running engine at high rpm's for a extended time - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• running engine at high rpm's for a extended time by burnt_servo on 20 Nov, 2008 18:42
• just came back from a trip to edmonton , and on the way back i was thinking about what might decide to break  on a 1.6 turbo after running it between around 4200- 4500 rpm for 3 to 4 hours nonstop .
  
  this is assuming a fairly fresh engine , 36mm oil pump and 0w-40 oil .
  
  funny thing is i couldn't help to think that the rear wheel bearings might be the first thing to give me problems .
• #1 by Jet A on 20 Nov, 2008 18:48
• Rings if not broke in properly.
  
  Constant rpm = bad for breakin
• #2 by burnt_servo on 20 Nov, 2008 19:11
• maybe i should rephrase "fresh "  ... under 200,000 k , even compresion , uses no oil , very little "blow bye " gas coming out of the breather tube , less than 5000 k on bearings ,   oil pump , timing belt and lifters  .
• #3 by AudiVWguy on 20 Nov, 2008 21:06
• Do you know what kind of boost was generated at that RPM. EGT's??
• #4 by arb on 21 Nov, 2008 06:52
• The light that shines twice as bright last half as long...  Anything you push to the upper end of the operating envelope for an extended period will have reduced life.
  
  Are you thinking of a Road Rally or something ? Why wind it so tight for so long ? My Cummins generator will run for 20K - 30K hours in part because it is 1800 rpm.
• #5 by burnt_servo on 21 Nov, 2008 08:40
• Quote from: arb

  Why wind it so tight for so long ? quote]  
  
  longggg sections of the drive from here to edmonton are long , flat and boring  , and i just happen to follow a truck out of the oil fields going into edmonton  averaging 150 - 160 kph . then when i went to go home  there where 3 vehicles ahead of me running in the 160 - 170 kph range .... made for a quick drive home .
  
  going through it this morning , and the rear wheel bearing are loose . needed the equivilent of 1/2 to 3/4 of a turn to tighten them up again ( i checked these before the trip ) .
  
  the ac and alternater belts are also loose , and worn  , and going to get replaced in the next couple days .  ( again these where checked and in decent shape before the trip ) .
  
  the engine is also louder  , similar to  either advancing the timing , or increasing the pop pressure . ( i'm thinking i just burnt all the carbon out of it )
  it also starts much easier in the cooler weather we are having right now .
  
  boost presure , just cruising on the flat was around 7  psi =/- a couple psi
  
  averaged 48 mpg
• #6 by arb on 21 Nov, 2008 08:56
• 48 mpg ? OK, so you're not pushing the load way up, just the rpm's. Cool. Yeah, better swap those belts. I'd repack those rear bearings with synthetic grease soon.
  
  It you had more time / money, you could put a taller geared trans in. Maybe put some taller tires on the front will bring down the engine speed a little. Use the Michelin low rolling resistance tires and you might keep the mpg will taller tires.
• #7 by burnt_servo on 21 Nov, 2008 09:02
• i 've been thinking about building a taller tranny for awhile now .... finding the parts  is a different question though .
• #8 by arb on 21 Nov, 2008 09:50
• What size tires do you have now ? The stock 175/70-13 ? If so they are 22.7" tall and 7" wide. If you can get some 14" rims and put a 195/75014 tires on it they will be 25.5" tall, 6.4" tread width, and reduce your RPM from 4200 to 3740 for the same speed. They should fit as it is only 1.4" larger radius. Easy change.
  Here's the calculator I used - http://scirocco.org/gears/