A very cool Evinrude 31.8 (521cc) race engine built by a good friend of mine. (based on a production 20-35HP block)This one of a kind is by far the most powerful OMC/Evinrude 31.8 (521cc) engine built.
Some more info from the engine builder…
The side carb fed twin piston ports machined into the block from the inside. No reeds and no flow restriction with the side carb. The front 2-barrel carb provided the initial mixture feed, with progressive linkage opening the side piston-port carb at ~ 1/2 throttle. At WOT, all 3 barrels were full open. That way, it provided good bottom-end punch and great top end performance.
Here is the answer from the engine builder of the Evinrude 31.8 (521cc) race engine when it comes to HP..!!
“I still have the dyno sheets………… but prefer to just mention that it was the strongest 31.8 ci engine to be run on the OMC dynos, by a considerable margin”
Here’s the engine on a Yamato 80 boat we borrowed to test it, if you look up close I’m backing off the throttle, it just wasn’t enough boat.
Sam LaBanco next to the #27 B&H Hydro. This is from Lake Zurich, Illinois in early 1980’s.
Yes..that’s Ziggy (in the hat) next to the very special Evinrude 31.8 (521cc) race engine.
