watercooled turbo q

hi, what did you guys do with the watercooling system of the turbo on the ej20? the radiator is up front, and so is the burp tank, and filler. id rather not have a 2nd filler in back and burp tank. im talking about the black plastic one that bolts to the intake manifold. Can i just block both ends, ie the one at the block, and the one at the waterpump? i doubt ill need the watercooling of the turbo.

any help greatly appreciated.
-Ryan

Why would you "doubt" youll need watercooling of the turbo?
Watercooled turbos are designed to run....well watercooled.
L8tr
E

You will have to move that filler tank as it will hit the engine bay in a bug. Unless you have your radiator higher than the back of the motor...you tank and filler will be at the highest point..the back. I Just have a turn valve bleeder on my radiator in case some air gets trapped. You cannot just block off watercooling pipes. The turbo water needs to drain back somewhere. There is also an expansion bottle off the filler/tank to take the expanding volume and allow air to escape.

Matt

i thought of that, but after reading how the watercooling of the turbo works, it dosnt constantly run water through it, that would seem pointless. it actually only pulls water through it when the engine is shut off, so you dont need to let it idle or get a turbo timer. alot of the wrx guys upgrade to t3/t4 turbos and they dont have watercooling.

im pretty sure my radiator up front, with the filler, is the highest point in the water system.

alright, so lets say i do put the watercooling back on. do i have to raise that little black coolant tank so that the cap is the same height from the ground as the front radiator cap?

If your radiator sits in the bottom of the wheel well, shouldnt it be lower than the fill tank. Most of us have no filler cap at the front, only at the rear. If you have a cap at the front just keep them both...have the lowest one as a non pressure release cap with the expansion tank next to the high one.....

There must be some benefit in maintaining the watercooled turbo, otherwise Subaru wouldnt use them on the race cars. The sti turbos are watercooled also, and I thought they had constant water flow.
Matt

I've had the radiator cap off whilst the engine is running, at the time the level was low in the tank and I could see a flow from the turbo into the tank. I would expect to see a flow only when the engine is running.
You could run an uncooled turbo, but you might have to pay attention to the way you go about your cooldown.

rubyred wrote:i thought of that, but after reading how the watercooling of the turbo works, it dosnt constantly run water through it, that would seem pointless. it actually only pulls water through it when the engine is shut off, so you dont need to let it idle or get a turbo timer.......

errrrrrr M8, can you show me the documentation or the source that leads you to believe this?

Water is drawn thru watercooled turbos by a pressure differential by siting the turbo in a water line between somewhere upstream of the thermostat and immediately in front of the water pump.
Exactly the same setup as a cabin heater.
What your asking me to believe is that the waterin a Suby sits pretty much stagnant in a tubo and only runs thru it via a thermosyphon effect after the engine is shut down.
Are you aware as to how hot a turbo core actually gets? It will reach temps exceeding 800 deg. C, and glows a beautiful shade of white when it really hot. This one shown below is not that hot but i have seen one so hot that you can clearly see the impeller thru the white hot and translucent zorst housing!!!!!
http://www.ozsuperkart.net/images/XR6-T.jpg
This is probably just slightly above the boiling point of water that is just sitting there. How can having cooling water running thru the hot turbo be pointless?

This is crap, the water will boil and aerate the coolant as soon as the core temp exceeds 120 Deg C or so and this happens less than minutes after initial startup.
Just as the oil with boil and burn in a red hot turbo if the engine is shut down immediately after a hard run or the oil drain hose becomes blocked.

Thats why you bother to keep the engine going immediately after a very hard blast, just to simply keep oil flowing thru the core to remove heat from the shaft and bearings.

Yes, those dudes do eschew the water cooling as they fit NON water-cooled turbos. Thats simple really.
L8tr
Enn[ Edited on 31/7/05 by tassupervee ]

errrrrrr M8, can you show me the documentation or the source that leads you to believe this?

TurboByGarrett.com

To minimize the effects of heat soak-back, water-cooled center housings were introduced. These use coolant from the engine to act as a heat sink after engine shutdown, preventing the oil from coking. The water lines utilize a thermal siphon effect to reduce the peak heat soak-back temperature after key-off. The layout of the pipes should minimize peaks and troughs with the (cool) water inlet on the low side. To help this along, it is advantageous to tilt the turbocharger about 25° about the axis of shaft rotation.

-Ryan

Well theres an interesting take on things. Evidently, im not too old to be told something.......
Where does this particular bit of advertising actually appear?
L8tr
E

TurboByGarrett.com

Turbo Tech--->Turbo Tech 101, scroll 1/2 down, Oil & Water Plumbing

Is there any advantage in the coolant system if the burp tank is near the engine vs all the way in front of the car next to the radiator?

Thanks alot,
-Ryan

rubyred wrote:Is there any advantage in the coolant system if the burp tank is near the engine vs all the way in front of the car next to the radiator?

Thanks alot,
-Ryan

Yes. you MUST have a burp tank higher than the engine... and with NO 'downhill' pipes between it and the engine. As for a non water-cooled water cooled turbo...the WRX/VW conversion I did had flow 100 percent of the time. I'll make this really simple and save you a lot of head-scratching and $: you must retain water to the turbo and rear-mounted burp tank plumbed to original engine pipes/ports. No ifs, no buts

ya, im a newbie when it comes to watercooling, ive grown up with aircooled, and i guess its just an instinct of mine to make things simpler or less complex, because of the overall simplicity of the vw engine.

the turbo will stay watercooled. i will hook up the stock black tank that the turbo goes to, and from there hook up a burp tank setup. the radiator up front will have no burp tank.

i am assuming that it doesnt matter that my front radiator is higher than the coolant reservior/burp tank in the back because the whole system is under pressure correct? As long as it is higher than the engine. but correct me if im wrong.....

thanks a bunch guys,
-Ryan

alls good as long as your point of fill isthe highest point of the complete system