Quote:
Originally Posted by reflexx
Unlike turbos, you can't really go too big with intercoolers...
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I don’t want to start an argument here, this is an excellent write up but, the volume of the system DOES make a difference. So, a larger intercooler core than you need can be detrimental to performance. There is plenty of research to prove this. The supra boards have dynos of a 2JZ engine with 2.5 3 and 4" IC pipes, there was no real HP benefit to the larger pipes at the same boost levels but the turbo did come in slightly later.
Basically a system that is too large will make the recovery between shifts take longer (increase turbo lag), unless you don’t have a blow off valve. I don’t think most of us can afford a new turbo every 4k miles though.
The weight of the IC core is a GOOD thing reflexx. You want as much mass as possible acting as a heat sink. A large "thermal mass" will keep the outlet temperatures of the intercooler more stable during a pull or several. That is the main reason dragsters use A2W. Water has a very high specific heat causing the small A2W core to absorb as much heat as a very large air to air unit. I’m not trying to tell you that one is better than the other, just explaining why the larger size and mass of the IC core makes more power.
The large air to air IC core does have a benefit when dissipating heat. The time that the core takes to return to ambient after a pull is less due to the surface area (NOT THE VOLUME) of the core. So, ideally you want a core as thin and large as possible without increasing the charge volume. Ignoring flow restrictions an air to air core of say 10 by 10 by 1 inch thick will thermally outperform a core that is 10 by 5 by 2 inch thick. The thing is, thicker cores tend to have more mass. That’s what throws people off.
As far as pressure drop across a core goes, the lower the better. Beware though, I have seen some new cheap Chinese bar plate designs with air channels that are a bit too big on eBay lately. Meaning they have spectacular flow numbers but don’t cool the charge as low as some of the lower flowing CFM intercoolers. I don’t see them online too often but its something to keep in mind before bidding.
So let’s sum up:
Get a core with as much heat sink mass as possible (end tanks are not part of the core).
Keep the core as large and thin as possible MANTAINING the CFM you require.
Keep the volume of the system as low as possible (keep pipes as short as possible).
I hope this helps.
Jim