Water Feed Line From Bottom Of Radiator ?

[Dan_J]

now i've got an alloy rad with a lil heater line barb thats located at the bottom on the end tank that i've blocked off and have no use for.

seeing that hot coolant goes to the top of the rad and leaves at a cooler temp at the bottom i figure if the pressure is pretty much that same from the water feed outlet off the block compared to the barb off the rad then this could to used to keep the turbo much cooler as obviously the block gets quite hot.o

other then adapting to a smaller line off the barb to the same size as the water feed it should work just the same way, another note is that for common de+T conversions( VLT /SR20DE+T) where there is no water feed thread on the block they just tap into the heater hose.

so anyone want to confirm or shoot down my theory just on the water pressure alone?

[tricstar]

the water feed to the turbo is only there for when you shut the engine off, to help get rid of heat soak.

its the oil that does all the work while its running.

thats my understanding anyway

[Dan_J]

i understand that the oil is there to reduce the friction in the thrust bearing and i figure that water is there to rid the cartridge of the extra heat as the engine is running.

when the engine is off there would be not much water pressure to do any 'heat soak' work, other then the pressure quickly dies off as the engine is turned off

i remember reading an article where the new mini's turbos were catching fire due to the electric water pump failing

Edited July 11, 2012 by Dan_J

[GTSBoy]

google the term "thermosyphon".

[discopotato03]

Virtually all engine blocks have a water drain plug near the lowest point in the blocks cooling jackets .

Simplest way is to remove this plug and drill it out so you can braze a water or fuel line barb fitting in it . This becomes your turbos water supply line .

It must run uphill all the way to the turbo .

It works best if the turbos water outlet line runs uphill to a point close to the engines main water outlet near the top rad hose The logic in this is that your engine is hot enough at shut down for the thermostat to be open .

The trouble with picking up water at the radiator is that in some circumstances the engine wil draw water through it bypassing the thermostat and running you engine cool at low revs and light loads .

As was said the reason to water cool a turbo is that oil flow stops after shut down and the turbo has considerable heat energy stored in the turbine housing - and exhaust manifold . IMO if retrofitting turbo water cooling I wouldn't worry about finding ways to have the cooling system pump water thriugh it for running cooling purposes . The critical time is just after engine shut down and the turbos water cooling system has to thermosyphon because the water pump has stopped so isn't moving any coolant .

Thermosyphon means hot water rises (hot water is less dense and lighter than cooler water) and the rising heated water draws cooler water behind it .

You MUST ensure turbo water lines run uphill because if they go down then up steam bubbles can form a vapour lock and the water flow can stop .

If this happens and your turbo boils all the water out of its cooling jacket you are back to square one meaning no cooling .

If you set it up right and can hear a boiling gurgling sound from your turbo after shut down don't panic , this means its working properly and the boiling water exiting the turbo is doing its job by transporting the heat elsewhere ie up and hopefully out to the radiator and in my old FJ20ETs case the overflow bottle .

I wouldn't waste money on fancy braided lines , for Garrett BB turbos I get 2nd hand SR turbo water lines and banjo bolts and run steel lines far enough away to escape radiated heat . Then I link the system up with good quality EFI fuel hose because its more than good enough to withstand cooling system heat and pressure .

Simple cheap and works , A .

[Dan_J]

well i've learn't something there ,

so

1. some water will bypass the thermostat meaning longer initial warm up times

2. as long as the hardline from the lower rad goes at an increasing plane with no dips it can work just the same as the water feed on the block

how bout if the feed line dips down as it goes to the water feed input on the turbo would that still be a problem as it would be going straight into the turbo water passage so no air can collect ?

now obviously this isn't some thing that would be needed although if it does work pressure wise there would be a benefit to the cooling aspects to it, not a huge difference though

Edited July 12, 2012 by Dan_J

[discopotato03]

I suggest you get water from the block not the radiator and return it to the head somewhere near the top rad hose barb . Water can only bypass the thermostat if you plumb it to do so . My FJ20 got it from the blocks drain bung hole and retured it to the heads thermostat bowl area , we drilled a hole and tapped it for a brass barbed fitting .

If you access water on the wrong side of the thermostat the water pump draws water through the new water line plumbing .

With an RB that has the thermostat at the bottom hose you would use the std water source at the back of the block or go looking for a lower drain bung hole if it was an early non turbo spec block .

The water plumbing does not have to be vertical it just has to slope uphill , what you are avoiding is a trap (think toilet S bend) where air can sit in a hump or high point that isn't the top end of the plumbing .

A .