Engine bay temps and your intercooler piping

It seems there are plenty out there operating under the assumption that engine bay temps are very hot compared to compressor outlet temps and therefore, insulating your intercooler piping is a good idea.  This blog will be short since math is hard to dispute.

First question:  How hot does it get under the hood?

Feel free to peruse this research paper on the underhood temps of several vehicles in several scenarios but I’ll summarize.

Idle @ 1000RPMs – 75C/167F (no convective heat transfer!)

Flat road at 60MPH – 30C/86F

Hill at 70MPH – 65C/149F


Second question: How hot does the compressor discharge air get?

The equation for such a thing is


Tin = 70F + 460 = 530 deg R

Pin = -5 psig + 14.7 = 14.2 psia

Pout = 14.5 psig + 14.7 = 29.2 psia

Pout/Pin (compression ratio) = 2.056

Assume an awesome compressor efficiency of 78%



In conclusion,

a very efficient compressor running at a relatively low compression ratio outputs air that is significantly hotter than the test vehicles underhood temps in all scenarios by a minimum of 44 deg F.  Insulating this heat energy with silicone tubing instead of aluminum is a bad idea and can contribute to early onset “heat soak” of your intercooler and will most assuredly increase intake air temp post intercooler as well.

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1 comment
  • Really enjoyed this article post.Much thanks again. Cool.

    loanemu on

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