Does this mean you're starting a new thread called "Standalone cooling system (long ish)"?

 

Perhaps I'm missing something here, but how about this? This would be for a single rear mount, just duplicate on the other side for duals. Y pipe ahead of the turbine exhaust inlet. Each leg of the Y has an electric exhaust cut out, one open, one closed. The open side goes to atmosphere during cruising/daily driving. The closed side goes to the turbo turbine inlet. No heat, no pressure, no movement of the turbo shaft. Essentially, it is at rest and is isolated and consequently needs no oil pressure. Driver turns on the "turbo" switch, or goes to WOT, or however you would like to trigger it, your choice. "Turbo switch" turns on the electric oil pump. 0w-20 Mobil One pressurizes the turbo oil supply. An oil pressure switch sends current to a relay that energizes the atmo exhaust cut-out to close, and the turbo supply exhaust cut-out to open. Turbo now has exhaust pressure to spin up and plenty of cool oil. If oil pressure drops, the relay goes the other way (two way relay) and the exhaust cut-outs reverse and the turbo is again isolated. The turbo is safeguarded. Yes, there will be a delay after the "turbo switch" is turned on, but for a street racer guy, or a street/strip car, this is not a problem, as you know ahead of time when you will need the turbo and when you won't. The rest of the time, the engine will be NA, and allow the turbo oil reservoir to cool down. This adds expense and complexity but the system is safeguarded. If the dual exhaust is already there and is stainless steel, all that need be done is replace the mufflers at the back with this system, recouping some of the expense. There is one more problem that I will cover if someone is interested.

 

Most turbos I have seen (unless very large) would be turning a few thousand rpm even at idle. Your by-pass deal might be sized large enough to not have enough energy to turn the turbine/compressor wheels, (but if it does the turbo is trashed quickly). A buddy killed a turbo idling in the parking lot when he disconnected the feed line vs the drain line to check oil volume coming out of the turbo.

Just saying.

Tom V.

 

Hi Tom, There wouldn't be any energy going to the turbine because the exhaust cut out to the turbine is closed. The other exhaust cut out is open, bleeding off all exhaust to the atmosphere. I assume these new electric cutouts seal pretty well, so nothing would reach the turbine inlet until the cut out is powered open.
At the end of my post, I mentioned one last problem, but I had to go to supper. The last problem is the vaccuum through the inlet side (compressor) could very well cause the turbo to spin slowly. Then it would ruin the bearing. So, up near the engine, yet another valve of some kind would be needed to let the engine draw air in somewhere other than through the turbos. Or you could have the oil supply pump run all the time, which would require a more expensive but dependable pump.
So why would anyone want to go to all this complexity and trouble to have the turbo in the back? I've got a v8 Chevy in a Mazda RX7. It is traction impaired on the street, so any weight that I can move from the front to the back is worth the complexity and expense.

 

Aluminum Racing Seats and lead weight in the back seem to me to be an easier alternative, but keep after it!

Tom V.

 

Newbie here...sorry if this thread is old or dead, but I have a question. In a rear_mount turbo system and standalone oiling, why worry about the heat for oil cooling? My twisted thinking is oil pressure regulated to the inlet aide of the turbo, gravity feed into an open atmosphere holding tank and a pickup that loops back to the turbo. 300 to 500 is norm at the header....cooler at the back end of the car. Synthetics operate fine at 500 to 700. Apologies again if this has been answered.

 

There's a little less heat in a rear mount, but I think your temps are off. It's not uncommon to see the pre turbo hot side glowing red (front mount), and exh temps between 1000-1500 degrees. The turbine is the restriction, and heat is needed.