Curious~ Have an extra engine and want to make more HP - page 2 - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• #15 by dodger21 on 29 Mar, 2011 15:36
• I am not asking about making power with it being NA. Turbo sizing I can do.
  
  Shorter (talking a little bit!) rod length allows for more RPMs while at the same time better cam profiles for allowing more duration, over lap, IP timing, etc.
  
  I am wanting to know what guys have done for valves (size, grinds, material), cups, head profiles, etc.
  
  Bunch of hard *ss here, aren't there?
  
  
• #16 by R.O.R-2.0 on 29 Mar, 2011 16:50
• Quote from: dodger21 on 29 Mar, 2011 15:36

  I am not asking about making power with it being NA. Turbo sizing I can do.
  
  Shorter (talking a little bit!) rod length allows for more RPMs while at the same time better cam profiles for allowing more duration, over lap, IP timing, etc.
  
  I am wanting to know what guys have done for valves (size, grinds, material), cups, head profiles, etc.
  
  Bunch of hard *ss here, aren't there?
  
  
  

  
  why do you need your bottom end to be capable of a million rpms? its still only gonna see around 6000, period, end of story, unless you miss a shift and hit second gear shifting from fifth.. what gain is there to be had if the rest of your engine cant support more than 6000 rpms, but the bottom end can?
  
  there can not be any overlap in diesel cams, the pistons would mangle the valves if there was.. there isnt much gains to be had by way of cams like on a gasser engine..
  
  none of us really do much valve work we slap an AAZ head on there and be done with it.. only the most OFF-THE-WALL builds use big valves.. and most people, when replacing their valves use stainless, or inconel valves.
  
  nobody changes the pre-chambers for performance, its not needed. only time they get changed, is when they are cracked..
  
  and most people just lightly port the head.. there are some crazy users who go balls deep and hog the ports way out..
  
  most people just advance the timing to ~1mm on the IP and call it good..
  
  see, when you have more specific questions, you get more specific answers..
• #17 by dodger21 on 29 Mar, 2011 19:23
• See, that is what I was looking for.
  
  I have been told to look for AKI and saurkraut. Been looking up threads on them. Nice!
  
  The reason behind the higher rpms is when torqued is applied more evenly though the RPM band, the less stuff breaks, the better turbo applications for racing.
• #18 by nathan_b on 29 Mar, 2011 19:51
• right.. and the point of racing is to not break your engine.. lol
• #19 by RabbitJockey on 30 Mar, 2011 04:22
• there is actually over lap on our cams, and diesel burns too slow to rev high enough to change the geometry of our engines to suit
• #20 by theman53 on 30 Mar, 2011 05:09
• I thought that you wanted to make N/A power. Turbo is different. Port polish, swirl polished valves, AAZ head, custom exhaust and intake manifolds, cone filter, 2.5" Downpipe or 3" and the same size tubing all the way back no muffler. Have the pistons coated with that special heat barrier coating. Big stinking turbo *many out there, but search AKI 76 and MJF for nutty ones*, have the turbo ported, intercool it, and most importantly buy a pump like the one Libbybappa was selling or send one off to GILES at performance diesel injection.
  
  After all that make sure your injectors are spraying good. Hate to trash it all on a general maintenance item
• #21 by macka on 30 Mar, 2011 06:51
• You can mod your pump if you know what you are doing, otherwise, leave nothing to chance, and the pump to Giles. Also Vince Walden has some part munbers on his web site. One is for GTD nozzles, a good upgrade if you are getting the injectors rebuilt. Basically the way I understand the porting of the head is that you want to deflash it (remove the casting seam bumps) gasket match it, and leave it rough. Exhaust open up to a port match and from the manifold back, all one size. Get mandrel bent tubes for angles so as not to restrict it.