2007 Tahoe Q7sf need new prop

[GoneHuntin]

Recently purchased this boat
20ft 6 inches
mercrusier 4.3l alpha one 190hp
4400 at WOT with just me and 3/4 tank of gas
39 mph gps
current prop that came on boat was told that was 14.25 x 21 3 blade aluminum
the current prop has been dinged and shaved on by former owner
future upgrades
smart tabs which i had on my 98 tahoe q4 in the past

current issues -
holeshot is not good
want to plain at lower speeds(smart tabs should greatly help)
prop seems to lose traction in corners
I am on the very bottom of my WOT recommended range which is 4400 to 4800

improvements looking for -
I would like to get my WOT up closer to the top of the range 4700 - 4800
I definitely want better holeshot and lower planing.
I want the prop to stay hooked up in the corners etc

I would think with my WOT at 4400 i should be able to accomplish what I want without losing any top speed or maybe gaining top speed as I still have 300 rpm to play with.

I was thinking a four or five blade prop but wondering which pitch in those options since I can raise my rpms some.

Thanks

 

[GoneHuntin]

Re: 2007 Tahoe Q7sf need new prop

bump

 

[craze1cars]

Re: 2007 Tahoe Q7sf need new prop

My best random guess:

4 blade, 19 pitch, 4 blade Solas Amita or Titan (aluminum vs stainless....you don't specify your preference)
4 blade, 18 pitch, 4 blade Stilletto (available in stainless only)

There is a chance you will need to drop to a 17 pitch in the Solas....that 19 might not bring your RPMS up high enough. However I fear a 17 will over-rev. The fact that your current prop has been modified, has some damage, and is possibly NOT a 21?? (you don't sound real confident that it's a 21). That data makes a solid recommendation difficult...

A local prop shop or marina that will permit you an exchange option or test drive would be my #1 recommendation. Mail-order guessing can be very expensive if you don't get lucky on the first attempt....

 

[GoneHuntin]

Re: 2007 Tahoe Q7sf need new prop

I will get the specs off the prop next time i am at the boat. I know it is the stock prop that came with the boat and that is what the specs are that i got from tracker. It seems like i should be getting much better top speed out of this boat when compared to tests i have read about the same set up. It appears there is alot of slip with current prop.

 

[craze1cars]

Re: 2007 Tahoe Q7sf need new prop

It appears there is alot of slip with current prop.

Nicks, dings, bumps against rocks, and subsequent home-file repairs will indeed create a lot of slip in an prop that may have been biting well before it was messed with...and it may have a different pitch than it used to have....it's easy to "move" a prop blade and acutally change the pitch with a single impact.

Knowing the pitch stamped on the prop can be helpful, but may be a bit meaningless depending on the extent it has been modified from original.

Have you actually calculated slip? Need your drive ratio to do it...

 

[GoneHuntin]

Re: 2007 Tahoe Q7sf need new prop

A little more info the prop is 48-832832A45P21 which is 14.25 x 21P. The drive is 1.81. I appear to be around 21% on the slip which seems really high.

 

[GoneHuntin]

Re: 2007 Tahoe Q7sf need new prop

So after doing some research I am guessing the concept is if went to
4 blade 21p then WOT would probably drop to 4200-4300
4 blade 19p then WOT would probably be around 4500
4 blade 17p then WOT would probably be around 4800
or are my figures off.

The other option I was looking at was a high 5 but would not really know where to start with that one. It appears that the 1.81 was the high altitude option which is not normal for this area so not sure how guy I bought the boat from ended up with it.

 

[craze1cars]

Re: 2007 Tahoe Q7sf need new prop

Those sound like reasonable educated guesses.

Only a test drive can answer for sure. I have no experience with High 5 so I cannot offer any assistance there.

 

[GoneHuntin]

Re: 2007 Tahoe Q7sf need new prop

Anyone have an idea what a high five or similiar prop would do in my situation?

 

[GoneHuntin]

Re: 2007 Tahoe Q7sf need new prop

Well I decided to go the cheaper route and got a solas rubex 14.5 x 17. If it over revs they will let me bring it back for exchange. I should get it out this weekend. I also installed my smart tabs today as well.

 

[Pierutrus]

Re: 2007 Tahoe Q7sf need new prop

I just came upon this and I've basically have the same setup except mine's a 19'.
I have 3 props for my boat..........Different reasons for all 3.
The one that came with the boat was the 14.25"x21p aluminum which puts it at about 5100rpm@ 52mph gps depending on the outside temp and elevation.
Then the second is a 3 blade SOLAS 14.25'x17p stainless which is for pulling fat arse skier's out of the water..........Man, that one will jerk their arms out if your not careful. The hole shot is unbelievable, but the WOT is around 5600rpm, so you have to watch it. This is not the cruising around prop........
My "just" cruising around prop is a 14.25x22p aluminum that does about 47mph @ 4500 rpm's. This prop gives me the best gas mileage for some reason. Don't care with the price of gas these days!
I would recommend going back to a "brand new" stock prop to see where you are.
You can get a 14.25x21p aluminum for about $110 delivered to your door.
Just to see where your at.