Brave7012

A question on above. I am currently running a 178mm with ECU tune. IAT goes up as usual. I read that for many after fitting a 80mm TB, the boost acutally drops, so does that translate back to reduced IAT ? If so , how many degree did it drop.

Thanks.

HYEPWR

the equation to calculate Supercharger exit temp is:

Tout = Tin + (Tin x [-1+(Pout/Pin)0.263]/SCeff)

where

Tin=Ambient temp in F + 460
Pin=Preassure pre Sc + 14.7
Pout=Preasure out the supercharger + 14.7
Pout/Pin=pressure Ratio

So for a stock E55 on 75 DEGREE day we get

Tin=75F + 460=535
Pin= -0.5psi +14.7 (guess)=14.2
Pout= 10.5psi + 14.7 (peak psi per MAP sensor)=25.2
Pout/Pin=1.77

Tout=198 degrees F

So if a stock car had NO IC....it would see Inlet temps of 198F on a 75 degree day.
usually a stock car will be under 130F .......so, we can assume the intercooler in the car removed 68F of heat....so it has an efficiancy of 55%.

Now on a pulley"d car......same 75F day...the peak boost may reach 14psi. That works out to a supercharger outlet temp of ~225F!! Thats almost 30 degrees more.

Using the same IC eff of 55%........that means a stock car that maxed at 130F inlet temp will now consistanly go over 144 Degrees F!!!!

If you could theoretically drop Boost preasure by 2 psi peak....you would get 207F SC outlet temps and ~135F AIT's

This is in theory---Holding several variables constant.

IC efficancy on a E55 will tend to go DOWN as Inlet temps go up.....as the ic cannot remove enough temp.

hope this helps...

Brave7012

Thanks. Great help !

HYEPWR

I never sat down to do the math.....but after doing it....its so clear how absolutely terrible the stock IC on the E55 is......55%?? Wow, thats BAD!!The efficiency of an average air/water IC should be usually between 75%-95%. If our stock cooler was even 75% efficient---we'd never go over 115F AITs

I guess thats why we need SLR coolers.