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Next step.
Just wondering what y'all think would be the best next step in my project....
It HAS been running flawlessly, but has a few things I'm just not totally satisfied with... The Boat is a '05 290sc . The engine is a Procharged 555" that made 1000 hp @ 6000 RPM in full marine dress on the dyno. I'm running an XR drive with an Imco standard length lower. 1.36 Ratio 3.5" prop shaft depth. The boat accelerates HARD Has NO problem hitting mid 90's everyday loaded with fuel / coolers / people... and I've seen a best thus far of 99.7 MPH @ 6000 RPM spinning a P5x 25 that was pitched up to a 26 by Hydromotive.. With the HP I'm running I would've though it would have gotten another 5 mph out of it.. I've tried a couple of different Bravo props and none seem as fast on top and take WAY more trim to carry the bow. My lake is usually rough so I can't run around much at a high trim position without the bow going skyward.. Guess my biggest complaint is the cruise RPM... 40 MPH @ 3000 RPM trim 1 50 MPH @ 3500 RPM trim 2 60 MPH @ 4000 RPM trim 5 (neutral) 99.7 MPH @ 6050 RPM trim 5.5 Would switching to a 1.5 gear ratio allow me to run more prop ? So, maybe get a better cruise speed AND more top end ? (or blow the drive) Steve Stepp suggested I try a 1" shorty.. Would that possible result in a higher top speed but MORE mid range slip hurting my cruise speed ? Is the Imco the best lower to be running. Is there anything to be gained with a Speedmaster lower maybe ? One last thought was maybe change the blower pulley to make my max boost (10 psi) at 5500 RPM instead of 6000 RPM like it's set now and prop up accordingly. ? Just wondering what y'all think.. :) TIA.... Doug https://cimg4.ibsrv.net/gimg/www.off...cd827e1d0d.jpg https://cimg7.ibsrv.net/gimg/www.off...0da536d569.jpg (P.S. It DOES have twin ram steering now.. just haven't gotten a picture ;) ) |
1.5 ratio will allow you to run more pitch. I think you'll find your missing speed. The only reason to run a 1.35 ratio drive is if you run out of useable pitch prop with a 1.5 ratio.
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That and I would try a one inch shortie drive. The IMCO drive is the best drive for your application. did you try a labbed BRAVO 26 ???
If you can get on plane with a 4 blade prop it should be faster than the 5 blade. Also that 5 blade is causing a lot of transom lift. One other thing you could try is to cut the bell off of the back of your 5 blade. This should lower the back of the boat so that you don't need to trim as much. I could not run a 5 blade because it caused too much transom lift even with the bell cut off. |
Originally Posted by Boatally Insane
(Post 4639974)
Just wondering what y'all think would be the best next step in my project....
It HAS been running flawlessly, but has a few things I'm just not totally satisfied with... The Boat is a '05 290sc . The engine is a Procharged 555" that made 1000 hp @ 6000 RPM in full marine dress on the dyno. I'm running an XR drive with an Imco standard length lower. 1.36 Ratio 3.5" prop shaft depth. The boat accelerates HARD Has NO problem hitting mid 90's everyday loaded with fuel / coolers / people... and I've seen a best thus far of 99.7 MPH @ 6000 RPM spinning a P5x 25 that was pitched up to a 26 by Hydromotive.. With the HP I'm running I would've though it would have gotten another 5 mph out of it.. I've tried a couple of different Bravo props and none seem as fast on top and take WAY more trim to carry the bow. My lake is usually rough so I can't run around much at a high trim position without the bow going skyward.. Guess my biggest complaint is the cruise RPM... 40 MPH @ 3000 RPM trim 1 50 MPH @ 3500 RPM trim 2 60 MPH @ 4000 RPM trim 5 (neutral) 99.7 MPH @ 6050 RPM trim 5.5 Would switching to a 1.5 gear ratio allow me to run more prop ? So, maybe get a better cruise speed AND more top end ? (or blow the drive) Steve Stepp suggested I try a 1" shorty.. Would that possible result in a higher top speed but MORE mid range slip hurting my cruise speed ? Is the Imco the best lower to be running. Is there anything to be gained with a Speedmaster lower maybe ? One last thought was maybe change the blower pulley to make my max boost (10 psi) at 5500 RPM instead of 6000 RPM like it's set now and prop up accordingly. ? Just wondering what y'all think.. :) TIA.... Doug https://cimg4.ibsrv.net/gimg/www.off...cd827e1d0d.jpg https://cimg7.ibsrv.net/gimg/www.off...0da536d569.jpg (P.S. It DOES have twin ram steering now.. just haven't gotten a picture ;) ) |
Originally Posted by Tinkerer
(Post 4640238)
That and I would try a one inch shortie drive. The IMCO drive is the best drive for your application. did you try a labbed BRAVO 26 ???
If you can get on plane with a 4 blade prop it should be faster than the 5 blade. Also that 5 blade is causing a lot of transom lift. One other thing you could try is to cut the bell off of the back of your 5 blade. This should lower the back of the boat so that you don't need to trim as much. I could not run a 5 blade because it caused too much transom lift even with the bell cut off. With the 4 blade prop, the boat rides wet to the windshield with the prop shaft parallel to the hull .. It gets on plane just fine with a 4 blade, and I agree, should be faster with it, but it seems I have to trim too much to carry the bow so it loses efficiency Here are results from a Cutting Edge labbed 4 blade 30 pitch It had a STRANGE handling issue no other prop has caused..Anything over 75 MPH the boat would start to porpoise. Even dropping the tabs wouldn't stop it..The only way to stop it was to trim the drive WAY up to get it to carry the bow. 41 MPH @ 3000 RPM trim 1.5 50 MPH @ 3500 RPM trim 2 61 MPH @ 4000 RPM Trim 5 (propshaft parallel to hull) 70 MPH @ 4500 RPM Trim 5 and after driving through the porpoise.. 99.1 MPH @ 5750 RPM Trim 9 And again.. The P5X 26 results Hydromotive P5x 26 pitch 40 MPH @ 3000 RPM trim 1 50 MPH @ 3500 RPM trim 2 60 MPH @ 4000 RPM trim 5 99.7 MPH @ 6050 RPM trim 5.5 I have a Bravo 30 that was lightly labbed by Cutting Edge I need to run yet and get some solid numbers.. I need to put a 1" 1.5 ratio shorty on my Christmas list... :) THANKS !!! Doug |
Originally Posted by Boatally Insane
(Post 4640278)
And again.. The P5X 26 results Hydromotive P5x 26 pitch40 MPH @ 3000 RPM trim 150 MPH @ 3500 RPM trim 260 MPH @ 4000 RPM trim 599.7 MPH @ 6050 RPM trim 5.5 Doug |
Originally Posted by SB
(Post 4640299)
You have some experiences of this test drive you need to tell us. Way insane ! :)
It's the SECOND time I posted that and the board automatically re-formats it without the carriage returns.. I eddditted it again.... :) |
Originally Posted by Boatally Insane
(Post 4640278)
The 5 blade DOESN'T need as much trim.. It carries the bow perfect with the prop shaft parallel to the hull. (position 5 on my indicator)
With the 4 blade prop, the boat rides wet to the windshield with the prop shaft parallel to the hull .. It gets on plane just fine with a 4 blade, and I agree, should be faster with it, but it seems I have to trim too much to carry the bow so it loses efficiency Here are results from a Cutting Edge labbed 4 blade 30 pitch It had a STRANGE handling issue no other prop has caused..Anything over 75 MPH the boat would start to porpoise. Even dropping the tabs wouldn't stop it..The only way to stop it was to trim the drive WAY up to get it to carry the bow. 41 MPH @ 3000 RPM trim 1.5 50 MPH @ 3500 RPM trim 2 61 MPH @ 4000 RPM Trim 5 (propshaft parallel to hull) 70 MPH @ 4500 RPM Trim 5 and after driving through the porpoise.. 99.1 MPH @ 5750 RPM Trim 9 And again.. The P5X 26 results Hydromotive P5x 26 pitch 40 MPH @ 3000 RPM trim 1 50 MPH @ 3500 RPM trim 2 60 MPH @ 4000 RPM trim 5 99.7 MPH @ 6050 RPM trim 5.5 I have a Bravo 30 that was lightly labbed by Cutting Edge I need to run yet and get some solid numbers.. I need to put a 1" 1.5 ratio shorty on my Christmas list... :) THANKS !!! Doug Running the numbers 1.36 30p 5750rpms = 120mph theoretical speed. 1.36 26p 6050rpms = 110mph theoretical speed. 1.5 32p 6050rpms = 122mph theoretical speed 1.5 34p 5750rpms = 123mph theoretical speed Dialing in a prop on your current setup is what I would try before changing drives. Are you tied to Cutting Edge props? I have no experience with them. Brett @ bblades has treated me awesome and his props have impressed me. Might give him a call. |
A lil more thinking... My bblades labbed 30p B1 needs 6 to 6.5 on my Livorsi indicator at WOT. The 28p bblades labbed B1 likes 5.5 to 6.
If you are trimming to 9 that's way too much. I would check and make sure the drive is not out of the gimbal ring ears at that position. The 5 blades lift the stern as mentioned and push the bow down. This keeps you from having to trim out as high. Not good for top end though. These Velocity's seem to run best speed with the nose in the air and high on the pad vs parallel to the water. I'm still of the opinion you have alot to gain with the current setup by dialing in the prop. |
Spoke with Max Machine Worx..
He brought up that my Imco anti cavitation plate may be part of the issue of it not carrying the bow decent with a 4 blade... He suggested I try a stock 1.5 ratio lower and go from there... GOOD news is, I just happen to have one laying in the garage... :) |
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