- Joined
- Mar 8, 2009
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you could go with custom S-pipes to use the silent choice.
When I worked at Champ, we used to make all of EMI's heat exchangers
S-pipes, don't know if there would be enough room. How would they be installed?
you could go with custom S-pipes to use the silent choice.
When I worked at Champ, we used to make all of EMI's heat exchangers
316 is better for corrosion than 304
http://www.mcmaster.com/#standard-bu...elbows/=uodfln elbows
http://www.mcmaster.com/#standard-tu...ttings/=uodgiu $45 per foot
http://www.onlinemetals.com/merchant...=902&top_cat=1 $118 for 10ft
and for the inner exhaust section
https://www.onlinemetals.com/merchan...=901&top_cat=1 $190 for 8'
http://www.mcmaster.com/#43645k318/=uodicr elbows
If you have a tig welder, you now have the materials to make these yourself.
To find tip speed, you need to know (prop) RPM, and circumference (pitch doesn't matter)
With a 15" (1.25' dia) prop, you would have a circumference of [Pi] times D[diameter] or 3.1416 x 1.25' = 3.93 (feet)...........roughly 4ft.............
@ 5600 RPM is approx 93 revolutions per second................ (5600 divided by 60 )
THEN divide by the drive ratio (1.66) ======> 3373 prop RPM or approx 56 prop revs per sec
The tip of one blade would travel approx 4ft (the circumference) every revolution
Since the blades make a "round-trip" 56 times per second, the tip speed is approx 56 times 4' or approx 220 ft/sec
[there's also the speed through the water which would make the actual speed and direction (vector) of the prop tip through the water not exactly in a perfect circle......)
Now the real question is what RPM, speed, blade angle and load produces cavitation. That requires you to know a few more "things" like blade area, number of blades, viscosity of the liquid, diameter, RPM, and a whole lotta math! yada yada yada!
I found some info on cavitation of marine propellers including one that was written by some guy for his PHD dissertation!! (OMG!!)
I'm gonna have to defer to Bruce on that stuff!! I'm only an EE from 1978. I'm great with Ohms and Kirchoffs Laws........but not all that great with Computational Fluid Dynamics!
I agree this thread is fun, we get to live vicariously through you. I don't envy the transom work but I want you to remember how happy it will make you when it's sorted and you are tooling around in the boat.
Here's a scenario, you are cruising at middle rpms on a beautiful afternoon and some twit wannabe starts to pull into your comfort zone. Maybe you used to back off because your boat wouldn't accelerate that well. After the boat is done you can either back off or bust on by, easy peasy, push throttle, feel the torque, hear the engine, smile. It's good to have choices!
I just love to go from an easy loafing plane to 3/4 or 7/8 throttle for a burst.
ps. grammar and spelling police say"moot" point.
If I remember correctly the original boat used the 2.0, engine at 300HP and a 20 pitch prop set. Installed the 502MPI with 415HP and went to 24 pitch props. If the engine comes back as 525HP I don't see going up to 28 to 30 pitch. Hope the change with the 1.65 or 1.81 will put me using my same prop sets.