MBC and broomstick mod.. what else - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• MBC and broomstick mod.. what else by BellCityDubber on 13 Jun, 2006 10:35
• Well, I finally got my other issues sorted out.... and today I decided I'd install my manual boost controller and do something about the pop-off valve (BOV)
  
  so I did the broomstick mod, and adjusted the MBC and I'm seeing 15lbs boost (~1 bar)
  
  my question is, I havent adjusted the max fuel very much, if any at all.... I know diesels arent like our gasoline couterparts.. so would running lean still be bad for the turbo.... and at 1 bar of boost, what should my fueling rates be like....
  
  excuse my ignorance, I'm a n00b
• #1 by vwmike on 13 Jun, 2006 12:39
• Forget most of what you know about gas engines when you're working on a diesel. All you need to know is fuel = heat and boost = cold.
  
  At idle your diesel runs a rediculously lean air/fuel ratio. Stoich is still in the same range as on a gas engine but you would only see that at full power. Your engine was actually running hotter before you increased boost pressure as the ratio of fuel to air was higher.
• #2 by BellCityDubber on 13 Jun, 2006 13:09
• thanks!
  that clears a bit up for me, so I'm really not in any danger just upping the boost without fueling.....
  
  
  I'm still contemplating on how to up the fuel appropriatley to make a tad bit more power.
• #3 by vwmike on 13 Jun, 2006 14:15
• Upping the boost pressure without upping fuel shouldn't cause any harm (I won't say can't because there are a lot of other factors involved). Upping fuel without upping boost can be very harmful though. If you want to increase fueling under boost then you need to make adjustments to the LDA. If you do a search I'm sure you'll find a million different topics on the subject.
• #4 by BellCityDubber on 13 Jun, 2006 15:05
• yes, I've seen write ups on the lda and anroid pin....
  
  perhaps that and an intercooler is the next way to go
• #5 by 745 turbogreasel on 13 Jun, 2006 22:34
• Upping the boost cools the chage, but also moves your turbo toward the end of its efficiency range where the charge heating begins an exponential increase, so if you haven't already, INSTALL AN EGT GUAGE before turning up the fuel.
  I just set my MBC about the same as yours, and althugh I spool up a lot better, and have a little more power, my EGTs haven't realy changed at all on a given stretch of road(I just move a little faster).
  I just set the adjusting screw on the safety valve so it pops at 15, and my boost just below that...it hasnt popped since.
  
  Edit I forgot, I now have almost no smoke under load
• #6 by BellCityDubber on 14 Jun, 2006 01:29
• I was wondering about EGT's while driving around testing it out earlier tonight... since I do not have an EGT gauge, I didnt really want to push my luck, which is kinda why I posted this thread...
  
  I have the stock K24 turbo on my TD, and as far as I've heard the k24 reaches peak efficiency at 14 or so PSI...  after this would it not just start making more heat.... and as far as boost cooling things down.... doesnt compressed anything contribute to heat? <hence>
• #7 by 745 turbogreasel on 14 Jun, 2006 02:33
• Quote from: BellCityDubber

  
  
  I have the stock K24 turbo on my TD, and as far as I've heard the k24 reaches peak efficiency at 14 or so PSI...  after this would it not just start making more heat.... and as far as boost cooling things down.... doesnt compressed anything contribute to heat? <hence>

  
  
  As I understand it, and I don't think my choice of words is perfect here...
  
  Increased boost blows more air through, allowing the parts to disipate heat faster=lower EGTs @ same power level
  
  Compressing adds heat, but once you pass that threshold, and the impeller starts to stall or cavitate, heating gets drasticaly worse.
  
  +1 and -1 = 0, EGT remains about the same.
• #8 by vwmike on 14 Jun, 2006 12:28
• Moving up to 15 psi isn't so drastic as to push the turbo out of it's efficiency range. It doesn't get badly inefficient until over ~25 psi without an intercooler. An EGT gauge is definitely a good idea though whenever you make any changes.
• #9 by BellCityDubber on 14 Jun, 2006 16:23
• Yes, I would like an EGT gauage but time and money are kind of short at the moment...
  
  as for my boost adjustment... really I only hit 15 psi while in 3rd gear doing some serious accelleration (like a merge on a highway)
  
  other than that I sometimes break 10 psi... but not often..... that boost +1 -1 analogy really clears up some questions I had.
  
  I dont think I'll be adjusting fueling any time soon, but I would like to get an intercooler installed......
  
  thanks for all the help.
• #10 by 745 turbogreasel on 15 Jun, 2006 00:36
• Realy?
  I hit 11 PSI between 2300 aned 2400 RPM in any gear, then there is a sucking noise, and I'm at peak boost before 3000
  
  My turbo is a stock old .42 .48 T3 on a 2.4 liter....
  I deburred my exhaust manifold, and have a K&N fiter, but I doubt that changes much.
  
  Does your MBC have a bleed hole?
  I don't.
  Maybe its just driving style.  I usualy floor it untill i am speeding.
• #11 by BellCityDubber on 15 Jun, 2006 01:16
• I dont really start spooling until around 1800... in 1st..
  
  yes my mbc has a bleeder hole....
  
  I dont normally speed. but I keep my foot down pretty far until I get up to speed...
  
  I guess I granny the car. (coz it was my grannys car) I rarley take it to 3500