I have 178mmASP with 71mm machined down SC-Pulley which equals the 185mm. LET-HE and Johnson CM30, splitted IC-Reservoir and have ordered the upgraded IC(under the SC). I dont expect much better Peak-Intercooling under boost with the new IC, but better Recovery-Cooling when you let off the throttle. This is also important for me when I drive on the Autobahn. When my SC is removed from the engine during install of the new IC, I have planned some more little things to lower IATs
. I will post the results.
By how much the air is cooled with the IC is difficult to say, because it depends on outside temperature, boost and the most important HOW LONG YOU STAY ON THE THROTTLE under boost. When I look at the diagrams I would estimate it is cooled down 50-60 Deg Celsius (120-140degF), when I compare it to my dataloggs.
The intercooling of our cars is only built for a short run to 250 km/h under full boost and then you drive 250 km/h with the throttle-body only "half way open". The car is at its limit only for a few seconds. For daily driving or 1/4 mile races (11-12 seconds full throttle) the Intercooling is good enough in my opinion.
Its difficult to say if the 178mm is better than the 185mm. I like the midrange punch of the 185mm VERY MUCH in daily driving. Maybe the 178mm is a little more efficient in the highest RPM. In my opinion it is a personal choice.
I am very interested in the Dyno-Results with the new Mid-Size C3-SC Pulley stacked with the 178mm. According to Code3 the results are very good, and it is worth for him to build a Mid-Size Version of th SC-Pulley...Good option for the 178mm owners or Marketing? We will see...