<VV> turbocharger

[jvhroberts at aol.com]

 Yes, they do have a good amount of coolant flow around the bearings, but it's the heat soak AFTER shutdown that cokes up turbos and their respective plumbing. This is when the thermosiphon effect becomes truly effective. When running, it's the oil flow that takes care of things, the water cooling is to take care of things after shutdown, when the heat is soaking back through the turbine shaft and bearing housing bolted to the turbine housing, after the oil flow has stopped and has usually drained out of everything, leaving precious little oil to take heat away from anything, and it just sits there and fries, except now we have a housing full of coolant, convecting away nicely as the VERY hot coolant rises into the head(s), falls in the cooler block, and enters the bottom. 





 





 



-----Original Message-----

From: shortle <shortle556 at earthlink.net>

To: Frank F Parker <fparker at umich.edu>; jvhroberts at aol.com

Cc: virtualvairs at corvair.org

Sent: Mon, 25 May 2009 3:04 pm

Subject: Re: <VV> turbocharger













I worked in a new car dealer (Volvo cars) as a service tech. in the eighties and 

replaced many a turbocharger (made by Garrett) because the cars were smoking out 

the tailpipe. We also replaced the oil feed pipe as it was a requirement for 

warranty reasons. Most of these units were not getting oil to the turbo due to 

not changing the oil enough or by not letting it idle after driving. Then in 

1987 they changed to a water cooled turbo and that pretty much ended the turbo 

jobs unless the owners never changed the oil. Then in 1989 they started using a 

Mitsubishi turbo that was also water cooled but had a feed pipe almost twice the 

size of the Garretts. These turbos seemed to last the life of the car so long as 

the owners were reasonably conscience of oil change intervals. Of course the 

water cooled turbos got A GOOD AMOUNT OF COOLANT FLOWING through the center 

section from the water pump. It was not a siphon effect that would keep it cool 

but a pressurized flow. All these cars used EFI and wastegates, and starting in 

1985 they all had intercoolers.

Timothy Shortle in Durango Colorado



-----Original Message-----

>From: Frank F Parker <fparker at umich.edu>

>Sent: May 25, 2009 12:18 PM

>To: jvhroberts at aol.com

>Cc: virtualvairs at corvair.org

>Subject: Re: <VV> turbocharger

>

>>

>> Ball bearing turbos also have oil feed and drain lines. There's no other way 

to keep them cool enough. And during operation, oil is THE primary coolant. 

However, should you decide to make yours wet, do consider the thermosiphon 

option.

>>

>I like the thermo siphon idea but it does not apply in the GT series 

>case. I just measured the restrictor size in the oil feed line in my 

>turbo and compared it to a normal id of a conventional feed line. There

>was 94 times LESS area to feed oil in the GT turbo line. It is pretty

>clear that oil is NOT the major cooling in this case but the continuous

>flow of water. In a normal BB turbo, the oil line is restricted. Maybe

>some older BB turbo used nonrestricted lines. In that case, oil could be

>considered to be siginificant to cooling but to make a blanket statement

>that ALL bb turbos use oil as main cooling is not correct. Explain how

>94 times lees oil cools as well.

>I do like the thermo idea but it does not apply for mw where I need 

>cooling all the time, not just at shutdown

>

>frank

>>

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