Mercury Revolution 4 Prop Report

[mjw930]

Over the holidays I couldn't pass up an opportunity to buy a 23P Merc Rev 4 prop to try on my 22C. Well yesterday I was able to get out on the water and give it a try and I was pleasantly surprised with the result.

As you can see from the pictures the prop looks daunting sitting next to the 23P Turbo 1 Poodle was gracious enough to let me try last spring (and eventually sell to me at a great price). I wasn't feeling very confident that I would be able to spin it up from just looking at it sitting on the bench.

As I reported earlier, in the "True Lies" thread, I am seeing some very good performance from the Turbo 1 but there are some downsides. The most notable is vibration. Throughout the cruising rev range this particular Turbo 1 induces some significant vibration, enough in fact for me to consider taking a look at the coupler and verifying my drive alignment. The other handling quirks with the Turbo 1 is a propensity to porpoise at cruise speeds if too much trim is applied and a significant list to starboard when you back off the throttle for no wake zones. However, these are not significant issues and some of them, like the porpoise and listing are as much an issue with hull design as the prop.

The Rev 4 was a hit from the first time I popped the boat up on plane. Time to plane was pretty close with the drive tucked in but I found it interesting that with the drive trimmed to level it popped up on plane (nosed the bow over) almost a quickly. Trim required at slower cruising speeds was less than the Turbo 1 or a Cleaver with neutral being the sweet spot. Anything above neutral trim below 40 mph would introduce porpoising which wasn't surprising considering the bow lif this prop provides. With the modest trim and its ability to pop up on plane with neutral trim it all but eliminates playing with the trim between no wake zones and the 35 mph intermediate zones we see on our local rivers.

Performance at fast cruise was stellar. The prop maintains a very impressive slip performance of roughly 6% from 2500 RPM through 3500 RPM and drops to below 6% from 3600 RPM to WOT of 4600 RPM (see below).

RPM Speed Slip
2500 34 6.34%
3500 48 5.55%
4000 55 5.30%
4600 63 5.68%

WOT top speed was roughly equivalent to the Turbo 1 @ 63 MPH with 3/4 tank fuel, 2 passengers and light gear. This was, however, in fresh water vs. the salt water running of the Turbo 1.

At anything over 50 MPH I could not get the boat to porpoise, regardless of trim angle. The prop carries the bow with no problem all the way up to the trim limiter though it will wash out a bit when you get well into positive trim.

I could not get the prop to blow out with neutral trim in even the tightest turns. Set to it's optimal trim for a 50 mph cruise it was rock solid carving the faster turns of the St. Johns River.

For the issues reported with the Turbo 1, the Rev 4 will also porpoise with too much trim at slower speeds but is able to carry the bow at slower speeds than the Turbo 1. It also will list to starboard on rapid deceleration, roughly the same as the Turbo 1 so this is mostly a hull / torque issue and not something you will look to a prop to cure.

And the single biggest thing that will have this prop on my boat 99% of the time, virtually NO VIBRATION!

All in all, if you have a 22C with modest power I think you owe it to yourself to check this prop out. Surf ebay, there are 2 or 3 sellers that have these for under $400.

[smokediver]

hey , thanks for the write up ! I wonder how the new merc. Fury prop would stack up ... 3 bladed much like the enertia with the new alloy ... I would run a rev4 but am a little leary hanging it on an alpha drive .

[Air 22]

Over the holidays I couldn't pass up an opportunity to buy a 23P Merc Rev 4 prop to try on my 22C. Well yesterday I was able to get out on the water and give it a try and I was pleasantly surprised with the result.
As you can see from the pictures the prop looks daunting sitting next to the 23P Turbo 1 Poodle was gracious enough to let me try last spring (and eventually sell to me at a great price). I wasn't feeling very confident that I would be able to spin it up from just looking at it sitting on the bench.
As I reported earlier, in the "True Lies" thread, I am seeing some very good performance from the Turbo 1 but there are some downsides. The most notable is vibration. Throughout the cruising rev range this particular Turbo 1 induces some significant vibration, enough in fact for me to consider taking a look at the coupler and verifying my drive alignment. The other handling quirks with the Turbo 1 is a propensity to porpoise at cruise speeds if too much trim is applied and a significant list to starboard when you back off the throttle for no wake zones. However, these are not significant issues and some of them, like the porpoise and listing are as much an issue with hull design as the prop.
The Rev 4 was a hit from the first time I popped the boat up on plane. Time to plane was pretty close with the drive tucked in but I found it interesting that with the drive trimmed to level it popped up on plane (nosed the bow over) almost a quickly. Trim required at slower cruising speeds was less than the Turbo 1 or a Cleaver with neutral being the sweet spot. Anything above neutral trim below 40 mph would introduce porpoising which wasn't surprising considering the bow lif this prop provides. With the modest trim and its ability to pop up on plane with neutral trim it all but eliminates playing with the trim between no wake zones and the 35 mph intermediate zones we see on our local rivers.
Performance at fast cruise was stellar. The prop maintains a very impressive slip performance of roughly 6% from 2500 RPM through 3500 RPM and drops to below 6% from 3600 RPM to WOT of 4600 RPM (see below).
RPM Speed Slip
2500 34 6.34%
3500 48 5.55%
4000 55 5.30%
4600 63 5.68%
WOT top speed was roughly equivalent to the Turbo 1 @ 63 MPH with 3/4 tank fuel, 2 passengers and light gear. This was, however, in fresh water vs. the salt water running of the Turbo 1.
At anything over 50 MPH I could not get the boat to porpoise, regardless of trim angle. The prop carries the bow with no problem all the way up to the trim limiter though it will wash out a bit when you get well into positive trim.
I could not get the prop to blow out with neutral trim in even the tightest turns. Set to it's optimal trim for a 50 mph cruise it was rock solid carving the faster turns of the St. Johns River.
For the issues reported with the Turbo 1, the Rev 4 will also porpoise with too much trim at slower speeds but is able to carry the bow at slower speeds than the Turbo 1. It also will list to starboard on rapid deceleration, roughly the same as the Turbo 1 so this is mostly a hull / torque issue and not something you will look to a prop to cure.
And the single biggest thing that will have this prop on my boat 99% of the time, virtually NO VIBRATION!
All in all, if you have a 22C with modest power I think you owe it to yourself to check this prop out. Surf ebay, there are 2 or 3 sellers that have these for under $400.

Nice Report:wink:..What engine(HP), drive and gear ratio are u running?

[mjw930]

Nice Report:wink:..What engine(HP), drive and gear ratio are u running?

330 hp 7.4L, 1.5:1 Bravo 1

[Air 22]

330 hp 7.4L, 1.5:1 Bravo 1

Sweet...:wink: Are the speeds you posted gps?

[mjw930]

Did I miss you commenting on a vibration from the Turbo? Can you ship it to me please?

I didn't comment on the vibration because I wasn't sure if it was prop or mechanical and it's not horrible, just very noticeable. I have a balancing rig I use for my motorcycle wheels that I was going to put it on to check weight but I never got around to it. My experience has been that 3 blades have more vibration than 4 blades and I was attributing it to that but it may be out of balance too.

I drop it off @ UPS Monday or Tuesday so you can have a look. I did ground the prop once at low tide but it didn't hit anything hard. I ran a file down the leading edge and it's straight and true so when you see the file marks you'll know what that was. The vibration was the there before that "incident".

Don't get me wrong, the Turbo 1 performs very well, the Rev 4 just does a bit better in MY application.

[BUIZILLA]

what was the speed increase/decrease? at the posted rpm check points?

[mjw930]

Sweet...:wink: Are the speeds you posted gps?

Yes, GPS speeds for WOT and 3500. My Lavorsi speedo for the others accounting for it's measured 2% error.

[mjw930]

what was the speed increase/decrease? at the posted rpm check points?

From my records and memory

RPM Rev4 Turbo
2500 34 30
3500 48 45
4000 55 52
4600 63 63 (bounced rev limiter @ 4700 with Turbo and too much trim)

The Rev 4 carries the bow better allowing be to reach best speed at close to neutral trim between 3500 and WOT. That means I'm using more power pushing the boat forward than trying to carry the bow with trim in the midrange.

Neutral trim @ WOT was 4500 RPM @ 61 mph. Positive trim got me the extra 100 RPM and 2 MPH. Too much positive trim dropped the speed back to 61 but didn't bounce on the limiter (I don't think).

[BUIZILLA]

I've got a 23 Fusion of Grizzly's that with his permission i'll send you to try out

would be very interesting to see what if any difference there is between those 4 blade samples.

[mjw930]

I've got a 23 Fusion of Grizzly's that with his permission i'll send you to try out

would be very interesting to see what if any difference there is between those 4 blade samples.

That's great but I don't know when the next time I'll get out will be so the prop may sit here for a month or so.

Perhaps, if there is going to be a Mt. Dora get together this year we can do some testing there.

[BigGrizzly]

Buiz you do have my permission It may be more prop then he neee. In my opinion the rev4 is THE best prop merc makes. They finally came out with a 25 after the politics subsided on the Bravo1. Smoke As for the alpha, it won't have any issues with the rev 4. Yes most of the times the 4 blade gets rid of some vibration. I am surprised you could feel vibration on a 22 with that combo. There are other options also.but I think your just about there.

[Pismo]

Were the vent holes open or closed up during your tests?

[mjw930]

Buiz you do have my permission It may be more prop then he neee. In my opinion the rev4 is THE best prop merc makes. They finally came out with a 25 after the politics subsided on the Bravo1. Smoke As for the alpha, it won't have any issues with the rev 4. Yes most of the times the 4 blade gets rid of some vibration. I am surprised you could feel vibration on a 22 with that combo. There are other options also.but I think your just about there.

Were the vent holes open or closed up during your tests?

Randy,

Just so you know, I think the vibration issues are mechanical and the difference between the 3 blade and the 4 blade just masks the issue. There's still a vibration I feel in the wheel but with the 4 blade it's a higher frequency and lower amplitude which makes sense considering the extra blade. The vibration with the 3 blade is noticeable by my wife in the passenger seat, she said she didn't feel any significant vibration with the 4 blade. I'm suspecting something inside the drive and I'll be calling my drive guy later today to discuss it with him. When the drive is hot the issue shows up (or is amplified). It also slams into gear when it's hot vs. the normal thump when it's cool. I've put off calling because I don't want to hear the answer ;)

I measured both props and the Turbo 1 is actually better balanced than the Merc Rev 4 but both are pretty good. The Turbo is about 5 grams heavy on one side and the Rev 4 is about 8 grams heavy on one side. Neither should have any effect or produce a vibration I could feel. I did notice that one blade on the Turbo is about 1/16" "shorter" than the other 2. For this measurement I had the prop on the balancing rod and measured the distance between a fixed point and the rear tip of the blade at it's furthest distance from the front of the prop. The Rev 4 was pretty much spot on. Again, not enough of a difference to be noticed IMHO. I don't have a pitch block so I can't measure the relative angle of each blade.

Also, I tried the Rev 4 out of curiosity and because I got it on ebay a lot cheaper than I expected. Sometimes deals are just too good to pass up. And you are right, I don't think it's going to get any better than it is now, there's nothing left to do but enjoy the ride. With my wife working retail hours we don't get a lot of time to go boating. Because of that I don't want to waste it testing, that's why we didn't do a back to back test on the same day. I know that would have been the proper method so please take the numbers posted above with a gain of salt knowing this wasn't a proper prop testing session but more of a subjective review.

Pismo,

This is with the vent holes plugged but I run through hull and I don't have the exhaust bellows installed between the outdrive and the transom plate. Some believe it makes a difference, I don't think it matters at the speeds I'm running.

[Pismo]

Randy,
Just so you know
Pismo,
This is with the vent holes plugged but I run through hull and I don't have the exhaust bellows installed between the outdrive and the transom plate. Some believe it makes a difference, I don't think it matters at the speeds I'm running.

I agree the holes would only make a difference at low speed.

[BigGrizzly]

Thanks for the response. and actually studying the props. I do agree that the 4 masks the problem that you may actually have. The vibration may never be found. So I am with you on enjoying your boat. Just so you know the prop balance is important but the numbers are small not great but acceptable. The other thing that you probably can't is pitch progression per blade. That is a more significant issue, again probably not your issue. What surprises me is the three blade is better balanced. The 4 blade is easier to balance. Thanks for the info.

[DonziJon]

I'm just wondering: How is a prop balanced? Is it just Static balanced.. like bubble balanced.... or is it Dynamically balanced by say... spinning it at a few thousand RPM on a balance machine.

If you have a prop that you suspect may be unbalanced, maybe you could try pulling the prop OFF the prop shaft..and rotate the prop +/-180* then reinstall it on the shaft. Would it make a difference? Maybe the prop shaft has just a small amount of runout to make a difference with the prop in one position on the shaft but not in some other orientation Vs the shaft. John

[BigGrizzly]

Good idea Jon, it has happened before. I have been there. And all this time I though you erer over the hill with me.

[HOWARD O]

What an awesome write-up, mjw930. I am anxiously awaiting a bit warmer weather to get Cuda's boat wet.

With the exception of the drives, your boat seems to be the closest in power to mine than any of the other regulars here. Joe has it fitted with a 24 pitch Turbo 1 and I can't help but think that it'd be a tad over propped, although I obviously haven't tried it yet.

Have you tried a 24 Turbo 1 on yours? After trying to garner as much info as I can on this Merctrans, sounds like over propping is a big no-no for it's health. They say to err on the high side of the rpm range for the good of the tranny. That Rev 4 sure sounds great!

[HOWARD O]

Thought Cuda had the extra plate conversion done?
Regardless, a lot of what you read on them doesn't apply to our lightweight boats. Yes, you can blow em up (right Randy?? :) ) but you kind of have to try. I'm running more HP than you through a stock one in the X (yes, lighter still) and have not toasted it in 8 years.. Slipped it a couple times, filled it with water once, but it keeps on trucking..
That's great to know and yes, he did have the extra plate conversion done when it was rebuilt. I guess it's unfounded paranoia, but I am totally unfamiliar with merctrans and TRS combo.

Anyway, don't want to derail the thread. I wish the rain would leave and get a hair warmer so I can do some testing myself! I've at least got it running well! :boggled:

[mjw930]

Not being familiar with the TRS, is that a 1.5:1 drive? With the 23P Turbo 1 I can bounce the limiter with positive trim. For my motor that's 4700 RPM. Joe may have propped that boat to never hit the rev limiter and with the motor further forward the CG is different too. All these things need to be taken into consideration but I suspect you'll be happy with the 24P.

[HOWARD O]

Not being familiar with the TRS, is that a 1.5:1 drive? With the 23P Turbo 1 I can bounce the limiter with positive trim. For my motor that's 4700 RPM. Joe may have propped that boat to never hit the rev limiter and with the motor further forward the CG is different too. All these things need to be taken into consideration but I suspect you'll be happy with the 24P.

As far as I know, it is 1.5:1. CG is further forward but with the TRS and the tranny, it's got to be a tad heavier than yours too. Have to wait and see, but Joe knows his stuff and if he was happy with it, I'm sure I will be too!

[BigGrizzly]

Since I have a 22 with a TRS and merctrans and have used the Revolution on that boat with a 330 merc454 in it. The drive is a 1:50 to1 ratio. The engine is mounted 7.5 inches farther forward then a bravo1. The trans weight is only about 60 maybe 70 pounds. My boat did very well with the rev4. Now I will say the TXP prototype(long before production) kicked the rev's and Turbo1 arse.

[HOWARD O]

Since I have a 22 with a TRS and merctrans and have used the Revolution on that boat with a 330 merc454 in it. The drive is a 1:50 to1 ratio. The engine is mounted 7.5 inches farther forward then a bravo1. The trans weight is only about 60 maybe 70 pounds. My boat did very well with the rev4. Now I will say the TXP prototype(long before production) kicked the rev's and Turbo1 arse.

Grizz, I have read on a few boards that the TRS and merctrans combo are good for a 20-30 hp loss over the Bravo. That seems like an awfully high number to me, what say you?

Is the TXP in production now and are you saying the prototype was better than the production prop? What exactly is a TXP, 4-blade?

I'll leave it at that, but I could pepper YOU with questions all day long! :confused:

Nope, I lied. I have searched and you are the obvious one to ask about ATF. What do you run in your merctrans? I know type f, but is one any better than the other?

[BigGrizzly]

I though so too, but I put mine on the back of a motor and loss in forward is mimimal, with the Merc trans. However with the Borg velvet drive is is quite a bit more bur not the dog they talke about on OSO. I did blow the stock one which was 21 years old and never been apart, with my 69u8 Hp blower with a heavy hand once just showing off. The extra plate one worked well until last year then something went wrong with the pressure pump seal or internal linkage. To me it is a good package and I am not contemplating changing except to maybe a Konrad shorty, which uses the same trans. BTW I had 6years and 700 hours on it before the it let go this spring. I am now using a used one from an old hornet by way of an X18 from Forrest.

[BigGrizzly]

I for got the hp draw was 7HP at 4400 rpms, which does not equate to one mph.

[HOWARD O]

That's a lot of ponies. I expect this one will last a good while then, even if I do opt for a little more hp down the road......wayyy down the road. Sounds like the bad rap on these trannies is a bunch of bologna, especially with lower horsepower and I would bet especially with small blocks.

7 hp is nothing, I wonder who came up with the numbers I had read about? Rumor mill run amock! :lookaroun:

[BigGrizzly]

I don't know the numbers sounds like the Velvet drive numbers. The people probably pulled the numbers from a beer bottle:nilly:. I did it on the Dyno with before and after to get the numbers. The funny part is it was an easy setup, maybe 20 minutes from start to finish. Its nice to work with somebody that knows what they are doing-not me for sure. Not to make you feel even better, Merc stopped because the TRS and Trans was expensive to make. Also it is one of the smoothest around. I once talked to Brownie about changing to a Bravo1 and he told me not to waste my time. So I stayed with it and I am not sorry.

[BUIZILLA]

does your drill press spin 5,000 rpm ?

:nilly:

[BUIZILLA]

your not going to measure total potential hp draw at 1700 rpm..

[BigGrizzly]

Actually full pressure is at 725RPM. I did that first in the lathe. However it shifts in and out fine at 180 RPM I did the high Rpm thing because sone yoyo ond oso esaid it uses more hp up there I was being kind with the 7 hp it is a little less, not much. You want to have some real fun do the TRS Drive vs the bravo drive.