G-teched my td today - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• G-teched my td today by Cheesetoast on 22 Nov, 2004 03:23
• the results, prettygood for stock, let the modding begin:
  
• #1 by farkman on 22 Nov, 2004 08:20
• Those are some pretty good numbers for stock   . But why does torque peak, drop off and then climb again? In my owners manual it says the 1.9TD is supposed to peak at 107lb-ft from 2400-3000 or 3200 rpm, I don't remember the higher value. And isn't the stock weight of a Golf around 2700-2800lbs, or am I missing something. So what plans do you have for it?
  
  Peter
• #2 by fspGTD on 22 Nov, 2004 11:11
• If you look at the little chart on the right, "RPM chart for HP and TQ plots", you can see the time section that the G-tech used to make the HP & TQ vs RPM plot, and notice that the low end of the RPM chart is right after a shift.  Since it's right after a shift, there could be a spike in hp and torque values from flywheel energy being released, so a "blip" in the readings in this area should be disregarded.
  
  Also, remember you can't compare G-tech hp with crank hp or even chassis dyno horsepower.  It is a different set of number (lower values than either crank hp or chassis dyno numbers.)  G-tech numbers are also not corrected for atmospheric conditions.
  
  The weight of the vehicle needs to be gross weight - which is, weight of vehicle (dry, crub weight) plus weight of fuel, plus weight of driver.  The fuel and driver part can easily add 200lbs (more or less.)
  
  That said, 70 G-tech hp obtained by cheesetoast is darned good!  But you're not serious that this is a stock motor are you?  (The revv-limiter does looks stock-ish...)  I'm going to have to g-tech my Rabbit again now that it's back up and running with it's new cylinder head...  
• #3 by fspGTD on 22 Nov, 2004 11:16
• This thread has some g-tech plots of someone with a 1.9lTD - before and after revv limiter mods: http://www.hostboard.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=4037&t=701
  
  The before revv limiter mods look very similar to cheesetoast's (70hp max) but you won't believe how transformed the graph is after a few mods!
• #4 by fspGTD on 22 Nov, 2004 12:59
• Cheesetoast - the technique for measuring hp vs torque curves recommended by G-tech is, to shift into gear very early so the engine is at a very low RPM, and then floor it all the way until red-line.  That way the G-tech gets a very wide range of valid RPM data to use.  You want to drive it differently for testing hp and torque vs RPM than you would for measuring 0-60 or quarter mile time.  What I usually do is launch the car at a medium intensity in 1st gear (not harsh, but not too gentle either so the G-tech knows it's no longer sitting still), and then shift directly to 3rd gear at a point where the starting RPMs are low (IE: 1250RPM, etc) and then flooring it all the way until you feel the governor main spring kick in and retarding power at max RPM.  You can do a similar process but in 4th gear instead of 3rd if you want.  Just remember than different gears will give different horsepower results so be consistent with what gear you take your readings in.
• #5 by VWRacer on 22 Nov, 2004 14:30
• IIRC, my G-Tech manual recommends whichever gear is 1:1 (normally 4th gear), in order to get the correct conversion factor. Testing in a lower gear ratio will give unrealistically high hp and torque readings.
  
  Stan
• #6 by Cheesetoast on 22 Nov, 2004 16:03
• yes, the engien is stock, 251,000km, car was towed to mechanic dec 2002 according to my records. (200,000km) " tow in car, will not start was overheating re &re cylinder head.  sent head out for pressure test and reface installed new  head gasket, timing belt, cam seal, crank seal, thermostat replaced oil, oil filter and air filter"
  
  so it was somewhat rebuilt.    yeah 3000 weight was a bit high, car weighed 1250kg on the scale with me in it, then my buddy came too, so it was somewhat around 2900-3000 pounds.  no engine mods except for the first on in the somg diy thread, where where u disconnect one wire.  oh, also no resonator or muffler, stock exhaust.
  
  What i did for the test as my buddy said to do was launch first medium power, then shift to second at 2500 rpm and floor it to redline
  
  

  Quote from: "fspGTD"

  
  The weight of the vehicle needs to be gross weight - which is, weight of vehicle (dry, crub weight) plus weight of fuel, plus weight of driver.  The fuel and driver part can easily add 200lbs (more or less.)
  
  That said, 70 G-tech hp obtained by cheesetoast is darned good!  But you're not serious that this is a stock motor are you?  (The revv-limiter does looks stock-ish...)  I'm going to have to g-tech my Rabbit again now that it's back up and running with it's new cylinder head...  
• #7 by fspGTD on 22 Nov, 2004 17:29
• Manufacturer's recommendations for taking horsepower and torque vs RPM measurements with the G-tech pro competition are here:
  http://www.gtechprosupport.com/support/HP1.htm
  
  Quote from that page:
  "Before doing any runs, you must decide in your head which gear you are going to use for all your measurements:
  * A general rule of thumb is that you should use the lowest gear where you won't experience any wheelspin/wheelhop/clutchslip under full throttle acceleration.  For many unmodified cars, even sports cars, 2nd gear is fine for this.   You will have to see for yourself.  Some higher powered vehicles might need 3rd gear to get clean, smooth acceleration throughout the entire RPM range.
  * Unlike a chassis dyno, it is not necessary to do a run in 4th gear.  It is more important that you use the same gear for each run.
  * The higher the gear you use, the lower your numbers will be, due to aero drag.  You are going much faster at 3000 RPM in 4th gear than at 3000 RPM in 2nd gear.  The higher the speed, the greater the aero drag, and thus the greater power loss to aero drag."
  
  Also for our cars, a heavy-flywheel will take a hit to hp & torque in the lower gears more than the upper gears.  Also as we have turbos, turbo-lag will show up as more of a hit in the lower gears than the higher gears (where the higher-loaded, slower accelerating engine allows the turbo more time to spool up)
  
  For my testing, I prefer to use the gear that I use most often when autocrossing (which ends up being 3rd), as I figure it's most representative of actual performance when it's being raced.
• #8 by VWRacer on 22 Nov, 2004 17:53
• Quote from: "fspGTD"

  * Unlike a chassis dyno, it is not necessary to do a run in 4th gear.  It is more important that you use the same gear for each run.

  
  Hmm, that's the very sentence I had in mind, but I obviously mis-remembered it!  :shock:  :wink:
• #9 by farkman on 22 Nov, 2004 18:03
• Cheesetoast
  
  Did you get a 0-60 time from your testing? If not, you mind doing one so I can see how fast(or slow) a stock A3 Golf is. By the way, about what temperature was the run done at?
  
  Thanks
  
  Peter
• #10 by Cheesetoast on 22 Nov, 2004 20:40
• sorry, no 0-60, i should have done it, didn't think of it.  temperature was about 4-8 degrees celcius i think
  
  

  Quote from: "farkman"

  Cheesetoast
  
  Did you get a 0-60 time from your testing? If not, you mind doing one so I can see how fast(or slow) a stock A3 Golf is. By the way, about what temperature was the run done at?
  
  Thanks
  
  Peter