Thinking of building my own heat exchanger..

[FHI-prez]

I don't think it would be too hard, but I don't have a good starting point as far as how big the copper pipe would have to be to get sufficient flow through the motor.
The next question would be if it would be worth it. I could probably do it pretty cheap (I've got friends with machine shops :D ) So the aluminum, powdercoating, and tig work wouldn't cost me a dime. I just would need to come up with a plan.
I'm thinking pretty simple stuff here.
Belt driven water pump, or maybe even an electric water pump (this may be a better idea) to circulate water through motor. Use fresh water to indirectly cool that. I could build an aluminum box with a coil of copper tubing. The box would have to have 4 pipe fittings in it. Two of the fittings would be the inlet and outlet of the copper pipe inside the box. The other two would be an inlet/outlet for the fresh water to cool the box. I could even have a good size drain so I could get rid of built up sand and such inside the box, or maybe the outlet could be put strategically to facilitate the removal of the sand. :messedup:
The varibles are many, but I'm thinking that the biggest would be a shear lack of water/antifreeze volume as it would only be a total of motor volume and what is in the copper pipe.
Maybe I'm thinking backwards. Maybe I should have the copper pipe circulate the fresh water, and use that to cool the antifreeze/water filled tank. This way I could even put a radiator cap on it and have an over flow tank in case it heated up.
Hmm this could be a pain in the ass, kinda like reinventing the wheel! :notam:
Any other people dickin' around with this idea, or am I just being retarded? :rolleyes:
Nick

[Unchained]

I think the closed cooling system heat exchanger would have a lot of merit but it would add weight and take up space.
You can buy those units off the shelf. I've seen them on marine diesels.
They're not very big, about 5" OD x 24" long as I recall.
It seems like you could just use a chevy factory aluminum water pump.

[FHI-prez]

Yeah, in fact CP performance has a bunch of different sizes and shapes. It would be infinitely easier to get one off the shelf. But for some reason I like to do things the hard way.
I think they do have A LOT of merit other than the obvious weight gain. :idea: I have TONS of room in my engine compartment so that's not much of an issue.
I know I could do it, just not sure if I should. :D
I'm thinking the tricky part would be to get the system adequate to cool the beast without going overboard and adding too much weight. It would suck to get it all done and not cool the motor enough. If it ran too cool one could always restrict flow. ;)
But I think it could be done pretty small because of the high flow these jet pumps kick out for engine cooling. It seems you could get away with very little actual coolant (reletively speaking) with all that nice cool fresh water available. The right thermostat could keep things pretty stable temp wise too. :idea:
Nick

[steelcomp]

Twice now I've seen guys with aluminum radiators on their race boats. They were v-drives, so there was room behind the motor, but I was thinking that was a pretty cool idea. No warm up bucket, no mess, total temp control. One even had an electric fan.
I don't think I'd do it to my boat, (not this one) but I thought for them, great!
just my .02

[quiet riot]

I built an all alum one for my sbf. I mounted it on the back of the engine and routed it so it was self draining to the pump and exhaust so I don't need to ever drain any fresh water. Seemed to work alright this year though I haven't used it much lately cause I've moved and been busy.
The box (about 8"x5"x16" I think) was made from 1/4" plate and I just welded a bunch of alum tubing that I bent into rows inside which carries the fresh water. I welded an alum fill neck from a radiator shop on top and ran the lines accordingly.
Sorry, no pics cause I don't even know where my camera is after moving, and the boat is buried in the shop. It keeps my approx 700+ hp n2o motor at 190 deg with a 160 t-stat when running hard, 180 deg for normal cruise. And with 6 rows (bent into 3 stacks) of 3/8 id tubing that is angled to be self draining, it seems to flush all the sand out.
jd

[victorfb]

i think its a great idea. it must be a common thought as you are the third person to have mentioned it in the past couple weeks. i too have been thinking the same thing and basically came up with the same plan as yourself. i have the aluminum water pump (edelbrock) which im sure would work fine and not add so much wieght. and as for adding wieght with the exchanger, i dont see it being all that much heavier. i figure it would be like having a gallon jug of water back there, maybe a couple pounds more. but nothing to make a differance that i can imagine. my thought of all this came from after opening my water lines only after a couple river trips and seeing alot of calcium build up on all the aluminum fittings. the mineral content of the river water must be incerdibly high, and mix that along with the electrolisis that the battery is causing through the block, all the aluminum parts are going to get eaten up fast. i run aluminum heads and intake so this scares me.
im in the process of designing a better filtration system first. also toying with the magnetic field surrounding the water line idea aswell. the magnetic field trick works well on lines, and can actually clean the inside if lines by directing all the molicules in parrallel which then actually scrapes the shale off the inside of the lines. i just dont know how well this will work when the water enters the block and is now redirected to more open chambers, basically re-mixing the melecular structure. running a filtration system such as they do on motorhomes would be easy and would eleminate quite a bit of the mineral content entering the system, but the larger contaminants (sand, plant life, ect.) would clog it up too fast. so then what? a pre-filter/screen to catch the larger stuff, then the fine element filter for the minerals? now were talking a complicated system to keep small and save room and wieght. so now we are back to the exchanger idea since we are taking up room and adding wieght anyhow. but will comletely eliminate all contaminants.
i hate when two or more ideas bounce around im my head at the same time. the echo is overwhelming. :D

[FHI-prez]

I built an all alum one for my sbf. I mounted it on the back of the engine and routed it so it was self draining to the pump and exhaust so I don't need to ever drain any fresh water. Seemed to work alright this year though I haven't used it much lately cause I've moved and been busy.
The box (about 8"x5"x16" I think) was made from 1/4" plate and I just welded a bunch of alum tubing that I bent into rows inside which carries the fresh water. I welded an alum fill neck from a radiator shop on top and ran the lines accordingly.
Sorry, no pics cause I don't even know where my camera is after moving, and the boat is buried in the shop. It keeps my approx 700+ hp n2o motor at 190 deg with a 160 t-stat when running hard, 180 deg for normal cruise. And with 6 rows (bent into 3 stacks) of 3/8 id tubing that is angled to be self draining, it seems to flush all the sand out.
jd
Yeah, I would like to see pics of it. I'm thinking of just getting some soft copper and make it into a coil. I can get a aluminum tube to fab into a tank with a removable top. I wonder how long the copper would last with all the sand in the fresh water :idea: I could make a big coil that just barely fit into the tank, then go back to the top with a smaller coil, all one piece, no joints or elbows. It would probaly be easier to make it short and squatty instead of long and skinny, would be much easier to make the coils. I'm gonna have to sit down and draw this puppy out.

[Aluminum Squirt]

No experience with one but from what I've seen they don't have to be very big. All of the cool water and the liquid/liquid heat exchange makes for a far more efficient system than the air/liquid you find on cars. Good luck and lets see some picks as you get going on the project-Aluminum Squirt

[CrdStang]

After pricing even used heat exchangers I thought about making my own too. I've got a TIG welder, so maybe I'll actually do it one day.
Keep us posted how it goes, and Quiet Riot, post some pics when you find your camera.
It'd be a good thing for my boat since it's going to run in salt water...

[ttmott]

Here is the one I built. Since I run in both salt water and fresh water I made it from stainless. There is over 300 feet of tubing in it. Make sure you calculate the heat transfer you need from the unit. The easiest way is to calculate the heat from combustion and remove 50% as work and 10% as exhaust heat then add 5% back for friction. The remining heat is what needs to be removed. You will need to know the heat transfer coefficient of the tube material and the tube surface area exposed to both the glycol loop and raw water loop. Lastly the combined surface area of the tube should be at least 1.5 times that of the suction diameter of the water pump. The good part is you can run glycol and a thermostat. Make sure you have a expansion tank and a recovery tank. My twin turbo engine stays rock solid at 180 degrees at idle or WOT. That is one of the big problems with jet boats with no thermostat the combustion chambers never get to temperature and the oil stays cold and wet. Weight, if you are concerned, is around 70 pounds total wet with pump and all. My boat could care less about a little extra weight.
Tom
http://www.***boat.com/image_center/data/520/1030DSC00233.JPG
http://www.***boat.com/image_center/data/520/1030HEAT_EXCHANGER_FAB_COMPLETE.JPG
http://www.***boat.com/image_center/data/520/1030DSC00371.JPG
http://www.***boat.com/image_center/data/521/1030boat2small-med.JPG

[Squirtcha?]

Got nothing to add to the conversation about heat exchangers, coefficients, calculations, and the like, but geez I love those two twin turbo boats (TTMott and unchained). That's some coolass stuff there.

[FHI-prez]

Got nothing to add to the conversation about heat exchangers, coefficients, calculations, and the like, but geez I love those two twin turbo boats (TTMott and unchained). That's some coolass stuff there.
I think I'm where Squircha's at :D I'm not sure WTF TTmott was saying with all that physics mumbo jumbo, but sounded pretty good. I either got in over my head with this idea, OR I'm just gonna use the good ole' fashion poke and hope method. ;)
Oh and ttMott.....damn! that set up you got there is just.....well ...damn! :supp: :supp: :supp:

[bottom feeder]

Go for it.
Some ideas to maby make it easier. Get a hold of your local aluminum supplier and get some ID - OD finned aluminum tube. It is offered in several sizes. Use standard aluminum tube for the outer shell. Be sure and follow ttmott's example with a removable end. You will need it sooner or later.
For more heat exchanger examples look at setrab, B&M tranny coolers and areoquipt offers a nice piece with the design all shown in their catalog.