Tuesday

Picking the Right Cylinder Heads



Picking the Right Cylinder Heads
By Don Terrill (c) - www.RacingSecrets.com

What needs to be decided and in what order:
  1. Head Design - It's been a long time since factory 23 degree Chevy heads were your best choice. If cost and rules won't stop you, get wild.
  2. Port Size - Manufacturers only advertise the Intake Port volume (cc), but the critical dimension is the area at the short turn - which is mainly dictated by the engine size & RPM.
  3. Material - Cast Iron or Aluminum? Unless the rules specify, I wouldn't mess with cast iron - aluminum is lighter, better at shedding heat and easier to fix.
  4. Manufacture - If multiple companies make heads that will work with your application, go with the one that has the best reputation for good castings - core shift, porosity, machining, etc.
Questions that need to be answered:
  1. Engine Size - The bigger the engine, the more port area it will need.
  2. RPM - Equally as important as engine size is RPM - the higher the RPM, the more port area required.
  3. Application - Is it a 6 speed drag car the operates in a 1,500 RPM range or is it a stock car that runs on a track with tight corners, dictating a 4,000 RPM range?
In a nut shell: First focus on getting the best port area (at the short turn) for your application and then on getting the most airflow through that area.

Want to send off a nasty email about how wrong I am? Well, first read this and then write your own article.