how to choose piping

[tjohn23]

i never post, i usually can find everything i need from searching but I'm having a hard time finding info on choosing piping and explanation.

im looking into an intercooler and piping for t-25 turbo intercooler inlet to outlet for 1g n/t throttle body.

since the throttle-body is 60mm this is 2.36 inches, what size piping should be used 2.5 inches?

the throttle-body opening is much larger than the compressor outlet of the turbo so how would this work?

also why wouldn't you want at 3 inch exhaust on n/t or low boost systems. im not understanding back pressure.

 

[DSM nOOb]

i never post, i usually can find everything i need from searching but I'm having a hard time finding info on choosing piping and explanation.

im looking into an intercooler and piping for t-25 turbo intercooler inlet to outlet for 1g n/t throttle body.

since the throttle-body is 60mm this is 2.36 inches, what size piping should be used 2.5 inches?

the throttle-body opening is much larger than the compressor outlet of the turbo so how would this work?

also why wouldn't you want at 3 inch exhaust on n/t or low boost systems. im not understanding back pressure.

As far as the intercooler goes I would just buy the vrsf kit and never look back until you plan to make 500+

As far as "back pressure" this is a common misconception. When people say you need back pressure what they are really referring to is "scavenging". This is when the exhaust creates a vacuum essentially sucking out the exhaust gasses every time the valve for the next cylinder opens.

In turbo charged applications you do not need to worry about this (I am sure special cases may apply but) because it will slow down your spool time. you just want the biggest opening possible for the gasses to exit so it won't slow down the turbine.