so i was on some other forums trying to understand turbos and such better.
i was a nice spool and with a linear? power curve.

as im reading these threads and so on i find one post where this poster says that you need to match your ic piping to the turbo and the same with the exhaust..and if you went with to big of a size youll suffer lag and low end ..
thats where i get confused at i thought with a turbo you wanted FREE flow anything


exhaust and intake... logically a bigger diameter means you can move more mass through the area (ie intake doesn't choke the turbo)

back pressure is a turbos biggest enemy sooo to get rid of back pressure you go BIGGER less restrictions

help me please

 

you sir are correct...i dont know who would say such a thing.....freeflowing means the turbo has to work less to fight backpressure....
http://fc3spro.com/TECH/TURBO/turbotech.html just a good read

 

SWEET!! i really have to start navigating that site better so much info!

and i was thinking of doing a 4 inch or (extreme) 5 inch turbo back... that would be INSANE (prolly not practical)

 

Definitely not practical or needed for 90% of turbos out there. 3" will do fine for most popular turbo choices.

To comment on your OP, having intercooler pipes that are too big will increase lag, due to the larger volume of piping that has to pressurize before reaching the engine. Bigger is not always better.

 

thats true i didnt think about that
if im doing a vmount set up 3 inch should be good for the intercooler? or should i stick to the standard 2.5.

this would be so much easier if i knew what turbo i was going with. right now i have a Garrett tv7512 with i think a 1.06 exhaust housing or a 1.20 exhaust housing ... i dont think ill ever spool that

 

Yes, that is true. If the piping is too big then it will reduce the velocity, which will reduce the momentum of the air. Also, larger tubing has more surface area, and given the same surface type that means more drag.

Since the velocity is based on air volume, the plumbing of a non-variable system is designed for a given engine rpm and turbo boost level. When the engine cycles through airflow rates above or below this tuned value, then the airflow is less efficient.

The place where you want a large diameter pipe is at the turbo inlet. Ironically, this is where most ricers install a restrictive "cold air" pipe, lol.

If you would like to learn more about the subject, see Corky Bell's "Maximum Boost" or "Supercharged!" books, available at most online book stores like Amazon.com. They are written so that regular people can understand the physics of producing boost, and the basics of how to put together a system.

Logic check: When you look at turbocharged Formula 1 or Indy cars that cost millions of dollars to produce and were designed by some of the best automotive engineers on the planet, what size is the plumbing?

... anybody with a college degree in the subject area.