What is a Turbo Inlet Hose (TIH)? What does a Turbo Inlet Hose do?

TURBO INLET HOSE

Turbo inlet hoses (TIH) are a vital component of the complete intake system in a turbocharged engine.  It’s the link from the intake to the turbocharger.  Like other components of the intake system, an upgraded TIH seeks to increase horsepower through easing restriction.  An upgraded air intake can accomplish this with smoother bends or a larger diameter tubing. Upgraded turbo inlet hoses often have these characteristics but there is another issue an upgrade can help with; preventing collapse.

TURBO INLET HOSE COLLAPSE

A collapsing turbo inlet hose is an issue often overlooked.  It’s easy to overlook since it only happens when the hose is under strong vacuum forces.  Intense vacuum only happens when the engine is under extreme load and the turbo is sucking in massive amounts of air.  If you’re inspecting the underhood components,  this is likely not a situation you’ll be able to witness.

As you can imagine, if part of the intake tract collapses, it will severely restrict airflow.  This restriction will result in massive power loss and cause a very poor driving experience.  You can avoid these issues by upgrading the stock turbo inlet hose.

AFTERMARKET TURBO INLET HOSES

Not all aftermarket TIHs are created equally.  Cheap turbo inlets are very prone to collapse. As a result, like many other upgrades and car mods in the automotive world, you get what you pay for. Even if a TIH is advertised as 4-ply doesn’t mean the ply density, weave, ply material or type, silicone layer thickness and grade are going to be on par with what you’d get from a quality product. COBB turbo inlet hoses are made exceptionally well and will not collapse even when used with the highest horsepower builds.

COBB TURBO INLET HOSE

There are several supported vehicles when it comes to turbo inlet hoses from COBB.  Among those vehicles are most EJ turbo Subarus, the Mitsubishi Evo X, and the Mazdaspeed3.  The most commonly installed COBB TIH is for the Subaru platform so that will be the focus as you read further.  The COBB Turbo Inlet V2 is a direct replacement for your 2008-2020 STI.

Each of these units feature custom, 6-ply, silicone construction which rejects high engine bay temperatures and keeps the intake air closer to ambient temperature. The steel wire reinforced design eliminates the issue of hose collapse that other inlet hoses suffer under vacuum at peak demand, yet allows adequate torsional flex. This flex will prevent any connection separation due to engine movement on the OEM engine mounts while under hard acceleration.

V2 TURBO INLET DESIGN UPDATES

The V2 Inlet has been updated to ease installation. Machined billet aluminum adapters for the Post-MAF hose and BPV return allow for a more secure fit. A plug-and-play adapter provides OEM level integration for the PCV connection. A change in fittings makes installation cleaner and prevents fittings from protruding into the inlet airway. Lastly, and most importantly, the overall path of the inlet tube has been tweaked to greatly improve fitment around TGV Housings and ease installation.  Although this fitment is improved overall, it’s still a tight fit!  Because of this, it’s the most difficult part of upgrading the turbo inlet hose; installation.

TURBO INLET HOSE INSTALLATION

Installing the turbo inlet hose isn’t the easiest installation.  The hose itself is in a very tight spot and snakes into the turbo under the intake manifold.  To further complicate issues, aside from connecting the hose to the intake and the turbocharger, there are several connections that must be made.

As you can see, this is a tough install.  However, it’s not too bad and can be done with basic hand tools and a little time.  COBB also has you covered with installation instructions that provide details for each step of the process.

TURBO INLET HOSE TUNING

Most upgraded turbo inlet hoses do require some tuning changes.  Many vehicles have COBB Off The Shelf (OTS) maps which support an upgraded TIH.  Check out the map notes for your vehicle to see what maps are compatible and any additional modifications required.  The map notes also detail power gains!