Real Time Thrust Tests with Complete Boats

Now, let me get off here... LSU is fixin to whoop up on Bama'
Roxy will have more to publish to ya'll soon enough

Ooops.......... What the hell happened.. :shock: :shock: . Man, that was not expected.. I was for Bama, but did not think a shut out was in order.. :violent1: :violent1:
 
Cant help but notice the boat that turned the most engine RPM's made the most thrust. Less ratio or less engine RPM's and less pitch= less thrust! You will make more thrust getting the motor where it makes it's steam then you will shooting for a faster prop speed. I'm told the Waterthunder motor will have a 2.68 on it soon and I hope to talk the owner into turning it approximately 5,400 and we will see what happens. I'm glade someone else is doing this because I learned one thing for sure when thrust testing. Every time you get results other then what people want or believe they will scream your not accurate or bad numbers. The only way to make somebody believe your results is to tell them what they want to hear. Won't be long you-all will be the bad guy's. HE-HE

PS I believe the numbers are reasonable considering a 500HP with a 2.38 turning low engine RPM's I WOULD SAY THOSE THRUST NUMBERS JIVE. But I bet allot of A/C guy's were screaming foul!

The truth always helps you to improve.
 
Bondsman, You are correct.



The lowest CM RPM and ratio had the highest thrust number.

The Highest Ratio and highest RPM motor placed #4.
 
Roxy7430 said:
Bondsman, You are correct.



The lowest CM RPM and ratio had the highest thrust number.

The Highest Ratio and highest RPM motor placed #4.
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So you need to provide pitch and blade length. There still is not enough information to derive any conclusions. I suspect that the R blades are being over pitched to keep the RPMs down. This will cause a lower maximum thrust. The bra strap has been undone, but we need to see more. It is time to see some HOOTERS! :D

Also put a 4 blade R pitched at 2 with the 496 BB WOT at 5400 RPMs using a 2.68 gearbox. Whitebear is correct. The R blade makes a ton of thrust at 2,000 RPMs when pitched correctly. The 4 blade R will also make more static thrust than the 3 blade R at 2,000 RPMs. This is also how Dave suggested that I setup my 418 WT based on his RnD. If this doesn't make more thrust than the current setup, I will buy the first round of drinks after my boat is tested. :D This is assuming that the BB can rev this high while turning this much prop. I haven't seen the dyno sheet for this motor. If it can't then we will have to see how much thrust my 418 WT can make while turning this combination despite having 78 fewer CI and weighing several hundred pounds less. :P

I was also wondering if the GTO team had any RnD that would suggest how to setup the 427 MAS so that it makes the most thrust possible. I'd hate to see a 500 HSP WT beat out a 600 HSP MAS. :lol:
 
Don't know why he needs to change his setup .he is making more thrust than everyone else. :dontknow: I don't know what is so hard to interpret about the first part of there findings.unless it needed to be in alphabetical order.I am sure there will be more info coming. I don't know what the results will be.but I hope you don't get upset if the 4 blade and six hundred horsepower ls doesn't do as well as the 3 blade strokers.
 
i said this 6 years ago that the 268 is great for motor that makes hp and tq in the high range but big blocks dont need the big gear/ its simple physics what i want to see is the 540 and the 74 water walker turning 3 g and put that q on the 220 8) i aready know how all this is gonna go ive ran about all these combonations in the past ten years in the woods. but theres a lot of new airboaters this is gonna help pick a combo for there boat so my hats of to you guys for puttin it out there, least yall aint talkin crap yall doing it :salute:
 
When talking about ratio and engine RPM's I was referring to small blocks. The small block that turned the most engine RPM's made the most thrust no matter what gear ratio was applied.
 
I plan to retest some time in the near future. I own the 427mas 602hp I was turning between 4900 and 5000 pitched at a full three. I hate to mess with the set up because i am crusing in still water at 2100 to 2200 wind and chop at 2700 the boat is very light and dosent need every thing the motor has to offer to move efficently. I have a hundred hp still on the table this is same set up pitched lower that blew a 1575 on the same equipment we just tested on a year ago. 1309 lbs is plenty to move this boat any where I want to go and it saves on gas and motor wear. The idea was to run the boats as we run them every weekend. I was as surprized as the rest of you when it appeared so low in the test. I have run black mud and lots of short green grass loaded to the max with set up as is with not a problem. I have 1000 rpm and a hundred hp to add should be interesting. The motor is making almost double the thrust of the aircraft boats as it is set up.
 
Waterthunder said:
When talking about ratio and engine RPM's I was referring to small blocks. The small block that turned the most engine RPM's made the most thrust no matter what gear ratio was applied.
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dave i know you know more about what makes carboats work to there best potential than most. but you got to admit these guys are putting out there for the ones that dont know to get there heads around, i understand why you cant post your results being your in the airboat biz, but these guys have no one to prove or awnser too, i find these test refreshing and informative and got a feeling they have only just begun :thumbleft:
 
No ,the small block with the 2.38 gearbox spinning 550 rpms's less than the small block with the 2.68 made the most thrust . Should be proud of that it was one of your motors.
 
anvil said:
I plan to retest some time in the near future. I own the 427mas 602hp I was turning between 4900 and 5000 pitched at a full three. I hate to mess with the set up because i am crusing in still water at 2100 to 2200 wind and chop at 2700 the boat is very light and dosent need every thing the motor has to offer to move efficently. I have a hundred hp still on the table this is same set up pitched lower that blew a 1575 on the same equipment we just tested on a year ago. 1309 lbs is plenty to move this boat any where I want to go and it saves on gas and motor wear. The idea was to run the boats as we run them every weekend. I was as surprized as the rest of you when it appeared so low in the test. I have run black mud and lots of short green grass loaded to the max with set up as is with not a problem. I have 1000 rpm and a hundred hp to add should be interesting. The motor is making almost double the thrust of the aircraft boats as it is set up.
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Anvil,

Do you have any information on how much your fuel mileage improved when you lowered your cruise RPMs? I was thinking about trying the same with mine. I was just wondering if you had any lessons learned before I did this. Thanks.
 
I think it would be less confusing if we identify the: 383 and 427 as SBC .......and the other 2 as LS motors.

The LS1 that performed poorly will be retested sometime in the near future. It was not tuned for the testing. It is an EFI with engine work done. Unfortunately the computer tune was changed to a stock tune just prior to testing. Kind of like taking your performance tune/chip out of your vehicle. The transom was also temporarily modified causing very substantial prop dip......close to 12". (There is a metal piece added on the transom to make it higher) We did not do any additional testing on this boat but will in the future for 3 things:
1. Less prop dip (approx 5" less)
2. Put the tune back in engine
3. More RPM

We will do one thing at a time to see what makes the most difference.....if any!
 
Hey anvil.when you did the 1500 pounds of thrust.was that also the time to 2 blade S out thrust yours.or was that after you pitched more.just curious.
 
You guys made me go did up an old photo of my first boat, I thrust tested it at least 20 times and the most i ever got out of her was 1580 and that was with a ZZ502 with a 2to1 gear and a 84" 4 blade K turning 4950 on the motor. The only side affect of a 84" prop with a 2 to 1 was that it was a loud sob when you stood in it, but it would run.
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Ranking of boats tested on the Thrust Trailer by Decibel readings @ WOT
 

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Ranking of boats tested on the Thrust Trailer by Total Lbs Thrust recorded @ WOT
 

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Ranking of boats tested on the Thrust Trailer by Total Lbs Thrust recorded @ Cruise
 

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Some of those participating were not able to weigh there boats at the time. Once I've recieved the few remaining numbers, I will again publish charts showing the Thrust to Weight Ratio (Coefficent) for both WOT and Cruise settings.....

And more to come after that....
 
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