Stock Location vs. Front Mount IC

by Tony DeQuick

Stock location intercoolers: The stock location intercoolers have the advantage of having less tubing and less total volume and they actually 'flow' better both than front mounts, believe it or not, under static and dynamic conditions. The OE location ICs do promote noticeably better spooling. The downside is they are subject to capacity saturation during a run, meaning they don't have enough heat transfer capacity to dissipate all of the heat from the charge. This starts to show up about 1/2 - 3/4 of the way through the run and the inlet temps will start to climb at a good rate. Prior to that, the OE location and front mount are pretty much so on par. That's why front mounts really shine on the big end.

On average, stock location charge intake temps are about 40F - 60F over a front mount, though that depends greatly on the combo. The reason people are able to run so fast with the OE location intercoolers is that even though the effectiveness is way down (like ~65%) on a car that is running 130+ MPH with one, the pressure drop is still null. Running this fast at 65% is costing 2-3 MPH. The lack of effectiveness is due primarily to the shorter charge-path-length. With a OE location intercooler, the charge path length is about 13" (for our V-4 anyway). With our V-2, it's about 24", so there is 1.6x the cooling capacity from the get-go.

The lack of effectiveness problem is magnified when people are welding together 13+ year old thermal cycled cores that leak like sivs. If you have a stretch made from stock cores, bring it to the Nats and stop by our booth. We're bringing our leak testing gear to demonstrate how bad these would fail an industry standard leak test for used intercoolers, which IMO is too liberal to begin with. Most leak at least 5x acceptable limits though these leaks help cut down the pressure drop . Plus, the OE intercooler wasn't a gem to start with and is really ancient technology wise. Specifically, the air fin is crude, the turbulator is outdated and the typical tube-to-fin-bond yield for an intercooler core furnace brazed with modern technology is far superior the OE intercooler.

Front mounts:   Front mounts have the advantage of having much longer charge-path-lengths or in English the distance the air charge and ambient air are in contact for cooling. Having the intercooler mounted up-front helps slightly, but not as much as people tend to believe. Keep in mind the air passing through the intercooler also has to pass through the condenser and radiator, which increases the ambient pressure drop, which cuts down the air flow through the intercooler.

Front mounts will cause the car to run hotter due to the increased ambient air flow resistance. Since there is less air flow through the radiator, the car will run hotter. That's why our three-pass aluminum units are designed to work at *low* air flow levels and we lay back the fin pitch considerably. Our aluminum radiators designed for use without front mounts have a different core matrix designed to perform better at higher air flow levels. In the deep south like S. Texas and S. Florida, a considerable investment in a cooling system is paramount in the summer. In the Midwest, you can usually squeak by in the summer with a good three-row copper/brass radiator though the hot days will take their toll when you're sitting in traffic. IMO A/C is not really optional in S. Florida in July when it's 96F with a 74% RH (the high RH really takes a toll on A/C loads as well) for a daily driver or in Texas when it's 113F.

So the bottom line: for now, the front mount will deliver more power. Stock location intercoolers will require a little more tuning to reap the full benefit since the intake charge temps will be higher so the A/F will need to be a little fatter.

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Tony DeQuick mailto:[email protected]
Charged Air Systems (847)543-7423 http://www.chargedair.com

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