Another Prop Question

[rs1lollie]

I have a 98 four winns horizon 180 rs 2480 lbs with a 4.3 gl 190hp, a sx outdrive with 1,79 gears and a 18 degrees dead rise
it has a Turning point 14.25 x 21 3 blade on it now. Running 4200 rpm's at 35 mph trimmed to achieve max rpm's and speed, I would think the boat should do over 40 mph, I would like to know what prop size I should try... 20 gal of gas and about 350 lb myself my wife and cooler on board...

 

[Sea Rider]

What's the max wot revs for that OB ?

Happy Boating

 

[Maclin]

That RPM is too low for the engine. If your numbers are accurate then you also have a lot of slip, almost 25%. Just going by the RPM and speed and gear ratio, and if the engine is in a decent state of tune then you need to get a lower pitched prop, start with a 19p. With a normal slip% like 11-12 your combo would be right at 40mph if it can get to 4600 rpm's with the 19.

 

[steelespike]

The 4.3 is rated for 4400 to 4800 rpm. should make close to upper 40s at 4800 with a 21" prop.
Is your speed by gps?Is the prop in excellent condition? Is the bottom clean and smooth.
Motor in excellent tune?
Any currents or tides to deal with?Does the boat respond to up trim?

 

[rs1lollie]

yes speed is from gps, bottom is clean and smooth, fresh water boat. like new prop no nicks or scrapes, rpm's are from dash gauge, dealer i bought it from put a new long block Jasper engine last year, with about 10-15 hours on it. I have all receipts from the repairs. starts and runs fine. going to check that throttle cable is adjusted and opening the butterfly's all the way, also plug wires don't look new along with distributor cap, might give it a tune up, (plugs, wires, cap and rotor).

 

[rs1lollie]

Update... Well I gave it a tune up , (plugs, wires, cap and rotor) along with checking the timing. Timing was WAY off at 14 degrees BTDC should be at 1 degree BTDC... I believe the mechanic that installed the new long block jasper engine, did not use the timing shunt that is required to time a Volvo 4.3gl. It runs like a new boat now, starts without giving it any throttle and quick throttle response, running 4600 rpms at 44 mph, very happy boater now.:joyous:

 

[Maclin]

Yay!

 

[rs1lollie]

now that i have it running like it should, I want to get a 4 blade prop so I can get on plane at slower speed, what size should i get??? turning point props says to use same pitch when switching from their 3 blade to their 4 blade...

 

[89retta]

I have a turning point 21 pitch 4 blade. Excellent prop running it on a 04 Caravelle 187 with the Volvo 4.3 GXI

 

[Maclin]

Follow what Turning Point says, then hit them up for advice if/when what they recommended does not work out.

 

[Sea Rider]

Just for the record, besides less throttle to plane faster and better slow speed while moving around a marina, dock, what plus do you get compared to same standard 3 blade prop. For the equation, both props achieving full wot revs on their respective combos.

Happy Boating