Intercooler piping size

TheNuker

Goblin Guru
What size piping are you all running on your TCs? I was first thinking 3" but I think it might be overkill for the flow even with the Z54 turbo. So I'm now looking at 2.5" piping.

There is a huge argument over turbo lag on larger pipes but the cubic area of the 3 in vs 2.5" pips can't make much difference with the flow rates of the larger turbos..... I think....

What are you running any why did you decide on it?

Nuker-
 

Briann1177

Goblin Guru
Which pipe section are you referring to? Intake, turbo-to-intercooler, intercooler-to -throttle body, or all the above?

It looks like the stock sizes are 3" for intake, 2.5" for turbo, and 3" for throttle body.
 

Desert Sasqwatch

Goblin Guru
Intercooler piping sizes have a lot of factors that can define what is optimal for a given system. In general terms, you want the least restriction to airflow into and out of the turbo. The inlet side is a no brainer, with the DF supplied MAF pipe at 3 inches. The outlet side is where the complications occur with the number and angle of the turns, plus intercooler restriction that all determine what sizes to use. Using the smallest diameter pipe gives the best airflow velocity - lessening turbo lag. But with pipe turns the velocity slows - a 180 degree turn significantly - so an increase in pipe diameter decreases the restriction on the airflow in a turn.

As Brian indicates, the DF routing steps the diameter up from 2.5 inches between the turbo outlet and inlet to the intercooler to a 3 inch pipe from the intercooler to the throttle body to accommodate the 180 degree turn in that pipe. The intercooler will be a flow restriction but this is required to slow the hot airflow velocity to get it to contact the cooling fins and eliminate the turbo compression heat. Airflow that's too fast through the intercooler may not remove enough of the heat and you will have too high IATs. Too slow and you may experience excessive turbo lag, but a larger intercooler internal volume can capture more heat and greatly reduce IATs - as long as the heat exchanger (for the air-to-water intercooler) is properly sized.

If you live in the desert, as I do, the biggest concern is getting heat out of system. So having an oversized intercooler and heat exchangers are a must have. A properly sized system should bring your IATs within 10 degrees (nominally) of ambient temperature and minimize turbo lag. Other tricks can be added to reduce temperatures to ambient or lower can be employed - heat exchanger water spray systems or even water/meth injection. But overall, stepping the sizes up from the turbo outlet should provide the best response and maximize cooling, whether using the DF supplied piping or something you are purchasing.
 
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