Project Focus ST- Making Power with Cobb Tuning!
It's been a while since we have done much with our Project Focus ST but that is about to change. In the past installments we worked on upgrading our car's suspension. With the suspension done it's time to focus on other stuff. What a bad pun. The other stuff is going to be handled with the arrival of a big pallet of goodies from Cobb Tuning.
Our stuff from Cobb is mostly going to focus on getting more easy and plentiful bolt on power from the engine with their Stage 3 Power Package with a few other goodies to enhance the car's handling as well. Man we cannot get away from these focus puns.
Our first piece of kit is Cobb's upgraded front mount intercooler. Although the Focus ST has a stock front mounted intercooler is it pretty small in terms of frontal area. The Cobb Tuning intercooler addresses this shortcoming with over twice the frontal area of stock. The Cobb intercooler also comes with 2.5″ mandrel bent hard charge pipes. It is a little known fact that hard charge pipes typically increase power! They do this by not swelling under boost pressure. By keeping the charge pipe volume constant, compressor workload is reduced and the turbine does not have to recover that power from the exhaust stream, reducing backpressure. This sounds farfetched but I have seen this repeated time and time again on many different motors. Sometimes, hard pipes also have better flow which also reduces compressor workload, however I have seen gains when the only major difference was a rigid vs soft pipe!
The Cobb Tuning intercooler is a bar and plate design that is 57% larger than stock with bespoke cast end tanks. The cast end tanks produce the best flow into the core for the packaging space allowed but cost a lot more to tool up. The end tanks have a generous OEM like bead on the entrance and exit ports to greatly improve holding under pressure. The intercooler has precisely located mounting brackets to make an easy bolt on install a cinch. Two holes have to be drilled in the bumper beam for two mounting bolts but this is a super simple deal. The intercooler retains the use of the factory bumper beam which we really like.
The Cobb Tuning intercooler kit comes with quality hardware like these 4 ply reinforced, thick, swell resistant silicone hose couplers and very positive T-Bolt clamps. Like we were explaining, if the couplers resist swelling, compressor work is reduced and more power can be produced at the same boost level.
The best design practices for an efficient intercooler core are to have a thin core with a lot of frontal area if it can all package correctly. 90% of heat exchange gets taken care of in the first 1.5-2″ of any core. This makes thick cores much less efficient. The Cobb intercooler has a reasonably thick 3.5″ core. We think 4.5″ thick cores should be avoided if at all possible. Overall the Cobb core is a little wider than stock but much taller with more flow area for less pressure drop across the core. Less pressure drop also reduces compressor workload and turbine induced backpressure. These factors create power in addition to the effects of better charge cooling. The Cobb intercooler typically drops the intake charge temp 100 degrees over stock and allows for more aggressive tuning as a result.