whats faster

Hypothetically ...disregarding WOT. and all the other stuff.
say on a simple V6 engine . What prop would make it go faster?
14.25 x 25. Or a. 14.25 x 17

Re: whats faster

You need to know WOT RPM and Speed.

Re: whats faster

All depends on engine rpm's vs torque to turn the prop under the water load it's facing, prop slip, and boat's water resistance. If a 25 drops you off the torque curve then your engine will lug down and in some instances just crap out.....die. On the flip side, if a 17 doesn't load the engine adequately, you could hit rated rpm's right-outta-da-hole.

So, I answered your question, but I didn't tell you anything of value...........it all depends.....upon the situation and the equipment.

Mark

Re: whats faster

Did you guys miss the word "Hypothetically"?

Given the same RPM and a engine capable of doing it, the higher numbered pitch (25) would be faster.

If this is anything other than hypothetical, then the other guys make valid points.

Re: whats faster

Struc said:

Did you guys miss the word "Hypothetically"?

Given the same RPM and a engine capable of doing it, the higher numbered pitch (25) would be faster.

If this is anything other than hypothetical, then the other guys make valid points.

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Can't answer the word hypothetical as it is irrelevant in the realm of this discussion. Got to answer fiction with facts!!

HTH,
Mark

Re: whats faster

Assuming the motor can turn both props up to its max rpm the 25 would be faster top end.
hole shot would be very slow compared to the 17.

Re: whats faster

Why waste time on a question like that? It is along the same line as, which is heavier, a one pound brick or a two pound brick?

Re: whats faster

jimmbo said:

Why waste time on a question like that? It is along the same line as, which is heavier, a one pound brick or a two pound brick?

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I remember it this way: Which is heavier a pound of lead or a pound of feathers. Grin

Re: whats faster

I would say a 25 pitch prop, is WAY to much prop for a "simple V6". But I supose its all about, the "simple" part.

Re: whats faster

Texasmark said:

I remember it this way: Which is heavier a pound of lead or a pound of feathers. Grin

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I remember it as that way, but I figured a lot of people would get confused so I used an example which would not require any thought

Re: whats faster

jimmbo said:

Why waste time on a question like that? It is along the same line as, which is heavier, a one pound brick or a two pound brick?

Click to expand...

OMG that's funny. Permission to reuse and recycle.

V

Re: whats faster

It takes more power to turn a 2 pound brick than a 1 pound brick.

Re: whats faster

This is more like asking "What is the difference between?"

Re: whats faster

David Carrera said:

Hypothetically ...disregarding WOT. and all the other stuff.
say on a simple V6 engine . What prop would make it go faster?
14.25 x 25. Or a. 14.25 x 17

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WOT and "all that other stuff"
dictate which prop would make a boat go faster.

Your question is akin to me walking into a shoe store, and asking the salesman "Hypothetically, with out knowing my shoe size, the intended use of the shoes, or the shape of my feet, which shoe would fit/work the best?" The shoes I recieve could be too big for my feet, too small for my feet, or just don't match up with the shape of my "hull".

Re: whats faster

Or "how high is up?" There once was a song with a line that said: "Together all alone". How does that work?? As for the 25 vs 17 P here's the scoop.

1) It is very possible the 17P on a very light boat hole shot be great but would result in the engine spinning so high that all internal parts would look for the escape route through the side of the block. On a very heavy boat the 17P may be a correct prop.

2) It is very possible the 25P on a very light boat would have a poor hole shot but may run like a bandit on without the "parts through the side of the block" problem due to over reving. On the other hand, a 25P prop on a heavy boat might prevent even getting on plane so top speed is sort of a non-factor.

3) your question is best answered by example. Get in your car, put the gear selector in anything other than D or OD. That represents a 17P prop. Now hammer down and run five or six miles wide open. The rev limiter will kick in to prevent over reving (if your car has one).

Now repeat the test with the gear selector in D or OD which represents the 25 P prop. Since the car will shift through the lower gears it will accelerate the same as the 17P and speed will likely be much higher. Now here is the caviat -- your boat doesn't have multiple gears. So the 25 P prop would be a complete dog for hole shot.

Re: whats faster

jimmbo said:

I remember it as that way, but I figured a lot of people would get confused so I used an example which would not require any thought

Click to expand...

Had to laugh big time at this one.

Re: whats faster

To use the car analogy, drive 6 miles in 1st gear with your foot on the floor. Not good. Then try to take off in 4th gear with your foot on the floor. Not good. So just get a jet boat and put 2 lbs of bricks and 2 lbs of feathers in the bow.