Need Prop advice 180 with 4.3

[bowtie4x4295]

Just purchased a 1997 Dynasty Elanti 180, it has the 4.3 carbed mercruiser, so HP should be around 190. The factory prop is a 21P Aluminium. The problem is the boat will leap out of the hole and get on plane almost instantly, at WOT it will turn around 5200 RPM. I am trying to get my rpm's at WOT to be around 4700-4800, so I don't have to throttle back.Weight is reported at 1775lbs. Was wondering if going to a 21p SS would be beneficial, or should I jump to a 23p. I usually have the wife, daughter, dog and myself on-board. Speedo says around 50 mph, which matches the gps. I am in Alabama approx. 220 feet above sea level in the Alabama River.

Mike

 

[ruf1967]

Re: Need Prop advice 180 with 4.3

the 23 will bring it down about 200 rpm and top speed will go up a little

 

[nlain]

Re: Need Prop advice 180 with 4.3

I have a 2004 SeaRay 185 Sport with 4.3L 190 hp Alpha, advertised dry weight, 2650, it came with a 23 pitch prop and I have seen 50@5200 with just me in the boat, 49 gps with me and wife with other stuff. A 23 pitch should bring your rpm down and speed up. You may want to get on Iboats and see if the prop test can be used in your case, that way if you need to change props after a test run you can without having to buy another one.

 

[steelespike]

Re: Need Prop advice 180 with 4.3

Do you know that the boat has the factory 21, usually 2 inch increase
in pitch will lower rpm by about 400 rpm.Going from al to ss can change that
depending on the prop it could lower rpm and increase speed others could increase speed and rpm. Of course increasing pitch should lower rpm but how much again depends on the design.

 

[bowtie4x4295]

Re: Need Prop advice 180 with 4.3

Well my main goal is not necessarily to attain a higher max speed, but more to get WOT to where it should be, without having to throttle back. Although acquiring the correct prop could result in a higher top speed, hole shot isn't an issue. The only one that gets behind it is my 10 year old daughter, and then its at slow speeds. I just am trying to avoid checking the tachometer constantly, although I check it regularly. Could be a result of the boats weight being only 1775, rather light vs. some on the market today.
What would be some recommendations on some good SS props for mild water sports and joyriding? Probably in the 23P range.

Mike

 

[bowtie4x4295]

Re: Need Prop advice 180 with 4.3

No help?

 

[Tail_Gunner]

Re: Need Prop advice 180 with 4.3

http://boatpropellers.iboats.com/Me...andard&**********=383589601&*******=363987834

5200 with a 3blade 21 alum

2oo drop for ss 100 drop for 4 blades ...4900

Lots of midrange tourqe and good hole shot.

__________________________________________________________________

http://boatpropellers.iboats.com/Me...andard&**********=383589601&*******=363987834


Best overall top speed 3 blades probably 4900-5000 rpm...Lots of cupping on that stilletto it will act like a normal 22 pitch 3blade ss


While this will not cut your rpm to under 4800 you run you at the very top of the band for very short burst's....It will keep you in a good safety zone while maintaining a good hole shot and midrange power (low planing speeds) at which i assume 95% of your boating will occur.


http://boatpropellers.iboats.com/Me...andard&**********=556710880&*******=363987834

There's 4600-4700

http://boatpropellers.iboats.com/Me...andard&**********=556710880&*******=363987834

again 4600-4700

I would assume a marignal hole shot.....the 4 blades will lower your planing speeds while that big 23 might get you top speed..... but a 23p or a 22p in a 3 or 4 blade is a lot of prop for a 4.3 in a 18-19' boat. I would hope you have a 4 barrel carb you gonna need some top end tourqe on a 4.3...Not it's strong suit.... High rpm tourqe that is.

 

[Just for fun]

Re: Need Prop advice 180 with 4.3

Bowtie Mike, I'm new to prop discussions, but I posted my story a week or two ago about my prop change results. I've learned that there are general rules about prop pitch, (200 rpm drop per inch) but when you change prop manufacturers and designs, surprises are not uncommon. My 18' Chaparral (2100 lbs empty) also has the 190 hp 4.3. I had a 21" aluminum turning 4800 rpm (may have been hitting the rev limiter on mine) and wanted to try a 23". I tried a 25" Laser II stainless (long story why) and my rpm only dropped to 4600 and my speed jumped about 4 mph (58 speedo, probably 46 GPS) I would have expected much more drop by adding 4 inches pitch and a cupped stainless prop. Read my post for the details. I think I'll eventually put a 23" on it.
What drive ratio is your alpha one? Mine is 1.81. I believe a high ratio will sometimes allow a steeper prop. That may be why mine worked fine with a 25".

 

[bowtie4x4295]

Re: Need Prop advice 180 with 4.3

I am almost sure mine is a 1.81, which I think I am turning so many rpm's. I rechecked it this weekend. With a minimal load it will do 5200-5300 rpm, I have to pull it back to get it to 4800. I am thinking a 14in 23p SS like the Laser II would pull me back where I need to be. 200 for the swap to SS and 200 for the jump from 21p to 23p. It pulls like a tractor from a dead stop.

Mike

 

[Tail_Gunner]

Re: Need Prop advice 180 with 4.3

http://forums.iboats.com/showthread.php?p=1682899&highlight=Laser#post1682899


Quote:
Originally Posted by walleyehed
Dern-it TG, I wanted to give my input....
I wanted to say I thought you would likely be disapointed...the Laser is good on light, fast boats such as Bassboats of light design.
I tried one on the I/O Glastron in the garage...just couldn't get it to hook good enough to justify using it. It just does NOT work well on any boat with much for weight to the rear-end.

Agreed but it was cool at first to here that 4.3 spin up and roar like i was going some where in a big hurry...but nope notta.. Now just what does a guy do with a 22p laser with a flow tourqe hub not even a blemish on it...and it dont work on his boat... god the agony.......
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[180shabah]

Re: Need Prop advice 180 with 4.3

Just gonna through another option out here. Does it have to be Stainless?? A turning point Hustler is a great aluminum prop with more rake and cupping than usually found on Aluminum props. It is vented(also not usually found on Aluminum props) to give great hole shot and it costs less than half of any SS prop out there.

I have a shifting prop now, but I carry the Hustler as a spare, or to use when we go to shallow or unfamiliar water.