DIY conversion to closed cooling- difference in Tstat housing?

[CamaroMan]

Im busy looking into a closed cooling conversion for our motor im putting into our latest boat (79 searay).. Closed cooling will allow me to run a vortec block and alu intake without having to fork out $350 bucks for the iron marine version (open/raw cooling).. Well thats my login anyway.

Can anyone tell me what the difference in the Tstat housing is between open/closed? Does the closed have a bypass on the cool side of the stat?

I have drawings clearly showing closed cooling flow- Might just drill/tap a brass barb into the existing Tstat.

tx-

 

[Scott Danforth]

completely different plumbing

need to know if your looking at a half-system or full system?

basically you get different parts, as you cant easily modify what you have

 

[CamaroMan]

Scott - full.. apart from the blocking of water ports and routing the flow, the stat is all i need to look at really..

 

[Scott Danforth]

a marine vortec dual-alloy manifold (bronze water side, aluminum everywhere else) is only about $50 more than the automotive aluminum version.

such as the Edelbrock 2516

which is a lot cheaper than a HX conversion

 

[Scott Danforth]

Scott - full.. apart from the blocking of water ports and routing the flow, the stat is all i need to look at really..

you dont block water ports

for a half system
you connect a standard single output water-neck to the inlet of the HX
you connect the large HX output to the lower waterpump inlet
the raw water inlet on the HX comes from the raw water pump
the raw water outlet of the HX goes to the exhaust manifolds

for a full system

You connect a Water neck for a full system HX (from your HX system supplier)
you connect the large outlet of the water neck that is T-stat controlled to the large HX connection
you connect the smaller outlets of the water neck that is constant flow to the bottom of the two exhaust manifolds
you connect the top of the HX manifolds to the coolant inlet manifold for the HX (may be part of the HX)
you connect the large lower hose from the circulating pump to the inlet manifold for the HX (may be part of the HX)
you connect the fill line from the over-flow tank on the HX to the fill port on the inlet manifold for the HX (may be part of the HX)
you connect the raw water inlet on the HX to the raw water supply from the raw water pump
you connect the two HX raw water outlets to your exhaust elbows.

A half system HX will be about half the size of a full system HX

you need to buy all plumbing, brackets, etc in a kit with the HX for the system you intend to have.

 

[CamaroMan]

scott - I believe one blocks the passages from manifold to riser as the riser is purely raw cooled where manifold is part of the closed on a full system, thats what i was referring to..

Im hoping to do some plumbing, tapping if necessary and add a heat exchange and is necessary mod the stat housing to achieve good results.

I have 2 manifolds lying around here and they can be had for 100 online, the marine ones are $350 last time i checked?

The jegs ones are 400 deer and up!

 

[Scott Danforth]

And a proper HX kit will be over a grand

trust me, its a completely different T-stat housing

Not to mention you need to have enough expansion and draw down volume for the system.

Which one of the HX manufacturers are you looking at?

Sen-Dure
San Juan
Champ / Alfa Laval (Factory Mercruiser for late product)
R&D
Monitor (Factory Mercruiser for earlier product)

 

[CamaroMan]

was looking at used sendure exchangers on ebay and locally - around for about 150.. might be able to get a stat housing form a closed system, dont wanna drop a grand on a system. trying to do it on the cheap.

Alternatively i can put old SBC heads on the vortec block .. since i have to put a motor in - I have a vortec and SBC both ready to go in.. 2 months before the sun starts coming out and id prefer a closed system-

I will put temp alarm switches on the risers so i can monitor the system.. Still on the drawing board tho-

 

[Scott Danforth]

boats and cheap do not go together

you have to make sure that the system you are buying is for a full system for the motor size and power that you have
Mercruiser has about 45 active HX's for the 4 motors that they have for a reason (Not including Mercury racing, oil coolers or PS coolers.) the number of passes, diameter of shell, length of shell, number of internal baffles, baffle spacing, baffle cut, etc. all vary to balance engine side pressure drop, raw water side pressure drop along with heat transfer.

i have never seen a good used HX, most are removed because they failed and were patched