SuperChiller water supply

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Ratmoul

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« on: May 09, 2017, 07:38:32 AM »
Hi. I am new to the whole hotrod jetboat thing and have recently purchased a nice 1978 Bahner with a blown BBC. As part of tidying up some of the plumbing, I am wondering what might be the normal/best way to supply the SuperChiller intercooler. I understand that these can sometimes be too efficient at idle and strip the fuel from the mixture, so I was wondering if a mini-scoop on the hull or rideplate would be the way to go, so that it was only supplied when the boat is under way? What size of mini scoop and what line etc.?
ps  third time I have had to type this. disappears when I try to attach a picture. drag/drop does not work. can we not just select one out of my pictures??    Tom



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« Reply #1 on: May 14, 2017, 02:50:25 PM »


Hi. I am new to the whole hotrod jetboat thing and have recently purchased a nice 1978 Bahner with a blown BBC. As part of tidying up some of the plumbing, I am wondering what might be the normal/best way to supply the SuperChiller intercooler. I understand that these can sometimes be too efficient at idle and strip the fuel from the mixture, so I was wondering if a mini-scoop on the hull or rideplate would be the way to go, so that it was only supplied when the boat is under way? What size of mini scoop and what line etc.?
ps  third time I have had to type this. disappears when I try to attach a picture. drag/drop does not work. can we not just select one out of my pictures??    Tom

Hi Tom,

Welcome to SCJB.  Pictures are always a good thing.  I only use the mobile app, I can't comment on the website.  The Picture icon gives me the option to go to my gallery, however the camera icon crashes the app.  I believe that is an OS issue rather than app bug because I have the same problem in other apps  Anyway, looking forward to seeing pictures.

My opinion on the best way to plumb an intercooler is to come directly off the pump bowl at the 12 o'clock position (like a Prime-a-Jet install).  I have also plumbed to the 3 o'clock position opposite the cooling line, but I feel that the 12 o'clock position will facilitate pump priming, bleeding air from the pump.  The distance to drill the bowl from the suction surface will depend on which bowl you have and if you have a transom adapter and where it is located on the bowl.  Basically, you want to drill through enough meat in the bowl flange to achieve good thread engagement.

Some insist on huge -10 or -12 supply line size from 1/2-NPT.  I think that -8 line from a 3/8-NPT fitting is sufficient.  the faster cars are switching over to one supply and two outlets instead of two in and two out.

Ideally, you want a high volume of flow without exceeding the recommended pressure for your chiller.  Reducing restriction on the return side by plumbing the with dual -10 lines and as short a run as possible, dumping overboard will provide the least resistance and help keep heat exchanger pressure low.

I am not a fan of the scoops or any other types of pickups.  First, they create a lot of drag and will kill a few MPH.  Second, there really isn't a good place to put them, through the hull.  Either the pickup will be out of the water while on plane or it will be causing detrimental effects to lift or, if located on keel before the pump intake, the disturbance its presence makes in the water being picked up by the pump intake could drastically reduce suction pressure.  Both of these defeat the whole purpose of the blower by reducing MPH and ET.

The only logical place for a scoop type pickup is in the ride plate.  This, however, presents its own set of compromises.  First problem is real estate.  The only place on the ride plate that has enough room to mount a rather large fitting and line is between the bowl flange and suction flange, coming off with a 45-degree fitting and the line routed between the suction flange and transom plates.

Some negatives of mounting the pickup scoop in the ride plate.  Valuable lift is lost from the disturbance to flow under the ride plate.  I mentioned drag earlier.  Drilling a 3/4" or larger hole in the ride plate removes a healthy chunk of material, weakening the ride plate.  At first glance, this doesn't seem like it would be a big deal.  1) While on plane, the ride plate is supporting a large percentage of the weight of the boat.  2)  All ride plates experience "cavitation burn" from the disturbances created by the shoe biting edge, shoe and ride plate fasteners, and the mismatch between the shoe and the front edge of the ride plate.  The cavitation burn fatigues the bottom surface of ride plate, causing it to warp.  3)  The warping is compounded by the additional drag caused by the scoop.  In the short term, this will distort hook into the ride plate and a bent ride plate in the long term.

Regardless of where you get your water supply, you will need some kind of filtering to prevent the heat exchanger from filling up with sand.

I would try to regulate pressure as close to the chiller as possible.  You will experience a pressure drop at the chiller if you regulate pressure back by the transom, reducing flow through the heat exchanger and reducing its efficiency.

I think a pressure relief bypass is a bad idea.  I wouldn't want to do anything that deprives the chiller of flow.  I would recommend a pressure reducing valve or a gate valve.

Good luck,

Joe
  • Boat #1: 1991 Hallett 20.5'
"I want to roll with my brother Joe" - Joe Bateman - January 29, 1950 ~ November 27, 2013

 


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