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Blown BBC Water Pressure

50onRED

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What is a healthy water pressure for a blown BBC? Converting my drive water pickup to a transom pickup with sea strainer and dual output Latham pump to feed my intercooler and block separately. I have an unused bilge dump port which I plan to run to the intercooler with a pressure bypass valve plumbed between the cooler and the port. But my question is how much pressure should I shoot for?
 

4Waters

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Had to🤣🤣

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DarkHorseRacing

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What is a healthy water pressure for a blown BBC? Converting my drive water pickup to a transom pickup with sea strainer and dual output Latham pump to feed my intercooler and block separately. I have an unused bilge dump port which I plan to run to the intercooler with a pressure bypass valve plumbed between the cooler and the port. But my question is how much pressure should I shoot for?
5 to 10 pounds, depending on the speed you’re doing. Not to exceed 12-15.

You should have a pressure relief on the sea strainer. Then let the pump do whatever amount of water it wants given the engine speed to whatever needs cooling you have coming from the pump.
 

Bpracing1127

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my dads old daytona saw about 9 psi at full throttle and cruising was about 5-6 psi

much more than that you will blow gaskets
 

DarkHorseRacing

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my dads old daytona saw about 9 psi at full throttle and cruising was about 5-6 psi

much more than that you will blow gaskets
Or milkshake the oil.

We ran into that with our jet boat. Had to add the pressure relief to not overpressurize the cooling system. Weak link is the gaskets between the intake manifold and the heads.
 

Bpracing1127

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Hmm. You guys are saying an engine can't take more than 10PSI of water pressure?

Normal sealed cooling systems are 14-20 PSI....

Weird.
more like 15, biggest thing is it will spike
 

DarkHorseRacing

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Hmm. You guys are saying an engine can't take more than 10PSI of water pressure?

Normal sealed cooling systems are 14-20 PSI....

Weird.
I haven’t seen anything higher than 15 psi on our TCM 1200 at full tilt. Not totally sure where the gauge is reading this at though. But I figure the sea strainer can only handle so much as most have that lexan cap.

The point on most transom or drive intakes is to ensure a constant supply of water to the pump. You don’t need a specific pressure before the pump because the pump will provide that at whatever the pump is set for. But you don’t want the strainer not getting enough water or it can’t supply a constant amount.

Jets on the other hand are your pump and you still need pressure control because the jet can over pressurize your cooling system pretty easy. I recall the pressure dump on our jet was a really good stream.
 

DarkHorseRacing

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Regulate engine to 15 or less , we run intercoolers on separate "divorced" systems
On our jet, our intercooler was not on the jet circuit, it was only pressure fed from a hull pickup so essentially only cooled at speed. I assume this was so the fuel didn’t puddle in the intake manifold at idle.

With our I/O, I think the intercooler comes off the sea strainer so maybe it’s the same principle but getting water after the strainer and only when enough speed pressurizes it.
 

Western Flyer

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Regulate engine to 15 or less , we run intercoolers on separate "divorced" systems
Haven't installed a water pressure gauge, yet, running out of dash space, but with the intercooler separate from the engine cooling water, running a -16 to the separate strainer, -12 to the intercooler and two -10 outs, I figure I gotta be OK?
 

jetboatperformance

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Haven't installed a water pressure gauge, yet, running out of dash space, but with the intercooler separate from the engine cooling water, running a -16 to the separate strainer, -12 to the intercooler and two -10 outs, I figure I gotta be OK?
Is your IC system still "pressure fed /via engine systems "? or "passive" (scoop)
 
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Western Flyer

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Separate scoop in the hull bottom. I should have mentioned it's a V Drive
 

mattyc

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What is a healthy water pressure for a blown BBC? Converting my drive water pickup to a transom pickup with sea strainer and dual output Latham pump to feed my intercooler and block separately. I have an unused bilge dump port which I plan to run to the intercooler with a pressure bypass valve plumbed between the cooler and the port. But my question is how much pressure should I shoot for?
Just a thought, are you asking about pressure in the intercooler circuit or the motor circuit?
 

scottchbrite

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I had run some pretty high water pressures in my boat while trying to get the thing setup (jet boat). I saw 30 plus at times. My concern was never the head gaskets. It was the core plugs (freeze plugs). I did have one pop out once. That was a mess. I feel 15psi is a good number. It’s enough to push out any air pockets and not have any worries.
 

MK1MOD0

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On our jet, our intercooler was not on the jet circuit, it was only pressure fed from a hull pickup so essentially only cooled at speed. I assume this was so the fuel didn’t puddle in the intake manifold at idle.

With our I/O, I think the intercooler comes off the sea strainer so maybe it’s the same principle but getting water after the strainer and only when enough speed pressurizes it.
My blower motors were on a separate system for the inter coolers with thru hull pickups. Teague said not to run them on the pump system because it can cause fuel to pool at idle . Ps. It was an I/O cat.
 

Teague_JR

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You will need to run both the drive pickup AND an extra through hull pickup to a dual inlet one outlet sea strainer to supply your new latham pump with sufficient water.

Desired pressure matters where you measure it. Right off the pump at the inlet to an oil cooler like on a mercury racing motor you want 30-40 psi. In the block that will drop to 15-20. Outlet to the headers there isnt much restriction left in the system so you will only see 7-15
 

50onRED

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Just a thought, are you asking about pressure in the intercooler circuit or the motor circuit?
Good question, I was asking in general but should they be different?
 

50onRED

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My blower motors were on a separate system for the inter coolers with thru hull pickups. Teague said not to run them on the pump system because it can cause fuel to pool at idle . Ps. It was an I/O cat.
Fuel to pool at idle? I wonder why..
 

50onRED

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You will need to run both the drive pickup AND an extra through hull pickup to a dual inlet one outlet sea strainer to supply your new latham pump with sufficient water.

Desired pressure matters where you measure it. Right off the pump at the inlet to an oil cooler like on a mercury racing motor you want 30-40 psi. In the block that will drop to 15-20. Outlet to the headers there isnt much restriction left in the system so you will only see 7-15
I’m changing the drive lower so no more water pickup. I planned to use the dual outlet Latham and plumb the intercooler to one outlet then the other side of the pump to the block and out to the oil cooler like it was set up originally. Currently I’m running a stock Mercury pump and see 10-12psi max. I’m not sure how much the Latham pump will make.
 

50onRED

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It happens in the intercooler if it’s too cool . ( only at idle) A bit of heat at idle keeps the fuel suspended.
Interesting. So maybe plumb one side of the Latham to the oil cooler then through the intercooler then out the back? that way it’s pre heated a little?
 

MK1MOD0

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Mine just had the pickups , with no pump to the inter coolers . it would pressurize once on plane with a blow off valve that would open at a set pressure. Simple and no pump to fail. Not sure if ya want to add heat once it’s up on plane ??
 

50onRED

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Mine just had the pickups , with no pump to the inter coolers . it would pressurize once on plane with a blow off valve that would open at a set pressure. Simple and no pump to fail. Not sure if ya want to add heat once it’s up on plane ??
I see, that makes sense. If that’s the case I might just ditch the dual outlet Latham and keep my mercury pump and just use two pickups. One for the motor and a second for the intercooler by itself.
 

MK1MOD0

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Yes. That’s how I had mine . My drive would supply water to the motor, and a separate pickup to the intercooler. It’s simple and reliable.

Edit. Pic. There were two water discharge hoses. One open another had a pressure relief so it couldn’t overpressure. You can see the valve and water hose at the rear of the intercoolers
B815B3A9-28BA-4326-997C-4A600AB57D32.jpeg
 
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50onRED

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Yes. That’s how I had mine . My drive would supply water to the motor, and a separate pickup to the intercooler. It’s simple and reliable.

Edit. Pic. There were two water discharge hoses. One open another had a pressure relief so it couldn’t overpressure. You can see the valve and water hose at the rear of the intercoolers
View attachment 1197807
Very nice
 

DarkHorseRacing

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I see, that makes sense. If that’s the case I might just ditch the dual outlet Latham and keep my mercury pump and just use two pickups. One for the motor and a second for the intercooler by itself.
For the intercooler, if you have good hoses and fittings then don’t bother with a pressure regulator on it. On our TT BBC in our jet we ran as much water through it as we could from the hull pickup. The more water the better the cooling. Maybe it’s recommended to put a regulator on it these days (Water pick ups are better now) so you can if you want.

By the way, the intercooler is 100% its own circuit. Like Teague_Jr mentioned the first stop for water out of the pump is the oil cooler, then the block then the headers. Oil cooler absolutely must get the water first. Intercooler water only goes through it on plane.
 

MK1MOD0

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Just to be clear. My intercoolers had two dumps each. One was a straight hose . The second had the pressure relief valve. I imagine those pickups puts a ton of water at 130 +. So a second dump is probably a good idea for safety. Here is a shot of the starboard engine with the straight dump

491F753C-293D-45D2-8657-2F63CFA1C69C.jpeg
 

mattyc

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Good question, I was asking in general but should they be different?
I wouldnt think so. My 500 with a whipple is pumped water through fuel cooler, oil cooler, p/s cooler then motor picked up through a thru hull. Intercooler is simple pressure fed through the pickup in the drive. Using a gen4 style hardin pump. Typical closed cooling systems will operate up to 15psi cooling system pressure. On my old big block I would 25psi at wot, never had any issues.
Do you plan to use efi and fuel cooler? Or carbs?
 

50onRED

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I wouldnt think so. My 500 with a whipple is pumped water through fuel cooler, oil cooler, p/s cooler then motor picked up through a thru hull. Intercooler is simple pressure fed through the pickup in the drive. Using a gen4 style hardin pump. Typical closed cooling systems will operate up to 15psi cooling system pressure. On my old big block I would 25psi at wot, never had any issues.
Do you plan to use efi and fuel cooler? Or carbs?
It is a carbureted setup
 

mattyc

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It is a carbureted setup
No fuel cooler then. I dont know if anyone really monitors water pressure through an intercooler circuit. In closed cooling systems, coolant caps are commonly 15psi and like I said before i ran up to 25 at wot. I think the weakest link would likely be the intake gasket between the head and intake manifold but a quality gasket installed correctly with proper fitting components should take 25psi. Adding a pressure relief valve can help regulate your water pressure but keep in mind the size of the fittings on the pressure relief. Depending on the volume of water you pick up vs the restriction on the outlet ( likely the holes in the tailpipe ) a pressure relief wont do a whole lot if it cant bleed off enough volume to reduce the overall water pressure. Really is something you'll have to monitor and make adjustments as necessary. You said you are changing the lower unit and cant use that as a pick up? What lower are you going to use?
 

50onRED

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No fuel cooler then. I dont know if anyone really monitors water pressure through an intercooler circuit. In closed cooling systems, coolant caps are commonly 15psi and like I said before i ran up to 25 at wot. I think the weakest link would likely be the intake gasket between the head and intake manifold but a quality gasket installed correctly with proper fitting components should take 25psi. Adding a pressure relief valve can help regulate your water pressure but keep in mind the size of the fittings on the pressure relief. Depending on the volume of water you pick up vs the restriction on the outlet ( likely the holes in the tailpipe ) a pressure relief wont do a whole lot if it cant bleed off enough volume to reduce the overall water pressure. Really is something you'll have to monitor and make adjustments as necessary. You said you are changing the lower unit and cant use that as a pick up? What lower are you going to use?
Im swapping my sprtmastwr for an Imco Lower. I guess it’s not that I can’t use the Imco lowers water pickup. I can, it just seems like every Daytona I see with a similar setup uses a stand alone sea water pickup with sea strainer. I definitely want a sea strainer and a secondary fine sediment strainer to feed the intercooler. Bottom line I want the best possible setup.
 

BassLakeCruiser

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I commented in your other thread a few nights ago but this is what I have on my big NA Schiada. The little cap comes off and you can adjust the pressure. I have it to open at 15 lbs at what would be the thermostat housing. @50onRED
 

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50onRED

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I commented in your other thread a few nights ago but this is what I have on my big NA Schiada. The little cap comes off and you can adjust the pressure. I have it to open at 15 lbs at what would be the thermostat housing. @50onRED
Where’d you get that relief valve? Looks like it’s SS?
 

mattyc

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Im swapping my sprtmastwr for an Imco Lower. I guess it’s not that I can’t use the Imco lowers water pickup. I can, it just seems like every Daytona I see with a similar setup uses a stand alone sea water pickup with sea strainer. I definitely want a sea strainer and a secondary fine sediment strainer to feed the intercooler. Bottom line I want the best possible setup.
I hear ya. No strainer on my intercooler but I periodically back flush the intercooler, food for thought
 

Blackmagic94

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Just run a water heater blow off valve at 15 psi plumbed in. I do this on the jet boat and never get more then that in the engine
 

Teague_JR

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I’m changing the drive lower so no more water pickup. I planned to use the dual outlet Latham and plumb the intercooler to one outlet then the other side of the pump to the block and out to the oil cooler like it was set up originally. Currently I’m running a stock Mercury pump and see 10-12psi max. I’m not sure how much the Latham pump will make.

Where are you getting your water pressure reading from in the system? How is your intercooler CURRENTLY plumbed? You have no extra water pickup for it?

Do not pre heat your intercooler feed.

You should keep the drive plumbed in as a pickup, even if its an IMCO lower. You can always port the water pickup in the IMCO nose cone forward and back a little bit, like you're porting an intake manifold.
 

50onRED

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Where are you getting your water pressure reading from in the system? How is your intercooler CURRENTLY plumbed? You have no extra water pickup for it?

Do not pre heat your intercooler feed.

You should keep the drive plumbed in as a pickup, even if its an IMCO lower. You can always port the water pickup in the IMCO nose cone forward and back a little bit, like you're porting an intake manifold.

I’m building the motor right now. The boat was plumbed for an intercooler from the factory it just never had a hood cut in the hull for the pickup.

I’ve been emailing Josh at Teague all day. I think we have a game plan.

I’ll fill everyone in once it’s all settled
 

Teague_JR

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I’m building the motor right now. The boat was plumbed for an intercooler from the factory it just never had a hood cut in the hull for the pickup.

I’ve been emailing Josh at Teague all day. I think we have a game plan.

I’ll fill everyone in once it’s all settled
Good josh will get you squared away
 
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