Need New Prop for 2012 Tahoe Q5i SF

pilot4net

Seaman
Joined
May 24, 2005
Messages
57
Good morning everyone, I am looking for a new prop for my '12 Tahoe Q5i SF with the 4.3L MPI 220 HP Mercruiser with the Alpha I Gen II outdrive . I am pretty sure the final drive ratio is the 1.62 and the prop from the factory is the 21p aluminum.

With the factory prop, the holeshot is pretty sluggish and is the main thing I would like to improve with the new prop setup. While I do want a better holeshot, I also want to maintain a good WOT top end speed. Now, in smooth water, trimmed out to the point where the speed no longer increases but rpms do (and prop will eventually blow out), I can get around 4900-5000 rpms at around 45 mph (gps). Sometimes when trimming up looking for top speed, I can bump the rev limiter and have to trim down just a tad.

Mostly, we use the boat for cruising with 3-4 adults and a couple of kids. During the summer months we will throw a tube or wakeboard in the water for the kids or young adults to have fun on. As expected, performance from the original prop during these watersports activities is rather poor with the boat heavy loaded.

So, in conclusion, looking for a better stainless prop to provide a better holeshot and good top end performance. I have been told that the High Five is very popular amongst watersports enthusiasts but I'm not sure we need that many blades in the water since we are not into watersports that often. I am thinking a 4 blade prop with a slightly lower pitch might do the trick but not sure which prop would be the best as there are LOTS of props like this.

I have heard lots of people say the Rev4 is an awesome prop as well as the Enertia, the Vensura, and the High Five but I am looking for some of your opinions who have similar boats and similar power plants to try and make the best decision.

Thanks for everyone's help here and look forward to hearing everyone's thoughts.

Thanks!!
 

Starcraft5834

Lieutenant Commander
Joined
Jun 2, 2013
Messages
1,677
Re: Need New Prop for 2012 Tahoe Q5i SF

"in conclusion, looking for a better stainless prop to provide a better holeshot and good top end performance".

your own conclusions are accurate.. 4 blade with less pitch...... I think you will get what you are looking for. 4 blade = hole shot increrase, on plane quicker, better steering at lower speeds, your top end speed will go down a few mph... overall, I believe a 4 blade benefit superior to a 3 blade overall......... 4900-5000 rpm? that seems a bit to high for that motor, I think your spec is 4600-4800 ish.. a 4 blade with say 17 pitch should bring you down to 4500-4600 and hum along nicely..........
 

dan02gt

Chief Petty Officer
Joined
Aug 30, 2012
Messages
463
Re: Need New Prop for 2012 Tahoe Q5i SF

You're really only getting 45MPH out of that setup? If you're really turning your motor 4800-5000RPMs your prop is slipping like crazy. You should be seeing at least 50MPH with that boat. You may want to have that tach checked out.

I run an Enertia and like it. Hole shot is good but not great, mid range and top end is great.
The Rev4 is a big boy prop and is really to much for our little 4.3L MPIs so I would stay away from that.
The High 5 is a great water sports prop but lacks in mid range cruise efficiency and top end.

If you want to try a 4 blade the Powertech SFS4 is a great prop from everything I've heard. I would go with a 19P for what you want to do. It should greatly improve you're hole shot and mid range. It's also going to slip a lot less than your aluminum 3 blade so you should see a nice bump in top speed with a decrease in RPMs.
 

pilot4net

Seaman
Joined
May 24, 2005
Messages
57
Re: Need New Prop for 2012 Tahoe Q5i SF

Yeah, I agree that I should be seeing more out of current setup but I think that the tach is reasonably accurate since the rev limiter is supposed to kick in around 4950 or so (according to dealer and what I have read in Mercruiser's literature) and the rev limiter kicks in right about 5000 RPMS on the tach. The RPMS range where I stop seeing 'real' speed increases is probably around 4500-4600 and increasing to just before limiter only gives me maybe 0.5-1.0 mph gain. What pitch Enertia are you running Dan and what kind of performance are you seeing with it...

I am talking back and forth with Ken and he is suggesting the SFS4 also.

Anymore thoughts or suggestions are welcomed!

Thanks!
 

dan02gt

Chief Petty Officer
Joined
Aug 30, 2012
Messages
463
Re: Need New Prop for 2012 Tahoe Q5i SF

pilot,

I run the 21P Enertia. With 2 adults and 30 gal of fuel I see 55-56MPH on the GPS with the motor turning 4700-4800RPMs (taken from Mercury SmartCraft). The Enertia carries a load pretty good and I typically see 53-54MPH with 4 adults on board. The hole shot is good but not great.

I'm thinking adding a 4 blade to my prop "collection" and will be getting the SFS4 from Ken also. I want to use it for heaver loads (6+ people) and/or rough water. I'm torn between the 19 and 20P for the SFS4.
 

jestor68

Commander
Joined
Jun 12, 2012
Messages
2,308
Re: Need New Prop for 2012 Tahoe Q5i SF

I'll refer you guys to the test of a Tahoe Q5 on the Mercury web site. Their results were 51 mph @ 4800 rpm using a 21 Black Max with a 1.81 ratio equaled 5% slip.

Your numbers don't add up to a 1.62 ratio. In fact, the recommended pitch with that ratio would be 19 to achieve a similar speed, rpm, and slip number.

Is your prop damaged in any way? Are you trimming up too high and causing slippage, which would result in higher rpm with a lose of speed.

Granted, the testing was done with just the tester in the boat and you're hauling a few hundred pounds more weight. That might cause you to lose a couple hundred rpm(4600?) and a couple mph off the top speed.

I might suggest you try a Solas or TP aluminum 21 pitch before before sinking $500 in a fancy SS prop.

You might be pleasantly surprised at the improvement. All aluminum props are not created equal.
 
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koolkat

Recruit
Joined
Jul 3, 2013
Messages
3
Re: Need New Prop for 2012 Tahoe Q5i SF

pilot,

I run the 21P Enertia. With 2 adults and 30 gal of fuel I see 55-56MPH on the GPS with the motor turning 4700-4800RPMs (taken from Mercury SmartCraft). The Enertia carries a load pretty good and I typically see 53-54MPH with 4 adults on board. The hole shot is good but not great.

I'm thinking adding a 4 blade to my prop "collection" and will be getting the SFS4 from Ken also. I want to use it for heaver loads (6+ people) and/or rough water. I'm torn between the 19 and 20P for the SFS4.
 
Last edited:

koolkat

Recruit
Joined
Jul 3, 2013
Messages
3
Re: Need New Prop for 2012 Tahoe Q5i SF

pilot,

I run the 21P Enertia. With 2 adults and 30 gal of fuel I see 55-56MPH on the GPS with the motor turning 4700-4800RPMs (taken from Mercury SmartCraft). The Enertia carries a load pretty good and I typically see 53-54MPH with 4 adults on board. The hole shot is good but not great.

I'm thinking adding a 4 blade to my prop "collection" and will be getting the SFS4 from Ken also. I want to use it for heaver loads (6+ people) and/or rough water. I'm torn between the 19 and 20P for the SFS4.
 
Last edited:

koolkat

Recruit
Joined
Jul 3, 2013
Messages
3
Re: Need New Prop for 2012 Tahoe Q5i SF

pilot,

I run the 21P Enertia. With 2 adults and 30 gal of fuel I see 55-56MPH on the GPS with the motor turning 4700-4800RPMs (taken from Mercury SmartCraft). The Enertia carries a load pretty good and I typically see 53-54MPH with 4 adults on board. The hole shot is good but not great.

I'm thinking adding a 4 blade to my prop "collection" and will be getting the SFS4 from Ken also. I want to use it for heaver loads (6+ people) and/or rough water. I'm torn between the 19 and 20P for the SFS4.

You have a special boat there,21p/ 4700-4800 rpm/ 55 to 56 mph? ya right. i have tried all the enteria props same boat and thats never going to happen..maybe on the dream meter but not on a real GPS. The best i have ever seen is a true 50mph at 7 percent prop slip.
 

dan02gt

Chief Petty Officer
Joined
Aug 30, 2012
Messages
463
You have a special boat there,21p/ 4700-4800 rpm/ 55 to 56 mph? ya right. i have tried all the enteria props same boat and thats never going to happen..maybe on the dream meter but not on a real GPS. The best i have ever seen is a true 50mph at 7 percent prop slip.


Um Ok I think we're not understanding each other here. I have a Stingray 198LX is that what you have? Or do you have a Tahoe Q5i. The Stingray has a faster hull than a Tahoe PERIOD!! My number are right in line with all the other Stingray owners on the Stingray owners site. There is nothing magical about them. I have a 21P prop with a 1.62 Alpha 1 outdrive. 56MPH @ 4700RPMs is 7% slip (adding 1 to pitch to account for cupping). I only used my boat as an example for the OP to have something to compare to as far as props are concerned.

If you're getting 7% slip with a 21P and running 50MPH you don't have a 1.62 ratio outdrive you have the 1.81 ratio and your number are right where they should be for a Tahoe Q5i.
 
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