max driving rpms - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• max driving rpms by Blue Haze on 22 Oct, 2013 07:20
• I am about to drive my 82 caddy from Ca to Co.  I have a 1.9 AAZ turbo motor in it and it will be loaded with moving stuff.  What should be the max rpms for sustained driving?  I currently tach  about 2700 at 70 mph.  I am thinking no more than 3000?   
• #1 by theman53 on 22 Oct, 2013 09:14
• Max rpm for cruising should be fine at 4,000 rpm. Iirc hillfolk has a low geared trans and TACHS that everywhere he goes. Plus he has smaller summer tires that add to that. If you are at 2700 to do 70 your only rpm limit should be how fast you want to go. Watch your water and oil temp and run it.
• #2 by bajacalal on 22 Oct, 2013 10:48
• Worry more about your EGTs. CA to Colorado is "uphill all the way." These motors were made for high speed driving but not high temperatures. Up the long grades you need to downshift and back off the throttle.
• #3 by damac on 22 Oct, 2013 13:44
• Interesting question.  I have a 90 mile commute, but have not done much more than that on long trips on highway 5.  I settle in on those trips at about 5mph over whatever speed limit is posted.  I think we are close in rpms if the charts I read are correct with stock tire height and fn tranny.
  
  I have auber instruments aftermarket gages with alarms so I don't pay as much attention to gages as I have in the past.  I do know what my oil pressure, water temps, egt's are like and how my 1.6td should "feel" so I go by that most often.  I do peek once in a while for the heck of it.  I don't think you can notice your fan kicking on for example at high speed.  For me its too noisy and there is less of a power drain when the fan hits over being idle in traffic.
  
  All I can say is I have had a fleet of these between me and family members for 5 years now daily driving them.   Only problem I have had thus far is one td motor was driven until it locked up due to a coolant hose bursting.  driver saw low cooalant light flashing and tried to just get over the next hill before pulling over   thats the day i started installing those auber gages in my drivers
  
  So from my perspective I just drive them.  In the morning there is a 45 minute or so stretch where I have to go up to 85mph or so to keep up with the left lane traffic and I do so because of all the trucks on the right and dumb drivers.  I have never experienced even a hiccup during those times.  Its more on/off the throttle driving instead of being pinned so egts nor does the coolant temps change like I was attacking a hill or being stuck in idle traffic.
  
  So like was mentioned I can't really give info on sustained hills.  I attack them around here for maybe a minute at a time and this is when my coolant temps rise, and my egts hit peak.  Worse lugging in fifth gear than screaming in 4th at the speed limit.
  
  5th gear pulls so terribly and raises egts when on/off the stock boost that I would also have to suggest downshifting to 4the gear and slowing down and holding vs. pinning it.  That is what the egt gage has shown me if meltdown is a concern.
• #4 by 92EcoDiesel Jetta on 23 Oct, 2013 08:59
• I think peeking at gauges will cost you in the long run. The only sure way is an audible alarm that will get your attention immediately.
• #5 by bbob203 on 23 Oct, 2013 09:14
• When I was driving into nm and as I had my eyes on the guages more than the road.
• #6 by 92EcoDiesel Jetta on 23 Oct, 2013 10:05
• Quote from: bbob203 on 23 Oct, 2013 09:14

  When I was driving into nm and as I had my eyes on the guages more than the road.
  

  
  That may also cost you in the long run, and that cost is irreplaceable.
• #7 by Blue Haze on 23 Oct, 2013 20:11
• I'm in Santa Fe, NM now last leg to Elizabeth, Co tomorrow.  My speedo is off 3 mph I'm taching 2600 rpm at 70 mph.  I determined this by using my GPS I think it is more accurate than the speedo.  I put 14" wheels on it some time ago.  I'm traveling the southern rt I 40 to I 25 less hill climbing and glad of it.  I am having some trouble with overheating on the long hills.  I'm running right up to the last line before the orange lines on the stock heat gauge but have had to slow down to get it to cool 3 or 4 times.  The cools days I think are also helping.  I think my biggest problem is that I just put too much weight in the truck.  Pulls fine I have only had to go to back to 4th about 4 times.   Only getting 32-33 mpg.
• #8 by Syncroincity on 23 Oct, 2013 20:28
• Is the tach calibrated? What size/type pulley is on the alternator (assuming a "W" connection here). I read somewhere that AAZ alt w/ clutched pulley & serp belt would read low vs the original alternator as the pulley is smaller diameter than the v-belt pulley.
• #9 by TylerDurden on 24 Oct, 2013 01:46
• I keep the radiator fan switched on when I'm towing. My AC is inop, so I just move the dash control to those settings.
  
  I keep a jumper wire in the car that I can use to bypass the resistor, to keep the fan on high speed.
• #10 by Blue Haze on 24 Oct, 2013 15:20
• I made it all the way to Co.  w/o any more problems.  I used the original alt when the mtr swap was made so the pulley size should be Ok.  I only have gauges for oil pressure, volts and rpms in addition to the stock temp.  I held the usual 30-35# oil pressure all the way lower than I like but seems to be what this mtr runs at.   Thanks all for your help