Prop Porting

[ddrieck]

Im a newbie so be gentle... 78 star craft, 500 50 horse Merc.....Was told I may need to port my prop and I have know Idea what that means.

 

[QuadManiac]

Re: Prop Porting

I've never heard of it and, apparently, neither has Google. (doesn't mean it doesn't exist, though, lol). Are you sure there wasn't some kind of miscommunication?

 

[Silvertip]

Re: Prop Porting

Porting a prop consists of drilling a hole in the hub behind each blade. This is a trial and error process and it can only be used on props with through-hub exhaust. It is quite effective on two strokes but less effective on four-strokes. What it does is allows a small amount of exhaust gas exit the hub and create bubbles behind each blade. This causes a controlled amount of slippage so the engine can get a little higher on its RPM band to help hole shot. If you are familiar with high stall speed torque converters on cars, it does about the same thing. It does not affect mid and high speed operation. Many stainless and high performance props are ported at the factory and may even be supplied with bushings with various diameters to dial-in the desired level of performance. Search the FAQ's. There is an article on how to do it. The key = start "small"

 

[guy74]

Re: Prop Porting

I have ported 3 different props on my 1988 60hp johnson. It provided much better performance for pulling up a skiier. Like said in the post above start small and work up untill you get the desired results. The three props that I ported were all 13 3/4" X 15 props, one is a Michigan Wheel, one an OMC, the last is a Hustler. The Michigan Wheel prop only took 1/8" holes to give me the slip I needed, but I had to go up to 5/16" on the OMC and Hustler to get enough slip. I'm deep water stating a 175lb slalom skiier in double highwrap boots with a 60hp, and pulling at a top speed of 30mph.

 

[Texasmark]

Re: Prop Porting

Hey Guy, wasn't the Hustler already ported? What'd you do enlarge the existing holes?

Like I have stated numerous times in other threads. I had a 17' deep V, padded bass boat type thing with a 115 Merc (a real dog of a hull type to get going). I had a ported Merc Prop. I weigh 250# and it isn't fat. The ports made all the difference in the world in my hole shot coming up on slalom.....yet had no effect on WOT. Agree, ports don't work in all situations, but where they do, they do.

Besides if they do nothing for you and you want them out you can always plug them.

Mark

 

[John_S]

Re: Prop Porting

Not all Hustlers are ported. The two I have for my Nissan 40hp were not ported. These are the older silver painted ones with the older rubber style replaceable hub. Because Hustler advertised the ventilation holes back then, I called their technical service dept. That indicated that some of the smaller outboards they found that the holes provided only marginal improvement. The newer black props have them too, but it is not found in their literature. I think they got tired of people asking what I did.

 

[guy74]

Re: Prop Porting

Mark, No the hustler wasn't ported when I bought it. I found out if you drill it in the same place that you are supposed to drill an OMC prop you hit right on top of the spokes in the barrel, so I had to move back a little bit farther.

 

[QuadManiac]

Re: Prop Porting

Brilliant idea, and just goes to show that Google doesn't know all, nor do I!

 

[Texasmark]

Re: Prop Porting

Well, porting and not is an interesting subject as to does it do you any good.

On my '89 Ranger and 115 Merc is was obvious that there was something to it. I may have been running an origional Laser, don't know, but it was a Merc SS HP prop of some type.

On my son's 150 with a Laser II you get a good hole shot, but don't get the "overdrive feeling" I got with mine. Don't know why...engine, boat, prop????

The Hustler I bought was for a 90 hp Merc. Have no idea what smaller or larger have to offer.....that's why I state the facts when I say something....this is how it is with this machine.....who knows what to expect with others.

Sorry, best I can do.

Mark