pitted/corroded throttle body and non sealing butterfly and porting options

1. barwell1992 Frequent Poster Joined: Mar 2011 Rugby Posts: 752 saxo vtr 02, 150bhp yamaha FZ1:)

   #1 13th January 2013, 18:11

   Just stripped down my Throttle body to give it a good clean, and notice a fair amount of corrosion/ware im guessing this is from the obstruction's in the TB design increasing pressure on that area of the TB when opening the throttle thus eating away at the metal,
   
   also with the throttle butterfly closed i can see light around the edges im not sure if this should be the case, from what i have seen before they allways close fully but thats on multi body'd applications
   
   not sure if any one has seen the above two things before ?
   
   
   
   
   
   This bits a bit of fun really
   
   i have seen the huge debate on hear about non ported TB vs ported Tb and im tempted to get another TB and remove the steps on the mill at work i can see the need for the 2 of the indented steps due to the design of the intake but not the 2 protruding lips that seem far to large and obstructive to give any benefit other that to smooth the low speed throttle control
   
   
   
   
   on another note has any one ever bored out the throttle body as im tempted to give it ago at work on the lathe, im just not sure about how far i could take out the walls near the spindle (and i know bigger is not all ways better)
   
   the down side to going bigger would be the need to increase the intake manifold to suit as theres a lip that the TB sits against that runs flush with the inside of the TB and im not sure that theres enough meat to be able to remove it.
   
   maybe not this big but you get the idea
   
   
   i know its not worth it etc etc but im intrigued as i can do it for free in my lunch hours any advice would be good
   
   cheers
2. user_16747 Banned Joined: Jul 2007 Posts: 4328

   #2 13th January 2013, 18:30

   Port match it if possible
   
   So there is no step between the tab and plenum
   
   I have a modified one on my 406 and did notice a diffrmerance but then again at the same that was fitted I also fitted
   
   Ptfe inlet manifold gasket and tb gasket
   Port matched all parts of the inlet tract
3. barwell1992 Frequent Poster Joined: Mar 2011 Rugby Posts: 752 saxo vtr 02, 150bhp yamaha FZ1:)

   #3 13th January 2013, 19:00

   its maid a fair bit of difference just cleaning it, i think when i have some spare cash i will get another and port and "polish" and grind out some of the protrusions and maybe even stick the car on a dyno and do a back to back run
4. user_16747 Banned Joined: Jul 2007 Posts: 4328

   #4 13th January 2013, 19:14

   Can also remove part of the spindle and fit lower profile screws in the butterfly all help with power
   
   It's an old school method that used to be done with great results on SU carbs amongst others
5. yr51ocw Frequent Poster Joined: Oct 2005 Posts: 751

   #5 13th January 2013, 19:26

   the throttle on the 16v TU engine is massive for the amount of airflow going through it, I would be very surprised if it was causing a restriction of any kind. I suspect those steps in the throttle are there to aid driveability at low throttle openings.
6. barwell1992 Frequent Poster Joined: Mar 2011 Rugby Posts: 752 saxo vtr 02, 150bhp yamaha FZ1:)

   #6 13th January 2013, 19:45

   its a 8v 3 plug mate not a 16v