24 x 7 prop talk / help!?
05-25-2017 | 06:50 PM
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24 x 7 prop talk / help!?
Need some help with props......
Boat is a '91 Sunsation Rocket.... Similar to the rest of the 24' x 7' hulls (Pantera, P&D, Banana Boat, Superboat, etc.)
BBC with Bravo1 1.5 ratio
Previous motor was a 454/330hp with Edelbrock aluminum 110cc chamber / 290cc intake / 118cc exhaust marine heads, Edelbrock 7562 manifold and Crane H-296-2 cam.... allegedly was 500hp range but who knows.....
With a stock B1 prop 26pitch:
3500RPM - 40mph
5400RPM WOT - 74mph and chine walking like a *****...
_________________________
With a Mercury Revolution 4 prop 25pitch:
3500RPM - 45mph
5400RPM - 74mph (same lol)
Rev4 prop gave amazing plane time and excellent mid-range speed and same top speed as B1 but far more stable.
Ended up with a new motor...
489 stroker with Merlin I-043c heads 119cc chamber /320 intake / 137cc exhaust, same Edelbrock manifold, and custom grind cam (attached cam card in pics)
Dyno'd at 530hp / 579tq (dyno and graph in pics also)
So with that said, Im getting pretty much the same speeds with the Rev4 prop but its amazingly quicker getting up to those speeds....
What Im wonder is if I can step up to a bigger prop?? Maybe a 28pitch Bravo1 or if there is a bigger Rev4 prop out yet?
My thinking is maybe this newer motor makes more power down low, especially the torque as its a stroker..... It revs up amazingly fast and has almost no lag.... where as the 454/330hp worked motor made its power higher up possibly and had some lag getting up to that speed.... so the new motor is max'd out at that 5400/5500 RPM range considering the dyno graph.... So much more torque and HP is closer to 5000RPM or so.
I love that Rev4 prop, and pretty sure they came out with a Rev4 XP or something... and has a 26 and 26.5 pitch options... but its under the outboards section?? Isnt this still the same prop shaft that it would work??
Thoughts?? Suggestions!!? Thanks in advance.
Boat is a '91 Sunsation Rocket.... Similar to the rest of the 24' x 7' hulls (Pantera, P&D, Banana Boat, Superboat, etc.)
BBC with Bravo1 1.5 ratio
Previous motor was a 454/330hp with Edelbrock aluminum 110cc chamber / 290cc intake / 118cc exhaust marine heads, Edelbrock 7562 manifold and Crane H-296-2 cam.... allegedly was 500hp range but who knows.....
With a stock B1 prop 26pitch:
3500RPM - 40mph
5400RPM WOT - 74mph and chine walking like a *****...
_________________________
With a Mercury Revolution 4 prop 25pitch:
3500RPM - 45mph
5400RPM - 74mph (same lol)
Rev4 prop gave amazing plane time and excellent mid-range speed and same top speed as B1 but far more stable.
Ended up with a new motor...
489 stroker with Merlin I-043c heads 119cc chamber /320 intake / 137cc exhaust, same Edelbrock manifold, and custom grind cam (attached cam card in pics)
Dyno'd at 530hp / 579tq (dyno and graph in pics also)
So with that said, Im getting pretty much the same speeds with the Rev4 prop but its amazingly quicker getting up to those speeds....
What Im wonder is if I can step up to a bigger prop?? Maybe a 28pitch Bravo1 or if there is a bigger Rev4 prop out yet?
My thinking is maybe this newer motor makes more power down low, especially the torque as its a stroker..... It revs up amazingly fast and has almost no lag.... where as the 454/330hp worked motor made its power higher up possibly and had some lag getting up to that speed.... so the new motor is max'd out at that 5400/5500 RPM range considering the dyno graph.... So much more torque and HP is closer to 5000RPM or so.
I love that Rev4 prop, and pretty sure they came out with a Rev4 XP or something... and has a 26 and 26.5 pitch options... but its under the outboards section?? Isnt this still the same prop shaft that it would work??
Thoughts?? Suggestions!!? Thanks in advance.
Last edited by cdaniel525; 05-25-2017 at 06:55 PM.
05-25-2017 | 07:04 PM
#2
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From: Toledo Oh
few things to think about...
1. what do you have for steering? it those speeds in that hull you need full hydraulic
2. have you laid a straight edge on the last few feet of the bottom?
3. I believe the rev 4 only goes to 25
4. the Rev 4 has more bow lift than the bravo 1, If you dont get enough bow lift on that hull it handles like crap. (I tried an old school cleaver, lifted the stern not the bow, and the boat was down right scarey)
5. How deep is your drive? A deep drive on a narrow hull single can get a lot of side torque increasing as you go up in prop size.
1. what do you have for steering? it those speeds in that hull you need full hydraulic
2. have you laid a straight edge on the last few feet of the bottom?
3. I believe the rev 4 only goes to 25
4. the Rev 4 has more bow lift than the bravo 1, If you dont get enough bow lift on that hull it handles like crap. (I tried an old school cleaver, lifted the stern not the bow, and the boat was down right scarey)
5. How deep is your drive? A deep drive on a narrow hull single can get a lot of side torque increasing as you go up in prop size.
05-25-2017 | 08:32 PM
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few things to think about...
1. what do you have for steering? it those speeds in that hull you need full hydraulic
Standard cable steering with hydraulic assist...... So far no issues running WOT, lol... Not looking but to go a few more MPH
2. have you laid a straight edge on the last few feet of the bottom?
I haven't done that yet, so I will definitely do that next time I get in the water since the boat is on a lift. Is a 4 foot level good? or need something shorter or longer. I definitely was thinking its possible Im at the hull speed limit or there might be a hook holding me back.
3. I believe the rev 4 only goes to 25
Thats what I thought too.... then I found this the other day.... http://www.mercuryracing.com/boat-pr...volution-4-xp/
4. the Rev 4 has more bow lift than the bravo 1, If you dont get enough bow lift on that hull it handles like crap. (I tried an old school cleaver, lifted the stern not the bow, and the boat was down right scarey)
Yes, I found this out when I switched to the Rev4 compared to the B1 it really lifted the bow much better.... settled the hull down completely at WOT
5. How deep is your drive? A deep drive on a narrow hull single can get a lot of side torque increasing as you go up in prop size.
Not 100% sure on the depth of the drive... Is there a simple way to measure? At least the boat is on the lift, but I need to try and measure from a raft lol
1. what do you have for steering? it those speeds in that hull you need full hydraulic
Standard cable steering with hydraulic assist...... So far no issues running WOT, lol... Not looking but to go a few more MPH
2. have you laid a straight edge on the last few feet of the bottom?
I haven't done that yet, so I will definitely do that next time I get in the water since the boat is on a lift. Is a 4 foot level good? or need something shorter or longer. I definitely was thinking its possible Im at the hull speed limit or there might be a hook holding me back.
3. I believe the rev 4 only goes to 25
Thats what I thought too.... then I found this the other day.... http://www.mercuryracing.com/boat-pr...volution-4-xp/
4. the Rev 4 has more bow lift than the bravo 1, If you dont get enough bow lift on that hull it handles like crap. (I tried an old school cleaver, lifted the stern not the bow, and the boat was down right scarey)
Yes, I found this out when I switched to the Rev4 compared to the B1 it really lifted the bow much better.... settled the hull down completely at WOT
5. How deep is your drive? A deep drive on a narrow hull single can get a lot of side torque increasing as you go up in prop size.
Not 100% sure on the depth of the drive... Is there a simple way to measure? At least the boat is on the lift, but I need to try and measure from a raft lol
Thanks for reply.... Answered the questions above...
Last edited by cdaniel525; 05-25-2017 at 08:34 PM.
05-30-2017 | 08:23 PM
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Ill keep an eye out for a hydraulic steering kit I can afford though
