VNT Rabbit tuning: intercooler + more boost - page 2 - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• #15 by malone on 12 Jul, 2005 15:12
• Quote

  Nice job! It's nearly into TDI territory for much less $$$ than a TDI.

  
  
  I believe it is in TDI territory. G-tech horsepower normally reads lower than wheel and brake horsepower because it factors in aerodynamic drag, drag from rear wheels rolling (unlike on a stationary dyno), etc.
  
  IIRC a stock 5-speed A4 ALH TDI (1999 to 2003) G-Techs at 75n-85hp. Results may vary by G-Tech device, operator, calibration accuracy, etc.
  
  80nhp with 12.5 PSI in a 1.6L IDI is amazing, especially with no noticable smoke from the driver's seat, and considering that a stock ALH TDI runs approx. 12 PSI.
  
  Congrats Jake for a fine tuning job.
• #16 by Slave2School on 12 Jul, 2005 15:32
• I would love to G-tech my car, I know it isn't that fast, but it sur feels much better than the 90hp it came with from the factory  With stationary dynos a stock tdi generally comes in around 85-89whp from what I have seen.
• #17 by fspGTD on 13 Jul, 2005 11:55
• Quote from: "malone"

  
  IIRC a stock 5-speed A4 ALH TDI (1999 to 2003) G-Techs at 75n-85hp. Results may vary by G-Tech device, operator, calibration accuracy, etc.
  

  
  
  Mark -  I was looking all over the web for this info earlier, but wasn't able to find it, so I'm glad you chimed in!  Do you have any .gtp files of a stock 5-speed TDI you could send me for comparison?
  
  By the way, based on testing I have done on my GTD autocrosser on both mustang chassis dyno and G-tech runs, I can verify that aerodynamic drag is significant.  With the GTD autocrosser, the G-tech reported 73 net hp while the mustang dyno had reported upper 80's wheel horsepower.  And mustang chassis dynos are known to give out lower numbers than other brands like dynojets.
  
  So stock ALH TDIs run 12psi... That's also good to know.
  
  I did a couple quarter mile passes yesterday.  I am not sure these represent the full perfomance of the current setup, because I had left the floormats in for the tests and noticed right after my runs that the driver's floormat had slipped over and was in the way of the accelerator pedal, limiting full throttle.  :oops:
  
  But anyway... here are the results:
  
  Run #1
  * ET - 16.6 sec
  * Speed - 82.4 mph
  * 60 ft - 2.62 sec
  * 0-60mph - 8.63 sec
  * comments: not the best driving on this one.  Slipped the clutch excessively at launch.  Upshifted too late.
  
  Run #2
  * ET - 16.5 sec
  * Speed - 81.2 mph
  * 60 ft - 2.48 sec
  * 0-60 - 8.42 sec
  * comments: Overall I drove this run much better.  The launch was more aggressive, tires chirped a little.  I felt like I nailed the shift points.  I traveled same stretch of road as before but in the opposite direction.  After I started this run, a UPS delivery truck approached from the far end of the unstriped 2-lane road I was testing on.  I probably should have aborted the test, but I decided to keep the run going and blew past him at probably close to 80mph - and he was approaching me too!  Boy am I glad he stayed over on his side...  
  
  Also - I had an opportunity to do a max EGT test.  After keeping the throttle nailed on the freeway up a hill for about 20-30 seconds (had to drag the brakes which I could start to smell to keep speeds below 95mph), the EGTs reached and plateaued at - it was either 1050 deg. F or 1150 deg. F, I can't remember.  :oops:  (I had to focus primarily on safe driving and safety around other traffic, etc.)  But in either case, you can see the temps are WELL into the safe zone - several hundred degrees F below the 1500 deg. F stock 1.6lTD pre-turbine temp limit.
• #18 by TDIMeister on 13 Jul, 2005 17:07
• Those are great numbers, Jake.
  
  Excuse to refresh my memory yet again: Is the EGT probe pre- or post-turbo?
• #19 by VWRacer on 13 Jul, 2005 17:18
• Wow...16.5 sec quarter in a diesel Raggit. Who'da thunk it...?!  
• #20 by fspGTD on 13 Jul, 2005 17:49
• Thanks guys!
  
  TDIMeister: EGT thermocouple is pre-turbine.
• #21 by lord_verminaard on 13 Jul, 2005 18:04
• Yeah, 16.5 with a 2.48 60' time is fast enough to beat the tar out of most people who arent ready for it.  And with an old diesel plainclothes rabbit, NOBODY is going to be ready for it.  
  
  Very nice work indeed.
  
  By the way, I thought stock ALH TDI's put out around 14 psi at max?? could be wrong.
  
  Brendan
  84 Scirocco 8v
  00 Camaro L36 M49
• #22 by fspGTD on 14 Jul, 2005 15:46
• Dad is daily driving the Rabbit again now, and will be monitoring oil consumption as well as the fuel economy.
  
  My dad is working next on sprucing the car up a bit, restoring some Audi4000 multi-spoke (ronal R8 style) wheels for the car next, and also has a euro chin spoiler for it on its way.  It's definitely going to stay looking for the most part stock classic westmoreland Rabbit diesel though.  I think my work with the engine tuning is for the most part done.  I could easily keep going with increasing the boost and fueling, but the car has more than enough power for him.  He is just happy as can be about it.
• #23 by vwmike on 14 Jul, 2005 15:58
• Quote from: "fspGTD"

  Dad is daily driving the Rabbit again now, and will be monitoring oil consumption as well as the fuel economy.
  
  My dad is working next on sprucing the car up a bit, restoring some Audi4000 multi-spoke (ronal R8 style) wheels for the car next, and also has a euro chin spoiler for it on its way.  It's definitely going to stay looking for the most part stock classic westmoreland Rabbit diesel though.  I think my work with the engine tuning is for the most part done.  I could easily keep going with increasing the boost and fueling, but the car has more than enough power for him.  He is just happy as can be about it.

  
  
  Where did he get the chin spoiler (duck bill?) from? Last I heard they were out of production.  
• #24 by fspGTD on 14 Jul, 2005 16:24
• I just ordered this for him earlier this week.
  
  I did notice that it was coming up as no longer available through the VW dealer.  As is now the Rabbit 1.6lTD/diesel automatic cold air baffle I was planning on getting for dad's Rabbit.  
• #25 by vwmike on 14 Jul, 2005 16:31
• Ah, he just got the shorty. That one is actually still available from VW. My friend has been trying to get his hands on one of the bigger 2 peice duck bills.
• #26 by veeman on 15 Jul, 2005 10:55
• Jake...
  
  Nice choice on the Ronals... Those will look sharp, although I believe the offset will be slightly different.  I had those on my rabbit for a while.  They remind me somewhat of the Corrado rims they had in 15's...
  
  Also... I've never heard of the cold air baffle you mentioned.  Do you have a pic?  What's the purpose of that part?  Does this keep engine heat away from the intake?
• #27 by fspGTD on 18 Jul, 2005 01:29
• The A1 turbo-diesel cold air baffle pulls cold air from around and above the passenger side headlight.  This one pictured is from my Rabbit autocrosser where it has been modified some, but should give you the general idea of the part
  [Edit - actually forget that pic! here we go - I found a great picture of the unmodified factory 1.6lTD air baffle:]
  
  
  Jetta turbo-diesels also come with a similar part, but it is different and won't fit a Rabbit.
  
  The Audi 4000 ronal style wheels actually match the 45mm offset of the stock 13x5 aluminum wheels that are currently on the car.  But I know that 38mm offset wheels were also found originally on Rabbits too, including the Rabbit GTI's.
  [Edit: here is a pic of the 14x6 Audi 4000 wheels.  They are the lighter weight, slim-spoke variety:]
  
  
  I heard back a report from dad on fuel mileage of his first tank of fuel -it was 51mpg for the first tank.  He also said the coolant temperature seemed to be reading 2 notches lower than where it used to read when it was naturally aspirated.  Exhaust gas temperatures also seem to be quite low when freeway cruising, about 450 deg. F at constant 65mph.  I'm thinking the EGTs are this low because of the extra intercooled air the VNT is pushing through the engine.
• #28 by jackbombay on 18 Jul, 2005 09:39
• Quote from: "fspGTD"

  Exhaust gas temperatures also seem to be quite low when freeway cruising, about 450 deg. F at constant 65mph.  I'm thinking the EGTs are this low because of the extra intercooled air the VNT is pushing through the engine.

  
  
     Wow, you'll have to bock the IC in winter to get the heater to work. The 51 MPG is great, city driving?
• #29 by fspGTD on 18 Jul, 2005 10:40
• City and freeway mix.  That tank did include my quarter mile and other "performance tests" though.  :wink:  It will be interesting to see what it gets on future tanks.  Dad drives more than 800 miles a week, so it shouldn't take long before we see more fuel economy data.