win/win situation. so the low cost is because of the switching of only the compressor side? I always thought that the difference in price between the two was considerable. I guess I was misinformed

 

I have this 18g, 20g down for a long time... the price per HP you get when compared to other 650 rwhp type turbos is huge... not sure what you have been told...
mark

 

Assume Atmospheric press = 14.5
Atm press @ 5,500' = 12.0

%loss @ 1 bar = (29.0-26.5)/29.0*100% = 9.1% (intake pressure, not HP)

 

Does the boost control in the Porsche DME target gauge or absolute pressure? My 1bar flash often shows 1.2 on the gauge at 6000+ft

 

Absolute pressure but not very accurately. The point is that in order to get the same pressure at higher altitude the turbine will have spin faster, perhaps faster than is efficient. Larger turbo might be needed at higher altitude to maximize output.

 

Thanks, you'll definitely move down in compressor efficiency trying to maintain boost and your IC efficiency is already down so a better compressor is win-win. Just curious what the DME was trying to do.

 

yup, this is pretty close to my calcs for 6000 ft. The higher the pressure of the turbos the less the loss you will see. So I calculated my loss using 1.2 bar at 6000ft. Cars running 2-3 bar like evo's will loose considerably less power at altitude. Still a 9% loss is noticeable when your talking 500+ hp.

 

I may be wrong but are you using millibars regarding 29.0? Isn't standard day (sea level, 15 c) 29.92 mb? It wouldn't change anything much. I just want to make sure I'm not thinking about something else.

 

29.0 is the total pressure in psi (~14.5 psi atmospheric for an SAE day and another 14.5 for 1 bar of boost)

 

As I suspected I was confused .

Mb would be 1013 and 29.92. I'm with you now.

Edit: Sorry for the tangent. Now back to our scheduled thread.