Post Gordon ~ Thoughts, Commentary & Reflections

Discussion in 'Road Stories' started by Victor_V, Jun 2, 2013.

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  1. double yellow

    double yellow Road Train Member

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    Forced Induction Primer:

    Turbochargers use mostly wasted energy (heat from the exhaust) to create more power without a bigger engine. It works by forcing more air into the engine than atmospheric pressure would otherwise allow. More air means more fuel can be injected = more power. Cue Tim Allen grunt...

    The turbocharger's compressor is like a fan inside the intake tract. Attached to it by a shaft is the impeller, a similar fan-like device located in the exhaust stream. The engine's exhaust has to turn the impeller to escape, this turns the compressor which forces more air into the engine.

    Normally you'll reach a point where you want to control the boost. The usual method is a wastegate -- a port that opens allowing exhaust to bypass the impeller, which prevents the impeller from spinning any faster.

    So what's the intercooler for?

    Recall the ideal gas law: PV=nRT
    P- pressure
    V-volume
    n- amount of gas
    R-ideal gas constant
    T- temperature

    If you want more air ("n") in the same amount of space ("V"), then you need to increase the pressure ("P"). In turbo parlance, you want more boost. But when you increase the pressure, a side-effect is that you also increase the temperature ("T").

    An intercooler (automotive terminology) or charge air cooler (diesel terminology) is basically a radiator for your turbocharged air. Hot air passes through the inside, while cool air (or sometimes water) flows around the external fins extracting heat.

    Intercooling allows you to make more power at the same boost. It isn't a requirement though, intercoolers were rare in the early days of turbocharging.


    PS: by the time you actually split cottonwood, you've probably worked up enough sweat not to need a fire...

    PPS: If you're going to burn cottonwood, mix in some manzanita or similar hot-burning hardwood. Cuts down on the smoke. Besides, manzanita can't usually be burned straight in today's fireplaces -- too hot.
     
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  3. tsavory

    tsavory Road Train Member

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    It lools like it will bolt up but may need to swap the bellhousing drive line will be close but have a guy near by (so mechanic says) that can properly adjust it if its to long and make a new one if its to short.
    Yeah if either of knew specifics would remove first and add a high gear to helo bring down rpms at highways speeds just dont have time to research and get it done right now so will be happy to get in and works properly.
     
  4. Zippe1

    Zippe1 Bobtail Member

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    Hope for a Happy & healthy new year to us all! Thanks' to Victor for this thread and all of the contributors for all the informative posts! I must offer the one shout out, Go Green, my Daughters' Alma Mater. Zippe.
     
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  5. Victor_V

    Victor_V Road Train Member

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    Hi, Zip! Glad to hear from you!

    Just to show that great minds think along the same lines, here's Veltman on variable-geometry turbos (like the Mack has) saying pretty much the same as Bright One above:

    Okay, I'm feeling good. Veltman from Stanford and Bright One from Northern California (a culture to its own, for sure) agree...

    Here's Veltman again:

    Yuppo, feeling good! Bright One said the turbo 'works by forcing more air into the engine than atmospheric pressure would otherwise allow'. So somehow we have like this mouse in a cage effect of exhaust gases turning the impeller that turns the compressor which stuffs more air into the engine.

    Oh, very, very cool! Thankfully, all I have to do is drive the thing.

    Veltman goes on to say:

    So to burn fuel, you need air. The turbo, then, is a pump that increases the air in the cylinders above atmospheric pressure so the injectors can squirt even more fuel to burn... okay, okay. I'm with you guys, so far!

    Burn more fuel, get more power! What a concept...

    Then Veltman has a cartoon diagram showing the flow of hot exhaust gases into the turbo before exiting out the exhaust and the air inlet into the compressor and back into the engine cylinders. Here's the caption:

    You can gander at Veltman's paper here http://large.stanford.edu/courses/2010/ph240/veltman1/

    We can probably pull some stuff off YouTube on turbocharging, too!
     
    Last edited: Jan 1, 2015
  6. double yellow

    double yellow Road Train Member

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    I have to disagree with Veltman on this point. High performance naturally aspirated engines have been exceeding 100% VE for decades.

    To breathe in more than 100% of the available air, these engines use acoustic tuning (technical term: Helmholtz resonance). By adjusting the length of the exhaust headers & intake manifolds, engine designers can tune for a narrow range of rpm where the sound waves (from combustion or closing valves) reflect back at just the right time to force a little extra air through the intake or to suck just a little extra air out of the exhaust.

    [​IMG]
    [​IMG]

    This is why when you buy headers for a popular engine, say the 350 chevy, they often have a number of options to suit various applications (longer tubes generally being tuned for lower rpm, and shorter being tuned to use fractional wavelengths for higher rpm).

    [​IMG]
    [​IMG]

    Toyota (er Yamaha) had the first production engine in the US to use variable resonance tuning, introducing its "TVIS" intake system on the 1984 MR2. Put simply, it was 2 intake manifolds in one, with a valve that would switch to a shorter runner length once you reached about 5000rpm. Made a little bump in dyno graphs:

    [​IMG]

    Ford (er Yamaha) did a similar thing with their DSI on the 1989 Taurus SHO.
     

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  7. Victor_V

    Victor_V Road Train Member

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    Exhaust Leaks

    On the practical side, as a driver, when you look at your exhaust and your turbo, one thing you would want to notice would be any exhaust leaks going into or after the turbo.

    The engine compartment is so noisy when running that you're not likely to hear an exhaust leak like you might on a car or pickup, that husky sound. More than likely you will spot some soot around the clamps before the turbo or after. This was a real problem with the mail contractor that I drove for and the shop always got their nose out of joint when I wrote this stuff up and wanted it fixed. You want what???

    They ALL leak like that!!! (Yeah, if you don't fix them... )

    Sometimes I would drag the lead mechanic over and have him put his hand where I had mine, to where he could not claim he couldn't find the leak, something he often did. Sometimes there'd be a nickel-size hole or a long crack. But usually it was a loose clamp that was sooty.

    The shop actually painted my exhaust black with high heat paint thinking I'd have difficulty finding the sooty spots. Didn't. Lead mechanic got so frustrated that he pulled the entire exhaust off, replaced it with all new, and then pulled the C-15 (bigger Caterpillar engine) truck off my run and left me with a smaller C-12. They still have an 89% Vehicle Maintenance CSA.

    But he DID have to fix it. He just didn't like it.

    Just imagine yourself as exiting exhaust. Now, do you want to travel into that impeller and push like a little mouse or would you rather just escape under a clamp out into the atmosphere?

    Hey! Yeah! Take the easy way out and, if lucky, you'll probably find some way into the cab (there are always small openings) and put the driver to sleep--you can at least make him/her fight to stay awake!
     
    Last edited: Jan 1, 2015
  8. DenaliDad

    DenaliDad Retired Wheel Dog

    Comment

    As a somewhat-educated nerdy kind of guy, I do appreciate references, including graphs, when a writer discusses a technical topic. Whether they are "right" or not, doing so is much better than just reading words or opinions. Thanks for yours, Victor and double yellow.
     
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  9. ampm wayne

    ampm wayne Heavy Load Member

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    I had the day off today.

    My run tomorrow is a two stop load going to the St.Louis area.

    The first stop is in Bridgeton,Mo. The second stop is the same as Victor and I delivered to on Wednesday.
     
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  10. Victor_V

    Victor_V Road Train Member

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    Think next time I get that run, will run out 70, fuel on the way and fuel again on the way back on 70. The extra 18 miles across I-64 likely eats as much time as second fuel.

    AND chock my wheels. Saw the sign, knew I needed to chock, had brain fart between truck and dock. Nice to have a Big Brother take care of it, tho. Thx!
     
  11. tsavory

    tsavory Road Train Member

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    Well was not a good day the new to me autoshift does not have a spot for the splitter ther rear housing is 5" shorter so no way to make it work or take two to make one after some research it appears the new was full auto not just the top 2 gears. So off in the am to return and hunt down a proper tranny.
     
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