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In 2017 Mike posted this reply about his SST 60 and Mod 56 OMC successes. Over the last few years several T boat people have built modified 56 powerheads both Bridgeport and oval port powerheads. I don’t believe Mike ever built an oval port mod 56.
I have seen the dyno sheets and raced against many of his SST 60 powerheads. As he mentioned in his post over 100 hp at the crank was common. The difference in the dyno sheets was the rpm the engine first developed maximum hp and how long the motor produced maximum hp. Mike’s best performance motors on the race course were those that developed 100 hp at 6500 to 6700 rpm and held that hp up to 7600-7700 rpm. Some of his motors made more hp but they peaked and only held that advantage over a narrow rpm range. Off the dock acceleration, strong mid range and good top end was key when racing on a 35 second lap race oval. Mike’s powerheads were always at or near the top finishers.

So here is the post from 2017
Mike Wienandt ...I have built over 15 national championship winning SST 60s. The last 8 years I have run been about 100 - 102 hp at the crank. We dyno with the exhaust housing and gearcase so we match correct exhaust back pressure. The mod engines I make for lake racers or X class inflatables are now up to 118 hp. This is with stock SST 60 carbs. I'm working on one right now that is very over due. Porting includes finger porting, Boost port reground, A lot of grinding in the transfer ports, Exhaust port reshaping and timing edges of all ports to my own specs. Stock head with welded smaller thermostat hole, then re-machine to smaller ccs and angled squish band added. SST 60 reed pedals and grinding in intake and matching the case. Bored to .030 over with Line2Line coated pistons from Pro Marine. Stock SST 60 tuner. We have over 350 dyno runs doing development work on these. Dyno all computerized so no bull crap. Can't argue with the win history.

Mike mentions a lot about how he modified the motors. He isn’t using different components but rather working with the original parts and just improving them.
It doesn’t sound like “bigger is necessarily better”. A common mistake with many new engine builders is being too extreme with the porting. And using non original parts.
You build enough of these motors and you know what works and what doesn’t. Certainly the in-house dyno is an advantage.

There are enough of Mike’s SST 60 motors on T boats in Ontario that you can compete with. I don’t know of any Mod 56 Mike motors in the area, but that could be because the people won’t say what they are running.

A 118 hp T boat 56’r and it has to run over 80 mph.

Got an email from one of the T guys who has been working on a mod 56 OMC for a few years. He said Mike W hasn’t been working on any 56 OMC powerheads for several years. There isn’t any demand.

I checked Mike’s Facebook website and couldn’t find anything related to OMC 56 powerheads.
https://www.facebook.com/profile.php?id=100057338234295

It would be an excellent learning tool if we could get our hands on one of Mike’s 118 hp mod 56 powerheads.
The purchase price will be a problem with the Canadian dollar at about 70 cents. I don’t know how much the mod 56 powerheads originally cost. I do know that Mike’s special sleeve, special crank SST 60 drop on powerheads cost $5000.00 US back in 2004-2008. Other SST 60 powerheads built by different builders were $2500.00. US.

SST 60 became a very expensive class to race back then.

Oh, just another comment. The 1987-8 omc fishing 56 powerheads are sometimes called “sandcast” by most people. They were not sandcast made...the term is “production” cast.
The inside finish is smoother and the block flows better than the later lost foam cast blocks. The production method was changed to lost foam casting because that process was less costly. So when you hear either term the person is telling you it’s the different block. Easy to see the glue lines looking in the ports if you don’t know the part numbers of the blocks.

At 118hp out of a 56ci that is very close to what the southern boys are getting from the mod 90 Yamaha motors! Would these 118 hp blocks be the “production” blocks with Bridgeport sleeves or maybe Oval sleeves? Thats a big jump in HP over the 105-107hp from the sst60 power heads! I wonder how long they last??