Turbo placement, exhaust heat and back pressure.

[Jon421]

I came across this turbo kit that is designed very different from most. The turbo itself is placed behind the rear axel, below the gas tank approx 10-12 feet away from the engine.

http://www.ststurbo.com/inc/iview/264?idx=7&p=8054

More pics can be found here:

http://www.ststurbo.com/camaro_install_pics

Any thoughts on this?

How does temperature of the exhaust gas (vs. the exhaust pressure) impact to the efficiency of the turbo?

 

[GregLocock]

It has a huge effect. That turbo is going to see less than half the volumetric flow rate that one in the usual place would see.

Since the power output of the turbo is volumetric flow rate* change in pressure, you can see that this is not likely to be a good idea.



Cheers

Greg Locock

 

[SBBlue]

Here's some calculations. . . .

Assuming: 1) Boost pressure of 14.7 psi, 2) Turbocharger turbine and compressor -- 60% effciency, 3) exhaust gas temperature at the manifold -- 1700 deg F, 4) exhaust gas temp at turbocharger in back of car: 1200 deg F (the website said the turbocharger ran 500 degrees cooler in the back).

This figures come from using the standard air tables.

Compressor work: 47.25 BTU/min/lb air

Turbine energy: 78.75 BTU/min/lb air

exhaust back pressure with turbocharger mounted to the exhaust manifold: 1.77 atms absolute, or 11.28 psi relative pressure.

Exhaust back pressure with turbocharger mounted behind the gas tank: 2.14 atms absolute, or 16.92 psi relative.

The net result will be that you will have considerably more turbo lag then you would otherwise. If the turbo was used all the time (as with a diesel engine), your fuel efficiency would take a hit. For practical purposes, a spark-ignition (gasoline) engine really only uses the turbocharger with the throttle wide open. Therefore, you should not notice that much a difference with fuel efficiency unless you are running the the throttle wide open all the time.

 

[Chumley]

Jon421: Your link is comical.

Tiger Woods all ready knows how far he can hit his 7 iron. He doesn't need any engineering calculations to tell him that, nor, during a tournament, does he consult an online website for advice. Why not?

Because he has all ready "made" that shot, as well as screwed it up 100,000's of times.

Some real smart person once said, "I failed my way to success."

Chumley

 

[Andy330hp]

yeah, that's one of the worse ideas I've seen in a while