why to use a boost controller? - page 1 - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• why to use a boost controller? by carrizog60 on 12 Oct, 2006 08:31
• as topic says?
  i have friend that aren t running stock boost and dont have boost controlers...
  any differences in using one? :idea:
• #1 by wyldman on 12 Oct, 2006 09:40
• If your stock,you don't need one.
  
  Once you start turning up the fuel,and blocking off or adjusting wastegates and BOV's,then you could possibly overboost,and do some damage.
  
  You only need enough boost to keep the engine well fed,and EGT's down.Anything more is a waste,and could possibly do damage.This is where you use a boost controller,or some method to limit max boost.
• #2 by carrizog60 on 12 Oct, 2006 11:15
• so is just for sfe?
  no performance advantage?
• #3 by wyldman on 12 Oct, 2006 12:19
• Too much boost is a waste.....there is no additional performance gain,unless you add more fuel to go with it.
  
  At higher boost levels,you also start to lose efficiency,unless you step up to a bigger turbo.
  
  Keeping the boost down,to just what you need will great extend the life of the engine,turbo,etc.
• #4 by Benjamin on 12 Oct, 2006 14:14
• i dont use a boost controller, the wastegate is always closed.
  the boost dont go to high, i can increase with putting more diesel in to the engine. i drive 18psi now.
  
  Greetz, Benjamin (sorry for my bad english)
• #5 by carrizog60 on 12 Oct, 2006 14:48
• ^^^thats my question...
  why to use a boost controller when you can simply close the wastegate and control it with fuel?
  better response?any gain beside safety?
• #6 by wyldman on 12 Oct, 2006 15:07
• While you can control it with fuel.....why ?
  
  If your happy with the power level,and boost levels aren't alarmingly high,then yes,you can run without one.
  
  If the boost levels are too high,with out the right stuff,you will lift the head off the block,and pop the headgasket.At this level,you need to control the max boost,and maybe switch to a more efficient turbo.It allows you to keep your fueling to make the power,yet not damage stuff.
  
  What kinds of mods have been done ? What boost levels are you seeing ?
• #7 by HarryMann on 12 Oct, 2006 18:12
• Are you sure?
  
  More boost doesn't up cylinder pressures (more than the boost pressure, insignificant) unless equivalent fuel is added. Yes the compressor efficiency may drop off and outlet temps go up a bit when overboosting, but thats what intercoolers are for.
  
  Just more air (boost) just ensures all the fuel is burnt?
• #8 by QuickTD on 12 Oct, 2006 19:13
• Quote

  More boost doesn't up cylinder pressures (more than the boost pressure, insignificant)

  
  
  Oh, but it does. The boost pressure at the start of compression is multiplied by the compression ratio. At atmospheric pressure (zero boost, 14.7 psia) and 23:1 compression ratio, end of compression pressure will be 323 psi. It will actually be higher due to the heating from compression but for the purposes of this argument we'll leave that part out. The same 23:1 compression engine will have an end-of-compression pressure of 668 psi @ 15psi boost. At 25psi that figure rises to 898 psi and at 30 psi it hits 1013 psi.
  
  These are rough figures, volumetric efficiency and other losses/gains are not taken into account , but you get the idea.
• #9 by wyldman on 12 Oct, 2006 19:35
• QuickTD beat me to it,I don't think I could describe it much better than that.
  
  While I'm no fancy scientist,who can figure out all the math and stuff,I have blown my fair share of head gaskets due to overboosting.I learned the hard way.Keep the boost down to only what you need to keep EGT's in check.That would probably explain why most turbos use a wastegate,it's there for a reason.
• #10 by zagarus on 13 Oct, 2006 00:35
• but will 15 psi kill the engine running a stock 1.6l?
• #11 by HarryMann on 13 Oct, 2006 03:05
• Quote

  These are rough figures, volumetric efficiency and other losses/gains are not taken into account , but you get the idea.

  
  
  I do indeed, feel like deleting my post it's so stupid, as I could probably do that calculation myself at a push  :oops:
• #12 by carrizog60 on 13 Oct, 2006 04:14
• the engine is all stock now.
  it is a 1.6D rebuilted engine so i cant go crazy...
  it has 1.6 euro gtd injectors pump.also kkk24 turbo.
  it has a bmw intercooler (60x23x5cm) but the pipes still missing.
  i am seeing 0.6 bar and the engine doesent smoke but it start to heat after a short moment of high way boosting...
  i will try to see how the i.c helps on that and maybe change the thermostat with a lower one as the temperature always sits in the midle mark.
  as soon boosts kiks in it will start to heat and i have to ligt gas to prevent over heating... :?
  no oil/water consumed...
  i removed front lip, some says thats the reason as the termo may be getting fresh air from the front and doesent open at the right temp...
  
  cars still pulls fine(180km/h easy)
• #13 by lyeinyoureye on 13 Oct, 2006 05:05
• Quote

  Oh, but it does. The boost pressure at the start of compression is multiplied by the compression ratio.

  
  
  What about peak pressure during combustion? Wouldn't that be the limiting factor because it's that maximum pressure at tdc plus the increase in heat from combustion? For instance, on a NA, when the piston is at TDC at ~325psi, won't the pressure when the fuel is injected and combusts be much higher than that? In other words, isn't there some maximum safe level of boost w/o increasing fueling that can be achieved, because during combustion the peak pressure is much higher?
  
  Or for that matter, wouldn't that be more of a problem with timing advanced, because the cylinder has to move up a bit before it can move down, so the peak pressure is higher compared to retarded timing, when the fuel combusting can push the cylinder down faster, instead of building up pressure until the cylinder passes tdc and then being able to relieve it by pushing it down when the timing is advanced?
• #14 by entuzijast on 13 Oct, 2006 20:24
• You asked why to use boost controller instead a simple wastegate adjustment..
  
  Wastegate works in a way that it's opening slowly when boost is raised, and at the given max. boost, it's opened completly....
  So, with wastegate adjustment, you cant't get the boost "instantly", as the wastegate regulates it slowly til it's max. value that is given...
  
  That is what I was told when I asked the same question....