Performance Upgrades DF30A ?

[jackreno]

Any ideas on performance upgrades for a DF30A model year 2015.

My small rib boat with a 12 pitch prop runs right at 32 to 33 mph at 6300 rpm's, with a 13 pitch prop my speed is the same but rpm's are 6050, I am also past the 10-20 hour break in, so I was wondering of any performance hacks or parts that anyone knows that works, would like to use the 13 pitch prop and get 6300 rpm for faster speed, yes I have my boat/gear light as possible even replaced the lead acid battery with a lithium battery.

??

[2014DF25ARS]

Have you read Moonlighter's advice on prop & motor setup? I gained about 150 RPM by raising my DF25A about 5/4 in on the transom of my 13 ft aluminum runabout. I also had my 11-pitch Suzuki alumimum prop (came with my motor) measured, and it measured about 12-in pitch. So my single-point experience says that Suzuki may rate their props with slightly lower than actual pitch. If your 13-pitch prop is a different brand, I wouldn't assume you are comparing apples to apples.

If you find a way to use your 13-pitch prop, I'd be interested in buying your factory 12 prop... I need more pitch after raising my motor!

[jackreno]

During break in I damage my Suzuki 12 pitch prop, so I bought 2 Solas props for my final test, 12 and 13 pitch, my motor is set at the right height, I suppose I could go up one more on the bolt holes and see if it helps but I might be to much out of the water since at full speed and trim my anti-vent plate is just above the surface.

I sure wish there was devices for outboards to upload new info into computers to change the fuel/air ratio and timing like we can get for our cars and trucks to unleash a little more HP.

Just seeing if I can get 35 mph or better.

[jackreno]

Was also wondering what are other 25/30 hp max speed are you guys getting.

[2014DF25ARS]

Have you used a "Propeller slip calculator" to find your theoretical performance? Several such calculators are available online. Regarding my performance, I've cut/pasted the long text below from a post I made on another website where owners of my Feathercraft aluminum boat hang out. My boat is a 13-ft Feathercraft "Deluxe Runabout" that weighs about 250 lbs without motor:

When I bought my new Suzuki motor, it was delivered with an aluminum prop that is marked as 11-pitch. After spending around $350-400 on other props, I've concluded that I probably should have stayed with the factory prop... In the results below, note that my motor is rev-limited at 6200 RPM. When it reaches this RPM, I believe the motor controller stops spark to one of the 3 cylinders, and the motor starts running like poo. I've learned that I do NOT want to operate within 500 RPM of the rev limit.

The motor is a 25 HP 4-stroke model DF25ARS. Gear ratio is 2.09

With the factory prop, I measured this performance with my 55 DR:

RPM GPS MPH CalcSlip
3500 13.9 20%
4000 17.5 12%
4500 20.5 8.6%
5000 23.5 6%
5500 26.25 4%
5900 28.25 4%

Note that anyone I spoke with said that 4% slip was too good to be true; they said that "good" slip would be on the order of 10-12%, and often as high as 25% or higher.

In search of an extra 1-2 MPH, my first move was to buy a stainless Solas 11-pitch prop on Ebay. With that prop, I got the following results:

RPM GPS MPH CalcSlip
3500 13 25%
4000 15.25 23.5%
4500 19.6 12.5%
5000 22 12%
5500 24.6 10%
6000 27 10%
6150 28.25 8%

I found that I could readily reach the 6200 rev limit with this prop. I only show results through 6150 because the motor runs stupid at the rev limit. You see that with this Solas prop, I gained about 250 RPM over the Suzuki prop, but didn't gain any speed. Confused by this, I took both props to a local shop to ask why. The magician at the shop measured the two props with a protractor-type gauge (as seen in photos on Joe's website). He told me both props have progressive blade pitch. The Solas prop ranged from 9 to 11, but the Suzuki prop ranged from 10 to 12 pitch. So the Suzuki prop has higher pitch than is stamped on the prop! This explains why the calculated slip for the Suzuki prop is so low. He also said the Solas prop has about 7 deg rake, while the Suzuki prop has about 11 deg rake.

With this information in hand, my next move was to buy a stainless 12-pitch prop. I bought a 12-pitch Stiletto prop, in part because I believe it is made by Precision Propellers in Indiana. But since then I've heard conflicting stories about where it may be manufactured. I got the following results with this prop:

RPM GPS MPH CalcSlip
3500 15 21%
4000 19 12.6%
4500 22 10%
5000 24 11.7%
5500 27 10%
5900 30 6.5%

Now I'm getting somewhere... My feeling is that the 28 MPH I was originally seeing was probably really around 28.5; my GPS shows only integral values, and I would occasionally see 29 MPH. And I believe the 30 MPH I saw with this new prop is probably just barely 30 MPH. So basically I gained about 1.5 MPH with the new prop - which I paid $200 for. (I'm avoiding thinking about the obvious question there...)

I took the Stiletto prop to the magic shop, and we measured it too. We got pitch from 11-12 inches, and rake of 12-deg aft.

The magician said that both the Solas and the Stiletto prop have a small amount of cup in them; the Stiletto probably has a little more cup - which caused his gauge to read 13-in pitch on the trailing edge of the blade - where one edge of the protractor is resting on the cupped edge of the prop.

My latest (and probably last) move was to raise the motor an inch on the transom - described earlier in this thread. I've since learned that raising the motor should have been my FIRST move - might have saved me some money thrown at props...

With my motor raised 1 5/16 in on the transom, I'm now hitting a solid 31-32 with the Stiletto 12-pitch prop @ 6000-6200 RPM, depending on trim angle. I don't have power trim on my motor, so I'm switching between the third and fourth trim pegs and wrestling with some porpoising under various conditions. So the short version is: I'm getting the same performance as you!

Good luck.

[jackreno]

Yes you are getting the same speed and performance as me with 5 less HP but you also have a 100 lb lighter boat as mine by your post, is yours a flat bottom, I guess I am getting close to the max on mine but just trying to squeeze every power out of it as I can, was hoping to see over 35 mph, maybe when I repaint my hull with some slick paint like the race boats do I could add another mph, so far I like the 12 pitch for the hole shot and it gets the same speed as the 13 pitch without lugging the motor..

Mine weights 350lbs before motor has a 8 gal fuel tank built in and 11 foot long.

Here is a pic of what I am trying to get over 35 mph.