Pirhana props are there overheating problems

[Jim Thacker]

I searched a long time to find a prop that would lift my 1776 proV delux lund out of the water with my 90 HP Honda. In fact I was told the Honda would perform just like the Yamaha 90 (2 stroke) that I sheared the lower unit off of. That was a lie.

I finally had to go to a 15 pitch in the HOnda to get up with a full load (and I usually have a very full load treking to my cabin which is 15 miles by water)

Problem was the 15 resulted in me redlining (6200rpm)the engine (which the dealer said was OK).

Anyway I heard aobut the Pirhana prop a few years ago b:^:%:%ought one and it worked. However I was just told but a propeller professional that these props restrict the water flow and so the engine heats up at high speeds eventually scortching your valves......... Is this true. If it were would I not see very hot water coming out of my pisser (that water that comes out of the back to show you your engine is pumping water). Anyway I really like the prop but will ditch it if it will cause this overheating..... %:%

 

[walleyehed]

Re: Pirhana props are there overheating problems

Someone, I believe, is feeding you a line of total crap....
cooling water is taken before the path of the prop.
Please do me a favor and call this "eggspert" and ask how it restricts cooling and post back.
I know for a fact there are 2 of us here that would LOVE to hear the explanation for that.
Also, depending on your expectations of a prop, there are much better props available for that application.

 

[Bondo]

Re: Pirhana props are there overheating problems

Ayuh,....... Make that 3 of Us........

 

[Jim Thacker]

Re: Pirhana props are there overheating problems

Someone, I believe, is feeding you a line of total crap....
cooling water is taken before the path of the prop.
Please do me a favor and call this "eggspert" and ask how it restricts cooling and post back.
I know for a fact there are 2 of us here that would LOVE to hear the explanation for that.
Also, depending on your expectations of a prop, there are much better props available for that application.

 

[Jim Thacker]

Re: Pirhana props are there overheating problems

As you might have guessed I am new to this and seemed to have screwed up the posts. But back to this experts analysis. He says that because there is not as much of an opening in the prop exhaust (it has reinforcing struts across the opening) the water does not pass through as quick as it should this restriction in flow makes cooling problematic. Looking at conventional props and then the parhana does show the conventional is completely unrestricted and water can come gushing out but the parhana does have some restriction. So because the water gets held up (cant get past these restrictions) pumping is slowed and the engine overheats........ It made sense to me as a novice..... and he was not trying to sell me a prop (I dont think)

So, you say this is not true???

How about some info on what else I might do to fix this problem. When I started out with I think a 19 prop I literally could not get up with any load..... they tried a 17 and it helped a bit but still with a good load the rpm would get to about 3800 and sit there........... it seems I need about 4200 rpm to get up.....then they gave me the 15 and it did work much better but top end speed was about 32mph at 6200 rpm.......... As an aside I would get 38 mph with my Yami 90 hp 2 stroke at about 5300 rpm....

Anyway this running at redline (6200) was not my favourite thing to do and when turning it woudl always goabove so I would have tho throttle back.

The parhana is better as I can get up with a fairly good load and travel at 32mph, but at least the rpm is around 5200..... but would like other ideas if it would make it even better......... I still rue the day I gave up my Yamaha 2 stroke 90 (I wiped out the lower unit mid May and no one had parts and it woudl take a month or more to fix so I traded it in [and got hosed on the trade] on the honda). I once had a load of 6 guys plus me...none under 200 lbs and a few closer to 300........(I know as an Admiral you are probably yelling at me now re over weight) ........anyway the Yami took a bit of time to get the torque it needed but it did get up

I really appreciate your help here and any ideas on how I can do even better than I am now would be appriciated mnowoukd a ikllthe couppicked up some guys and gohad hotaiinutn9neho loadeh

Jim Thacker

 

[walleyehed]

Re: Pirhana props are there overheating problems

Only a part of cooling water and exhaust is returned through the prop...
All thru-hub props have webbing ...that's what holds the inner hub to the outer housing...some are a bit different than others, and some may have "slightly" different back-pressure, but on a 4-stroke, that's even less noticable...
My opinion is, this guy is NOT a prop expert and likely knows very little of the technical side of props...
I'll put some numbers together and post back with a starting point.

 

[Crownie2]

Re: Pirhana props are there overheating problems

One comment I have at this point is that it is OK if the engine can reach 6,200 RPM's but just don't run it over 6,000 for very long.

Bob

 

[Jim Thacker]

Re: Pirhana props are there overheating problems

Actually the red line is at 6200 on the 90 honda and the salesperson said he checked and you could run it all day at 6200 because it was a 4 stroke. I never the less felt uneasy doing that and finally got the pirhana prop. But it was a good 20-25 hours of use where I often put it to the redline and left it there for 15-20 minutes at a time. There does not seem to be any long term damage that I have noticed and I have been using hte Pirhana for a few years now and only being able to get to avout 5300 rpm.

Waiting to hear from the Vice Admiral on what he thinks I can do to improve on my getting up with a heavy load.

thanks for the input

 

[Crownie2]

Re: Pirhana props are there overheating problems

Honda's web site says 6,000??

Unless you happen to have the brand new BF 90 that just came out - it's rated for 5,300 - 6,300.

Bob

 

[Jim Thacker]

Re: Pirhana props are there overheating problems

I guess it means generally ...... as on my Honda tachometer the red starts after the 6000, and although not numbered I judged it to be at about the 6200 and Larry, the guy that sold me the boat said it could easily run all day at that..... but I must admit I never felt that comfortable running at the redline like that...... And based on what their web page says I guess I was making the right decision going to a better prop as stopping running at that RPM.... by the way I guess you all know this but wow this is one great cite.......I am leaning a lot here...thanks