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Discussion Starter · #1 ·
first question, will running a left rotation prop in reverse to go forward have any repercussions on the drive or handling or stress on the steering ? second question, my boat is a 26' Firehawk cat w 502 mpi. I bought it w a 28p 4-blade. It would turn about 5200 and run about 80. I switched to a 31p 4-blade hydromotive, labbed. it ran 4600 and 82-86 mph, even 88-90 on the best air and water conditions. . I now have a 28p 5-blade and it takes off much better and cruises and accelerates better but the speed is only 78-79 at about 4800 rpm. if I lab the 5-blade, can I get a few more mph out of it? will that affect my cruise rpm vs. mph? I really like the 5-blade but I don't like giving up the mph. thanks.
 

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okiedave said:
first question, will running a left rotation prop in reverse to go forward have any repercussions on the drive or handling or stress on the steering ? second question, my boat is a 26' Firehawk cat w 502 mpi. I bought it w a 28p 4-blade. It would turn about 5200 and run about 80. I switched to a 31p 4-blade hydromotive, labbed. it ran 4600 and 82-86 mph, even 88-90 on the best air and water conditions. . I now have a 28p 5-blade and it takes off much better and cruises and accelerates better but the speed is only 78-79 at about 4800 rpm. if I lab the 5-blade, can I get a few more mph out of it? will that affect my cruise rpm vs. mph? I really like the 5-blade but I don't like giving up the mph. thanks.
You could get 2-300 rpm more and a couple mph but probably not much more than that.

How do you like your Firehawk? I looked at one a few years ago.
 

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You can't run a left rotation prop backwards if I understood your first question. If you meant running the LHR drive gears in reverse and sticking a RH rotation prop on it then that is a different story and I am not sure what the long term effects on a drive would be (But that is an interesting question if anyone wants to chime in).

If you lab your prop you should pick up RPMs which will lead to an increase in the MPH you are seeing from your set-up. If you know your gear ratio you can find several online calculators that will let you play with the numbers. You would likely pick up several hundred RPM by having the prop tuned/labbed but every prop will be different depending on how true it was in the first place.

I would guess that you would get back up to 80-81 if you can turn this thing between 5000-5100 and still keep your acceleration and mid-range power. If you really want to go back up in top speed I personally would consider trying a 29 or 30p labbed 4 blade to introduce some slip back into the equation (vs the 5 blade) to get your RPMs up while stll running the higher pitch. 4600 RPM with the 31p sounds like the engine is bogging down. Max RPM for your 502 is likely 5300-5500 if it is a stock/crate from GM. If you can turn a 29/30p labbed prop over 5000 RPM you would be pleased with the speed results.
 

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You can run a left handed prop on a Bravo by running in reverse.

However, I have been told it puts more strain on your top cap and I have also gotten different answers if it would hurt the gears since a wear pattern has most likely been established.

Some people like the handing of a lefty on single deep Vs. On a cat I doubt you will notice a difference.
 

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Right - I had trouble understanding the first question but that is what I was trying to get at.

Did you end up trying the switch to running in reverse? I have always been curious about that as I have heard of people doing it but have no personal experience with it. I am hesitant to give it a shot but that would be and easy way to switch from rotating out to rotating in and then back to out again.
 

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Discussion Starter · #6 ·
thanks for the responses

thanks for the responses. I am going to tyry to swap the guy my 4-blade 28 for the 5-blaed. if I trade, I'll get the 5 blade labbed. otherwise, I'm going back to my 31 4 blade. its faster than either of the 28s.
and, I love the Firehawk, very sweet boat. a couple of my friends would but one if they could find one.
 
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