Very interesting artical about HP.

[LubeDude]

Three different HP in same boat.

 

[Boomyal]

Re: Very interesting artical about HP.

Quite interesting LubeDude. I think that it would have been a more relevant test if they had used more diverse engines like 4 cl, V6 and V8.<br /><br />Apparently these engines were all of the same config and CID's

 

[Dunaruna]

Re: Very interesting artical about HP.

I like the quote - "$800.00 per MPH" (refering to the difference in cost from a 320HP to a 375HP).<br /><br />Good article, thanks.

 

[LubeDude]

Re: Very interesting artical about HP.

Originally posted by Boomyal:<br /> <br />Apparently these engines were all of the same config and CID's

The first two were 5.7s, the last one was a big block.

 

[Triton II]

Re: Very interesting artical about HP.

Yes, very good article with a clear explanation concerning cruising fuel economy versus load and engine size/rated horsepower. Thanks LD.

 

[mattttt25]

Re: Very interesting artical about HP.

i read that article in boating mag when it came out. i've tried to quote it numerous times to dispute various posts, but most of the time people just ignored me. as they clearly showed, the 280 to 320 jump gives you very little. just proves you really need to do your research before buying.<br /><br />thanks for finding and posting the article.

 

[craze1cars]

Re: Very interesting artical about HP.

Ahh...280 vs 320 may provide very little gain in HP/performance, BUT you go from carb to fuel injection. Turnkey starting EVERY time, nothing to adjust or mess with in later years during tuneups, and lower emissions. In my book, those are the biggest benefits of paying for the upgrade, not necessarily a small HP increase.<br /><br />This was quite a subjective test when they got the the part about calling it a "strong 280" and that the 320 was "barely making 320." I find those comments hard to swallow based on just a performance test. I would have liked to see them put the 280 and the 320 on a dyno before they alluded to proving/disproving Volvo's claimed HP ratings. It also drives me nuts whever I see magazines (boat, car, motorcycle, whatever) doing tests on engines that aren't broken in yet...but kudos to the mag for at least acknowleging this fact may have an impact on their findings.<br /><br />Nonetheless, an interesting article for people who are trying to make such a decision. My feeling is that boat accelleration is more driven by torque than by HP because it's happening at lower RPMs. I feel this likely explains the close tie between the two 5.7's vs. the "rocket" accelleration of the 8.1. More displacement = more torque, regardless of the HP rating at top RPM.

 

[sangerwaker]

Re: Very interesting artical about HP.

Great article LD.<br /><br />From a skiers perspective, the more HP, the better. I'd gladly pay the extra $$ for the new 8.1 in a new Sanger. I've skied behind one and that much HP is amazing.

 

[Jdeagro]

Re: Very interesting artical about HP.

Matttt25;<br /><br />I too have been saying for the past 6 years that HP is not always the answer to performance. Infact we have tested identicle, new, Maxums, one with a 5.0 V8 and the other with a 4.3 V6. The V6 in all tests was within 1 to 2 MPH and produced better fuel economy on the 19'SR. (With the small addition of Smart Tabs the 4.3 actualy ran a bit faster than the 5.0 without the tabs). You all knew I would through that in!<br /><br />There is more to boat performance than brute HP!<br />Infact, at some point the larger engines actually reduce performance. Hull design and efficiency is as or more important.<br /><br />What everyone needs to admit is that we can very seldom run the boat at WOT, and when we can it is for a very short time. Water conditions, load, speed laws, the wife, comfort, etc. hold us back.<br /><br />If you compare boats to race cars, you find that even though the Indy cars have been restricted in engine size for many years the lap speed has increased dramaticaly. Significant work has been directed at the chasis design. Even in the NASCAR circuit you would not see HP as the only solution to performance.<br /><br />It is a great article which I hope helps everyone understand that the old traditional thinking is not always correct.

 

[umblecumbuz]

Re: Very interesting artical about HP.

Although the article wasn't covering this point, the performance differences between a loaded and an unloaded boat showed up - which reminds us that it ain't all engine power that makes a boat perform. It also has a lot to do with the weight of the boat.<br /><br />Lighter boat equals more performance for a given power.

 

[QC]

Re: Very interesting artical about HP.

Great information, but I have more than a few problems with the article/test:<br /><br />1) For this test to be valid IMHO the engines needed to be properly borken in and the engines would need to be dynoed to assure that they are doing what they are supposed to.<br /><br />2) Needs to be performed on same boat with the same drive (I understand that gear ratio may need to change too). Parasitic losses from the drives could be different and the hulls could be slightly different too.<br /><br />3) No data on propeller or WOT RPM is given. I guess we are to assume that these things were setup properly, but there is no way to tell from this article.<br /><br />Not really trying to pick this apart, but I end up with more questions than answers. I agree with Boomer too, would have been nice to see a wider range to compare. I understand budget issues etc. but there is definitely more to this story. They get very close to a concern I had from the get go. Why does the 320 use the same amount of fuel at WOT? Unless it is propped wrong, running wrong or the data sucks, the 320 MUST use more fuel at WOT RPM. If all else is correct, more bhp requires more fuel. The answer they give is crap. Fudge factor? Pretty weak.

 

[bayman]

Re: Very interesting artical about HP.

Doesn't it make sense though...the extra weight is tipping the boat more, making the boat more inefficient.<br /><br />They need to do all the tests over with Nauticus trim tabs!

 

[bluewater19]

Re: Very interesting artical about HP.

Quiet cat. <br />4bbl carb VS. Multi port injection

 

[txswinner]

Re: Very interesting artical about HP.

Nautijohn what happens when smart tabs are added to the larger motor. I would think the benefits would be greater than the smaller motor, Making big engine performance even greater than the small. Just something to think about.

 

[BillP]

Re: Very interesting artical about HP.

QUOTE: Our throttle percentage readings were a revelation—and meant the death of a universal boating truth. When throttled down to cruising speed, the bigger engine used just about the same amount of fuel as the smaller ones. How could this be? Simple. It takes a certain amount of fuel to produce a set amount of power, regardless of the engine’s size. And it takes a set amount of power to move a boat at a particular speed. In other words: It’s not the engine’s size, but the power it’s producing that determines fuel consumption.UNQUOTE<br /><br /><br />What a piece of work that article was! "Old truth", "universal boating truth". "new truth"? Which 16 yr old kid working on a chicken farm in the desert is this dude getting the "truth" from? The only sure thing in the article about engine size was: It’s not the engine’s size, but the power it’s producing that determines fuel consumption.

 

[QC]

Re: Very interesting artical about HP.

Originally posted by bluewater19:<br /> Quiet cat. <br />4bbl carb VS. Multi port injection

Yeah, I thought so too, and someone mentioned it above. But the Gi is MPI also!! In fact Volvo covers both engines with the same brochure.<br /><br /> http://www.volvo.com/NR/rdonlyres/A30941AF-37B1-42AE-8F23-E19454AD5049/0/57_DP_05.pdf <br /><br />Sumpin' aint right . . . Based on the brochure this looks just like software to me. Sooooo, if the engine's software is requesting the same max fuel rates at the same altitude with the same displacement, they're the same. No wonder they get identical results!! Frankly. I don't think Volvo is that evil, so something is wrong with the 320 or very right with the 280.

 

[QC]

Re: Very interesting artical about HP.

Originally posted by BillP:<br /> It’s not the engine’s size, but the power it’s producing that determines fuel consumption.

With very few exceptions this is accurate. Especially true with good diesels. The issue of throttle position makes spark engines (Otto cycle) more variable, but the case above is with both engines at WOT. So I consider the test totally 100% flawed and invalid. Other than that, great article!!!

 

[bayman]

Re: Very interesting artical about HP.

Okay, Quietcat has my favorite quote so far in this thread:<br /><br />So I consider the test totally 100% flawed and invalid. Other than that, great article!!!<br /><br />

 

[ewenm]

Re: Very interesting artical about HP.

the 320 uses little more fuel than the 280 because the 320 is EFI and mid range EFI is vastly more fuel efficient, the 280 on the other hand is a carby. at WOT both would be guzzling equally

 

[ewenm]

Re: Very interesting artical about HP.

Cancel the above comment its the VP GL thats a carby motor the Gi and GXi are both EFI maybe one is throttle body??