intercooler piping size

[hose101772]

As far as piping goes isnt the reason for using 2.25" pipe to keep the aircharge at 300fps or less for moderately sized turbos.The folks who make the larger intercoolers figure youre probably going to run a large turbo-hence buying the large intercooler-which will have higher cfm rating,therefore you will need even larger piping to maintain the 300fps "ideal" aircharge speed.

 

[SAUBIK]

Let's repeat the calculations for a turbocharger with a 550 CFM airflow capacity. We'll calculate the air velocity for 2.25-inch, 2.5-inch, and 3-inch intercooler piping.

- Turbo Flow Rate: 550 CFM (Evo 3 16g)
- Engine Displacement : 2.0L (122 cubic inches)
- Desired RPM: 8000 RPM
- Volumetric Efficiency (VE): 90% (0.90)
- Boost Pressure: 15 psi

Convert CFM to Cubic Feet per Second (CFS) - 550/60 = 9.17 CFS

Calculate Cross-Sectional Area for Each Pipe Diameter

1. For 2.25-inch piping:
3.97sq in
- Convert to square feet:
0.0276 sq ft

2. For 2.5-inch piping:
4.91sq in
- Convert to square feet:
0.0341sq ft

3. For 3-inch piping:
7.07sq in
- Convert to square feet:
0.0491sq ft


Calculate Air Velocity in fps and m/s

1. For 2.25-inch piping:
- Velocity in fps:
9.17 / 0.0276 = 332fps
- Convert to m/s:
332.0 * 0.3048 = 101.2m/s

2. For 2.5-inch piping:
- Velocity in fps:
9.17 / 0.0341 = 269fps
- Convert to m/s:
269.0 * 0.3048 = 82m/s

3. For 3-inch piping:
- Velocity in fps:
9.17 / 0.0491 = 186.8fps
- Convert to m/s:
186.8 * 0.3048 = 56.9m/s

Summary

For a 2.0L engine at 8000 RPM, 90% VE, and 15 psi of boost with a 550 CFM turbocharger:

- 2.25-inch piping:
- Velocity: 332.0 fps or 101.2m/s
- This velocity is above the optimal range (150-300 fps), which could lead to excessive pressure drop and potential inefficiencies.

- 2.5-inch piping:
- Velocity: 269.0fps or 82.0m/s
- This falls within the target range of 150-300 fps, making it a good choice for balancing airflow and pressure drop.

- 3-inch piping:
- Velocity: 186.8fps or 56.9 m/s
- This falls within the target range and offers lower velocity, which can reduce pressure drop but may be slightly oversized for this application.

Recommendation

- 2.5-inch piping is recommended for this application as it provides a good balance of airflow velocity (269fps) within the optimal range for turbocharged intercooler systems, ensuring efficient airflow with minimal pressure drop.

- 3-inch piping can be considered if you want to ensure even lower velocities, but it may be oversized for 550 CFM airflow and could introduce some lag.

 

[Capt Obvious]

My other car is a 996 Turbo and this same topic has been beaten to death for that platform too. A lot of people thinking bigger is better for the intercooler piping, but it's been proven time and time again that the factory y-pipe (2.25" x 2) is good to over 800hp with essentially zero gains to be had by moving up to 2.5" or larger piping until you're over the 1000hp mark.