I'm curious what you think is better and why:

A large intercooler where half of it is behind the bumper.

vs.

A smaller intercooler where the whole thing is exposed to air.

Now I know that incoolers can take heat out w/o being exposed to air, like a heat sink, but if the smaller IC is still be enough, wouldn't it perform better seeing that all the air would be going through a cooler part then some going through a hotter part (the unexposed part).

I know must of you will say the bigger one is better "because its bigger"...but if you are then give reasons that relate to my question.....

 

?

 

Like you said, an intercooler is a heatsink so its ability to dissipate heat is directly proportional to surface area. Even if a portion of an intercooler isn't directly exposed it will still function and be more efficient than the smaller fmic as you described. Aside from space issues, I personally don't believe you will ever find a problem or downside to running an oversized intercooler (within reason, of course).

 

There was a post on here not too long ago that got pretty long and detailed. Just search for "intercooler" in recent content. There was a discussion that went soemthing along the lines of you dont want to big of an IC becuase you lose pressure of you arent pushing enough psi. I think thats how it went.

 

It depends on how the tubes are blocked on the large IC. If half of EACH tube gets cooling air and the other half of EACH tube is blocked, then I would suggest the larger IC. If half of the total number of tubes get full air and the other half are completely blocked, then I would suggest using the smaller IC unless it is a really big restriction. Personally I think that unless your IC is bigger than your sofa, it isn't too big.

Regarding the previously mentioned post that said "you dont want to big of an IC becuase you lose pressure of you arent pushing enough psi", I read it and that part made absolutely no sense. By that logic you would want to keep your pressure up by using NO IC, which is pure bunk. You want that intake air just as cool as you can get it and the best way to do that without losing pressure is a big IC. Some people say "blah blah blah you want high velocity, man". WRONG! Velocity and pressure are a tradeoff. Converting low velocity to high velocity (a nozzle, big to small >, like on your garden hose) causes a pressure drop, and vice versa. Converting low pressure to high pressure (a diffuser, small to big <, a backwards nozzle) causes a velocity drop, assuming for both of course it is done smoothly and doesn't just turn all that flow energy into turbulence and heat. If you have high velocity in your charge pipes and IC, it is only because you used some of the pressure at the compressor outlet to do it. High velocity = high frictional drag in charge pipes and IC = high pressure drop and more heat generated.

The only thing that really matters to your engine is the pressure and temperature IN THE INTAKE MANIFOLD. Compare two identical engines, both make 12psi at the compressor outlet, but one has an IC and one doesn't. The no IC engine would have about 12psi and 250*F air in the IM. The engine with the big IC will have about 10psi and 100*F air in the IM. BUT, if you turn up the boost to 14psi at the compressor in the big IC engine, you can then have about 12psi at 100*F in the IM with the same 2psi pressure drop. Which would you rather have: 12psi @250*F in the IM, or 12psi@100*F in the IM plus the small amount of additional work needed to raise the boost 2psi? I know which one I would choose. Remember, PRESSURE<==>VELOCITY, a tradeoff, but that tradeoff starts in the compressor housing and ends at the valves.

 

Another aspect that is usually ignorred in the aftermarket is using ducting to force the air to go where you want - through the IC not around it.

For example you could have a core that is 12 x 24 = 2 square feet. It would be possible to fully use the cooling capicity of that core if you used ducting that only had a 1/2 square foot opening or a 1/4 of the cores SA.

So say you have the same core but the top half is covered by the bumper cover. If you took the time to make some ducting that brought the opening down to 6 x 24 you could have both a large intercooler and a bumper cover with no worrys of the top rows just letting hot air through.

 

Thats what I was thinking...to use ducting.

Also, a lot of the big cores have what look like really poor endtank designs. IDK, but an endtank that is 14" tall, only slightly tapered and has the IC in and out mounted on the bottom doesn't seem that much better than an IC half that size.

Its the case where 85% of the air goes through 25% of the core....

 

Most of the endtanks you see have space and reducing internal volume higher on the list then flow. Idealy there would be fins that divide up the air into 2 or 3 sections of the core but the manufacturing costs probably wouldent be worth the marginal gains.

Generaly I think the air will tend to spread itself out among the tubes naturaly but i'm sure some energy is lost in that process. But ya centering the inlet and outlet would help if that was an issue.

if you do need to make ducting make sure that it goes around all 4 sides.