2020 DF35A 30hp conversion.

[matt167]

I’ve decided that I’ll just run my little boat this year and possibly spend a couple of weekends on the big boat and see if I can get it good enough to launch. But I have always wanted to convert the 25hp to the full 30HP. I would have bought it that way but Suzuki doesn’t build a 30 in a short shaft so I had to do what I did. It’s now out of warranty so it’s safe to do.

Anyone know the part number I need for the ECU? I’ve looked but I can never be sure I’m looking at the correct thing

 

[99yam40]

title says change from a 35 to a 30.

to change HP I would think you would need to change amount of fuel and air. and maybe timing advance at WOT

Some may just change upper rpm limits

I know nothing about the Suzuki's

 

[matt167]

title says change from a 35 to a 30.

to change HP I would think you would need to change amount of fuel and air. and maybe timing advance at WOT

Some may just change upper rpm limits

I know nothing about the Suzuki's

DOH. It was early when I wrote it and I was surfing IPL’s at the same time. It’s an EFI engine. DF25A and the only difference is the spark arrestor is a restrictor on the 25hp and the money part is the different ECU. I just want clarification on the part numbers so I get the right one.

It does list 30hp 300 RPM higher than the 25hp variant

 

[jimmbo]

A gain of about 1 mph

 

[matt167]

A gain of about 1 mph

Yes, but I think I’ll get more bottom end out of it. The old 40hp twin actually wasn’t much faster if at all than the 25hp is, but the bottom end got a bit softer. I had to run a prop with more slip vs the one that came on the motor to make it run up to RPM spec, but that prop did have better bottom end. It just ran out at 5,500 RPM. I should be able to use the 25hp stock prop which I don’t remember what it is but it should run out, give me 1-2mph and that bottom end back.

The boat is rated for 40hp at the crank so a modern prop rated 30hp should be in the 75% plus range of maximum

 

[jimmbo]

An increase in Horsepower from any given Displacement, requires raising the Rpm at which the Hp is attained by shifting the Torque Curve Upward, which 95 out of 100 times results in weaker Low Rpm Torque. Repropping, with a lower Pitch will hide some of that, and allows the engine to operate in the raised Rpm Torque Curve.