You will not loose performance with this octane.

Mercury Outboard Customer Assistance

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