EGT Temps (Was NA now Turboed) HELP!! - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• EGT Temps (Was NA now Turboed) HELP!! by AudiVWguy on 05 Sep, 2007 07:22
• Looking for imput on what your EGT's are at highway speeds, say about 70 mph. The motor is a 1.6 na(30K) with a Callaway Turbo kit for an 81 Caddy. Everything's been ported and polished, 2.5in down pipe and exhaust. Intercooler from a Mitisubishi Starion (2.6L motor). Shell Rotella T Synthetic, Volvo oil cooler. Right now it has a rebuilt NA pump with the Gov Mod and Timing Spring done. The trans is a 3.67 with a .71 fifth.
  Okay, heres the deal, at 70mph I'm running 1 to 1.5 Lbs of boost all the time at this speed. So my EGT's are about 750 F. If I go uphill or run into a headwind it goes up another 100 to 150 F. The temp probe is mounted about 5" down from the exhaust wheel of the turbine. So, as I'm Driving I can watch the EGT slowly increase cause I'm always running a little boost at this speed. At what temp can I safely maintain and still keep tops in the pistons? Anything left to do to keep the heat under control?
  Thanks for your help!!
  Jeff B.
• #1 by jimfoo on 05 Sep, 2007 07:42
• So you are saying your max post turbo temps are 900ish? Probably ok, but I don't know how much the temp drops that far down the pipe. I had 1200 post turbo right after the turbo.
• #2 by zukgod1 on 05 Sep, 2007 08:09
• You need to move your probe pre turbo to get accurate readings.
  After the turbo can be off as much as 400 deg easy. Not to mention it's much slower to react after the turbo.
  
  I'll bet if you move it pre turbo you are seeing 1500deg on a hard pull.  :shock:
  
  Sure would suck to melt down your engine from a probe being placed incorrectly.
  
  
  dan
• #3 by Patrick on 05 Sep, 2007 09:33
• YOu may not like it, but get rid of the .367 gear. Your motor (and etg) will love you for it.
  Your engine is a big air pump. If you move more air through it (higher revs at the same speed) the temp WILL drop. IF you don't believe me, go out and make the same run at the same speed  with the car in 4th gear, then again in fifth. It's just working that little engine harder than it was built for with those gears........... That NA with no cooling nozzles might not take it too long!
• #4 by AudiVWguy on 05 Sep, 2007 21:54
• Thanks guys, Yah, I figgured I'm gonna hafta move the probe to the right spot. Man, what a pain!! I'm also going to put back the .75 fifth gear in the tranny.If that doesn't help I could also put back in the 3.94 tranny with the .71 fifth. By the way, where do you guys think the fat part of the torque band is for the highway? The tach says about 2800rpm at about 70 mph. (which I thought would be the fat part of the torque band, but I guess not......)
  Thanks,
  J.B.
• #5 by jimfoo on 05 Sep, 2007 23:31
• Quote from: "AudiVWguy"

  Thanks guys, Yah, I figgured I'm gonna hafta move the probe to the right spot. Man, what a pain!! I'm also going to put back the .75 fifth gear in the tranny.If that doesn't help I could also put back in the 3.94 tranny with the .71 fifth. By the way, where do you guys think the fat part of the torque band is for the highway? The tach says about 2800rpm at about 70 mph. (which I thought would be the fat part of the torque band, but I guess not......)
  Thanks,
  J.B.

  
  May not be the same for you, but my peak torque was at 3k RPM, peak HP at 3500 RPM.
• #6 by foxracer1 on 06 Sep, 2007 04:17
• I think your gear is fine. I wouldn't get rid of it if i had it.
• #7 by jtanguay on 06 Sep, 2007 08:15
• Quote from: "foxracer1"

  I think your gear is fine. I wouldn't get rid of it if i had it.

  
  
  yea.. just downshift into 4th if you're going on such a steep incline.  i would even recommend some water cooling and 18-20 psi.  that should help keep things cool (as long as the LDA isn't giving too much fuel)
• #8 by myke_w on 06 Sep, 2007 11:55
• I can attest that a 3.67 and .71 5th will make a motor LUG like nobody's business!
  
  I ran one in my jetta coupe back when it was a gasser, great mileagem, but I'd have to downshift for a headwind and passing was impossible without down shifting.
  
  pop that .75 in and you'll be far better off for it, the .71 was never intended to be used in any tranny but a diesel 5 speed 3.94 r&p, in that box it makes the final drive a lot like the 3.67 / .75
• #9 by AudiVWguy on 09 Sep, 2007 10:36
• O.K.   Here's the update. I moved the probe to the manifold. Callaway actually has a spot in their manifold to do this. It monitor's the gasses coming out of cylinders 1&2. So now at 70 mph the EGT says about 860 F. Acceleration onto the expressway brought the temps up to about 1100 F. I could have made it go higher if I kept my foot in it. The guage I have is digital, reads 10 degree increnments. It has a high temp warning at 1275 F. I think its made for over-the-road trucks.
  I got out the Callaway I stalliation manual and found a part where they talked about EGT's. They said when adjusting the fuel screw for maximum horse power you will see full load temps of about 1250 F. They really didn't say anything more about it. They don't have any warnings related to this in the manual. They don't say for how long you can stay at full load condition.
  So I still don't have an answer as to what is the maxium temp I can drive at for long periods and still keep piston tops.
  At this point I;m going to start researching a cheap method for water injection.
  Whats everybody else seeing on their EGT gauges??
  Thanks,  Jeff B.
• #10 by AudiVWguy on 09 Sep, 2007 13:49
• Thanks Andrew,
  The biggest IC I could fit in there is off a Mitsubishi Starion (2.6ltr mtr) single pass, the local Audi guru said it was a good design, reminded him of some Porsche stuff. So now I'm going to try to make my own water injection as an additional safety factor. Every little bit helps.
  Would getting a turbo fuel pump have any advantages over a NA one? Different fuel curve?
  ---Jeff B.
• #11 by gilligan5000 on 09 Sep, 2007 18:34
• from everything I've read the NA pump is the same except for the aneroid.  The only change to the fuel would be your off boost fueling.  Meaning while not on boost your NA pump is throwing way too much fuel in (because it cant tell when you are boosing) whereas a turbo pump will adjust fuel according to boost pressure. I hope that made sence.
  
  I always though over fueling was better than underfueling for egt's anyway , no?
• #12 by AudiVWguy on 11 Nov, 2007 20:30
• I recently built my own water injection system. Boost pressure switch set at 4 psi. I have tried various liquids, including windshield washer fluid (a little methanol in it), straight water, denatured alcohol. What seems to work the best is 50% denatured alcohol 50% water seems to give the best drop in EGT's. Anybody else played with water injection? Whats worked best for you?
  -JB
• #13 by cowboybootlegger on 12 Nov, 2007 09:39
• I would love to hear how you built your system, my EGT's are killin' me, and i
  can't afford a water injection kit as of yet... maybe some pics if you're willin'?
   
  
  Caleb