Revolution 4 vs High Five

[Tafflad]

I have a 20' runabout with 4.3L MPI
1:62 Aplha drive
All up wgt is 4040lb

It originally had 20" 4 blade Aluminium prop.
Use is for wakeboarding /skiiing / kneeboarding / hydrofoiling, all at recreational level only.

So interested in holeshot, ability to plane easily and keep on plane at low speed, plus help keep a consistent speed.
Most of work is 18-22 mph .... and occasionally skiing at 26-28mph ...... low end pull is more important than top end speed.
All boating is in-shore salt water.

On suggestion here I have put on a Rev 4 of 19" pitch ......
Mercury website & video seems to pitch this more at midrange off shore performance, is a High Five going to be better prop for my needs ?
Amazed at difference in size & weight, Rev 4 is almost double the weight.

I only want to keep the one prop ... so appreciate the advice.

 

[steelespike]

Re: Revolution 4 vs High Five

No help yet? I'll give you my limited knowledge.
While a ss prop will usually give the best overall performance the question is how much better when there a al props at about 1/3 the cost that deliver close to ss performance.
The rev 4 is a stainless prop so much heavier than the al prop.
Prop weight doesn't affect performance.
I'm pretty conservative so I wonder if the difference from a rev 4 is worth the investment
in a g High 5
I also believe the High 5 does better on high performance boats.
How did the rev4 compare to the al 4 blade?
What brand al prop was it?
Perhaps my post will draw others out.

 

[Tafflad]

Re: Revolution 4 vs High Five

The 4 blade was Mercury.
Rev 4 gave better Holeshot, and seemed to hold speed more consistently, I have picked up a High Five of eBay, just wondering which to keep.
If there is any specific test I can do other that WOT and time to plane?

The Rev 4 is huge compared to High Five ... and double the weight ... both of which may be good for holding speed better, but will it hold back holeshot as it's only a V6

 

[jestor68]

Re: Revolution 4 vs High Five

I have not seen any performance numbers, so it's hard to guess at what prop might be best. Mercury bills their 5 blade as the king of acceleration for water sports. It is not a high speed prop.

For your intended use, you'll want to prop to achieve 4800 rpm at WOT; no matter what prop you choose, as this will provide the best acceleration and speed holding at the speeds you'll be using.

So let's start there. Give us some numbers.

 

[Tafflad]

Re: Revolution 4 vs High Five

OK ... some numbers ..

Original Aluminum 4 blade 20" pitch
WOT 4800 44mph
----------------------
Changed to Rev4 19"
WOT 4260 44mph

I don't have figures yet for High Five

Have swapped props over will have numbers for that next week.

 

[Tafflad]

Re: Revolution 4 vs High Five

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[Ming15237]

Re: Revolution 4 vs High Five

Judging by your results the Rev4 prop is too steep a pitch for your motor. If you can only achieve a rpm of 4200 you are lugging the motor and that is VERY BAD to do.

 

[Tafflad]

Re: Revolution 4 vs High Five

What do you mean by 'lugging' .... do you mean too much load on the drive ?
The prop is a big heavy item (twice weight of High Five)

OK ... have changed to the High Five, will test that on next outing.

 

[Ming15237]

Re: Revolution 4 vs High Five

It's too much load on the engine, the engine is ment to operate at max rpm's which for your application is 4800rpms, if the rpm's went down with the new prop and can only achieve 4200 rpm's you are. Overproped and overloading the engine, this is a very bad thing to do the engine and is a very good way to damage the engine and most importantly the crankshaft, lugging the engine is the worst thing you can do to it!

 

[Tafflad]

Re: Revolution 4 vs High Five

So even though I dropped pitch, by an 1" which should have increased RPM by about 150, the fact it didn't, does this point to Rev 4 being too heavy for 4.3L. ?

 

[Ming15237]

Re: Revolution 4 vs High Five

So even though I dropped pitch, by an 1" which should have increased RPM by about 150, the fact it didn't, does this point to Rev 4 being too heavy for 4.3L. ?

When you say "heavy" if you are referring to the actual weight of the prop, that has virtually nothing to do with your issue, if by "heavy" you mean pitch of the blade you are correct. But please read the sticky in the prop section where you give us specifics of your boat. There are many on here that a MUCH more knowledgable than I am on this matter. I am simply stating if you lost 600 rpm's something is not right, and if the prop is the only thing you changed, the prop is to high a pitch for your application.

 

[Tafflad]

Re: Revolution 4 vs High Five

I'm just trying to understand.
I had a 20" 4 blade Al
Changed to a 19" 4 blade ss.
Yet rpm did not increase.

Be interesting to see what figures I get for the High Five.

 

[Radarman68]

Re: Revolution 4 vs High Five

I'm just trying to understand.
I had a 20" 4 blade Al
Changed to a 19" 4 blade ss.
Yet rpm did not increase.

Be interesting to see what figures I get for the High Five.

Going from 20" DOWN to 19" pitch, with both 4 bladed props, all other things being equal, should have increased your WOT RPM ~150-200 RPM. Since you DROPPED RPM, something is not equal. you either have a super cup 19, and/or the 20 is very worn and/or bad hub.

getting info on the High Five will help zero in on things.

 

[Tafflad]

Re: Revolution 4 vs High Five

OK .. just did test on 19" pitch high five ...
Same loading on boat.

WOT 4860 (fully trimmed out) 46 mph

 

[jestor68]

Re: Revolution 4 vs High Five

The reason your rpm dropped with the REV 4 is due to the blade design(off shore application) and about double the amount of cup. Plus, the SS prop is more efficient(better grip) than the aluminum prop.

That's not the appropriate prop for your boat.

The "lugging" mentioned earlier refers to the fact that your rpm range is 4400-4800 rpm at WOT. The REV 4 pulled the rpm below 4400, which is the minimum for your motor.

Since the "5" got you back up to peak rpm, it sounds like that one is more appropriate for your application; good acceleration and speed holding.

 

[Tafflad]

Re: Revolution 4 vs High Five

It certainly seems to be better suited ... behaved well, had much better holeshot ....
So one Rev4 to go on eBay methinks.

 

[jestor68]

Re: Revolution 4 vs High Five

You might want to verify the accuracy of your tachometer, since the Mercury prop selector is calling for 17 pitch in those prop categories with your 4.3L engine with 1.62 gear ratio, and the weight specified.

It calls for a 19 pitch if I plug in a V-8 engine.

You can stop any dealer and have them use their shop tach to verify the accuracy of your tach. Generally, if the tach is off, the error becomes greater as the rpm goes up. I mention it because the Mercury prop selector indicates about 4600 rpm with the 19 pitch "5", and you're indicating 4800.

Sometimes, cleaning the contacts on the back of the tach helps to get things working correctly again.

 

[Tail_Gunner]

Re: Revolution 4 vs High Five

Your playing with two different prop designs dont expect the same result's. The high five will hold the lowest plane and the rev4 will get the best top end. Rev 4 are as stated offshore prop's and they also like to run high in the water and your inboard runs deep...

 

[Tafflad]

Re: Revolution 4 vs High Five

You might want to verify the accuracy of your tachometer, since the Mercury prop selector is calling for 17 pitch in those prop categories with your 4.3L engine with 1.62 gear ratio, and the weight specified.

It calls for a 19 pitch if I plug in a V-8 engine.

You can stop any dealer and have them use their shop tach to verify the accuracy of your tach. Generally, if the tach is off, the error becomes greater as the rpm goes up. I mention it because the Mercury prop selector indicates about 4600 rpm with the 19 pitch "5", and you're indicating 4800.

Sometimes, cleaning the contacts on the back of the tach helps to get things working correctly again.

Tacho same on 2 devices ... original OEM Tacho and my GPS Ridesteady Cruise Control.
The former a basic analogue, the latter fully digital.