# Suzuki DF9.9 conversion to 20HP



## InSaneFisherMan (Aug 13, 2020)

I have the 2016 DF9.9BT and have converted to 20HP.

I installed a flame arrester first, and got probably 15HP (17mph) or close, but the engine would go into RPM limiting at WOT.
I then installed an induction tach and found the RPMs slightly high, so changed the prop (increased the pitch). Still had RPM limiting at WOT.
I then replaced the ECU and no RPM limiting at WOT.

Speed increase from 15mph (6000rpm) to 20.4 mph (6320rpm) WOT.

Flame arrester - $15
Induction Tach - $20
9 1/4 X 11 prop - $40
ECU - $285


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## InCogKneeToe (Aug 14, 2020)

Don't forget the Restrictor Plate.


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## InSaneFisherMan (Aug 17, 2020)

Its a restrictor in the 9.9 and flame arrester in the 20hp


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## DaleH (Aug 17, 2020)

InSaneFisherMan said:


> I have the 2016 DF9.9BT and have converted to 20HP.


Man, I had to look it up for myself! You just might be onto something here, as per Suzuki's website, they both weight the same and have the same piston displacement, bore and stroke. The LU gear ratio is the same and the only difference in their 'published' specs is the prop of course, and then the MAX operating ranges, but sounds like you identified the ECU as the other difference. 

The 9.9hp lists 4,700 - 5,700 RPMs and the 20hp lists 5,300 - 6,300 RPMs. I see the 9.9s selling @ $2,300 new vs the 20s selling @ $3,100 ... _hmmmmmmmmmmm_. More for electric start and remote operation use, but that includes a side remote control box. 

So it appears one _can save ~$460 _by buying the 9.9hp and doing the conversion as is. *Would be useful for places limiting the motor's horsepower, no????????????*


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## wmk0002 (Aug 17, 2020)

Nice work!

Is that typical cost for the Suzuki 20hp ECU or did you get a deal? Some other motors in that 20-25hp have ECUs that list for over $1000 which makes the conversions very impractical.


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## PATRIOT2 (Aug 18, 2020)

FYI . . . my 2019 DF20ATS2 does 25mph GPS for reference, 18 mpg, right out of the box (after break-in) but it was never about speed to start with.


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## InSaneFisherMan (Aug 18, 2020)

Can't speak for prices on other ECUs or for engine models, but the one I purchased for my motor was $285.

I made a mistake in the original post, it was $285, not $265.

Do not order the ECU in the attached clip unless you know it is the correct one for your motor!


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## InSaneFisherMan (Aug 18, 2020)

PATRIOT2 said:


> FYI . . . my 2019 DF20ATS2 does 25mph GPS for reference, 16 mpg, right out of the box (after break-in) but it was never about speed to start with.



My boat is rated for 25Hp, and I wanted a remote with electric start. Two separate boat dealers would not install the 25Hp remote because of the weight. They both would install a tiller without electric start.

The Suzuki dealer had a 9.9Hp remote, electric start, and power tilt on demo, and I got a great deal. 

By accident while searching for DF9.9 info, I found that the 9.9, 15, and 20 Hp are basically the same engine.

Did a lot of research and converted mine to 20Hp.


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## InSaneFisherMan (Aug 18, 2020)

wmk0002 said:


> Nice work!
> 
> Is that typical cost for the Suzuki 20hp ECU or did you get a deal? Some other motors in that 20-25hp have ECUs that list for over $1000 which makes the conversions very impractical.



Can't speak for prices on other ECUs or for engine models, but the one I purchased for my motor was $285.

I made a mistake in the original post, it was $285, not $265.

Do not order the ECU in the attached clip unless you know it is the correct one for your motor!


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