2.5" IC piping and 600HP??
He needs to keep the pressure drop down a bit, so less boost is needed to keep the car a bit responsive (or as responsive as it can get w/ 600whp.) 2.5 is fine.
Regarding response, I actually did the math at HMT.com, and I was a bit surprised. I can't recall the exact numbers, but when I used 2.5" and 3.0" in the formula, it was 40% extra volume but only adds 0.1 second to transient response (0psi to ~15psi) on a D16 @3500 rpm.
The key behind that is the engine consumption of air is FAR FAR greater than the volume in the piping. In simple terms, the engine is 'leaking' that air given its an air pump. In complicated terms (D16@3500rpm), to reach 15psi you roughly double the flow. That means you need the 84cfm the engine is using NA *plus* another 84cfm. Figuring 10 feet of 2.5" piping is roughly .34'^3, it only takes that extra 84cfm ~0.1 seconds to fill the piping to 15psi. This goes to show its the shaft speed that creates lag, not piping. The numbers are a tad higher since the cylinders don't wait for the pipes to hit 15 psi before sucking in the extra air.
The key behind that is the engine consumption of air is FAR FAR greater than the volume in the piping. In simple terms, the engine is 'leaking' that air given its an air pump. In complicated terms (D16@3500rpm), to reach 15psi you roughly double the flow. That means you need the 84cfm the engine is using NA *plus* another 84cfm. Figuring 10 feet of 2.5" piping is roughly .34'^3, it only takes that extra 84cfm ~0.1 seconds to fill the piping to 15psi. This goes to show its the shaft speed that creates lag, not piping. The numbers are a tad higher since the cylinders don't wait for the pipes to hit 15 psi before sucking in the extra air.
Trending Topics
Thread
Thread Starter
Forum
Replies
Last Post
DamonBoost
Forced Induction
6
Jun 24, 2002 06:03 PM





