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Topgun non step props?

Old 08-05-2020, 05:27 PM
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Default Topgun non step props?

looking for prop suggestions:

1999 topgun kevlar hull
no step
notched transom
555ci motors NA, according to dyno sheets:
748hp at 6100 Rpms
peak torque is 652 ft/lbat 5700 but starting at 4100 itís 630ft/lb
bravo xr drives max machine internals 1.5 ratio

I read a post here from long ago of similar boat running 30p

Im running Stock bravo 28s and canít get them much over 5000rpm

not looking to set any speed records but want to get the most out of my setup.
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Old 08-05-2020, 06:13 PM
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I ran those props on a 93 TG with 500 EFI's and spun them 5100 ...how deep are the drives
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Old 08-05-2020, 06:46 PM
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Gonna have to measure them buy theyíre standard Xr lowers w nosecones
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Old 08-05-2020, 06:52 PM
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I almost think I need to go down to 26s to get some more Rpms out, but seeing the other posts has me confused.

Should I be running smaller props faster or bigger props slower?
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Old 08-05-2020, 07:37 PM
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were you at the dyno sessions , you sure their making 750 hp.....what speed are you running
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Old 08-06-2020, 01:56 AM
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Something is not right for sure and I doubt its the props. You should be able spin the 28's much higher than 5000rpms with 750hp a side. The dyno numbers you said show plenty of torque above 4100 rpms, so its not like you have a lack of torque and need to spin them up to get over an rpm hump.
What GPS speeds are you seeing at WOT???

Last edited by Griff; 08-06-2020 at 12:50 PM.
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Old 08-06-2020, 07:23 AM
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Best so far is 72 on gps

I was not at the dyno sessions, I just have the reports from when these motors were built by previous owner.
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Old 08-06-2020, 08:36 AM
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The motors arenít making 750. Theyíre making 550 at best.
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Old 08-06-2020, 09:11 AM
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Originally Posted by Unlimited jd View Post
The motors arenít making 750. Theyíre making 550 at best.
i was going to say my warmed-up hawk 525's that we estimate are doing 550-575hp had me @ 72 mph top speed.
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Old 08-06-2020, 09:38 AM
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That would explain why something not adding up ...the dyno sheet shows 598 at 5000rpm

i just canít get past that with these props
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