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  • Users: dootdootdoot
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  1. dootdootdoot

    Bearing losses wrt rolling resistance.

    Huh, given how much aero drag increases I wonder if it's a trade-off? Thanks btw. :)
  2. dootdootdoot

    Vehicle efficiency and design wrt fuel costs.

    With government tax brakes similar cars, like the base Prius and base Corolla, have the same price at ~200k miles with gas at $2.50 a gallon. As gas prices increase the overlap point naturally drops, and both of these aren't nearly as economical as a 3L Lupo, which we unfortunately can't get...
  3. dootdootdoot

    Bearing losses wrt rolling resistance.

    I've seen that increasing tire/wheel diameter can reduce rolling resistance marginally and was wondering if this was hogwash or not. I was thinking it could be a possibility if bearing friction is higher than the rolling friction between the tire/road, so increasing the speed of the outside...
  4. dootdootdoot

    IDI diesel efficiency

    Talk about a small internet, that's where I found the info originally... I've read the posts on modifying a VNT turbo for the 1.6l and some of the pre-chamber talk, but I'm guessing I haven't even scratched the surface. I'll continue searching, and if you could post any pertinent links you may...
  5. dootdootdoot

    IDI diesel efficiency

    Aside from turbocharging, I've seen pumping losses in and out of the precombustion chamber, and thermal losses into the cylinder head mentioned as the main culprits behind the disparity in efficiency. But... I've never seen any quantification of which does what, and I was wondering if anyone...
  6. dootdootdoot

    Vehicle efficiency and design wrt fuel costs.

    should be in auto ot too, tried flaggin it, hopefully it'll be moved soon. ^^
  7. dootdootdoot

    Vehicle efficiency and design wrt fuel costs.

    From what I've gathered, even in the 1NZ-FXE engine, pumping losses reduce engine efficiency by a significant amount. For example, this is supposedly a model based on dyno data http://www-personal.engin.umd.umich.edu/~chrismi/downloads/HEVModel/FC_PRIUS_JPN.m and according to this the...
  8. dootdootdoot

    Pumping losses during no load closed throttle on Fi engines.

    Sweet, thanks for the info! So this probably means that accelerating up to some speed in the minimum BSFC throttle/rpm area, and coasting down to a lower speed, with some average speed, is more efficient than just driving with minimal load/maximal BSFC at the same average speed. Obviously the...
  9. dootdootdoot

    Pumping losses during no load closed throttle on Fi engines.

    Ah, I gotcha with the vacuum analogy. But since the pressure in the cylinder when the exhaust valve opens is probably less than the pressure in the exhaust, wouldn't that result in some air being sucked into the cylinder only to be pushed out again, with the remaining air being proportional to...
  10. dootdootdoot

    Pumping losses during no load closed throttle on Fi engines.

    With an automatic transmission, I can keep the car in gear, turn off the engine, and coast without any problems? If that's true then I can just do a couple runs coasting in gear with the engine on/off and TB closed/opn and compare that to coasting in nuetral to see if the majority of losses come...
  11. dootdootdoot

    Pumping losses during no load closed throttle on Fi engines.

    That sounds right. Iirc the 3L lupo disengages the transmission when coasting as well. I'm just wondering if there are pumping losses when the TB is closed and no fuel is being burnt. I.e. when coasting does the vehicle slow down faster because of losses in the transmission/differential/engine...
  12. dootdootdoot

    Pumping losses during no load closed throttle on Fi engines.

    Given the assumptions (which may or may not be correct ;) that a modern FI car with a TB has it closed during most "no throttle" deceleration, no fuel is being injected during this time, and most gasoline engines approach maximum efficiency at a reasonable rpm range depending on the gearing, and...

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