Is an external pump not a bad idea for a built 1.6? - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• Is an external pump not a bad idea for a built 1.6? by heywier427 on 28 May, 2016 13:41
• Wont be running super high rpm's, but wont be taking it easy either.
  
  Is it recommended to put in an inline pump to prevent fuel starvation/aeration at the pump?
  
  44/56 ko4, giles super pump, intercooled, 185psi injectors, 25-30 psi, arp everything.
  
  This is my first giles pump, and I don't want to kill it.  Just wanted to see how much better it really is to one of my pumps.  Been tweeking them for years getting them better and better. 
  
  What psi is recommended.  Thanks.
• #1 by ORCoaster on 28 May, 2016 18:24
• A properly running IP pump will draw in all the fuel it needs to provide fuel to the injectors.  Now should you have a plugged line or fuel filter prior to the IP then there will be a vacuum created on the inlet side of the pump. 
  
  Some folks have leaky fuel systems, poor seals and such that make it hard to start or run as there is air in the fuel line/pump and that affects performance. 
  
  When you put a low psi pump (3-4 psi) on prior to the fuel filter you in effect are force feeding the pump.  But it doesn't seem to mind as long as it is low psi.  The front part of the IP creates somewhere from 40 to 75 PSI as it revs up to the limit.  That increased pressure will advance the pump some for timing using a plunger on the bottom of the IP and it is connected with a small tab that moves the internal mechanism and cam.  That gets the back side to squirt the high pressure fuel into the injection lines sooner than at idle.  It is a very small movement of the cam plate.
  
  You can use the inline pump to keep the IP full if you have leaks that make it hard to start.  Anytime you tear the IP apart one of those pumps makes it easy to refill it.  Giles pump?  Not likely you will be modifying it. 
  
  I say save your money, keep the fuel filter maintained and watch for fuel and air mix back to the pump through a clear line. 
  
  Oh, there is that recommendation again.
  
  
   Sorry.  It just fits.
  
• #2 by heywier427 on 29 May, 2016 07:32
• Thanks for the info.
  
  The first thing I did was teardown the Giles pump!  Measured everything!
  
  I wanted to see/measure the spring used for the advance, as the lime green springs are unobtainium.  I'm waiting for the results of the spring testing, as my tester is old/mechanical.  Figure Id give it to a pro to compare to.
  
  I have always ran an inline pump, as it always had positive effects.  Yes its a run around, but who cares.  It has zero down sides. 
  
  It seems all the high hp engines run as much as 15 psi, but most are 5-7.  And bumping psi at the line, increases directly at the plunger, so that will need to be adjusted accordingly.
  
  I know I starved a few pumps.  Weather it was an air leak, a getting plugged filter, or just too much rpm, adding a pump stopped all that.
  
  Just wanted to hear what other high hp guys run.
  
  Been building and daily'ing a td's for hundreds of thousands of miles.  I kinda knew the answer to the question.  Just wanted to hear what other peoples experiences were/are.
  
  This forums search has kinda turned sucky in the past year or so.
  
  Thanks.
• #3 by libbydiesel on 29 May, 2016 07:38
• You say you have 185psi injectors.  I assume you mean 185 bar injectors.  FYI, raising the injector breaking pressure above stock reduces emissions but hurts fuel economy and power. 
  
  According to testing Burn did, the pressure at the supply passes on to increase the case pressure by the same amount.  The net result is that the difference between the pressures on the two sides of the advance piston is unchanged, i.e. a supply pump does not affect the dynamic advance.
• #4 by heywier427 on 29 May, 2016 07:49
• Interesting.
  
  So far 185 popping psi, has yielded the best results.  Maybe due to worn components.  This will be my first "everything fresh/rebuilt" engine/head/pump.
  
  Went from 135 to 155, to 185.
  
  I have the other set at stock 155, so I will start with those, and see what putting in the 185's do.
  
  I was always under the impression the pop psi, had to do with cam timing. I have always run a stock cam.
• #5 by libbydiesel on 29 May, 2016 10:35
• Cam timing?  Changing the pop pressure changes the timing of the injection (higher pop retards timing) but has no effect at all on cam timing.  The change in engine running you noticed when changing injector pop pressure was almost certainly from the resulting change in injection timing rather than pop pressure, unless you adjusted the actual start of injection to compensate for the change.  I have tested several sets of injectors timed to the same actual start of injection using a pulse adapter and strobe.  135 bar actually yield the best fuel economy and power but smoke more.  The fuel economy drops off noticeably above 155 bar. 
• #6 by ORCoaster on 29 May, 2016 10:47
• Went to post and see Libby beat me to the punch.  Note times
  
  
  Timing can be changed by different Pop pressures.  Just think about it, lower pressures develop earlier and thus the spray is going into the cylinder sooner.  Higher pressures must build then fire into the chamber.  So what you are doing is going from an earlier timing to a later one.  Basically from advance to retard.
  
  So time the engine at spec and add 185 bar injectors in place of 135 bar and you are running it behind its normal self, out of spec but maybe like you say better all around. 
  
  What you are experiencing is what many here have noted, written about and proclaimed for years.  Every engine is different unless it was new the day it started.  With so many parts and modifications over the years you really have to use specs as a starting point and adjust from there.
  
  That is why some just say tune by ear.  Which might be ok if you have good ears.  I use some fancy electronics to sense the actual flash of the fuel and time it that way on the flywheel.  It generally runs best at 93 mm not 88 as the label says.  But even the label has a + - thing on it.
  
  
• #7 by heywier427 on 29 May, 2016 14:58
• Thanks for both posts. And confirming what I meant to say, even if I said it poorly.
  
  Having a different cam changes the openings and closings of the cylinder.  Having different pop psi's can inject fuel at different durations of the cam lobe. 
  
  We are all getting at the same thing.
  
  I will put in 135's at first fire, and go from there.  Libby, your 135 best yield was na or turbo?
  
  Waiting on my mls hg...
  
  I am def. a hillbilly hand tuner   Set it to spec and turn from there.  Noise, egt, smoke, and power are all the indicators needed!
• #8 by libbydiesel on 29 May, 2016 17:40
• Quote from: heywier427 on 29 May, 2016 14:58

  Libby, your 135 best yield was na or turbo?
  

  
  Turbo.
• #9 by Toby on 31 May, 2016 01:23
• I am really surprised that no one has pointed out how foolish disassembling a new Giles pumps is. The chance of screwing it up is significant. Unless you have some sort of clean room, the chance of contaminating the internals is quite high. And after spending all that money you will never know if this one is as good as it was before poked your stubby fingers around in it. And you voided any warranty it might have had.
• #10 by ORCoaster on 31 May, 2016 12:20
• Well, I kinda thought that would be the case. 
  
  Giles pump?  Not likely you will be modifying it.
  
  But I didn't think He would take it apart just to measure it up and such.  Like you say, cost could have been considerable.  But then maybe some folks have extra disposable income.  We should ask.  If folks want to pay for us to send a pump to Giles and they pay I bet there would be some takers from here.
  
  I would not have cracked it open.
• #11 by heywier427 on 31 May, 2016 13:15
• have had lots of pump experience.  lots.
  
  its just a pump.  yes, it is an expensive pump, but there is no difference in taking apart this brand new one, and a 400k one.
  
  Its done at my kitchen table.  Yes, I am single
  
  I just wanted to see why people pay 800.00 to 1000.00 for a super pump.
  
  If you don't have a disposable income, you should not own a 35 yr old car.  (Edit) or at least some disposable income!
  
  Maybe it will explode and blow one of my stubby fingers off.
  
  boom.
• #12 by burn_your_money on 31 May, 2016 18:01
• Quote from: libbydiesel on 29 May, 2016 07:38

  
  According to testing Burn did, the pressure at the supply passes on to increase the case pressure by the same amount.  The net result is that the difference between the pressures on the two sides of the advance piston is unchanged, i.e. a supply pump does not affect the dynamic advance.
  

  
  Correct. When I worked with Giles we put one on on the test bench and cranked the feed PSI from 0 to 30 PSI (or so, it's been some years) with the pump at various RPMs. The advance piston did not move in the slightest. The only significant risks in running higher feed pressures are leaks (mainly due to old seals) and the front shaft seal blowing out. Apparently the 12v Cummins guys build a special retainer plate for their front seals.
• #13 by fatmobile on 07 Jun, 2016 16:44
• I'd think the higher pressure would push the seal lips against the mainshaft,.. maybe make it wear faster.