924Board.org

[Scorpio]

1)Whats are the best locations to get water feed from, to the T25 Garret turbo?
(perhaps tap into the water pump outlet)

2) ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' water drain'''''''''''''' ?
(perhaps tap into the thermostat inlet)

3)On the turbo housing does it matter which is feed and which is drain?

Im thinking tapping anywhere from thermostat out--->radiator---- >water pump in, is bad cause its not getting forced flow all the time.......unless convection currents are enough?
_________________
1979 NA
MS1..EFI..
GARRETT T25 TURBO
BILSTEIN SHOCKS
GT BASED CUSTOM BODYKIT

Brisbane , Australia
Think mean think fast
all youll see is
my Porsches Arse!!!

[gegge]

Maybe a good idea to make the subject and thread generic to any watercooled turbo?

I don´t have any answers, only more questions
* What is the gain with watercooling(while driving)?
* Keep the water running all the time, at WOT or only after engine is shut-down.
* Running an watercooled turbo without water connected, same as asking for disaster?
* Is it worth the effort to connect water to a sundaydriver or track car?
* Do you need a larger radiator since you put strain on the cooling capacity?
_________________
Carl Fredrik Torkildsen

924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs

[ideola]

I would recommend mimicking the 951 setup. Pull a feed off of the lower rad (cool side) and then return to the expansion tank. Swapping in a 951 expansion tank is a piece of cake and provides the necessary inlet. Getting a feed is as easy as having a nipple welded on to your existing end tank or putting a tee in the lower rad hose. To finish it off, add an electric booster pump. This pump really only needs to run after shutdown, but you could run it to make sure the turbo gets some benefit of water cooling while the engine is running too, and to aid the mechanical water pump, ensuring that the turbo circuit gets circulation during normal operation. Plumbing it in this manner will minimize the amount of heat soak caused directly by the turbo.

To answer gegge's questions:

• Q: What is the gain with watercooling(while driving)?
  A: I don't believe there is any appreciable gain, although you might be able to make the argument that cooler temps at the turbo may allow the engine to run cooler overall, but I doubt it is enough to make much of a difference while running.
  
• Q: Keep the water running all the time, at WOT or only after engine is shut-down.
  A: The primary purpose is after shutdown, which is when the main problem of heat-soaking (and subsequently coking) the bearings occurs.
  
• Q: Running an watercooled turbo without water connected, same as asking for disaster?
  A: Anecdotally, I don't believe this is a problem, as I've heard that some racecar drivers will actually disable the water circuit on their turbo. As long as you have adequate oil supply and proper warm down after hard runs, the water-cooling circuit is not absolutely necessary. In some respects, you can almost think of it as a luxury that makes a daily-driven turbo somewhat idiot proof.
  
• Q: Is it worth the effort to connect water to a sundaydriver or track car?
  A: IMO, it is relatively simple and inexpensive to do, and given the difficulty and expense of replacing the stock 931 turbo, I believe it is absolutely worthwhile insurance to help extend the life of the components.
  
• Q: Do you need a larger radiator since you put strain on the cooling capacity?
  A: Again, following the 951 example, the 951 rad is a few rows larger than the 944 NA / 924S rad, but otherwise identical. So yes, it is probably a really Good Idea to increase the capacity of the cooling system.

_________________
erstwhile owner of just about every 924 variant ever made

[Scorpio]

The biggest gain is in Turbo life. There are alooot of people running water and oil cooled turbos without the water lines with no major issues.

For me its there so ill use it to help in overall cooling. Ive read that alot of people running water lines dont need to use turbo timers...but then there are those that dont use turbo timers anyway..
Two extra water lines for peace of mind.

Dan can you confirm the 951 setup uses cool water from the lower rad pipe as a "water in" and sends "water out" to the expansion tank( i currently have a new 944 expansion tank )?... Does the 951 have this electric water pump?..ide prefer not to plumb in an electric water pump...but the water circuit you describe above , without an electric pump doesnt seem to flow...either through pump pressure or convection currents?
_________________
1979 NA
MS1..EFI..
GARRETT T25 TURBO
BILSTEIN SHOCKS
GT BASED CUSTOM BODYKIT

Brisbane , Australia
Think mean think fast
all youll see is
my Porsches Arse!!!

[ideola]

Yes, the 951 is plumbed as I described it, and yes, it has a Bosch auxiliary pump along with a relay that provides post-shutdown operation. I'm not sure how the circuitry operates during running, but I presume that the aux pump does in fact operate pretty much in continuous mode.
_________________
erstwhile owner of just about every 924 variant ever made

[gegge]

Summary and conclusion: