L03 AIR DELIVERY

Stock Restrictions

The main restriction on a factory L03 engine is the air snorkel.  It is VERY small and has the THERMAC assembly within it which creates an even larger bottleneck.

 

Possible Modifications

Air Filter

The first thing that I recommend to somebody wanting to mod their L03 is to yank the restrictive air cleaner assembly and install an open-element assembly with a K&N filter.  Here is a picture of the stock air cleaner assembly and snorkel taken form thirdgen.org...

You can see the little air inlet in the snorkel at the lower right hand corner of the picture.  That is the only inlet for air that the engine can get air out of.  Imagine breathing through a straw, and you will get the idea of how your engine is breathing.  If you look at your driver's side exhaust manifold, you can see a "pipe" going from the manifold to the snorkel.  That is your THERMAC system, which injects hot air into your intake to help the engine warm up on cold days.  That is a HUGE restriction.  If you pop off the corrugated hose between the air cleaner and the snorkel, you can look into the tube and see the THERMAC system in there and see just how restrictive it is.  That makes the tiny little snorkel look huge!

You could go with a dual snorkel setup, which has two of these snorkels (one on each side), but it is expensive, and they are sometimes hard to find.  They also don't offer as much air flow as an open-element assembly.

The Best way to change this setup is to get an open-element air cleaner and a K&N filter.  Here is a picture of my car's air cleaner..

With the open air cleaner, your engine gets a lot more air than either of the snorkel setups.  This is a relatively cheap mod (about 50 bucks) and will make a huge difference in how your engine breaths.  It offers only a small seat of the pants difference, but, you can tell that your motor is breathing a lot better just by listening to it.  The sound improvement is AMAZING.  It will sound like you put new exhaust on your car (well almost).

The installation is pretty straight forward.  If I remember correctly, here are the steps..

  1. Remove your whole existing air cleaner and snorkel

  2. Remove the THERMAC tube from the exhaust manifold

  3. Remove the THERMAC vacuum line from the throttle body and plug it

  4. Carefully remove the IAT sensor from the air cleaner assembly

  5. Drill the hole for the IAT in the base of the new air cleaner assembly

  6. Carefully install the IAT in the new base

  7. Remove the oil breather tube from the passenger's side valve cover

  8. Install a "push-in" type breather

To improve the air circulation under the hood, I would take off the rear hood seal.  It runs along the back of the hood and creates a seal between the hood and the top of the firewall.  If you take this off, it will allow more air to flow up into the engine compartment, which will get you more fresh air into the engine.

The only "bad" part of this installation is that the engine doesn't get the cool, dense, fresh air that engines really love.  Most of the air will be warm because it is, after all, under the hood of the car.  One way to fix this problem is to install some fresh air ducts that will direct fresh air right to the engine.  This will be coming soon.

 

Intake

Just like the section right above this one, you have a few options, depending on what throttle body you will be using, etc.

Here is the Edelbrock Performer TBI intake.