Some real good engine prop thrust Data

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Waterthunder
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Some real good engine prop thrust Data

Postby Waterthunder » Wed Sep 12, 2018 12:52 pm

https://southernairboat.com/wp/wp-conte ... t-trim.jpg


A lot of data correlates on this sheet. I was talking to someone at Sensenich about testing of a different blade profile and they said with prop thrust a REAL good base number with a reducted prop is 3lbs of thrust per HP. When you using power efficiently. Also I never forget the 1st small block I dyno'ed that broke the 600HP barrier made 602 HP and burned 301lbs of fuel a hour. It's pretty cool how so many numbers from so many angles all correlate to the same results. We now developing a dead accurate correction factor for air density aka corrected altitude so we can accurately compare results all year round. We already correct for that but I want to use our dyno mule in January and predict it's thrust within + or - 3lb's. Image
THE PROOF IS IN THE PROP!

"If you copy someone you will only achieve what has already been done."

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Slidin Gator
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Re: Some real good engine prop thrust Data

Postby Slidin Gator » Wed Sep 12, 2018 7:43 pm

Dave,

I commend you for posting this, this is exactly the data that is useful in comparing actual performance on a boat vs. peak dyno figures. :thumbleft:

Is there any chance you can add a "Ghost" line showing Steady state thrust for the same prop vs. the RPM curve? The result should show the advantage of a broad torque curve (increased low end thrust on tap), which I note is a key (and correct) element of your marketing. You have said in the past that you do not participate in the "Dyno" wars because peak Hp figures are mis-leading. But this chart, showing WOT thrust response from idle, is exactly the data that shows how a motor will perform on a boat and is the "Dyno" war data that will allow knowledgeable customers to become educated and properly compare options.

You probably won't convince everyone, but perhaps those are the customers to avoid anyway. :violent1:
I grew up thinking that I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540. A Bob Stossel original, still running strong.

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Waterthunder
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Re: Some real good engine prop thrust Data

Postby Waterthunder » Wed Sep 12, 2018 9:20 pm

Another thing I will be posting soon is we set a trigger RPM for our data logger and a max prop RPM. Then we sweep the engine thru the rpm range and we time the RPM sweep in milliseconds. The time it takes to go from idle to a set RPM. The best part is we also have a average thrust number. We will be doing some testing with a major prop manufacture again very soon. After the testing is finished we will write a very thorough and technical article for a magazine and we will post the data here also. There will be a ratio comparison of a 2.38 vs 2.55 vs 2.68 also
THE PROOF IS IN THE PROP!

"If you copy someone you will only achieve what has already been done."

http://waterthunder.com/
321-508-5316

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Slidin Gator
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Re: Some real good engine prop thrust Data

Postby Slidin Gator » Wed Sep 12, 2018 9:59 pm

Looking forward to reading it.
I grew up thinking that I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540. A Bob Stossel original, still running strong.

CarMotorBarge
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Re: Some real good engine prop thrust Data

Postby CarMotorBarge » Thu Sep 13, 2018 6:00 am

Waterthunder wrote:Another thing I will be posting soon is we set a trigger RPM for our data logger and a max prop RPM. Then we sweep the engine thru the rpm range and we time the RPM sweep in milliseconds. The time it takes to go from idle to a set RPM. The best part is we also have a average thrust number. We will be doing some testing with a major prop manufacture again very soon. After the testing is finished we will write a very thorough and technical article for a magazine and we will post the data here also. There will be a ratio comparison of a 2.38 vs 2.55 vs 2.68 also


Would be nice to use a 2.88 gear for testing. Especially if you are using a 3 blade JX or 4 blade R.

Showing the timing on the data logger would also be helpful.
14x7.5 Al David hull with 14 inch transom
419 CI Horsepower Barn LS3 with 2.88 Ox Box swinging 4 blade 83.5" R
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kwanjangnihm
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Re: Some real good engine prop thrust Data

Postby kwanjangnihm » Tue Sep 18, 2018 8:07 pm

Waterthunder wrote: The R blade made the most thrust at cruise and wide open. I will say when you over pitch a prop is when the R blade just walks away from the pack. It has the widest sweet spot of any prop we have ever tested period!

Dave does this quote still hold true, or has the J series moved into the numero uno spot? :salute:
" I don't care who you are back in the world, you give away our position one more time, I'll bleed ya, real quiet. Leave ya here. Got that? "

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Waterthunder
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Re: Some real good engine prop thrust Data

Postby Waterthunder » Wed Oct 17, 2018 12:07 pm

When we did some thrust testing with Sensenich we found the 3 blade JX produced around 38lbs more thrust then a 4 blade R. Right now in my opinion unless your solely racing or have a very odd combo the JX is the best around blade out there for gear reducted car motors.
THE PROOF IS IN THE PROP!

"If you copy someone you will only achieve what has already been done."

http://waterthunder.com/
321-508-5316

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pontoon outlaw
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Re: Some real good engine prop thrust Data

Postby pontoon outlaw » Wed Oct 17, 2018 1:01 pm

You guys setting up in lake winder again?

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SWAMPHUNTER45
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Re: Some real good engine prop thrust Data

Postby SWAMPHUNTER45 » Wed Oct 17, 2018 4:56 pm

You ever test S blades Dave ?

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Prototype
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Re: Some real good engine prop thrust Data

Postby Prototype » Wed Oct 17, 2018 8:33 pm

Dave,
Thanks or Thank You!

I know the JX seems to have some great aspects overall with exception of down low push. What you would consider pre plane numbers under 2k. I've actually found a stall factor at idle in a slight breeze. One thing I can say is the jx does not torque a boat no where near what a S blade does. The S is more predictable down low to top end. The JX tends to grab and let loose and grab again with a lot less torque roll.

No negativity implied but boats are subject to wind and real world stuff not found on a anchored motor thrust tester that can't test roll or grab.

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Re: Some real good engine prop thrust Data

Postby SWAMPHUNTER45 » Thu Oct 18, 2018 8:39 am

Dave if you have any S blade data I would be interested in hearing about your testing.

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GeeLeDouche
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Re: Some real good engine prop thrust Data

Postby GeeLeDouche » Wed Oct 31, 2018 1:57 pm

awesome information. thanks for putting in the leg work dave!
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