Twin O/B Sonic

Really surprised you're having problems still Craig. Do you think the center motor is too or is it turbulence from the other motors??
I have a low water p/u too but haven't needed it yet.
75 is very impressive too.
Take someone w/a camera tomorrow.
Good luck and be careful.
Gary

captaincraiger

Overheating problem solved. Pictures of my engineered transom pickup, ran the hose to the flush out fitting, plenty of water now, engine went to 190 degrees trimmed up but never overheated. Now I am going to have to figure out how to plum it into powerhead instead of through flushout. I am also going to have work on props. I have a array of props running on it now. I ran it today with a 27p 4 blade hydromotive prop turning 5700 rpm's, 28 p chopper turning 6000 rpm's, the center engine turning a 32 p cleaver prop 5800 rpms. cleaver is on center engine that is a 225 . gps speed today was 78.8 mph. I would like to find 1 28p lh chopper & a 30 or 32 p chopper for center engine, now the fun begins testing & tuning. I am very happy with the speed so far.

Twin O/B Sonic

Great news. 78.8... yowser! Freagin crusin, especially for out of the box.
You can plumb your water to the lower unit, just above the cavitation plate and a couple inches aft pf the leading edge. Find that style case w/a nose cone, and measure and duplicate where it's water line taps into the housing.
On props, I think a set of 28 Bravo One's will be tough to beat on your rig.
I'm testing them on my Sonic now and love them so far. Can run my motors higher w/them than anything else I've tried and they carry the bow very nicely which I' guess yours could use too.

captaincraiger

Took the boat out on Saturday for a few hours, Boat running fine now. I am still in the hunt for propellers. I am very happy with the way the boat is performing. I just took it out in the Kissimmee chain of lakes, The airboaters were wondering what the hell was going on with a triple engine boat cruising through Camp Mack. Plenty of water now in the chain of lakes. I would have ran it longer but the rains came through early. In search of a set of 28 bravo's to try.

salty dog

What are the other motors run temps? I thought 190 would be high should they run 150or 160 with a 143 t stats?

captaincraiger

all thermostats are gutted, temps on the outer engines are running at 175. I was thinking that 190 was high also but wont go over that now, so I guess the gauge might be off just a little, as long as hot horns aren't going off, not going to mess with it for right now, but now the ecu took a crap that sends a pulse to the tackometer. I am going to have to see if I can get it fixxed now, always something with a boat.

rhaines

Those are some great speed numbers. I might need to drive to Lake Wales and check that thing out.

Twin O/B Sonic

after going through everything on my 250 OMC's they run @ about 180*. News stats and impellers.
I even tried a trick we do w/the hot rod motors which is to replace the stats w/a stainless washer to reduce the water passage size to create/retain some water pressure while still allowing 100% flow and saw no change.
Up north in 70* water those motors run 145*. Down in here in 90 ambient air, 90% humidity and 85* water temps though......

captaincraiger

I am going to try turning the motors outward instead of inward just to see what happens with the temps & speed. I have always heard that turning them inward made them run faster, We will see how much speed it looses by turning outward. I am going out of town this weekend , so not sure about if it will be done by the weekend or not.

Twin O/B Sonic

on the old Sonic and w/set up exactly the same the starboard motor (spinning in) spun like hell and ran like crap. Switched em back and it ran perfect.
W/good gear cases, a 1000 lbs less weight and the motors 2" higher who knows but in my unscientific experiment it was another test that
went exact opposite of expert wisdom.
Based on that you may pick up doing the switch to spinning them out which is mostly standard these days.