SST 60 Modification questions

[HOGGY55]

Hello
My name is Max I race a formula 3 tunnel in New Zealand just for a bit of background to the few questions I have, the Formula 3 class in New Zealand is the only open hull class that promotes running mixed hull designs and is still largely run what you've brought. The class rules themselves stipulate that for all outboard hulls the must be limited to 1000cc or stock 115hp motor, the hydros in the class are 1650cc and the flatties are 2000cc or 12a rotary Naturally aspirated (rotary)

1.) I currently run an SST 60 setup on single barrel carbs but a lot of the guys in NZ run double barrel carbs (twin throat). I would like to know whether this is a faster set up than the standard single barrel and if so what/s to be expected and what are the draw backs of this change and where I would go to get said parts if I were to go down this road.

2.) I have also heard SST60 motors can be converted to an EFI setup has anyone achieved this and what was the outcome of it as I am hoping to build a couple motors to go with the one, I already have.

3.) The Next question I have is about propellers for sst60 and formula 3 boats was/is there a particular size that worked out better for most boats to improve straight away speed In New Zealand we don't do a lot of beach starts but usually run a big course that has around 800metre straights and 200metre corners as an average, I would very much like to carry as much speed as possible in these straights as the Hydroplanes in the class are much quicker maxing out at 110mph where most tunnels in NZ bar one reach 90-93mph I only have one propeller but seem to max out very quickly when pushing it the props measurements are 22.5 pitch x12.5".

For those wondering the boat is a Target Marine Hull (wood) and is setup with a 1.6:1 ratio gearbox I believe it and its sister ship went very well in the US and Canada, they were shipped to New Zealand in the early 2000s and did possibly 2 seasons before being sold off, mine of the two sat around since 2008 while its fibre glass double competed for most of that time, if anyone has more history and advice it is greatly appreciated.

Cheers
Max
MJL Racing

[sharpeye Mike]

Contact Fast Fred for all those questions. He's on this site but hasn't posted in a long while. In my opinion, he's a guru of the 3 cyl. OMC and can build you what you want or get you the parts you need.
Cheers back at you.
Mike G

[Brayo]

1-If you're chasing the hydroplanes' 110 mph speeds, twin throat carbs are worth exploring for the power boost, especially since others in NZ are using them.However, start with a single high-performance carb (e.g., Mikuni VM44) to simplify tuning and confirm gains before committing to dual carbs.




2-An EFI conversion is a high-risk, high-reward project. It could give you a competitive edge in NZ Formula 3, especially for throttle response and straight-line speed. However, given the cost and complexity, consider it for one of your spare motors as a testbed. Start with a carb upgrade (twin throat) for immediate gains, then explore EFI once you’ve confirmed class legality and have a reliable tuning part.


3 - Start with a 12.5” x 24” stainless 3-blade prop with light cupping. Test it on a calm day, logging RPM and GPS speed. If you hit 6000-6500 RPM at WOT and gain 3-5 mph, it’s a good match. If not, try a 25” pitch




For immediate gains, focus on the prop upgrade and a single high-performance carb. These are cost-effective and can close the gap to the hydroplanes