I'm no physics expert so..... Based on the above info suppose I provided the following info:
Ambient - 80
Boost - 20
IC efficiency - ??
Charge temp before IC - ??
Charge temp after IC - 99
What assumptions can you draw from this limited info??
Let's say about 375 hp, that's what my track speeds and car weight dictate. TE44 turbo.... IC tubing is all the same size as the stock 86 up pipe. IC is a CAS V2..... Throttle body is a 62mm.... Any of that help?
Well, there are some things you may be able guesstimate. I don't know what the compressor map is for that turbo but I'll pull one up that maybe is reasonably close (a 57trim Turbonetics):
If you are making 375WHP (with 15% drivetrain loss = 440HP) and lets use a standard guesstimate of 10HP per lb/min so you are flowing 44 lb/min which agrees with the guess in another post.
You are making 20psi boost but the CAS V2 has a pressure drop of around 3psi so you are running 23psi at the turbo. Your pressure ratio is ((23+14.7)/14.7 = 2.56. Looking at the compressor map above you might be in the 60% efficiency range.
Using efficiency to calculate turbo outlet temps with this formula (
http://www.gnttype.org/techarea/turbo/turboflow.html) we get an a turbo outlet temperature of 332F for the ambient temp of 80F. Does this sound right? If we look at the data from the Bob Dick intercooler test (
http://www.vortexbuicks-etc.com/ICtest.htm) on Table 3 page 15 we see that the CAS V2 had a turbo outlet temp of 319F when the TB inlet temp was 99F for their test at 21psi boost on a TE51 turbo. So the numbers seem within reason for a very quick guess.
So what can we gather from this? Well, we are out of the sweet spot of the turbo (highest efficiency) but the IC is doing a good job. If you had a perfect intercooler with no pressure drop we'd still be out of the sweet spot of the turbo. However, lowing the TB temps with alky would create more power. Airflow is proportional to density and density is inversely proportional to temps (but temps must be converted to K). Lowering the TB inlet temp by 30 degrees would increase the density by (99+460)/(69+460) = 1.056 or almost 6%. So there's power to be had by lowering the inlet air temp.
You can also see that by using a stock location IC with a turbo that has this sort of compressor map that without a good temperature drop through the IC or with heat soak in hot weather the TB temps would be very high and power would go down. Alky would definitely be a benefit for that type of combo and is the reason it works so well on the smaller turbos and/or SLICs as it lowers inlet temps at the TB.
Now if you went to a larger turbo with one like the compressor map below:
For the same 44lb/min and the same pressure ratio of 2.56 you are in a better efficiency range. Outlet temps from the turbo maybe only be 280F (a drop of 50F). So you could get away with a smaller IC or be more likely to running ambient temps after the CAS V2 IC (more power at the same boost). You wouldn't benefit from alky as much as with the smaller turbo. But in really hot weather it would still lower inlet temps after the IC. By looking at the compressor maps you can see that the larger turbo is much more efficient at the larger air flow numbers. Of course, the engine has to be able to make use of that air (such as ported heads).
I'm only referring to alky as it relates to TB temps here. Beyond that it still raises the octane and suppresses knock in one way or another which is probably how it helps people with the more efficient combos.