HX25 on a aaz ? - page 2 - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• #15 by davidskipper123 on 07 Apr, 2011 05:50
• and by optomising im assuming you mean a port and polish ?
• #16 by Alcaid on 07 Apr, 2011 05:52
• Yes, bigger valves wouldn't hurt either
• #17 by davidskipper123 on 07 Apr, 2011 06:04
• thats gonna be alot more than my budget can allow me thinks how much bigger we talking what are standard sizes ?
• #18 by Alcaid on 07 Apr, 2011 06:15
• The earlier AAZ heads has 8mm valve stems:
  Intake: 36.0mm x 8mm x 95.6mm
  Exhaust: 31.2mm x 8mm x 95.6mm
  
  Later on they moved over to the 7mm stem size:
  Intake: 36.0mm x 7mm x 95.6mm
  Exhaust: 31.0mm x 7mm x 95.6mm
  
  Something like 37mm intake and 33mm exhaust would be nice: http://performance-diesel.com/index.php?main_page=product_info&cPath=2_1&products_id=3 (made for VE TDI, so slightly longer (1.3mm) but would be perfect for a IDI application with a reground camshaft)