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5 blade EX vs 4 blade SW

Hayes96

Member
What is everyone’s opinion on the 5 blade props? Currently running the 5 blade 78” 2.0 on a 572 bbc at 17.5° @5000rpm and I don’t feel the prop speed is in the sweet spot of the 2.0 blade(2200-2700). My prop speed is 2100-2150 with a 2.3:1 reduction WOT. I have the option to go to the 5 blade 79.5” EX or go to a 79” 4 blade SW. I’m looking for low end push as primary goal. 6EECF43A-D555-4649-9941-B390BFB374F2.jpeg
 
Hayes96,

A little late to the reply on this, and some of my response/info is going to be cut and paste from another post I made.

Bottom line is Darrin at Sensenich is a great resource. Or give whirlwind a call. Both have been super helpful over the years with different airboats and props I have had. A little info on my boat below.

On the dyno my engine came in at 1143 peak TQ at 4300 rpm. 1119 peak HP at 5900 rpm, 93 octane. I told the builder to focus on 5400 rpm as maximum, turning 5 JX blades and a 2.55 box at Darrin’s recommendation over at Sensenich.

My Alaska/Utah boat is prob around 4,000 lbs all in with couple of guys, gear and 50 gallons of gas. It runs dry very well. I have the blades pitched for push not speed at 20 degrees. Max speed is 60 mph at 5,000-5,100 rpm.

When I was having this boat built at the end of 2019, the team at DB was split down the middle on 4 v 5 blade. 4 blades grabbing "cleaner air" v 5 blades and more surface area. Which is where I decided to pick up the phone and call Darrin.

In my reading, more and more boats pushing 4 or 5 blades are using 2.5 or 2.6 reductions v 2.3. So I would also be open to that conversation.

I also found that the sweet spot for (maximum low end push) for my current build is having the props pitched at 15, whereas I initially had them at 20.

PM me if you would like further conversation.

Pato Sicario
 

Hayes96

Member
Hayes96,

A little late to the reply on this, and some of my response/info is going to be cut and paste from another post I made.

Bottom line is Darrin at Sensenich is a great resource. Or give whirlwind a call. Both have been super helpful over the years with different airboats and props I have had. A little info on my boat below.

On the dyno my engine came in at 1143 peak TQ at 4300 rpm. 1119 peak HP at 5900 rpm, 93 octane. I told the builder to focus on 5400 rpm as maximum, turning 5 JX blades and a 2.55 box at Darrin’s recommendation over at Sensenich.

My Alaska/Utah boat is prob around 4,000 lbs all in with couple of guys, gear and 50 gallons of gas. It runs dry very well. I have the blades pitched for push not speed at 20 degrees. Max speed is 60 mph at 5,000-5,100 rpm.

When I was having this boat built at the end of 2019, the team at DB was split down the middle on 4 v 5 blade. 4 blades grabbing "cleaner air" v 5 blades and more surface area. Which is where I decided to pick up the phone and call Darrin.

In my reading, more and more boats pushing 4 or 5 blades are using 2.5 or 2.6 reductions v 2.3. So I would also be open to that conversation.

I also found that the sweet spot for (maximum low end push) for my current build is having the props pitched at 15, whereas I initially had them at 20.

PM me if you would like further conversation.

Pato Sicario
I went with a 80” 5 blade EX from whirlwind and love it. I turn it 5200 rpm at 15° with 2.3:1. 700hp 572 at 5200
 

SWAMPHUNTER45

Well-known member
Dagwood would probably have told you to try the 3 blade JX to start. Dyno # can be a mystery.

Sensenich probably would have
Offered you a $ for $ swap on the hub if you needed a 4 blade version and then just add a blade.

Proof is in the prop

If you need more push
The Kevlar JX race blade is snappy if you have the numbers you say.

I mean snappy !

Ask my how I know
 
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