The best Prop to buy ?

[Gringo69]

Hey guys,

looking to buy a new prop but not sure what to buy... I have a STV Pro Comp with a Merc 2.5 with the fat shaft and bobs nose cone (pics in my profile page) . I have run a Mazco RE4 28p and a Mazco RE3 27p, I am thinking I would like to try a clever or chopper type prop...looking for top end speed any suggestions on what I should buy brand, type, pitch ect .....also if anyone has a used one for sale that would be great.

[Dave Strong]

I would try to find a 28 ET to try, being as you altitude is somwhere around 12-1400' cleavers may not work the best. This is what I found with Cougars running at Salmon Arm, guys that came up from sea level didn't like how cleavers worked at altitude. But you just have to try a few to know for sure.

Dave

[Euroski]

Mercury 14.5 x 30p lab cleaver should run 107 with a 260/280!

[lance]

On the comment that cleavers don't work well on Cougar's at high altitude, I assume this is due to reduced aerodynamic hull lift at altitude. I've never really seen this mentioned. Usually horse power loss is just addressed with altitude.
I run a 21' Checkmate that traditionally needs lots of bow lift at sea level for max speed. I'm at 5000 ft and I've found that I need to use a huge amount of engine set back and props with lots of tip cup to get any bow lift and speed.
Maybe I should start a new post, don't want to highjack this thread.

[Dave Strong]

You have it Figgured, 5000' is a huge handicap. The rules still apply, I found every 1000' in altitude =2" in pitch. Plus as you go up in altitude props that have bow lift help. This boat is running around 1200' so would think an ET would be a good prop, little chopper and a bit of cleaver.

Dave

[Dave Strong]

The thing is as you go up in altitude 3 things happen, less horsepower, the water gets softer=less hydrodynamic lift,air gets less dense =less aerodynamic lift. What works around sea level does not work at altitude.

Dave

[whipper]

The thing is as you go up in altitude 3 things happen, less horsepower, the water gets softer=less hydrodynamic lift,air gets less dense =less aerodynamic lift. What works around sea level does not work at altitude.

Dave

Yep well said Dave.

5000 ft is on the extreme side of lakes to boat. You will never be as fast as other boats at lower elevations with the same power. There is threads on this as i have been battling this also. Im only at 2400-2600ft but same thing just not as bad. There are a couple of things that will {help} but again they just help. one thing is that everyone on the same lake has the same issue. Thats good to know in a race. It equals things out relative to any lake.

How i combat the thin air was a few ways. Add more air to the engine. I drilled 15+ holes in the cowl trying to induce more air into the induction. This really helps. Because you loose compression at altitude in my case 10psi. I put a set of 33cc heads on to get back some comp. I went from 120 across the board back to 130-135 stock comp with the tighter heads. I put a brucato adjustable acu on so I could fatten up the fuel curve to feed the heads more fuel to take advantage of the lower cc and the acu also came with a raised limiter. It takes more HP to turn a bigger prop to higher rpm for speed at any level from sea on up. The raised limiter allowed me to turn smaller props at higher rpm to achieve respectable speed and the Tighter heads assured good low end grunt with fattened fuel curve and the faster I go the more air I induce with mid range and top end curves adjusted to take advantage of the increased air the motor is getting also. This combination at 2400ft turned my 6400 rpm with a 30 pitch 89mph Allison with a 225pm to a 95mph boat at 7300 rpm with a 28 pitch prop. Regularly over 90 with a 26. 97 at 1000ft above. These numbers are more consistent with stock power at sea level with my setup. So at least I was able to achieve close to stock performance at 2400ft above with a few mods geared toward the altitude issues. The lowest elevation i have ever boated with my setup was 1000ft above at Kalimalka lake.I have to richen up the acu to run there or im way to lean.

So at 5000ft the best way to combat altitude would be over kill HP to at least get you to were a less hp setup runs. Then if ya hit the lower lakes your setup would be sick!! if you keep the same motor and want to get as good as you can these are the things i did to give me better performance. im sure SVS would also be a great addition but never tryed it but talked to guys in the same boat that said it also helped. Before I spend any more on this setup Ill get more HP 300+. Left stock that MIGHT get me performance in the 280 range and that would be just fine by me. Seting a motor up like i did takes alot of time testing differant things like plug reads ALOT!!! And head temps ext.. An EGT would have made things way simpler to tweek the acu and how my holes to drill. It took me a long time lets just say that before i was happy.
Simple answer. Buy the biggest badest motor that fits your boat. Then even at 5000ft you will have decent performance.

Your altitude is so extreme you would have to be carefull doing my approach if you ever boat at 2000ft or less!! My 33cc heads are fine anywere. You would need to go way tighter like 30 or even maybe 29cc to get your comp back. Then you have to feed them with the right fuel curve. Get your air mix setup and off to the races. BUT at say 2000ft or sea level for instance you end up with a full on high strung setup that has reduced longevity if not properly monitored and adjusted correctly for the big change in air density.

[whipper]

oh snap HIGH JACK sorry got carried away. Agree with Euroski... 30 Cleaver and or Dave ET both seem faster from what Ive heard and read on an STV than RE,s.

[lance]

Sorry to Gringo69 the initiator of this thread. Its his first post here! Thanks for the replies Dave and Whipper.

A few more details on my setup....I run a Checkmate 21' Pulsare 2100BR openbow. Generally at sea level, under optimum conditions, light load, 14" set back, low 90's are possible using a 300XS with this boat. I run a Yamaha 3.3 HPDI, HydroTec Phase III, Merc 1.62 Sportmaster, and 18" set back. My best at 5000 ft altitude is 80 mph using a 24" Promax prop. This is with 2 passengers, a trolling motor, extra 100# battery, and fishing gear. My max speed requires both passengers to sit in the back seat and I have to run max trim. I have a power jack plate so I've experimented with the prop shaft from 2" below up to 2.5" above the pad. I've also tried 10-15 different props.

The reason I've jumped on this post is that I've never felt like the bow is really lifting well and I've wondered if altitude effects lift as well as horsepower. I fish and waterski with the family so I never get a chance to run light and I've never had this setup at lower altitude. Since I max out the trim for best speed, I'm going to try trim extenders just as an experiment. I know dragging a sportmaster through the water at angle should slow you down but for whatever reason it works for me?

[Gringo69]

I found this prop and the price is right even gave Hill Marine a call and I can get it in a 30p....any thoughts ?
http://www.ebay.com/itm/Signature-Ou...-/151143711371

[whipper]

I found this prop and the price is right even gave Hill Marine a call and I can get it in a 30p....any thoughts ?
http://www.ebay.com/itm/Signature-Ou...-/151143711371

Though a 3 blade would be faster that is a sweet prop at a decent price. i would still wait and talk to more guys with your setup if top speed is what your after that one probably wouldn't be the best choice. Might be a decent all ronder but your Mazcos are probably better all rounders than that 4 blade cleaver. Do a search on hear fastest STV prop. Theres a million threads on that im sure. Find the setup closest to yours and see what there running with good results. And welcome to scream and fly..

[whipper]

Sorry to Gringo69 the initiator of this thread. Its his first post here! Thanks for the replies Dave and Whipper.

A few more details on my setup....I run a Checkmate 21' Pulsare 2100BR openbow. Generally at sea level, under optimum conditions, light load, 14" set back, low 90's are possible using a 300XS with this boat. I run a Yamaha 3.3 HPDI, HydroTec Phase III, Merc 1.62 Sportmaster, and 18" set back. My best at 5000 ft altitude is 80 mph using a 24" Promax prop. This is with 2 passengers, a trolling motor, extra 100# battery, and fishing gear. My max speed requires both passengers to sit in the back seat and I have to run max trim. I have a power jack plate so I've experimented with the prop shaft from 2" below up to 2.5" above the pad. I've also tried 10-15 different props.

The reason I've jumped on this post is that I've never felt like the bow is really lifting well and I've wondered if altitude effects lift as well as horsepower. I fish and waterski with the family so I never get a chance to run light and I've never had this setup at lower altitude. Since I max out the trim for best speed, I'm going to try trim extenders just as an experiment. I know dragging a sportmaster through the water at angle should slow you down but for whatever reason it works for me?

i would try a 28 drag 4 with that setup. They lift well real well. Also Give Todd Buck at Hydromotive engineering a call. He could also hook you up with a great prop for your setup. Sick motor Phase 111 NICE!!!! I guess your maxed out I would say. Props is the only place to look for speed and or lift with that setup. Some times with a heavier setup smaller wheels like 24 pitch dont lift as good i found. 26 Off shore i found to lift good and 28 drag4,s for sure lift great. Randy has done lots of testing with Drag4 props on your hull with 300xs motors at sea level with great results. Though at 5000ft you wont maybe get as fast with your motor you might still do better than the 24 pitch and lift better with a 28 drag. I wouldnt rule out a 26 off shore that Steve Smith makes also. the one i had took off like a pitch down and top speed like a pitch up. Might be worth trying also on your setup at 5000ft.

[pearlriverrat]

Depending on how much H.P. For top end 30-34 cleaver or 30-32 ET. 3 blade not 4

[Spinelli Propellers]

If you want the fastest prop and for it to stay together I recommend the Spinelli Bros. DR4.
Call me to go over your boats set up.
All my custom built props come fully blue printed, balanced and polished.

I will continue to tune it for free (you pay shipping only) for 60 days after purchase if I don't hit the nail on the head and comes with a one year materials warranty.

[pearlriverrat]

This should do you a little better than what you listed

http://www.screamandfly.com/showthre...-Lightning-P30