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  • Users: Junior37c
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  1. Junior37c

    two stroke motors in automobiles again

    hmm, I see. I suspect that a catalytic could bring the UHC down to ~1g/kwh but much beyond that is pushing it. Possibly going to a stratified charge as well as after treatment could get us there. But the target is a moving on, by the time that could be sorted the regulations will have shifted...
  2. Junior37c

    two stroke motors in automobiles again

    I'm not terribly up to date on modern automotive emission specs but maybe we can start to quantify this. The DI snowmobile engines I'm used to dealing with have no catalytic aftertreatment and emission numbers are approximately as follows on a production engine. This is also not a variable...
  3. Junior37c

    two stroke motors in automobiles again

    There are examples of 2-stroke DI motors with very very clean emissions, cleaner than the 4-strokes they compete against in those particular classes. Particularly outboard boat engines and snowmobiles.
  4. Junior37c

    When is it too late to pursue engineering professionally?

    If you're getting into it for personal satisfaction, there's no such thing as too late. However if you're getting into it for financial reasons, a future worth calculation can provide a much more qualitative answer than any number of opinions we can provide.
  5. Junior37c

    Old Engines are inefficicent at creating power/torque,WHY?

    They may not need it. But they want it, and they're willing to pay for it.
  6. Junior37c

    Old Engines are inefficicent at creating power/torque,WHY?

    Norm: I concur. BMEP and Piston speed is the fast and dirty way of calculating a rough estimate of power output. But even that method shows very clearly that a higher bore:stroke ratio is going to net you a higher amount of power with the same BMEP. Sadly there's a lot more to engine design than...
  7. Junior37c

    Old Engines are inefficicent at creating power/torque,WHY?

    I've seen some of those engines ya. And yes society seems so caught up in the cylinder swept volume that they neglect the more basic metrics. There seems to be an assumption that an engine with a larger swept volume will be massier. Altho you take that little 4 cylinder box 4 turbo, and start...
  8. Junior37c

    Old Engines are inefficicent at creating power/torque,WHY?

    I'd like to point out that the displaced volume is a rather arbitrary means of comparing engines. Personally I thought outright mass or geometric size is a much more relevant comparison. Doesn't sell as well on the paper perhaps, but I for one am extremely impressed with the LS7's mass specific...
  9. Junior37c

    The 21st Century Design Drafting Group

    The real question is will management stop using the buzzword of the minute and applying it on Engineers? Lean, Siz Sigma, Paradigm Shift, 7 Habits, Green, etc.
  10. Junior37c

    A woman inventer?

    vote #3 for "Miss Shilling's Orifice" it IS a shame that it all went down that way, she saved a lot of lives with that little contraption.
  11. Junior37c

    Educated Opinions on Climate change - a denouement or a hoax?

    lmao rb1957, my first thought was also immediately somewhat dirty. "it's the tip of the <insert biological reference here>"
  12. Junior37c

    Canadian working holiday

    Ya Fort Mac was hit hard, my understanding is that it's starting to pick up again with the price of crude back in the $80 range, it really needs to be over $100 for the Athabascan sands to be in high gear, but there's plenty of build projects underway. That said, I wouldn't recommend Fort Mac...
  13. Junior37c

    Canadian working holiday

    if you've got experience in oil&gas head for Fort McMurray in Northern Alberta, big money in that area, altho not a whole lot in the way of vacation material, and the winters are generally harsh. Newfoundland also has a fairly large oil/subsea industry and is probably better for a vacation spot...
  14. Junior37c

    Educated Opinions on Climate change - a denouement or a hoax?

    given the push for clean coal that is at the moment the most pallatable option politically that's capable of filling the grids needs. I'd say it's a big ask to take carbon sequestration off the table.
  15. Junior37c

    Is it possible?

    388hp on an 86mm squared 4 cylinder at 6250 rpm comes out to be right around 28 bar of BMEP. More than reasonable for an absolute pressure of 2.6 bar in my opinion. To put it in perspective that'd be just over 10bar at atmospheric pressure, which is actually relativly mild tune. Ofcourse you...
  16. Junior37c

    EGT versus equivalence ratio, methane fuel

    it'll depend heavily on ignition timing, valve/port timing and the distance the EGT is from the port/valve.
  17. Junior37c

    Power, Tire width, weight distribution

    gotta concur with imcjoek. however you can easily enough calculate the differences in power loss to spin up 2 wheel/tire sets of known inertias and decide for yourself if the inertia gain is worth the added traction.
  18. Junior37c

    Roughly, what would the effects of this cam change be?

    No experience with that particular engine but looking at the bore/stroke I'd be inclined to go with a shorter duration, tighter lobe centers and more lift. your 25m/s limit comes at 7800rpm, at 13bar BMEP and expecting peak torque at ~6500 so that it can have a nice fat torque curve and continue...
  19. Junior37c

    Roughly, what would the effects of this cam change be?

    I'd expect: reduced compression less peak torque a broader torqueband peak torque will occur at higher RPM reduced maximum cylinder pressure and therefor increased piston life. better idle quality and vacuum. increased NOx emissions All that said, this isn't that big a shift so these changes...
  20. Junior37c

    Calling it a day....but at what time?

    The legality becomes even trickier when liability comes into play. If you get in a car accident driving from a jobsite to your house rather than from the jobsite to your office, how will the insurance company look on that? Or if you fall off a ladder before your scheduled end time.

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