Downsides of 550 engine?

[72Miles]

Cute, but the Premium Fuel requirement is most definitely a downside. The cost difference in the fuel is probably not terribly significant, but the availability must be considered. If you've been buying gas "on the water" then you most definitely want to see if you can even get Premium where you are. I don't see many places selling Premium. It's mostly regular and mid-grade.

-Charles

No that's not a downside. If you don't have access to premium fuel, just don't buy a premium fuel engine. That's not a negative refection on the engine. Kinda like if you don't have water to put your Nautique in, it's not a "downside" of the Nautique.

[greggmck]

The fuel consumption of the 550 engine is about 13.5 Gal per hour at surf speeds. The H6 consumes about 6.3 Gal per hour. Now consider the price of premium fuel and the difference in fuel costs will be substantial. While this is a bogus marketing campaign to sell boats it does illustrate the fuel consumption of both engines. FYI after 225 hours of surfing in my H6 we average 6.2 GPH. See:
http://www.mmwatersports.com/boat-pe...-fuel-economy/

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[charlesml3]

No that's not a downside. If you don't have access to premium fuel, just don't buy a premium fuel engine. That's not a negative refection on the engine. Kinda like if you don't have water to put your Nautique in, it's not a "downside" of the Nautique.

Sure, as long as you ignore the fact that when you're using 87 Octane fuel, you're getting exactly the same performance as an engine that costs $10,000 less. As far as "you don't have water to put your Nautique in" goes, there are pretty much no Nautique dealers in the desert SW. There's a very good reason for that.

[greggmck]

Sure, as long as you ignore the fact that when you're using 87 Octane fuel, you're getting exactly the same performance as an engine that costs $10,000 less. As far as "you don't have water to put your Nautique in" goes, there are pretty much no Nautique dealers in the desert SW. There's a very good reason for that.

I think it is a stretch to say the 550 would experence a degradation in performance making it equal to 450hp when run on regular fuel. Many performance tests have shown the difference in HP measured between regular and premium fuel to be between 1.5 and 3%. So the 550 would provide at least 97% of its rated HP when run on regular fuel. That's about 533HP.

See: https://newsroom.aaa.com/2017/12/don...s-worth-price/

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[gmoniey]

@greggmck, wow...didn't realize the 550 would use more than double the gas as the H6...that's helpful insight. That video was helpful, but I'm surprised they didn't use the H6 in the nautique to make it an apples to apples comparison (or bigger engines in the other boats).

[blueroom]

I love my 550 engine. I would own one at any altitude. Other than some increased fuel usage, it’s all positives for us - more power, easier to winterize, etc.

We run premium in all our boat and non-car motors, because that is what our non-ethanol is. Much more important to me. I hate ethanol in marine applications.


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[Wayward]

For what it's worth, my dealer called PCM directly about the fuel octane requirements. I only had access to 89 on the lake at the time i got my 2016 with 550. PCM stated that while premium is recomended, the 550 is perfectly capable of running on anything 87 and above. It will be slightly down on power compared to running premium, but not much.

This makes sense considering, as of 2016, PCM is using wide band oxygen sensors. This, in conjunction with the knock sensors, provides the ECU plenty enough data to compensate fuel delivery on lower octane fuels. Also, it should be noted, all CARB tests, and certifications on this engine were done with 87 (it's a requirement now).

While 91+ is required for full power potential still, running 87 or 89 doesn't have the potential to damage these newer engines. They are perfectly capable of adapting.

That said, I would definitely suggest the OP also contact PCM, just to cover himself, and keep a record of the conversation.

[Wayward]

The fuel consumption of the 550 engine is about 13.5 Gal per hour at surf speeds. The H6 consumes about 6.3 Gal per hour. Now consider the price of premium fuel and the difference in fuel costs will be substantial. While this is a bogus marketing campaign to sell boats it does illustrate the fuel consumption of both engines. FYI after 225 hours of surfing in my H6 we average 6.2 GPH. See:
http://www.mmwatersports.com/boat-pe...-fuel-economy/

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What?? My max fuel consumption on the 550 while surfing was 8-9gph..... and after switching to a 3047 prop, it was 6gph. That was on both my 2016 and 2017. My 550s didn't burn any more fuel than my 2015 G21 with the 409. I never had a 550 with the 1.5:1, so maybe those burned a lot more with that setup....


also, a note on your other post- You are right, it doesn't seem that running lower octane fuel impacts performance all that much. According to the CARB testing (numbers are lower, because all engine accessories are on the engine. MC is the only company that rates their engines appropriately in this regard)

CARB certification hp on 550/87- 515 (379kw)
CARB certification hp on H6/87- 395 (291kw)

So, on 87 octane, the 550 still has 120 more hp than the H6..... big difference.

[Infinity]

That test was done at a really high elevation (burns more fuel?).....and they also said in later video that they used those 3 boats with those engines cause that is what they had available to borrow at that time.

[skiinxs]

Here are a couple quotes from the PCM owners manuals:

Non Direct Injected Engine Owners manual:
"NOTICE: PCM Fuel Injected engines are calibrated to operate on and provide optimum performance when using fuel with at least an 87 octane fuel rating. PCM’s engine control module incorporates Adaptive Learn Technology to ensure optimum engine performance is obtained when using fuel rated higher than 87 octane. If a slight pinging is heard during acceleration and the proper octane fuel is being used, it is considered normal. If a constant, heavy knock occurs, the engine should be evaluated by a PCM Marine Engines Premier service technician. ATTENTION: For optimal performance and reliability, the ZR4 application requires the use of premium 93 Octane fuel. WARNING: The XS7 / XR7 Supercharged applications REQUIRE the use of premium 93 Octane fuel. Failure to due so could result in poor engine performance and engine damage that is not covered under warranty."

Direct Injected Engine Owners Manual H6, the 450 is the H6):
"NOTICE: These engines have been calibrated to operate on 87 octane fuel. PCM’s engine control module incorporates Adaptive Learn Technology to ensure optimum engine performance is obtained when using fuel rated higher than 87 octane. Use of fuels lower than 87 octane will result in reduced performance, could cause engine damage and should be avoided. If a slight pinging is heard during acceleration and the proper octane fuel is being used, it is considered normal. If a constant, heavy knock occurs, the engine should be evaluated by a PCM Marine Engines Premier service technician. ATTENTION: For optimal performance, these applications should run premium 93 octane fuel."

The way I read this is that both should run premium, but the 450 CAN run on unleaded but will produce less power. I can confirm that the H6 produces much less power on lower octane as at one tournamet last year they put gas that they claimed was 91 octane in my boat but must have been only 87, as it was way down on power and I confirmed with my Diacom that it was in degraded mode with approx. 12 degrees of timing retard.

[Bevostein]

What?? My max fuel consumption on the 550 while surfing was 8-9gph..... and after switching to a 3047 prop, it was 6gph. That was on both my 2016 and 2017. My 550s didn't burn any more fuel than my 2015 G21 with the 409. I never had a 550 with the 1.5:1, so maybe those burned a lot more with that setup....


also, a note on your other post- You are right, it doesn't seem that running lower octane fuel impacts performance all that much. According to the CARB testing (numbers are lower, because all engine accessories are on the engine. MC is the only company that rates their engines appropriately in this regard)

CARB certification hp on 550/87- 515 (379kw)
CARB certification hp on H6/87- 395 (291kw)

So, on 87 octane, the 550 still has 120 more hp than the H6..... big difference.

I agree. I have never experienced 13.5 GPH. I'm in the neighborhood of 8 on average. More when we have a lot of people with us and less when just our family of 4.

The video calcs the 13.5 per hour by looking at the diacom while the boat is at surf speed with full ballast. I don't doubt that its pulling 13.5 GPH at that limited moment in time. However, I think that is a very misleading way to look at it. Ever watch the little instantaneous MPH gauges on cars when you hammer the throttle? That's essentially what they showed in this video. Its accurate data but such a limited sample that it doesn't paint the whole picture of GPH. They don't show what the boats pull at idle or cruising at power unballasted. I would guess the difference is not as great in those scenarios and if you are going to calc GPH it needs to encompass the entire operational time (idle, surfing, cruising).

I am not going to dispute that the 550 burns more than the H6. I am also not going to dispute that if you pull your boat out of the dock, surf nonstop and then park your boat (no idling and no cruising) then your GPH fuel burn will be high in both engines but higher in the 550. However, I believe the reality is most of us don't use our boat that way and therefore the difference in GPH on all operational time is not as shockingly different than some of the claims you see on the internet.

[greggmck]

@greggmck, wow...didn't realize the 550 would use more than double the gas as the H6...that's helpful insight. That video was helpful, but I'm surprised they didn't use the H6 in the nautique to make it an apples to apples comparison (or bigger engines in the other boats).

It's a marketing video with data to fool the uninitiated. The H6 is a great engine. If they did a test against the Nautique with the same H6 engine they would not be able to claim fuel savings of the superior opti-whatever hull

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[greggmck]

I have no first hand experience with the 550 engine. I was simply pointing to the measurement in the video. Folks that have actually measured sustained fuel consumption of the 550 should post that here. I was assuming that since the fuel consumption measured in the video matched my experience for the H6 that the measurement for the 550 was valid as well???

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[Wayward]

I have no first hand experience with the 550 engine. I was simply pointing to the measurement in the video. Folks that have actually measured sustained fuel consumption of the 550 should post that here. I was assuming that since the fuel consumption measured in the video matched my experience for the H6 that the measurement for the 550 was valid as well???

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Gotcha. I didn't know you were specifically noting what was shown in that vid. I missed that. One thing of note, is that is a 2015 G23 without the 2:1 gearbox.

Besides that, the video is showing consumption while under way. That will be much higher than average consumption while surfing. On average, while surfing, you are only under way probably 60-70% of the time. The rest of the time you are idling back to the rider at .05gph.

i think their point in that vid, was to show that the Centurion hull was the reason for the better consumption on the H6.....

In the real world, and the same exact boat, the 550 will probably burn more, but not very much more. Maybe 1-2gph at most. And if you swap to a higher pitch prop, that the 550 can handle, and the H6 can't........ you'll burn less with the 550 than the H6.

[Infinity]

It's a marketing video with data to fool the uninitiated. The H6 is a great engine. If they did a test against the Nautique with the same H6 engine they would not be able to claim fuel savings of the superior opti-whatever hull

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I have to respectfully disagree here as I have seen the same engine in 2 different boats have quite a difference in fuel burn due to differences in hull, 1 must have created a lot more resistance than the other. I don't know exactly how different the hulls are on those boats, but obviously a smooth flat v that cuts thru water easily will give much less drag than a wide hull that is plowing more water. Don't get me wrong, I have no knowlege of the exact differences in those 2 hulls and have no dog in the fight and am not looking to create conflict here. Just noting that a hull can definately make a difference on how efficient an engine is.

My boat averages 4.5GPH over the entire day and did all last summer, I am sure its burning more than that when surfing with full ballast, but no one surfs entire day....even if you do there is the idle time back to rider, etc. That is how I get my average and is the only number that matters to me cause that is how I use my boat.