Turbo or N/A for Max Fuel Economy? - page 3 - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• #30 by fspGTD on 29 Aug, 2005 19:42
• There were a lot of parts that were changed when you swapped the turbo-diesel engine, and many potential explanations for the 6mpg decrease in fuel economy.  It could be as simple a fix as the timing wasn't set right, to as complicated of a fix as the engine wasn't machined right.  But mere presense of a turbo being the culprit, I highly doubt.  Have you given it enough miles to get the new rings seated in?
• #31 by dieselweasel on 29 Aug, 2005 20:44
• Quote from: "Master ACiD"

  
  i honestly dont think you can get somthing for nothing. if that was true then every diesel in the world would have a turbo. but theres plenty of diesel forklifts, road graders, generators, waterpumps etc that dont have turbos, even large equipment like my ford 4.4 liter i4 diesel power head has no turbo.

  
  
  In my experience it's hard to come by any diesel engine made these days that's not turbo.  Turbocharged engines are definitely more thermally efficient.
• #32 by Northboundtrain on 30 Aug, 2005 07:50
• Wow, thanks for all the info.
  
  

  Quote from: "DieselsRcool"

  For best MPG lust use your na engine and pump. Add a turbo and don't turn up the fuel. Add a larger exhaust and use TD injectors. Install a cool air intake if you don't already have one. be sure your rings and valves are in great shape. Set the timing to turbo specs. Use stock size 13" tires.

  
  
  So if I do this, should I use N/A or turbo pistons during the rebuild?  Should I put on a hydraulic head or does it matter?
  
  Thanks
• #33 by jtanguay on 30 Aug, 2005 14:32
• n/a pistons should work, as long as you don't up the fuel.
• #34 by DieselsRcool on 31 Aug, 2005 10:54
• NA pistons are cheaper and work fine for moderate fueling/heat levels. Where you need the TD pistons is at higer fueling on long pulls where the pistons have a chance to build up excessive heat. The TD oil jet carries this heat to the oil cooler and on to the radiator. The excess heat will cause excellerated ring, piston and cylinder wear.
  
  Solid/Hyd head, no matter.
• #35 by DieselMonkey on 31 Aug, 2005 12:31
• You cant drop n/a pistons into a TD block because of the cooling jets. If you where to remove the jets... i dont know what would happen. Probably reduced oil pressure by quite a bit.
  
  Turbo diesels are no doubt the most fuel efficient. Put it this way.... by the book... Golf mk4 stock 90bhp TDi = 55 mpg, 64 bhp SDi is about 48 mpg. Not only a big reduction in power, but also in fuel efficiency.
  
  If you wanna go slow, a n/a diesel can be easy on fuel. My Jetta Eco does about 38 mpg... and thats driving it as hard as it possibly could be driven. You may as well call it a n/a diesel. The turbo is only there to increase air flow to reduce emmisions, not as a performance add on by any means.
  
  
  
  I heard somewhere that in parts of Austrailia its not legal to sell n/a diesels due to sparks that may leave the exhaust (fires in the bush). With the turbo, that spark stays in the turbine housing until it is no more.
  
  If you want fuel efficiency, fit a small, wastegate turbo, de-fuelled pump, if the engine is in good condition in relation to oil pressure and ring sealing, run a light synthetic like Amsoil or Mobil 1 in both motor and tranny. Keep the car as light as possible at all times, 13" / 14" wheels (steels are generally lighter than alloys...not talking jap racing wheels here) and tyre pressure set correctly. If its got EGR, blank it off and reduce any load on the crank thats not necessary (air con, PAS etc..)
  
  I ran 0W-40 in my 1.9D before fitting the turbo, for about 18 months. I ran that engine hard, and never any problems. Oil pressure now with 5w-40 Delvac is 110 psi at idle cold, so the 0w-40 didnt do any harm. Milage went from 480 miles to a tank, to about 550. It was a big difference, TDi's get even more impressive results.
  
  Of course, direct injection is the only way to go for fuel efficiency, thats my next project.
  
  regards, DM (below, picutre of my Jetta Eco.)
• #36 by DieselMonkey on 31 Aug, 2005 12:32
• You cant drop n/a pistons into a TD block because of the cooling jets. If you where to remove the jets... i dont know what would happen. Probably reduced oil pressure by quite a bit.
  
  Turbo diesels are no doubt the most fuel efficient. Put it this way.... by the book... Golf mk4 stock 90bhp TDi = 55 mpg, 64 bhp SDi is about 48 mpg. Not only a big reduction in power, but also in fuel efficiency.
  
  If you wanna go slow, a n/a diesel can be easy on fuel. My Jetta Eco does about 38 mpg... and thats driving it as hard as it possibly could be driven. You may as well call it a n/a diesel. The turbo is only there to increase air flow to reduce emmisions, not as a performance add on by any means.
  
  
  
  I heard somewhere that in parts of Austrailia its not legal to sell n/a diesels due to sparks that may leave the exhaust (fires in the bush). With the turbo, that spark stays in the turbine housing until it is no more.
  
  If you want fuel efficiency, fit a small, wastegate turbo, de-fuelled pump, if the engine is in good condition in relation to oil pressure and ring sealing, run a light synthetic like Amsoil or Mobil 1 in both motor and tranny. Keep the car as light as possible at all times, 13" / 14" wheels (steels are generally lighter than alloys...not talking jap racing wheels here) and tyre pressure set correctly. If its got EGR, blank it off and reduce any load on the crank thats not necessary (air con, PAS etc..)
  
  I ran 0W-40 in my 1.9D before fitting the turbo, for about 18 months. I ran that engine hard, and never any problems. Oil pressure now with 5w-40 Delvac is 110 psi at idle cold, so the 0w-40 didnt do any harm. Milage went from 480 miles to a tank, to about 550. It was a big difference, TDi's get even more impressive results.
  
  Of course, direct injection is the only way to go for fuel efficiency, thats my next project.
  
  regards, DM (below, picutre of my Jetta Eco.)
• #37 by moTthediesel on 31 Aug, 2005 14:21
• Quote

  In my experience it's hard to come by any diesel engine made these days that's not turbo. Turbocharged engines are definitely more thermally efficient.

  
  
  I rented a small tracked Bobcat loader for work one day last year. It had a tiny 4 cyl diesel for power, with the smallest turbo I've ever seen. The whole unit was no bigger than a softball.
  Would have fit nicely on my Norton :twisted: , but I think the rental guys would have noticed if it was missing  :lol:
• #38 by Northboundtrain on 31 Aug, 2005 21:16
• Quote from: "DieselMonkey"

  Of course, direct injection is the only way to go for fuel efficiency, thats my next project.

  
  
  What do you mean?  Convert an IDI to DI?  That would be a mod I'd like to see  :shock:  I'd also for sure want to  try it myself -- anything to avoid all the electronics of the TDIs.  While I admire the engineering that's gone into the newer engines, throwing parts and chips at them (even if I did have the money) to get better performance isn't my idea of fun wrenching.
• #39 by kynetx on 31 Aug, 2005 22:08
• If you could get it working, it would sound like you threw a handful of bolts into the engine since there would be no progression with the fuel volume.
• #40 by DieselMonkey on 01 Sep, 2005 00:08
• No i mean a TDi motor running a Bosch mechanical direct injection pump. Over here its take your pick. I know of more than 5 different makes and models of vehicle with pumps suitable. Perkins where the first way back when they designed a 2ltr straight and turbo diesel for passenger cars. Performance was useless...i'll have the pump thank you... even has boost enrichment.  
  
  Simon cooper, who might frequent these boards has a 2litre (1.9 TDI bored) with mechanical pump. It looks like a 1.6 GTD pump but i doubt he could get the performance he is from a TDi using a small piston IDI pump. It does have methanol injection, Garrett roller bearing turbo and an aviation intercooler.
  
  TDi engines with failed pumps can be bought for reasonable money. They last forever too, i've a 1996 1.9L with 165,000 miles and it has better compression and lower blow-by than both my IDI's. I have the ECU and g'box with that engine, but i want to try a mechanical DI. Probably get the same performance, just with more smoke.
  
  Regards, DM