Prop test data

[JDB]

I tested and still have (on the shelf) the17 Enertia you may be seeking.

Prop Testing

 

[Potomacbassin’]

Thanks JDB - did you settle on the 19p or 16p SWS, I couldn’t tell from the threads and signature? And sounds like from your testing the SWS was best all around?

I also read you have your motor mounted in the highest position, still the case and no issues? I was planning to datalog my 19p, swap to a 17p SWS, datalog and then start raising the motor - based on your experience I may go two holes to save on labor

Thanks!

 

[JDB]

Still learning and still experimenting but currently a 20p SWS in second hole from lowest (2nd from lowest motor height) as the smaller, 15" diameter seems happier down there.

Fuel Economy is improved with the 20 approx. 10% @ WOT and it turns 52- 5300 loaded and topped out so I'm in an rpm range few people seem to want to run in but the motor seems really happy.

I run nothing but 93 octane which hurts performance slightly but gives me peace of mind and some engine life insurance I feel.

Watersports or a large group onboard would dictate something in the 17 to 19 range and I can make a quick swap to optimize for the weekend but that's a rare occurrence so I'm really happy with my new overdrive!

I hope to update the other thread at the end of this summer.

 

[Potomacbassin’]

Ok folks, updated charts with the SWS2 15.25 x 19 test data from today's run.

No surprise that the 19p outperformed the Reliance 14 x 17 in most respects as the Reliance is apparently made for I4 motors under 200hp. As expected the 19p has greater speed than the 15.75 x 15 all along the RPM band but then runs out of HP at 5300rpm. This is where the VF engine (VMAX) might shine and get it into that 5500+ range. Top speed is similar at 45-46 with all three props. Hole shot is better by 500rpm and slip is dramatically improved in the mid and high range. Low rpm slip is still worse than the higher diameter 15.75 prop.

CORRECTION - in my previous post I had incorrectly calculated slip for the 15.75 x 15 (still had 17 in the formula) - this chart updates the formula.

Interestingly something happens at around 4000-4500 rpm where the 19p takes a non-linear drop in efficiency (GPH/MPG) - I have to assume because the motor is just hitting a wall where the injectors are dumping fuel to overcome whatever forces are at play. We knew the 19p was going to be too much for this motor, and the data backs it up. If I raised the motor and really trimmed in to the edge of porpoising then I might touch 5500 but this is all lightly loaded - with 4-6 extra bodies and full tank I'm probably lugging the motor.

I reached out to Ken at Propgods and his thought is I should try a Quicksilver Thunderbolt 15.5 x 17 next, and it can be quick shipped. I was not aware of this but the Quicksilver is a Mercury product that just doesn't have a Merc stamp on it so it can be sold by indy's. The Thunderbolt is a Mirage equivalent. I also intend to try the Merc Enertia / Quicksilver Q3 and if the back order clears out, the SWS 15.5 x 17.

Should have some results in the next few weeks and really get this dialed in.



Test data adding the 19p



Removing the MPH noise to show the 4000-4500 dropoff in fuel efficiency


Slip calcs, not sure what happened at 3500 perhaps I was hitting waves.

 

[PartyBarge]

Great Graphs! To be sure, a big thank you for all the effort you are putting into this. Good to see you also saw the problem with the previous slip vs. RPM chart. Maybe belay laying so much of the non-linearity on the motor. Boat/pontoon performance is a combination of many non-linear relationships. Just to name a few, speed vs boat drag, prop drag (not just thrust) vs PROP RPM and prop slip vs speed/RPM (as your last graph shows). Top that off with the non-linear relationship of prop efficiency vs prop RPM and it's a wonder any of the lines on your charts are remotely straight (linear relationship). Actually obtaining what linear results you have is largely a credit to progressive prop features like pitch, rake and swept area.

Yes, Quicksilver is a Merc product. They commonly have props of the same excellent design, but the Quicksilver may not have things like performance venting (typically not needed on 4-cycle engines anyway) or the highly polished finish of the Merc equivalent. Meaning: the Quicksilver is usually the lower cost twin. That's why I'm running a Quicksilver Nemesis rather than the Mercury Spitfire. Anyway, I'm sure Propgods is sending the correct mounting hardware (if you don't already have it) and that's all you need to gather a bunch more data with the QS Thunderbolt.

Oh yeah, as you suggested, for the 19p SWS raising the motor and/or more trim just to induce more slippage (prop ventilation) is not likely to be a good idea as that prop is already showing plenty of slippage on your pontoon. Also, the falloff in 19p fuel efficiency in the 4000-4500 RPM may be just the price you pay for having relatively high efficiency at 2500 RPM.....

 

[Potomacbassin’]

Makes a lot of sense, thanks PartyBarge! Good question about the mounting hardware - I assume the hub kit will have all that I need for the swap but I guess I'll find out. Dealer is still very backed up so I'm going to just run to a sand bar and swap out myself. The dealer and I are going to work out a return for the 19p - as time is no longer of the essence I'll try to have them order the SWS 17p and just have it as a spare whenever it shows up.

Quick update - after talking to Ken on the phone and going through all of the details we're going to try the Enertia / Q3 17p first. What's interesting is that while the diameter is smaller than the Mirage / Thunderbolt (14.5 vs 15.5") the blade area is not necessarily less because it is swept or skewed more (more rake?). I guess this is why so many people rant and rave about the Enertia since it's such a unique geometry and gets very good results. Should be here end of this week so hope to test this weekend.

PRaudio - just a follow up, thanks for the recommendation to reach out to Benny directly. The assigned rep (Neil) called and we talked through several items including recommended prop based on the Hull ID#. Since mine is a custom build they have no test data for it, but for the "stock" version of the boat he recommended a 15 x 16p prop, so I think the 17p's will be in the ballpark. Great guy, very knowledgeable (we had a long discussion about jack plates) so appreciate your assist on this!

 

[PartyBarge]

Will be good to see your data log for an Enertia. As you may know, they are the go-to prop for making a performance boat look it's best (for a stock prop). Not only do they have a unique combination of technical features, but they also use an exotic high-strength alloy for thinner blades. Not sure how much of the gee-whiz stuff translates to a pontoon boat... Look forward to knowing.

Hopefully the 17p will get you into the upper part of your useful RPM band. If any 17p will get you there, the Enertia should. With only one "gear" and a useful range of ~600 to 6000 RPM, the SWS 19 was costing you ~700 off the top (that's ~13% of the useful range). Forgoing that much is not satisfying.

BTW: You may want to hold off on ordering a 17p SWS until you run the Enertia....could be that a 16p is in your future......

 

[Potomacbassin’]

Good point - again great advice! Thanks!

 

[Potomacbassin’]

Ran to the sandbar today and swapped to the Q3 / Enertia 17p.

I didn’t have a chance to datalog but hit 49.1 at 5700 RPM so we’re getting there. It took me trimming WAY up (almost to the point of porpoising) so I’m convinced more than ever that the motor needs to come up 1 or even 2 holes. Added bonus surprise - dealer had finally mounted my bracket and power for the Garmin, so I was able to finally see bottom.

Datalogging next...

 

[PRaudio]

I always felt I should raise my motor from the lowest position until lately in which I noticed a wee bit of cavitation while making super sharp turns under power (i.e. quickly returning for a wakeboarder) with neutral trim. Not an issue when trimmed all the way down. Bennington reassured me the motor should be in the top hole for my configuration. Might be different for your SPS+ vs the buoyancy of my ESP. Also, I don't experience porpoising when trimmed way up.

You are also beating by top speed by a few mph at a similar RPM thanks to your SPS+ and my slightly heavier weight.

 

[Potomacbassin’]

I’m also SUPER stern heavy - I have the swing back, the 52 gal tank, the heavier V6 and I had a a custom order furniture layout that has the big dinette table sightly aft and smaller forward benches to give me a larger open bow for fishing. You can see the boat squat pretty significantly so at least in my case I think raising the motor will not cause ventilation as much as other boats that may be a little more neutral in weight distribution.

Ideally I’d like to put a thin jack plate on (4 inch) so I can play with the mounting height at will instead of relying on the dealer. I asked the Bennington technical rep if that would void the warranty and he - correctly I might add - said it would only void if a failure was proved to be attributable to the jack plate (so really just transom). I may roll the dice on this as I can’t see how a small jack plate would lever that transom and cause a failure. A big hydraulic with 10-12 inch setback I could see adding enormous stress.

 

[PartyBarge]

Looks like slippage for the Enertia is at a comfortable level. Lifting the motor should bump the speed as there will not be so much trim (poor thrust vectoring) or lower unit drag provided it does not increase slip (non-productive RPM) too much. Note that trimming to just short of porpoising is standard practice for speed with many boats at planing speeds. And as noted, high trim in a turn frequently causes a prop to "unload" due to increased ventilation. The stern heavy condition may not be much of a problem as the best at-speed deck angle is controllable and will be way different than the static floating angle.

Since the 17p Enertia may be the last prop you need, maybe the savings will go to a jack plate? Once you hit the correct motor height, a jack plate on a pontoon is only going to be a low bang-for-the-buck conversation piece. That said, one would make for a rooster tail at will...those are fun even if the boat isn't going all that fast.

BTW: I deal with a stern-heavy low-speed condition with a redneck transom wedge. Your pontoon/motor combo should only use the real-deal commercial product. Even 2 degrees more tuck under (negative trim) makes a big difference.

 

[Potomacbassin’]

Likely going with a Bobs Machine heavy duty version just to be sure. I understand it becomes a boat ornament at some point, but I also thought I read somewhere that setback may provide some advantages as well due to the angle of water coming off the transom. Then again I forget more than I remember these days so I could have that comepletely confused.

 

[PartyBarge]

I think you've got the concept about right. The setback MAY allow the motor to be lifted more prior to ventilation at speed...that can be a bigger problem for hole shot. Your pontoon is now about in the speed range for a typical 23' Center Console of similar weight and HP. That's notable even if it won't maneuver with a CC. Most of the CC's, bass boats and pontoons throwing rooster tails at less than 40 MPH I think are running hydraulic jacks that are adjustable on-the-fly just like motor tilt. That way a more reasonable/useful setting is easy to make when showtime is over. Note that is not a recommendation, just an observation. Most of the pontoons here simply blow away any rigging problems with HP. 400 HP pontoons are common enough that they are making the 300's look a little puny. In fact, someone put a stick-on "4" in front of the "90" on our motor....must have been our pesky kids again....

BTW: more setback will make your stern-heavy condition more pronounced.

 

[David G]

Still learning and still experimenting but currently a 20p SWS in second hole from lowest (2nd from lowest motor height) as the smaller, 15" diameter seems happier down there.

Fuel Economy is improved with the 20 approx. 10% @ WOT and it turns 52- 5300 loaded and topped out so I'm in an rpm range few people seem to want to run in but the motor seems really happy.

I run nothing but 93 octane which hurts performance slightly but gives me peace of mind and some engine life insurance I feel.

Watersports or a large group onboard would dictate something in the 17 to 19 range and I can make a quick swap to optimize for the weekend but that's a rare occurrence so I'm really happy with my new overdrive!

I hope to update the other thread at the end of this summer.

Why would you think running 93 octane hurts performance?

 

[JDB]

Because the burn rate is slower and the peak cylinder pressure in the combustion chamber occurs later than optimal, reducing power and fuel efficiency.
Or at least that is what most engine peeps tend to think.

 

[David G]

Because the burn rate is slower and the peak cylinder pressure in the combustion chamber occurs later than optimal, reducing power and fuel efficiency.
Or at least that is what most engine peeps tend to think.

I have seen that too, alos been in a dyno shop when they were testing 93 vrs 87 and it was a big gain.

 

[PartyBarge]

I have seen that too, alos been in a dyno shop when they were testing 93 vrs 87 and it was a big gain.

Ahhh...when I saw the post, I knew this would likely to get a bunch of comments. There are multiple reasons why results for various octane ratings are all over the chart. A couple things first. For more than forty years I've run at least one if not two turbocharged cars. Effective compression ratios and cylinder pressures are now part of my DNA. As JDB alluded to, gas octane is not a measure of power, it's a measure of resistance to detonation. Also it depends on how the octane rating is achieved. In the old days that was tetraethyllead (which reduced the BTU's per gallon). In today's era of gas-o-crap, it may mean just increasing the percentage of alcohol ( also decreases the BTU's per gallon). The best, and most costly, way is to start with a better base hydrocarbon and use more sophisticated refining (aka molecule restructuring) for best octane AND high BTU's (read: non-ethanol premium, yeah, it's expensive). And yes, I'm aware that E85 CAN BE a high performance/high octane fuel, but only IF the engine is designed and operated with that in mind. Used in a typical engine the fuel economy, as in MPG, is going to suck, as in a reduction of ~25+% from non-ethanol because that fuel is low BTU content compared to real gasoline.

Dyno shop results can be suspect for several reasons even when NOT looking at an engine designed for "high test". They tend to push various parameters and, in particular, ignition timing. That can easily take a perfectly fine regular gas engine and make it appear to need premium for high output purposes...primarily because the engine is operated outside what was intended by the manufacture.

In the case of the original post, that person may, in fact, know more than was in the post (he clearly knows when a prop is over ventilated). Here is an important piece of the story. He is targeting high cruise MPG by running a high (20P) pitch prop that the engine won't pull into the normal best-power band. For an engine that has high-tech flow/heads to be able to use ~10-to-1 compression with regular gas in the first place, that can be risky. (Note that it is only in recent (high-tech) years that anyone would consider running regular gas above about 8 or 9-to-1. (We have a regular gas GMC that runs 11-to-1 !!! ) He is intending to continuously run a high load at well less than normal high-load RPM's. The result will be high heat WITH higher than normal cylinder pressure at relatively low RPM. Consider that with the fact that RPM less than ~3500 is the danger zone for detonation! How do you cope? Well...it's best to start with an engine that has a knock sensor(s) feeding the ECM, next, have a cooling system in tiptop condition and, finally, run the best gas you can get even if the manufacturer specifies regular. (Maybe better than any of those things is a remap of the fuel/ignition curves, but who can do that...legally) Anyway, all of that may still not be enough to protect the engine or avoid having the knock sensor kill performance as the ECM dials back ignition timing (or some other method, like increasing fuel flow) in an attempt to save the engine...and kill MPG in the process. Proceed with caution!

 

[DejaWiz]

Yep, there is a huge difference between the octane ratings, even though the differences in numbering may seem small and insignificant.

In the case of gasoline octane rating, more does not always equal better (conversely to how most consumers are programmed to believe), depending on how things like (but not limited to) the engine control software is programmed, the tuning/timing of the engine, the camshaft intake and exhaust valve duration, the compression ratio, naturally aspirated vs pressurized, carburetor vs fuel injection, the flow rate of the air intake and carb/injection system, the restrictiveness of the exhaust, emissions equipment, etc.

It is within the realm of an ECU tuner to adjust the engine software to specifically utilize a higher octane rating fuel at all times, if the engine has adequate physical characteristics (see the examples in my list above) to be able to utilize it and get a meaningful gain from it.

If not, then usually the opposite happens: higher octane rating in a vehicle not configured for it will usually see a detrimental effect to overall efficiency and performance.

This is why I avoid ethanol-enriched gas whenever I can: the higher octane rating of ethanol (113) means it naturally burns slightly slower, thus reducing overall efficiency, even in a vehicle that is configured to se it. Vehicles that have separate EPA fuel economy ratings for straight gasoline and any manufacturer approved mixture/combination of E10, E15, E20, E25, E70, E75, E85, and E100 will reflect that the ethanol blends, while potentially raising HP ratings a little, will reduce fuel economy by a significant margin (I have experienced losing 2-3 MPG average when E10 is used vs straight gasoline in a 200HP 4cyl 4 door sedan), and that margin is usually enough to not justify running it depending on what the differences are.

For example, my last E85 capable vehicle was a 2007 Nissan Titan 4x4 that was EPA rated as follows...

E0 (straight gas):
12 city, 17 highway, 14 combined

E85 (85% ethanol, 15% gasoline):
9 city, 12 highway, 10 combined





Around my locale, E85 is about $0.50/gal less than 87-octane E0.

I drive an average of 16,000 miles per year.

Using the EPA "combined" ratings and the miles I drive annually, here is the break down:

E0 straight gas: 1,143 gallons @ $2.20/gal = $2515 per year
E85 blend: 1600 gallons @ $1.70/gal = $2720 per year


The same lines of logic can be applied to the wrongfully held thought process in which a higher octane rating means better fuel economy in a vehicle not specifically designed to require it at all times, which is simply not true...and usually the higher octane rating fuel will cost more, unlike the higher ethanol blends. But either way, one usually ends up paying more over the long run because of the lower efficiency.

 

[Potomacbassin’]

Heard a story of a guy mixing 4 gallons of E85 into a tank of 93 octane on his AMG and seeing power gains. Apparently the O2/knock sensor/ECM are picking up the octane increase (IIRC it blended to 98) and is either advancing timing or increasing boost or both.

Not suggesting most engines can do this (marine or automotive) but simply it probably really depends heavily on that particular motor and the design. Maybe it suffers, maybe it doesn’t?