Piping Size?!

[Dark DSM]

OK now in trying to figure things out, what is the ideal size of piping to use for a turbo system. I was going to go with 2.5 inch, should that ok, or should it be3" Let me know. Thanks

 

[VelocitàPaola]

2.5" is more than enough. Many of us run 2.25" piping, and those of us who don't, have 2.5" pipes. 3" is overkill.

 

[DSMcrazy3]

Like Paul said 2.25" is standard for IC pipes, however a select few have 2". Assuming that's what you're talking about.

As for exhaust 2.5" will do, but 3" is recommended.(incase you were referring to this)

 

[selmerguy]

I have 2 inch ic pipes and no problem. The bigger the pipes the more lag and pressure drop you will have. Not a whole lot of difference but alittle. Like the difference between spooling at 3000 or 3200 rpm. I would not go bigger then 2.5 on a four cylinder. The supra guys go real big sometimes. I have heard of 4 inch on those bad boys.

 

[VelocitàPaola]

Yeah, I saw a Supra with absolutely huge piping when I went to get mine made. It had to have been at least 3" IC piping with a 4" exhaust. Those sizes are definitely not recommended for our little cars. 2.5" IC pipes with a 3" exhaust is the point where you'll start realizing diminishing returns and/or performance losses.

 

[GSGoinFast]

2" here, but i may move up to 2.25 or 2.5 when i redo the piping

 

[XMasta19]

2.5" all around for me...turbo compressor outlet is only 2", but a silicone transition elbow solved that problem nice and quick.

 

[DSM90AWD]

If you're a believer of Corky Bell, he suggests a pipe size that will promote an internal airspeed of < .4 Mach (304MPH) at which point is the onset of excess drag.

Taking the calculations from this Honda-Tech thread based on a .4 Mmach limit in a straight pipe the maximum recommended airflow for each sized pipe:

2.00" = 585 cfm max (~400HP*)
2.25" = 740 cfm max (~500HP*)
2.50" = 913 cfm max (~600HP*)
2.75" = 1100 cfm max (~750HP*)
3.00" = 1300 cfm max (~900HP*)

* using cfm to lb-min conversion of .069 found HERE

Then again this disregards bends, transitions..etc which can increase flow at certain points so prol shooting for something in the middle would be best