Which turbo position is most efficient?

[350kmileford]

So, everyone knows that hot air expands. Thus, everyone has said to get the turbo as close to the exhaust ports as possible, where the gases will be the absolute hottest.

Everyone knows that stock Ford exhaust manifolds are very restrictive. So . . .

Would it be more effective to mount a turbo at the end of some long-tube headers (for optimum airflow, but more heat loss) or would it be best to use the stock manifold [for hotter gas(quicker spooling) but restrictive flow]?

Or we could solve this problem a bit by using shorty headers?

 

[Does10s]

Purpose built, equal length, long tube header(s) would be the best setup.
But almost always, the chassis is the determining factor in what can be done.
And if you mount the turbo lower than the oil level in the pan, you'll need a pump to get the oil to return to the engine.

In my experience, anyway you can get exhaust gasses into a turbo, it'll be very beneficial to the HP output!
Will

 

[StrangeRanger]

Wouldn't it matter on what you were trying to do with the car?

If it's a 1/4 mile machine where you can load the turbo against the converter than punch the transbrake, then the long tube headers would clearly be a better solution, although not necessarily an off the shelf set. The heat, pressure and vibration would all be likely to exceed the design intent of any off the shelf package.

If you're looking for an auto-x or open track machine, then a fabricated manifold with the shortest possible runs from exhaust to turbine and from compressor to carb or T/B is what you need to maximize the throttle response.

 

[350kmileford]

Won't the inlet oil pump be enough to also push the oil back up again?

 

[Does10s]

Won't the inlet oil pump be enough to also push the oil back up again?

Nope.
There's is essentially no oil pressure after the turbo. If you don't electrically pump it back into the motor, it'll just sit in the center section of the turbo and smoke up the entire neighborhood.
This is why most turbo system designs are "high mounted". So gravity will pull the oil away from the turbo.

Will

 

[350kmileford]

I believe you, but it is hard to understand. Oil gets pushed into the turbo, then what stops it from getting pushed out (and up)? Oh well. If all I need is another little oil pump, it may not be too bad.

 

[wallaka]

I believe you, but it is hard to understand. Oil gets pushed into the turbo, then what stops it from getting pushed out

The turbo's bearing cartridge is in the way.

 

[yodabiri]

I dont mean to hijack the post but has anybody ever tried using this type of placement for their turbo? It seems like a really unique and cool idea.

http://www.ststurbo.com/home

I may be considering this type of system. It seems like a very practical way to go about a turbo setup. If anybody can show me the faults in this system please do I want to have as much knowledge about this topic as possible.

Thanks!

 

[350kmileford]

There is more boost loss, slight turbo lag, more air & oil piping is needed, and the turbo is more exposed to road debris/damage. All in all, not horrifying cons. I wouldn't mind having an sts-style setup.

 

[XPC66]

I believe you, but it is hard to understand. Oil gets pushed into the turbo, then what stops it from getting pushed out (and up)? Oh well. If all I need is another little oil pump, it may not be too bad.

You need to be a bit careful. You will effectively be mixing dirty oil with clean oil in the CHRA if you send the return line higher. The extra column of oil acting against the supply may also slow the flow.

When the engine shuts down, oil is typically syphoned back from the supply line into the engine.... which is why you should give the turbo 30 seconds or so to spin down after a beating, before turning off the engine. When it does syphon it may pull the dirty oil accumulated in the CHRA back through the thrust bearing.

 

[bigcatchdaniel555]

I saw a speed tv show where they did twin turbos on the back like this on a ls6 vette. The dyno showed almost no turbo lag and a hp difference of about 3-5 hp loss to the back. So if your pressed for room or want it hidden this is a feasable option.

 

[wallaka]

Remote-mount turbos are an option. If sized correctly, there might not be noticeable lag in an engine that makes enough grunt on its own. It will still be down in horsepower, torque, and response from an optimized close-coupled solution, though. If you don't have much space, they are worth pursuing.

 

[Anonymous]

Oil gets pushed into the turbo, then what stops it from getting pushed out (and up)?

Because there are no seals that can handle it.

A turbo is designed to spin at 100,000 rpm at 1400 degrees.

Do you really think a rubber-lip-crankshaft-seal type of seal would handle that abuse? Maybe for three seconds and the rubber lip is gone.

That is, if you could ever get the turbo to spool up because of all the drag.

The only seals turbo manufacturers can come up with that can handle the heat, speed, etc that a turbo deals out is a simple little piston ring type thing on the turbine shaft. It is NOT a positive seal. It is just a "suggestion".

Oil MUST flow freely from the center section or all the oil pumped into a turbo will exit past the turbine wheel into the tailpipe!!!

Remote mount turbos..... if you think that is the way to do it, it is your money. I wouldn't do it for a number of reasons. Take it for what it is worth from a voice of experience.