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Author Topic: INDIAN 741 Supercharged...See you in 2011  (Read 204900 times)
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Calkins
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« Reply #105 on: June 10, 2009, 06:30:32 AM »

We're all nutz! cheesy
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Justin Calkins - Iowa Falls, Iowa
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« Reply #106 on: June 10, 2009, 08:20:34 AM »

Long as nobody gets sane everything will be just wonderfull, world will keep on turning like it always has.

              Ed
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octane
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The INDIAN "Saltcracker" 650 A-VBF




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« Reply #107 on: June 11, 2009, 07:54:22 AM »

I've had a few PM-comments about the intake / plenum
but I'll take it to this thread, as I'd be glad if someone more knowledgeable
than me (shouldn't be hard to find) could offer competent comments:







We're talking about the need for a certain size plenum
to create a "pressure-reservoir", to 'bridge the gap' between
the constant/even-pressure delivery from the blower.
and  the intermittent demand because of the 'un-even' (V-twin) firing order.
(On a single-cylinder the problem would be worse. On a multi it would be much less)


My calculations for the plenum-size is based on
Maurice Brierley's ( sixties supercharged Vincent drag-race hero)
book  "Supercharging Cars and Motorcycles",
and an exchange with Jeff/"Panic", of Victory Library fame
( I tried to linkto the supercharger-part of his site,but they seams to have vanished (Huh) )
and a few other sources.

Their seams to be an agreement, partly different depending on blower-type,
that the size of the plenum should be from 150 to max. 200% of the engine-displacement,
on a V-twin.
My engine is 600cc and my plenum is approx. 1190cc so that's pretty darn close to max.
(I just re-checked it, by filling it with water).

Theoretical there's a bit difference depending on the 'firing pulse'
which in my case is 42 degrees, so the phase/wave formation
is slightly different than, say, a 50 degree V-twin.

This is mostly theoretical but:
...despite the plenum/(boost-storage-tank), the two cylinders
because of the 'un'even' firing, will receive slightly un-even quantities of "supercharge".
Because of this, some folks, like Brierley, will run slightly (half a ratio) different compression-ratios
on the two respective cylinders, to ad up things.

Apart from all this; my plenum is not perfect by any means,
as I'm not able to make it perfectly 'stream-lined' inside
to avoid what Brierley refer to as "aerodynamic fungus"
...but I did my best, considering the means I have available.

« Last Edit: June 11, 2009, 08:05:26 AM by octane » Logged

"A designer knows he has achieved perfection
not when there is nothing left to add
but when there is nothing left to take away"

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panic
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« Reply #108 on: June 11, 2009, 11:34:57 AM »

..
« Last Edit: October 03, 2010, 09:35:34 AM by panic » Logged
wobblywalrus
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« Reply #109 on: June 11, 2009, 11:20:55 PM »

A couple of years ago I was waiting for the owner of a one-man shop to look in his junk parts stash for a tailight.  He was busy running a Harley on a dyno with a non-standard single-carb manifold setup.  It was a naturally aspirated engine.  He had taps in the intake tracts close to the heads and he was checking the intake tract vacuum in each cylinder while he ran the engine.

Being a curious guy, I asked him what he was doing, after he shut down the engine.  He said this manifold setup needed to be checked to make sure it was balanced.  He said he would weld and grind on the manifold as needed to make sure one cylinder was not getting more air than the other.  He had mercury filled vertical tube gauges that could measure both pressure and vacuum.  A horizontal line across the gauge tubes indicated static air pressure conditions.  Vacuum pulled the mercury higher than the line, and pressure pushed it below the line.  Or vice versa.

This really impressed me.  At low revs I could see the mercury jump due the the Harley's intake cycles.  At higher revolutions I could see the manifold setup feeding more air to one cylinder than the other.  One thing I also noticed was that the uneven firing order of a Harley meant there was more dead time between intake pulses every other cycle.  Sort of "chuff-chuff-pause-chuff-chuff."

Maybe this type of testing could help you fine tune your setup.
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panic
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« Reply #110 on: June 12, 2009, 11:20:46 AM »

..
« Last Edit: October 03, 2010, 09:35:53 AM by panic » Logged
panic
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« Reply #111 on: June 12, 2009, 04:01:32 PM »

..
« Last Edit: October 03, 2010, 09:36:10 AM by panic » Logged
jl222
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« Reply #112 on: June 12, 2009, 04:12:51 PM »

This also means, in practical terms, that if the plenum volume is large enough, there will be a delay of "X" number of lobe rotations before full discharge pressure is present in the cylinder at IVC. Until the entire plenum volume is pressurized cylinder pressure < inter-lobe pressure.
Until that time, the cylinder will respond (i.e., develop torque) first as naturally aspirated, then develop more power as the plenum pressure rises (probably asymptotic) to discharge pressure.

  Is that about the time it takes to twist the throttle evil

   JL222 grin
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panic
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« Reply #113 on: June 12, 2009, 04:52:03 PM »

..
« Last Edit: October 03, 2010, 09:36:28 AM by panic » Logged
jl222
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« Reply #114 on: June 12, 2009, 05:29:03 PM »

Supposedly, no.
The Corvair turbo engine was notorious for reduced response just from using a plenum to the 4 carb (140 hp) heads, rather than the original 2 openings.
How bad? Depends on volume vs. blower capacity vs. boost level vs. cylinder displacement.

   This is a ROOTS blower instant boost
   Even our centrifugal has instant boost, at a blip of the throttle boost registers on guage. If you new anything about supercharged engines you would know this.
   My tubocharged buick had instant boost also.

    JL222
   
   The 222 car has over 10 ft of 4 inch tubeing and an intercooler 24 x 14 before the air sees the engine [ still instant boost ]
« Last Edit: June 12, 2009, 08:55:43 PM by jl222 » Logged
ironwigwam
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« Reply #115 on: June 12, 2009, 05:54:32 PM »

Octane,
     In responce to your plenum, quote
We're talking about the need for a certain size plenum
to create a "pressure-reservoir", to 'bridge the gap' between
the constant/even-pressure delivery from the blower.
and  the intermittent demand because of the 'un-even' (V-twin) firing order.
(On a single-cylinder the problem would be worse. On a multi it would be much less)


My calculations for the plenum-size is based on
Maurice Brierley's ,
   end quote.
   It looks fine the way you designed the sweep in the center , just bring it over for BUB and build on that.
   Rocky
   Ironwigwam
   1957S/VG
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Stan Back
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« Reply #116 on: June 12, 2009, 07:09:51 PM »

I'm kinda thinking that Panic knows what he's talking about, even if I don't fully understand his second response.  And I guess "instant" is open to interpretation.

Stan
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Member of the San Berdoo Roadsters California's most-exclusive roadster club.
Celebrating 60th anniversary of racing on the salt.
jl222
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« Reply #117 on: June 12, 2009, 08:52:49 PM »

I'm kinda thinking that Panic knows what he's talking about, even if I don't fully understand his second response.  And I guess "instant" is open to interpretation.

Stan

  Instant ''immediate'' concentrated precooked food or beverage. such as premixed greyhounds but not as fast as you can drink them grin

         JL222 cheers
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wobblywalrus
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« Reply #118 on: June 12, 2009, 10:46:05 PM »

My post about the dyno was to tell about using it as a tuning tool.  I don't know a lot about superchargers.  Octane has been teaching me a lot during his build.

The dyno gives us an opportunity to be close to the engine while it is under load.  I spray soapy water on joints to check for leaks, both pressure and vacuum.  I listen for weird noises.  Then I turn off the lights and we look for wayward sparks.  We get traces for horespower, torque, and fuel mixture.  We rejet as needed.  All data goes into a notebook.  We figured out how to set jetting for B'ville while on a dyno near sea level in Oregon, by using our notes.

A good dyno operator is the most important thing.  Especially one who is familiar with engine type being tested.  Dyno tuning costs a lot, but it has really helped us.  It is a lot easier to fix stuff in the shop than out on the salt.



  , and  We use a dyno sparingly because it costs a lot, but we get a horsepower, torque, and mixture trace  and mi
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octane
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« Reply #119 on: June 13, 2009, 07:19:06 AM »

Thank you all, for your input !


Panic, I do believe I understand what you're saying.
Very informative.

Walrus; about the mercury-gauge etc. thing;
I do indeed have such a thing as the mercury vacuum gauge, right here.



I use it for synchronizing the carbs on my four-cylinder / four carb Honda GL1000
and my six cylinder / six carb CBX1000. ( as it's only a four gauge thing, I use one carb
as reference and adjust the others according to that one)


(Beautiful engine, don't you think)

It mercury-thing measures the intake vacuum, so I can of cause not use it on the blown engine.
There is no vacuum in the intake/plenum....there's pressure.
The bike will indeed go on a dyno as soon as it up and running (...very soon hopefully)


Supposedly, no.
The Corvair turbo engine was notorious for reduced response just from using a plenum to the 4 carb (140 hp) heads, rather than the original 2 openings.
How bad? Depends on volume vs. blower capacity vs. boost level vs. cylinder displacement.
Dunno much about Corvairs, but they were horizontally opposed engined,
so just for fun; have a look at my 1977 Honda Goldwing GL1000 , supercharger set-up,
that being a horizontally opposed engine as well.
Magnuson Magnacharger. 60 cubic inches. / 983cc. Runs slightly 'over-cranked'.(24 to 23)
Weber 26-34 two barrel carb



...also to compare blower/plenum sizes.


For your infotainment;
watch how fast that old blown Goldwing is
(Please disregard the clunky clutch. I wacked it within the first few miles after installing the blower.
Is now replaced by a Barnett clutch and stronger springs.)

Click the image and watch the video. Turn UP sound !




...and check how it picks up revs here:



(No silly: I'm not four feet tall. The bike is on a lift...ha ha)



BLOWERS RULE !!!!!!


« Last Edit: June 13, 2009, 07:52:59 AM by octane » Logged

"A designer knows he has achieved perfection
not when there is nothing left to add
but when there is nothing left to take away"

Antoine de Saint-Exupery
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