I guess thats why they also do turbine maps in pounds of pressure instead of degrees. Pick up a book sometime. TIP is usaully 2:1 on a street setup. So if you make 10 pounds of boost 20 pounds of tip is produced in the head to turbine area.(34.7 atmospheric) Once it goes to the otherside of teh turbine you goto to basically 14.7 Thats a 68 percent drop in absolute pressure. Comparitivly temps drop do to adiabadic efficiency of going to one temperture gradient to another and do not really "fuel" the turbine as much as you would think though it does help. 34.7 at 1500 (1940 absolute) degrees to 14.7 is around 822 degrees absolute at adibatic. Although thermal does creat alot of the gradient the specific heat of the atmosphere doesnt really diffuse fast enough to suck the turbine anyfaster. gas pushing pressure creates more work.
Also did it ever occur to you that to make 20 pounds of psi in the exhaust chamber means that the entire combustion chamber volumn is no where close to emptied? So on the next engine cycle you have all these inert gasses taking up space and not burning anything. If you can get TIP below 1:1 you really flush the combustion chamber and real power can be achieved.. but this is pretty hard to do. This is the same concept as putting on an exhaust system that produces 20 pounds of back pressure. You wouldnt consider a system like that any more performance then i would consider a turbo that produces 20 pounds of back pressure (tip) Also you gotta remember all the pumping losses associated with all that back pressure. The engine uses 68 percent more energy to complete the exhaust stroke under that much back pressure then it would naturaully aspirated (at the top of the exhaust stroke) (the energy used is perportionate with the gradient of pressures before and after) with a completely untuned log style header. Tuned length headers create negative amounts of pressure to suck out exhaust.
SO dont even come after me telling me my tip statements are erroneous.
Ex-cat cams dealer. Today we do motor mounts.. Tommorow. Intake manifolds
Pick up a book sometime. TIP is usaully 2:1 on a street setup. So if you make 10 pounds of boost 20 pounds of tip is produced in the head to turbine area.(34.7 atmospheric) Once it goes to the otherside of teh turbine you goto to basically 14.7 Thats a 68 percent drop in absolute pressure. Comparitivly temps drop do to adiabadic efficiency of going to one temperture gradient to another and do not really "fuel" the turbine as much as you would think though it does help. 34.7 at 1500 (1940 absolute) degrees to 14.7 is around 822 degrees absolute at adibatic. Although thermal does creat alot of the gradient the specific heat of the atmosphere doesnt really diffuse fast enough to suck the turbine anyfaster. gas pushing pressure creates more work.
