posted 03-03-2014 01:24 AM ET (US)        

There is an interesting article on Wikipedia about supercharging, which has really opened my eyes about the load they place on the engine, and their use in automobile engines.

The Wikipedia article says:

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Mechanically driven superchargers may absorb as much as a third of the total crankshaft power of the engine....

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That is a very much higher figure than I imagined. Previously I had used an estimate of ten percent of total power of the engine for the load of a supercharger on a Verado. The ten-percent figure seems conservative by the Wikipedia article standards. I am certain the load depends on the peak boost produced. It is hard to say with precision what the load on the Verado might be, but just hearing that the upper bound might be 30-percent of total engine power is quite a sea change.

The Wikipedia article notes that premium automobile marques (that's brands for readers who don't work in the auto biz) like Mercedes were using superchargers in some of their top models in the early 2000's, but the present trend is to use turbocharging. The turbochargers are more efficient because they recover energy would otherwise be wasted; that energy is from the pressure of the exhaust gases. A few of the more exotic models from luxury marques continue to offer engines with supercharging.

Using energy that would otherwise be wasted is completely analogous to the E-TEC fuel injectors. Those patented devices capture the mechanical energy of the rebounding injector bobbin, which is otherwise wasted, and use it to generate the electrical energy that will run the next injector cycle--well, at least part of the next cycle. If they generated all the energy then they would qualify as perpetual motion machines. But the analogy is a good one to the turbochargers, which in a similar way harvest energy from the exhaust gases of the cylinders.

Wikipedia articles tend to generally be well written and subject to a lot of expert review and revision. (That has been my experience with many Wikipedia subjects in which I consider I have expert knowledge, which, unfortunately, is not in any subject related to superchargers.) Thus I consider Wikipedia to be a good source of information.

Wikipedia notes that supercharger engines usually have problems with fuel economy. It says:

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This is where the principal disadvantage of a supercharger becomes apparent. The engine has to burn extra fuel to provide power to drive the supercharger.

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I believe this trend can be seen in the fuel burn data of the Mercury Verado. The fuel burn really climbs when the engine is pushed to its maximum rated horsepower, as the supercharger will be needing power to create the boost that will create the higher engine net output power.

Creating a supercharger for an outboard engine which will be subjected to salt air when operating in saltwater is another problem in engineering a supercharged outboard engine. Judging from the lack of any mentions of problems with the Verado supercharged due to salt corrosion, I think Mercury must have done a great job with their supercharger. They probably engineered it with special consideration for saltwater, using special metal alloys and perhaps non-metallic components.

The notion that only Mercury has employed a supercharger suggests to me that the use of a supercharger in an outboard is not a method seen as a standard or traditional approach to improving performance, based on having no other outboard manufacturers using that approach.

I highly recommend reading the entire Wikipedia article if you are interested in learning more about superchargers. It seems like a very comprehensive overview of the supercharger. See

http://en.wikipedia.org/wiki/Supercharger

posted 03-03-2014 08:04 AM ET (US)            

Although this article is ten years old and was written in 2004, it is a gold mine of information about the Verado, It even includes information on the rate of fuel flow. At full throttle twin 275-HP Verado engines were burning 212.7-liters per hour, or 56.2-gallons per hour, while making 275-HP. Converting that to brake specific fuel consumption, we have 0.64-lbs/HP-hour per engine.

It must be remembered that the Verado the article is taking about was the first generation, and a few years later Mercury would come out with the Generation Two or Gen2 or Gen II models, in which the fuel consumption was reduced. More recent reports have a 250-HP Verado--they don't seem to make a 275-HP version any more--burning 26.5-GPH, suggesting a BSFC of 0.66-lbs/HP-hour. Gosh, that is actually higher than the original Verado. For comparison, a Honda BF250 at full throttle burns 22.8-GPH, a BSFC of 0.57-lbs/HP-hour. That difference of 4-gallons per hour must be the fuel being used to turn the supercharger.

I highly recommend reading that 2004 Australian article for two reasons. The Aussie boating press seems to love technical details, and often gives more technical information than American boating press, which seems to concentrate more on non-technical aspects like cowling ornaments or styling. And I often find that press about a new product from its introductory period will have a greater scope of information than is found in later coverage, when any new technology in a product is not so new anymore.

posted 03-03-2014 09:17 AM ET (US)            

Wikipedia is not a scholarly or accurate reference in my opinion as it is public and can be updated by just about anyone.

According to the logic of Wikipedia the Verado SCI 350 makes over 450hp but the supercharger is robbing the difference? I don't think logical people buy that.

posted 03-03-2014 10:12 AM ET (US)            

1.) Do you really think that the supercharger on the Verado is robbing 1/3 or even 1/4 of the power from the engine?

2.) How much boost are the Verado's using?

Instead of quoting and posting links to nonsense that does not relate to the Verado, I would like to hear your own opinion on those questions.

posted 03-03-2014 10:32 AM ET (US)            

Your own estimate goes against your link and previously when questioned about how you determined your 10% theory all you did was site more unsubstantiated internet links.

My entire point to these discussions is to illustrate that the Verado is not like a blown street car engine. It is completely different and for all you know, it only takes 12-15hp for the supercharger to run.

posted 03-03-2014 11:56 AM ET (US)            

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I am not the one who started this thread..

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I agree you did not start this thread.

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...nor am I the one that is putting faith in unsubstantiated internet links/

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I agree that you do not put faith in the internet.

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Your own estimate goes against your link...

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I disagree. Both my estimate and the Wikipedia article point in the same direction. You are quibbling about the magnitude. You quibble about both sources regarding the magnitude. Let he help you resolve this:

Unless you believe in the tooth fairy, you must believe that a supercharger needs energy to run because it accomplishes work: it compresses air. By compressing air, a supercharger causes an engine to produce more power. There is some relationship between the total power an engine produces when operating with a supercharger and how much of that total power goes into running the supercharger.

It is completely logical to assume that the benefit of running the supercharger is greater than the load of the supercharger. But it is also logical to assume that there must be some portion of the total engine power produced that was spent running the supercharger, and this power is not available as part of the useful power of the engine.

The Wikipedia article suggests that the power consumed by a supercharger can be as much as 30-percent of the total power. I suggest that in the case of the Verado it might be 10-percent.

We know, from the law of conservation of energy that the value cannot be 0-percent. This means the value must lie in some range, from 1-percent to 30-percent.

We can further estimate that the value cannot be very close to 1-percent, otherwise the use of a supercharger would represent a fantastically efficient way to boost engine power. Using the Verado block as an example, we see that with use of supercharging we can increase the power output from a 1.7-liter engine to 200-HP while without supercharging the same block makes only 75-HP. If supercharging could add 125-HP to an engine but consume only 2-HP in the process, it would be something of a miracle device. Generally devices like that which can add so much power to an engine and yet consume so little power themselves are typically employed on a very wide scale. Because the supercharger remains such a specialized and rare device in engines, particularly in outboard engines, it is reasonable to assume that it must not be a miracle device, that is, it does not create 62-times more power than it consumes itself. If it were, the supercharger would be a fantastic energy amplifier, and it would be used everywhere in engines.

On that basis, I dismiss the notion that the power consumed by a supercharger is very low. If it were less than 10-percent of total engine power, I believe that the supercharger would be used in many more applications that we see now.

If you wish to make an argument that the supercharger can consume less than 10-percent of total engine power and yet provide more in power boost than it consumes itself, please go ahead. I have repeatedly asked you to document your expertise in these matters and provide us with your wisdom, but your reluctance confuses me, leading me to wonder if you have any expertise.

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...when questioned about how you determined your 10% theory all you did was site more unsubstantiated internet links...

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I have never cited any internet source in our recent discussion that suggests the power of the Verado supercharger consumption is ten-percent of total engine power. You must have been dreaming.

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My entire point to these discussions is to illustrate that the Verado is not like a blown street car engine.

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You have not illustrated anything of the kind. I believe you have made that declaration, but you have illustrated nothing.

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...and for all you know, it only takes 12-15hp for the supercharger to run.

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I am sure at some throttle settings the power needed to run the supercharger on a Verado is 15-HP. You fail to state what percentage of the total engine power is being consumed. I have asked you earlier to explain your theory of how much power is consumed by the supercharger on the Verado as a percentage of total power produced by the engine. Please explain your theory, and, if you have a demonstration of it, I would love to see it.

If you are referring to a 200-HP Verado, and if you claim 15-HP is used to run the supercharger, then the total power ouput would be 215-HP. As a percentage, 15-HP would then be 7-percent.

If I understand your claim, you wish to dismiss my estimate of 10-percent and replace it with your estimate of 7-percent, and at the same time declare I know nothing about the subject, should be ignored, have no basis to comment, and so on, yet you are an expert. And our estimates differ by 3-percent? Amazing

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All of your links mean nothing since the Verado shares very little in common with them.

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posted 03-03-2014 12:25 PM ET (US)            

Since the conversion of fuel to horsepower is determined by the BSFC, we can find out how much horsepower we can get from 3.7-gallons of fuel in one hour in an engine that has a BSFC of 0.57-lbs/HP-hour:

(1-HP-hour/0.57-lbs) x (6.25-lbs/1-gallon) x 3.7-gallons/1-hour = 40.6-HP

Now we assume the Verado makes power as efficiently as the Honda, so the extra 4-gallons of fuel the Verado burns every hour must be going to make 40.6-HP that does not show up at the propeller shaft.

(Let me pause for a moment to note that I have given the Verado the BSFC of the Honda, even though there has been a huge argument made by jharrell in another thread that a small displacement engine like a Verado is more efficient than a large displacement engine like the Honda. By using the Honda's BSFC I am really minimizing the power that the supercharger is going to be found to consume. If I used a lower BSFC the Verado could make even more horsepower with it because it is claimed to be more efficient due to its small displacement. Thus I am handicapping my own example.)

Now we look at the 250-HP Verado and see that 40.6-HP must have been used running the supercharger. This suggests that the total power was 290.6-HP, and the 40.6-HP used to run the supercharger represents about 14-percent of the total power produced. Quod erat demonstrandum.

Now we have four estimates of the power consumption of a supercharger:

--Wikipedia says "as much as 30-percent"

--the data from a Verado 250, which calculates to 14-percent

--my estimation of 10-percent

--OMCroberts assertion of 7-percent

posted 03-03-2014 03:28 PM ET (US)         

http://www.mercurymarine.com/engines/engine-tests/third-party/?ID=101&

http://cdn.powerequipment.honda.com/marine/pdf/props/ Wooldridge%2022%20SS%20Offshore%20-%20BF200.pdf

http://www.evinrude.com/Content/Pdf/neutral/performanceReports/PE570.pdf

Mercury Verado 200: 18.7 GPH
Honda 200: 19.1 GPH
E-TEC: 20.91 GPH

Why don't you run the loss numbers on that? Kinda blows your theory doesn't it?

How is this possible given your theory that a supercharger always has more parasitic load than a NA engine?

posted 03-03-2014 03:54 PM ET (US)            

You state "--OMCroberts assertion of 7-percent

It is very clear to everyone that my comment was pulled out of thin air to simply illustrate that your have no idea about how much power it really uses. I never claimed or intended to prove that the supercharger used a certain amount of power. I will not do this because I realize that it is impossible without engines, a dyno, test lab and several other things. That is my whole point.

posted 03-03-2014 04:04 PM ET (US)         

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It must have taken jharrell hours to find the outlier data to try to refute it.

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Another article, this one from an Australian boating magazine website....

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posted 03-03-2014 04:37 PM ET (US)            

A 115-HP Fourstroke burns 10.5-GPH, for a BSFC of 0.580-lbs/HP-hour

A 200-Verado, burns 20.03-GPH, for a BSFC of 0.636-Lbs/HP-hour.

It is clear from the BSFC that the un-supercharged engine is more fuel efficient. Since the two engines are of different horsepower, we take the GPH of the un-supercharged engine and scale up by the ratio of the horsepowers to find what it would burn if it could make 200-HP at its same efficiency:

10.5 GPH X 200-HP/115-HP = 18.26-GPH

Now we compare the 200-HP Verado to our imputed 200-HP Fourstroke:

The Verado burns an extra 1.77-gallons of fuel per hour. This fuel must be used to run the supercharger. We can impute the horsepower by figuring it from the BSFC of the FourStroke, or 0.58-lbs/HP-hour:

We find the supercharger horsepower is

(1-HP-hour/0.58-lbs) x (6.25-lbs/1-gallon) x 1.77-gallons/1-hour = 19.1-HP

Now we figure the supercharger has consumed 19.1-HP so the real power output of the 200-HP Verado must be 219.1-HP. This makes the supercharger power consumption as 19.1/219.1 = 8.7-percent.

That is darn close to my 10-percent estimate.

By the way, the goal here is to demonstrate that the supercharger clearly needs some power to be run. It must consume some sort of energy. It is interesting to see the magnitude so we can have some sense of how much power is being produced per liter of displacement. The goal is not to prove that there is no instance of a non-supercharged engine that actually consumes more fuel than a supercharged engine. The goal of the initial study that prompted this discussion was to see how much horsepower was being generated by liter of displacement. As I have said many times, and please bear with me while I repeat it, to pretend there was no horsepower used by the supercharger as a load on the engine is not very scientific because it suggests an abhorrent situation of free energy. So we are simply trying to get a handle of how much extra load is imposed.

It should be realized that citing of some anecdotal data in which a non-supercharged engine uses the same or even more fuel does not constitute proof that a supercharger uses no power. That just cannot be true.

As a sidebar, it might be interesting to collect many reports of the GPH of the various models of engines and see how much consistency there is in the data. It seems like in the boat test data there is the potential for an engine to perhaps never get to its full horsepower if the particular application is not letting the engine wind to its maximum power band. These variations can affect the accuracy of the GPH data.

I am also glad to point out that if any of these engines are not really making the horsepower we have assumed they are making, then the method cannot be used. For example, if the 200-HP Verado only makes 190-HP, we get a much different outcome. And in a similar way, if the 115-HP Fourstroke makes only 108-HP, we also get a different outcome

posted 03-03-2014 04:42 PM ET (US)            

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The 1.7 liter engine of mercury 4 stroke line does not only make 75 HP. It also make 90 HP and 115 HP.

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posted 03-03-2014 04:52 PM ET (US)            

Re politics, I think you have a future. You want to pretend you never said a Verado consumes 15-HP in the supercharger. I asked you what horsepower engine you were talking about. Since we have been talking about a 200-HP Verado, I just made an inference--a reasonable inference--that you were still talking about a 200-HP engine. I could have tried to alter what you said by suggesting you were talking about a 150-HP engine, which would have made your statement completely aligned with mine: both 10-percent. I was much kinder, I took your statement to be in reference to the 200-HP.

posted 03-03-2014 04:57 PM ET (US)            

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Your data is based off a simple sticker on the back of the engine. As our previous discussions have proven, the HP can be different from the sticker.

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You have to stop bringing this up, for two reasons:

--first, I already mentioned this before you did, and

posted 03-03-2014 05:00 PM ET (US)            

This is what I said (anyone can see it several posts above).

" for all you know, it only takes 12-15hp for the supercharger to run."

posted 03-03-2014 07:52 PM ET (US)            

The BLOWER used on a 71-Series diesel is not a SUPERCHARGER nor was it designed to be one. It is simply a device designed to flow a lot of air at very low pressure to blow the exhaust from the cylinder of a two stroke diesel when it is around bottom dead center of the power stroke.

The SUPERCHARGER cited and erroneously called a BLOWER when used on the 502 CID gasoline engine to supercharge the intake air charge has little resemblance to the BLOWER it used to be. It is highly modified to include the drive system in order to develop enough flow to pressurize the intake system.

IMO, the 1920s technology used in the mechanisms has no relevance to the very modern and efficient SUPERCHARGER on Verado engines.

posted 03-04-2014 09:47 AM ET (US)            

If I demonstrate a set of calculations based on published data, and derive a number from those calculations, and I lay out clearly the basis for how these calculations were made, you should not reply by saying that you can disprove all of that by making up a new number, apparently by randomly choosing a new number which is different from the number I calculated. This does not constitute any sort of logical rebuttal, valid proof, or debunking.

All of these discussion are built on the assumption that we are willing to accept certain data as valid. We accept the horsepower as valid data. We accept the fuel flow as valid data. When we use the valid data to calculate new parameters, those new parameters have the same validity as the original data, as long as the method of calculation is based on valid assumptions.

As a result, when I demonstrate that the amount of power consumed by a supercharger on a Verado can be shown to be a particular percentage, you do not disprove anything by randomly selecting a different number and declaring that you think that might be a more accurate number.

posted 03-04-2014 11:50 AM ET (US)         

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All of these discussion are built on the assumption that we are willing to accept certain data as valid.

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Why don't you accept my data as valid? It seems to come from the same sources you cited?

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A 200-Verado, burns 20.03-GPH, for a BSFC of 0.636-Lbs/HP-hour.

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Where did you get this information, from a single report? My report shows only 18.7GPH I also find a report of the 115 using 11.1 GPH

11.1 GPH X 200-HP/115-HP = 19.3-GPH

The 115 burns an extra .6 GPH Its BSFC is .60-lbs.

(1-HP-hour/0.60-lbs) x (6.25-lbs/1-gallon) x .6-gallons/1-hour = 6.4-HP

So in my data the supercharger actually adds 6.4 HP rather than taking 19.1 HP based on your formula.

We can go back and forth cherry picking all day.

posted 03-04-2014 12:06 PM ET (US)         

Verado 200 18.7GPH
E-TEC 200 20.91 GPH

The E-TEC burns an extra 2.21 GPH Its BSFC is .65-lbs.

(1-HP-hour/0.65-lbs) x (6.25-lbs/1-gallon) x 2.21-gallons/1-hour = 21.1-HP

posted 03-04-2014 01:30 PM ET (US)            

If jharrel wants to attack my method, he should point out the flaw in the method. That one data set contradicts the conservation of energy when used with the method cannot be certain to disprove the method. The data may be bad.

Jharrell want to suggest that if any engine can be found without a supercharger that reports to use more fuel than another engine of same rated power [WITH] a supercharger, it suggests the supercharger must use no energy. I reject this notion because it is inconsistent with the conservation of energy. I attribute the outcome to bad data.

Re the power to run E-TEC injectors: this is better demonstrated by comparing the same engine with and without the E-TEC injectors, as I have compared the same engine with and without the supercharger., The comparison proposed above brings in too many variables, and fails to isolate the E-TEC injector as the controlled variable.

ON FUEL EFFICIENCY

The main interest for me in this thread is to find a method to deduce the energy used by a supercharger, specifically the one in the Verado. A secondary interest is the fuel economy of such engines. I turn to fuel efficiency.

jharrell wants to suggest that engines of smaller displacement may be more efficient at producing power than engines of larger displacement. I accept this suggestion, but not on the basis offered by jharrell. jharrell suggests reduced frictions and what he says are "pumping losses" will improve the efficiency. These are general claims. I can see friction might be less with smaller pistons and cylinders. I don't quite grasp pumping losses. However, I can make a corollary with automobile engines.

In automobile engines I see a trend toward smaller displacement engines. I see a trend to boost their power with turbocharging. I make the following inferences:

--because automobile engines are under constraints to meet fuel economy, they must be moving to smaller engines as a way to improve fuel economy;

--because automobile engines want to improve fuel economy they use turbo-charging instead of supercharging, because turbo-charging is more efficient.

I also see a general trend in outboard engines:

--outboard engines use wet exhaust paths, cooled with water

--because outboard engines use wet exhaust paths, they cannot use turbo-charging methods,

--because outboard engines cannot use turbo-charging methods, some use supercharging methods.

My conclusion is that there may be--indeed there must be--some preference toward smaller displacement if fuel economy is a goal for the engine on this basis: if there were a preference for larger displacement, we would probably see automotive engines getting larger in displacement, but we see the opposite trend.

If supercharger increased engine power without actually using power to run the supercharger, or if it increased engine power significantly while consuming insignificant power in the supercharger, its use would be much wider in all power generation than we see in actual practice.

The randomly selected data I have used to demonstrate these beliefs is claimed to be coincidental. To support or reject that claim will require more data be analyzed to determine the consistency of the data. I don't have enough interest to collect and analyze more data.

My present beliefs or conclusions are:

--operating a supercharger requires power input

--the action of the supercharger increases power output in greater proportion than the power needed to operate the supercharger

--the ratio of the amount of total power in a supercharged engine compared to the amount used to run the supercharger probably lies in a range from 1-percent to 30-percent

I believe I can represent jharrell's general line or beliefs which as follows:

--all of the above beliefs of jimh are true

--there is a possibility that the inevitable load of the supercharger can be compensated for by very crafty design of other aspects of the engine which reduce parasitic losses in the engine, so that when taken as a whole, the supercharger engine, when operating at full supercharger boost, actually has no more parasitic losses than a similar engine that does not use a supercharger.

In regard to the last premise, this cannot be true. If there is an engine, which by crafty design can reduce its parasitic losses enough to compensate for the added losses of the supercharger, then one could argue that those same crafty methods could be used on the engine without the supercharger, and that engine would be more efficient because it is not losing power to the supercharger

I have made precisely that argument in my comparison of the Verado and the FourStroke. They are built on the same engine block. I believe they are identical except for the supercharger, with possibly one exception: the supercharger engine has a dry sump lubrication system.

ASIDE: I am looking forward to jharrell's reply. I find that discussing this topic with jharrell is very informative, and leads to greater understanding on my part of the topic. jharrell's comments have caused me to carefully re-think my initial beliefs. In general, I do not find that there is any harm in learning more about a topic, and no harm in having a good discussion.

posted 03-04-2014 04:27 PM ET (US)         

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That outcome defies the conservation of energy. The method he used seems reasonable.

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That one data sets contradicts the conservation of energy when used with the method cannot be certain to disprove the method.

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I reject this notion because it is inconsistent with the conservation of energy.

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I made no such claim, all engines have parasitic loss, with or without superchargers. None of my data contradicts the conservation of energy. No heat engine may be more efficient than its theoretical Carnot limit (around 40% in gasoline engine), All engines we are discussing have efficiency below this limit and are therefore wasting more than 60% of the heat energy released by combusting gasoline. This energy is wasted through inability to harness the energy or parasitic losses.

An engine that runs hotter under higher compression ratio's are generally more efficient at converting the energy in gasoline into useful mechanical energy. Supercharged engines generally run hotter and have higher effective compression ratios.

Therefore even if the supercharger has more parasitic loss, it may be more efficient at turning heat energy into crankshaft energy, thus it is entirely possible to show a BSFC that is lower than it's NA counterpart. Using BSFC as a measure includes both parasitic loss and conversion efficiency and would be a very poor way to isolate parasitic loss as the data shows.

In your quest to single out Mercury and the Verado you have lost the forest for the trees.

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The comparison proposed above brings in too many variables, and fails to isolate the E-TEC injector as the controlled variable.

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I have shown through my data there are too many variables to properly isolate a supercharger.

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In regard to the last premise, this cannot be true. If there is an engine, which by crafty design can reduce its parasitic losses enough to compensate for the added losses of the supercharger, then one could argue that those same crafty methods could be used on the engine without the supercharger, and that engine would be more efficient because it is not losing power to the supercharger.

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The flaws in your logic are as follows: 1. A supercharger allows for a smaller engine, possibly one with less cylinders to produce the same power as a larger one. 2. Supercharged engines run hotter at higher compression ratios which can result in more efficient conversion of energy. 3. Any "crafty" design could be applied to the supercharged engine, so then see #1 and #2.

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In a classic two-stroke-power-cycle engine with port induction, could you call the lubrication system a dry-sump lubrication system?

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posted 03-04-2014 04:52 PM ET (US)            

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I made no such claim [that a super charger uses no power]

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I am glad you are not claiming that superchargers use no power. Some of your examples caused me to make that inference. By declaration you intended no such implication, you have clarified you position. Thank you. We agree, I think, that a super charger consumes power from the engine.

I do object to something you are implying with this statement:

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In your quest to single out Mercury and the Verado you have lost the forest for the trees.

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First, I don't quite understand the forest and trees metaphor. Maybe you can tell me what you mean without a metaphor. Next, I have not singled out Mercury because the Verado was made by them. I have singled out the Verado because it has a supercharger, a profoundly different approach to outboard engine design. Also, I am not on a quest. Although quest means investigation, it carries with it a tone of religious fervor. I would find it more reasonable if your wrote:

"In your investigation of the power consumed by a supercharger, for example in a Verado outboard, you have [done something wrong]."

Let me describe what I have done so far:

--based on the assumption that a supercharger must consume some power, and

--based on the assumption that the amount of the total power consumed by a supercharger is probably more than 1-percent and less than 30-percent, and

--based on some inferences I made about the general use of superchargers in automobile engines, and in reading some other various sources of information about supercharged engines, I have

--estimated that a supercharger on a Verado outboard might be consuming about 10-percent of the total power produced

I then utilized some data about the rate of fuel flow to provide a method to demonstrate this, but I later decided the method was not very good, in part, because you demonstrated that impossible outcomes could be produced if certain data were selected.

So far I have heard a great deal from you about many related topics, but I have nothing from you about the power consumed by the supercharger in a Verado. I am beginning to wonder if you are intentionally withholding any comment about that. This is the main point of discussion. Let me ask you directly:

posted 03-04-2014 06:48 PM ET (US)         

A. The power needed to compress intake air to the desired boost pressure at the required flow rate.

B. The adiabatic efficiency of the particular supercharger.

C. The power returned to the crank by the pressurized charge on the intake stroke.

D. The extra power captured at the crank due to higher temperatures and compression ratio.

E. The lower parasitic losses due to friction, mass, windage, etc. from a smaller engine making equivalent power.

The following formula should work:

(A / B) - (C + D + E) = total power consumed by the supercharger.

If only A is what you are after, then find the CFM and boost pressure at an RPM and calculate it.

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First, I don't quite understand the forest and trees metaphor.

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A is a tree, engine performance a forest.

posted 03-04-2014 10:30 PM ET (US)            

You never did answer my question. May will try again:

In your opinion what is the percentage of total engine power consumed by the supercharger in a Verado at full power?

posted 03-04-2014 10:42 PM ET (US)            

Great post- You drove the point with the following insight.

" E. The lower parasitic losses due to friction, mass, windage, etc. from a smaller engine making equivalent power."

For all we know, the total power required to spin the rotating assembly of a 2.7 liter 300hp Verado and supercharger could be less then the total power required to spin the rotating assembly of a 4.0 liter 300hp Suzuki Four Stroke.

To go so far to point out the supercharger load we must know all the other variables as well.

posted 03-05-2014 09:05 AM ET (US)            

I agree. Mercury outboards suck in more air in the US than any other brand. I guess the only thing that may prove is that there are a lot of Mercurys sucking air out there. ;=)

posted 03-05-2014 09:14 AM ET (US)            

OMCrobert seems to be fascinated with ABC's. I can simplify things quite a bit:

A = TOTAL ENGINE POWER PRODUCED

B = POWER TO RUN SUPERCHARGER

C = ALL OTHER LOSSES OF POWER

D = NET POWER OUTPUT

These are related by

A - B - C = D

The percentage of total power consumed by the supercharger is

Percentage = 100 x (B/A)

For example, we might have an engine with the following

A or TOTAL POWER PRODUCED = 240-HP

B or POWER TO RUN SUPERCHARGER = 22-HP

C or ALL OTHER LOSSES OF POWER = 18-HP

D or NET POWER OUTPUT = 200-HP

Then we would calculate percentage of total power to run supercharger as

Percentage = 100 x (22/240) = 9.2-percent

posted 03-05-2014 04:36 PM ET (US)            

I am working a new method. I will describe in detail shortly, so please stand tuned.

posted 03-05-2014 06:14 PM ET (US)            

I was certain that once you set your self up as the judge of who is the expert, selected your expert, and endorsed his method, it would be child's play for you to complete the task set out by jharrell. Since you have repeatedly described me as a provider of nonsense and a fool, I don't know why you would expect me to provide you and jharrel with a solution using his method.

You need to either provide us with the calculations using the method you have endorsed, or explain why you cannot provide them.

posted 03-05-2014 06:28 PM ET (US)            

I find this whole conversation comical and you just keep digging deeper and deeper in an attempt to save face.

You will try in vein to come up with an accurate number but we all know that you can not. But please continue to try.

I am really enjoying this thread almost as much as the Etec HO thread because all I have to do is let you continue to talk to make a fool of yourself and lose creditability.

I can not wait til you dazzle us with your new calculation and understanding of the supercharger gleamed from google and the power internet.

posted 03-05-2014 07:50 PM ET (US)            

What percentage of total power at full throttle is consumed by the supercharger of the Verado?

I look forward to hearing from you on this.

posted 03-05-2014 08:11 PM ET (US)            

I have set up the Verado so its propeller shaft is driving the dynamometer. The Verado is a 200-HP engine. When I run the engine at full throttle, the dynamometer reads 200-HP.

Please describe how I measure the power consumed by the supercharger. I went to a lot of trouble to set this up, based on OMCrobert's insistence that any other approach would be "nonsense theatre" and "baffling drivel."

OMCrobert, please give me the rest of the procedure.

posted 03-05-2014 08:28 PM ET (US)            

I will now rig a separate motor (variable speed electric motor)next to the Verado with a belt to supercharge and match engine RPM the entire time with the electric motor. Not very complex but does the job.

posted 03-06-2014 08:55 AM ET (US)            

You are a true wordsmith [Notice how OMCrobert is trying to distract me with this opening phrase. He tries to describe my reply as based on using words, but it is based entirely on following his method. If I am to get an electric motor, I will need to know what power is needed. This need was created by OMCrobert and his method, not my me or due to use of words--jimh.] and can certainly introduce a smooth transition to another topic [and here, being quite adept himself at changing the topic, OMCrobert changed the topic, and he began to discuss the thread as a topic in itself. Sorry, you need to stay on the topic of superchargers, not talk about the thread itself. Being "a smooth operator" myself, I can easily detect when you try to change the topic--jimh]

posted 03-06-2014 10:53 AM ET (US)            

Let me describe my method to determine the percentage of total power at full throttle that is consumed by the supercharger of the Verado. I mentioned earlier I was working on a new method. Actually I have thought of two new methods.

The first method: ask someone who probably knows the answer. Since it is clear that neither you or jharrell know the answer, and you have both been doing a very good job of bobbing and weaving (to continue the boxing metaphor) to avoid answering the question, I am giving up on both of you as a possible source of an answer. You (and jharrell, too) are henceforth relieved of any burden from me of trying to answer my question. I will turn to someone else for the answer. It may be a while before I am able to find the proper person. I am not certain if this method will work. There is the possibility that even the people who designed the Verado do not know with any sort of precision how much power it is consuming in the supercharger. For their purposes, to create a nice engine, it may not have been necessary for them to actually measure this parameter. I will let you know of my progress on this path.

The second method I conceived is actually quite similar to your method, as it is a method to measure the power consumed by the supercharger from the actual operation of an engine. To measure the power applied to the supercharger, I propose to measure the torque being applied to the input shaft of the supercharger. The power is delivered from the pulley being driven by the belt. Some means of measuring the torque being transferred from that pulley to the drive shaft will be necessary. A special pulley will be fabricated. There will be an inner and outer rings, connected by a spirally wound spring. The spring will be compressed by the torque as the power is transferred from the outer ring to the inner ring. There will be scale marks on the rings. At rest a mark on one spring aligns with a particular mark on the other ring. When torque is applied, the spring compresses in proportion to the force, and the markings change their alignment. At rest, various forces are applied to calibrate the markings. The engine is operated, and a strobe light is used to stop the rotation so the alignment of the marks is observed under rotation. From this device we can measure the torque on the input shaft of the supercharger. We can know its speed of rotation. With RPM and torque, we deduce the horsepower. My method requires the construction of some specialized measurement apparatus. Since I didn't need the dynamometer, I have sold it. I will use the money to build the specialized device.

posted 03-06-2014 04:16 PM ET (US)            

quote:

---

A. The power needed to compress intake air to the desired boost pressure at the required flow rate.

B. The adiabatic efficiency of the particular supercharger.

---

The "A" is the actual energy or force or power that resulted from the supercharger compressing the air, that is the output work it performed

"The "B" is the efficiency at which the supercharger can convert its input energy or force or power into its output work.

We might think, well, we just figure it like this:

The supercharger puts out about 10-HP of "work" from its compression of the air, that's the "A" factor. And the supercharger converts its input power to its output work by an efficiency of, say, 85-percent. Then we could conclude that the input power must have been 10-HP/0.05 = 11.8-HP

In terms of a practical application, I don't know how one could ever figure out the efficiency of the supercharger without measuring its input and output powers in the first place. How would we know the "adiabatic efficiency" of the supercharger unless we measured it by comparing its input power to its output work?

posted 03-06-2014 07:59 PM ET (US)            

I think that when the supercharger is not providing any boost, that is, when all of its boost is just being spilled into the waste gate--so named because it is a way to waste the output of the supercharger--then the power to drive the supercharger is a load on the engine that may not be helping to create more power. But the power to turn the supercharger when it is not compressing any air is low, so it is probably not a concern. I am not concerned about any power loss there.

posted 03-07-2014 01:12 PM ET (US)            

In all outboard engines we measure the power at the propeller shaft. This is the net power output from the engine to the propeller shaft, but the total power produced by the engine has to be greater. Among all outboard engines there are similar loads on the engine in addition to the propeller shaft. For example, they all have to operate an electrical generator (usually called an alternator) to generate electrical energy.

Most engines to not have to operate a supercharger--they don't have one. The Verado has been described as being profoundly and fundamentally different from all other outboard engines because it uses a supercharger.

Because of this fundamental difference, I thought it would be interesting to look at the supercharger as a load on the engine to see how much power it consumed. Based on what I have read--and, please, excuse me for saying I learned something by reading about it--a supercharger can consume a significant amount of the total power produced. My interest is in finding a good estimate of this power.

Methods have been proposed which suggest ways to measure the power if one has an actual engine in operation and has very specific and unusual measuring equipment available. There is not much value in exploring these methods because they are very difficult to implement. The notion that a measured value could be obtain by some method is a reasonable notion, but it does not lead to arriving at any particular answer in this discussion.

Methods have been proposed which suggests ways to calculate the power based on knowing particular values. For example, if we knew the actual output work being done by the supercharger, and we also knew the efficiency of the conversion of input energy to output work, we could deduce the input energy. But there is no basis provided in that method by which we could learn the efficiency, so no solution can be provided.

Another method suggests we could infer the total engine output power from the total fuel being burned, and subtract the shaft horsepower to find the lost horsepowe, which could then be apportioned to the supercharger But that method requires that all the fuel be converted to energy. We know that perhaps in some cases all the fuel is not converted to energy, and this creates a situation in which we might not really know the total horsepower very accurately.

posted 03-07-2014 02:25 PM ET (US)         

Your 8.7 percent came from a report of 10.5-GPH for the 115 and 20.03-GPH for the 200 Verado.

I found other reports from the same sources showing 11.1 GPH for the 115 and 18.7 GPH for the Verado. With that data the Verado has 3% less power being used then the 115.

This is obviously not the best method.

posted 03-07-2014 02:45 PM ET (US)         

quote:

---

Who cares if the Supercharger is robbing the crankshaft 15 hp. The engine is still pushing 60 hp and takes half as long to hit 60 mph

---

It doesn't matter if all you care about is power and speed. Throw a bunch of fuel at the problem and get your solution using more displacement or forced induction.

I think jimh is trying to make some point about efficiency, that is how much fuel is needed to get that power. However I have shown this is complicated to answer, many factors contribute to the overall efficiency of the engine.

posted 03-08-2014 08:12 AM ET (US)            

Regarding the fuel flow data and its variation, I am going to start a new discussion on that topic to explore why there is so much variation. Perhaps we can discuss that in the new thread.

I have never made any claims of being interested in establishing the efficiency of the supercharging process. This discussion comes as an outgrowth of the survey of power produced by liter of displacement. My particular interest in the supercharged engine is to appreciate the extra power it must make in order to to run its own supercharger. Such extra power (which does not appear at the output shaft and is usually neglected), when considered as part of the total power produced, tends to show how much power a supercharged engine produces per liter of displacement.

posted 03-08-2014 09:35 AM ET (US)            

This link
i177.photobucket.com/albums/w231/Whaler-Fleet/ Montauk190Efficiency_zpsa15983aa.jpg

posted 03-09-2014 10:56 AM ET (US)            

According to the Boston Whaler boat test data as presented by Peter, there is no engine speed range in which the supercharged engine delivers better fuel economy than the non-supercharged engine, except a single data point at almost full throttle setting of the non-supercharged engine.

Also, the chart shows a larger displacement engine produces better fuel economy than the supercharged engine at the same boat speeds, except in Region 1. This is somewhat counter-intuitive, because I did not expect to see that the Verado with supercharged excelled only at idle speeds in comparison to engines of larger displacement in terms of fuel economy.

This data of fuel economy does not make much of a compelling case to choose the Verado option.

posted 03-10-2014 09:46 AM ET (US)            

I don't think I saw anyone else mentioned this. The parasitic losses of the SC is going to be the energy to use to spin the supercharger plus the resistance of air being compressed. I bet mercury engineers now what this is but even the most hardcore performance enthusiasts probably isn't going through effort to dyno'ing the motor and isolating the SC.

The energy used to spin the sc will alway be present but the resistance to compressing air is going to vary from ~0 to X. For instance 4000rpm could be easily be the supercharger producing no boost so resistance of the air being compressed could next to nothing while in a different load @ 4000rpm the supercharger could be produce x psi of boost with a substantial amount of energy being used compressing air. I had a centrifical supercharger for one of my cars. When I spun it by hand took more a lot effort than I expect. The supercharger was gear up to spin faster than the motor rpm's. ~10:1

posted 03-12-2014 01:29 PM ET (US)            

It takes the same power to move a boat a certain speed. If one engine has to run at a faster speed to create that power, it does not mean it creates more power. If it created more power, the boat would go faster.