SELECTIONS: Tuning : Exhaust

Power Train

Perrin Top Mount Intercooler

TurboXS Top Mount Intercooler + BOV

APS Front Mount Intercooler...Notice the extra piping to plumb to the front of vehicle.


Chilling Out Before the Big Boom!

Somewhere between Stage I and Stage II, a larger intercooler is recommended?but may not be absolutely necessary until stage II.

The intercooler sits between the turbo charger and the engine. Its job is to cool the compressed/charged air that comes from the turbo. By cooling this charge (remember cold air takes up less space than hot air and is therefore "denser"), it is theoretically possible to fill the cylinders with a denser air/fuel mixture.

What really means is that you may be able to safely run with an extra pound of boost (say 16 psi vs. 15 psi)?and you will loose less power on those hot summer days?a larger intercooler on its own will make little power difference.

The debate over a top mount versus a front mounts intercooler rages on?which is better. It probably all comes down to preference and how far you want to take your ride. You see, while it is true that a front mount has a greater cooling potential, the questions remain "Do I want to have a body shop tear the front end of my car up?" or "Do I want to lose my driving lights?" or "Do I lose any chassis, structural rigidity, or crash worthiness?"

Other questions a front mount intercooler brings to the table stem from the fact that you will be adding approximately 5 feet of tubing that the "turbo charge" will have to pass through before reaching the engine (contrasted with 6-10" for a top mount intercooler).

With that much tubing, are there significant pressure losses (read decreased turbo boost) that will require you to run the turbo hotter? Many vendors say there is little or minimal pressure loss...Therefore, make your own decision...

Just one thing...if you plan on making BIG POWER (more than 400 hp) will need a front mount intercooler

Blow Off Valves (click to see BOV Pics)

Even though blow off valves (BOVs) are all the rage, it is important to remember that you do not gain horsepower with a BOV.

The BOV does, however, affect throttle response, saves your turbo from back pressure, and reduces turbo spool-up in between shifts.

p>Furthmore, if you plan on making more than 17-18 psi boost...You should replace the stock blow off valve.

Now there is a lot of debate of what kind of BOV to get. There are basically 3 kinds:

  • BOVs that vent to the atmosphere
  • BOVs that vent back to the Intake (pre turbo)
  • Hybrid BOVs that vent to both the intake and atmosphere (some are even adjustable).

Venting to atmosphere is fine most of the time...and that is what that cool, loud popping sound between gear shifts you hear in the WRC cars.

However, the factory BOV vents back to the intake and accounts for the air in the intake when it sets air/fuel ratios between shifts. At its worst, your car will temporarily run rich between shifts and could even hesitate/stall. For most vehicles and various stages of engine management, however, this is not a significant issue (most people never even notice anything).

In order to avoid any potential air/fuel issues it may be preferrable to get a high performance BOV that either vents solely to the intake or a HYBRID that vents to both.

A HYBRID really gives you the best of both worlds...especially the adjustable ones like the GFB Stealth. You determine the volume of sound by choosing how much to vent to atmosphere




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