Some real good engine prop thrust Data

[Waterthunder]

https://southernairboat.com/wp/wp-content/uploads/rtMedia/users/585/2018/09/thrust-graph-cut-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.

 

[Slidin Gator]

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:

 

[Waterthunder]

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

 

[Slidin Gator]

Looking forward to reading it.

 

[CarMotorBarge]

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.

 

[kwanjangnihm]

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:

 

[Waterthunder]

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.

 

[pontoon outlaw]

You guys setting up in lake winder again?

Sent from my [device_name] using Southern Airboat mobile app powered by Tapatalk

 

[SWAMPHUNTER45]

You ever test S blades Dave ?

 

[Prototype]

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.

 

[SWAMPHUNTER45]

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

 

[GeeLeDouche]

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