292 inline 6 with prealpha drive for 19.5 cuddy

[RDTBC]

9” long X 4” diameter

 

[Scott Danforth]

A bit small. Just the two ports?

 

[RDTBC]

Yes, just a flow through. Two 1 1/2” ports.

 

[Scott Danforth]

Is your lower thermostat housing aluminum or cast iron?

I would pick up an aluminum one and weld on a 1" diameter section of tube as a hose bung

 

[RDTBC]

I believe it’s aluminum.

 

[Scott Danforth]

There are water pumps with a 1" port on the inlet almond side the 1-3/4" port

 

[Scott Danforth]

I believe it’s aluminum.

Your exhaust manifold looks crusty. You would want to run a new one when running a heat exchanger. Did your motor get boiled out?

 

[RDTBC]

Your exhaust manifold looks crusty. You would want to run a new one when running a heat exchanger. Did your motor get boiled out?

The exchanger may be a little crusty, but I recall it being in decent shape… I’m planning to remove the end caps to rotate the water inlets orientation, so I’ll get a better view then.

The block was from a wood chipper which ran coolant. It was in good shape and I DIY ‘boiled’ it out…

 

[RDTBC]

I ran electrolytic rust removal on the block. Not sure how well it removes rust within the block, but like I say, the block was not in bad shape (nothing like a raw water cooled marine block).

 

[Scott Danforth]

Your exhaust manifold rust will plug the heat exchanger.

The block will be good

 

[RDTBC]

Seems like the obvious answer here is to run with a half FWC system and just replace the manifold when the time comes…

 

[RDTBC]

Opened up the manifold. It looks to me like the rust is still pretty superficial. If the HX can support full cooling, I think it would be worth cleaning out the manifold to allow for a full FWC system. Is there a calculator or table I could use to assess the HX size?

 

[Scott Danforth]

Here are pics of both a full system and half system.




Your exhaust manifold would need to be new or risk plugging up the non-cleanable side of the HX

There are no sizing tables. There are proprietary calculations.

However a 4" x 18" 2- pass bundle will handle about 15000 BTU per minute (a 175hp motor and it's exhaust, or a 350hp motor only)

Remember, an internal combustion engine making 175hp has 175 HP worth of engine heat, about 175 HP of exhaust heat and about 175 HP of crankshaft torque

 

[Scott Danforth]

If you plumb as a full system, your 292 is putting out about 200hp. You will run hot when water temp is over 75

 

[RDTBC]

Ok. Great info. Thanks for the sketches. You mention an 18” long HX, however the one I have is 27” long. Subtracting ~3” for the ends I’m left with ~24” tube length. Can I proportion your calculation up: 24/18 X 350 = 465Hp, meaning the HX would be suitable for 230HP motor + 230HP from exhaust manifold. Do I understand correctly?

 

[RDTBC]

And, any idea which thermostat housings would fit this motor and have a 1” outlet? I’ve been trying to find something like your sketch, but have not had any luck.

 

[Scott Danforth]

And, any idea which thermostat housings would fit this motor and have a 1” outlet? I’ve been trying to find something like your sketch, but have not had any luck.

May have to buy a new aluminum one and have it modified

 

[RDTBC]

May have to buy a new aluminum one and have it modified

I have a spare thermostat housing and water pump which I could drill out and tap for 3/4” NPT. I’m a little nervous that it doesn’t leave much material around the outer edges which could cause either the pump or the thermostat housing to crack…

 

[Scott Danforth]

or just drill the threads and weld on a section of 1" diameter pipe

 

[RDTBC]

Slowly progressing this repower project. The 292 is running and ready to be installed in the hull.

I’m in the process of removing the old front engine mount and replacing with new side engine mounts. After removing the front engine mount, it seems I have a bit of a mess…

There was a half inch depression below the engine mount which retained water. The fibreglass must have become saturated and subjected to freeze thaw cycles. It’s all spongey, black and scrapes up when scratched with a pry bar. I understand this hull had some work done many years ago, and I suspect they blew glass over the hull, but could not sprayed it below the engine mount. This resulted in a local depression which was out of site and held water over the years. I shined my phone light from above and could see light through the hull (it was dark at the time) in a few spots.

Any thoughts on how best to proceed? I’m thinking I’ll grind out the rotten glass… and hope i find solid hull before punching through…??? If this goes well, I’ll grind a 12:1 taper and set about filling in the void with chopped mat and/or 1708. If I punch through… then I guess I have a real dilemma.