Merc 200hp on a 1974 Tsunami 20' - Propping Performace
 

Ok Guys,
Many people were asking me for Updates. Here you go... and I will continue posting my Testing. Originally had the Engine in the bottom Hole on Transom, I could Not get it High Enough.

Installed 4" Setback Jack Plate Still have 2" of adjustment on the Jack. Right Now at 1/2 Trim I can Get the AV Plate above the Green Water. (Should I raise The Jack some More so the AV is out With the Engine Tucked All the way in?)

Today I tested 19p Mirage Plus and 21P High Five.

Full Load of Fuel 50 Gallons with battery's at the Front. Keep in Mind I am Running at 3500 Feet Elevation.

GPS - 19p Mirage
3400 RPMS - 30.2 MPH
WOT - 5000 RPMS - 46.7 MPH

GPS - 21P High Five
3400 RPMS - 27 MPH
WOT - 4800 RPMS - 43.6 MPH

I am thinking that a 17p Mirage Plus will still be Too Much. I am considering the 4 Blade PowerTech in a 16p.

I am looking to get the RPMS to 5800 at My Eleveation with this Load and it should be perfect.... Anyone have some Ideas on.....

Where to set the AV Plate in Relation to TRIM and PROP Ideas?

Thank You
Robert

The elevation thing is tricky. I would move the engine up. On the trailer make sure the cavitation plate is 1.5" - 2" up from the bottom of the V. 4800 and 5000rpm WOT is lugging the motor down too much. I really surprised at the numbers, but it must be the elevation and the engine sucking wind. You might look into tweaking the carbs for that elevation. If you can prop the engine for 5800 WOT you'll get the best fuel economy.

Given the information you've provided with the other props. The original Enertia 17P will get you very very close to 5800rpm. I still think your missing a few hundred RPM with your current setup. Try posting on screamandfly.com after you play with your engine height.

Tim.. Thank you for the Input. I am going to raise the Engine another 1/2" it already looks Jacked to the Moon. I am guessing i can at best get another 200 Rpms out of the current Set up. The Question now is... 16p Power Tech or 17 Enertia or 17 Mirage... Any thoughts?

I have access to a lot of Props...but Nothing in a 17 / 16 pitch. So far from all the other posts i have read... the big winners seem to be the powertech and the Mirage plus.

Thanks again Tim appreciate your input.
Regards,
Robert

16"p 4b PowerTech is too much pitch. You'll still not be able to achieve 5800 rpms WOT.
Figure on getting an effective 1.5" to 2" extra pitch from the 4th blade. So you're still in the same range as a 17.5-18" 3-blade.

I ran a custom 3b Powertech 15.25"Dx16.5"P on a Mercury 200 on the back of my 20' Seafari. Max RPM was 6050 at about 53 mph lightly loaded, and 5800 rpms WOT at max load. (I also had a nose-cone and low-water pickup with a manual jack plate)

You want to propped so as to be able to achieve Max of Max at Max.
That's maximum end of the recommended maximum rpm range while at maximum recommended loading. It's really a good idea...

I am assuming you have a carb 1993 mercury 200.

Page 191 shows jet chart. =>

http://www.hedges-uk.com/boat/Merc/o...0Magnum%20.pdf


3B-34 - FUEL SYSTEMS
90-824052R2 SEPTEMBER 1997
High Altitude Jet Chart
Factory installed main fuel jets are normally adequate for proper performance up to approximately 5000 feet
(1524m) above sea level. Between 2000 feet (609.6m) and 5000 feet (1524m) the reduction of the main fuel jet(s)
may result in improved performance and fuel economy. Above 5000 feet, however, it is recommended that main
jet size be reduced as shown per 1000 feet (304.8m) in the following chart.

Father... Thank you for the Input... So are you saying i need to go as low as a 15p on a 4 blade to hit Max of Max of Max? I am not too shabby and getting The Set Up...and I am picky kind of like bushwhacker.. Been Jacking IN 1/4" Increments Now i can pull 5150 and Its up high but the Water Pressure Gauge which i installed is still good.

If i decide to run a 3 blade I think i am Going to Roll with the Enertia in 17p. Which i should be able to Spin at 5800 Here where I am at and close to 6200 on the Coast. Thoughts? I would love to have the jack Plate Marked to Run the Enertia here at altitude and then mark and test if for the Powertech when on the Columbia river and the Salt water...

Thanks for your Input Much Appreciated.
Robert

Tim... Sweet, I tried to find those Charts and even called a couple of Dealers. You would think i am speaking Chinese to these guys... I am like Good God your Mechanics work on this Stuff every day... Can you have someone check the Shop manual? These are Dealers who I buy a lot of stuff from... but I will Not be buying from in the Future... When i get the ... UMMM... NO.. We are not your Personal Mechanic... Look it up on the Internet. The guy was a total Ass... Thanks for Putting this up for me I aprpeciate it.

Still working on the Set Up... I have my jack Plate all the way up... and Still think I can move the Engine up a couple of Holes and bring the Plate down. I have plenty of Water Pressure but i did not want to Go more until i get a Enertia or Powertech... I hate doing things TWICE for no reason.

Keep You posted...If you have ideas.. All Ears.. I surely do not mind being the Guinea Pig..

Thank You Robert

I have been told that the Mirage Plus and props in likeness are to big from the 2.4 Mercs.
These prop were designed for the 2.5 and opitimax motors.

The diameter and weight is the difference.

The Enertia Eco is supposed to be a good choice in a newer style,but these motors need a 13.5 dia. prop.

I have a 1989 200 with a worn out no named prop(I mean razor sharp and less than the original13.5 dia) and on a 1998 20ft SF and I turn 6500-6800 at 48mhp.

I want to try the Eco or find an older 13.75 in a 19p or 21p.

I do agree that the smaller diameter props seem a little friendlier on the 20 seacraft.

GOS's 1993 200 is a 2.5L. I've run both a 15P x 15.75" diameter mirage and 15.5" x 17P Mirage Plus on my 2.4L. They do work great even on 30+ year old 2.4L merc's!!

Unless I am mistaken the Mercury Enertia ECO prop is 16" in diameter.

The reason I say 16" is too big for the Mercury 2.4 and 2.5L lower Units is that I originally bought a 13P 16" blackmax prop thinking that would be the prop for a 175hp pushing a 23 seacraft. There was major cavitation/vibration issues no matter what the engine height was set too. The blades from the 16" Blackmax prop barely cleared the cavitation plate on both 2.4L and 2.5L lower units. The 15.75" x 15P Mirage was fine running at the same height where the brand new 16" diameter x 13P blackmax prop had issues.

I am fairly certain the 16" Enertia ECO will give you the same problem on 2.4 and 2.5L mercs (enough that I wouldn't make a $700 gamble), but I could be wrong . . . I can tell you the older 14.5" diameter 17P enertia works great and that's what I run now on my 175 2.4L pushing a 23.

https://www.youtube.com/watch?v=jg7cdv1w1vE

I cant find the info now but if my memory services me correct I read a report done a while back that showed the 17P Enertia vs the Enertia Eco and there was little gained. If I remember right the Standard Enertia out preformed the Eco in every category except on mileage and even that was a minimum gain. In the Eco line up the 17p was one of the last size props to come out due to mercury could not improve on it to get any better performance to make it worth producing. Due to the demand for it they made it any how but most were not happy with the Eco in 17p and say the standard Enertia is better in the way it preformed. But the eco is a completely different prop than the standard and not sure why mercury used the same name but they would be in two different classes in my mind. I think that the eco props do good on big twin cc's that make long runs offshore, with 10% better fuel burn a 50 mile one way trip out to the fishing grounds like here in NC, you will see the difference when you re-fuel. I don't think many liked the 17p and had good luck with that size eco but Now in the 19p and up, that's a different story...

My prop knowledge is limited so thank you for being more clear.

I was just told that with my 2.4 a smaller diameter and lighter weight prop was the way to go.

I did not know there was an Enertia and an Eco Enertia.
I thought they were one in the same.:cool:

You can run 14" and larger diameter props. On my previous 20' Seafari I ran a PowerTech 3B prop that was 15.25" diameter with 16.5" pitch on an 2.4L Merc, achieving .08 slip at WOT. (originally 150 hp, but reman'd including balancing and polishing to produce >200 hp on the dyno, although I had changed the lower unit to a 4.75" Merc 1:62 lower from a 3.0L 225).

It isn't just diameter and pitch:

• total rake,
• rake progression,
• total cupping,
• number of blades,
• blade cup %,
• blade length to base ratio,
• total blade base circumference (possible to have over 100%, i.e.; overlap for extra stern lift)
• blade-tip shape and angle

ALL of this makes a difference. Different designs have different slip ratio on different hulls, as well.

.25 slip ratio at cruise is about average. Slip below .2 at cruise is great. Slip below .1 is unheard of except at max performance numbers. Most high performance boat builders shoot for a .25 - .20 slip ratio at cruise, and .15-.20 slip at 90% power.

Propeller slip is unused/unavailable horsepower and torque that you're still burning the fuel to produce.