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Old 01-12-2005, 01:58 PM   #1
vrago OP
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Location: Occidental, CA - Sonoma County
Oddometer: 898
ScaryFast Power Now Intake Baffle

OK, I may be a sucker, but nothing ventured.

Since I have and FCR on my 640 (hear that, cult of the BST), I figured I'd do some extensive research on more response from the FCR. I checked out some of the reviews on the Power Now intake baffles.

Maybe Snake oil, like the perpetual motion machine spinners in this months Cycle World.

Vendor says, baffle on intake side of carb reduces turbulence at less than half throttle and improves responsiveness on lower end. The also have a power now plus which is a baffle for the head end, which reportedly acts much like porting and polishing in that it aids top end.

I will give it a try. I'll even have some witnesses at this weekend's tech event. Look for a report to follow.
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Old 01-12-2005, 03:30 PM   #2
meat popsicle
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Location: Circumlocution Office of Little Dorrit
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Quote:
Originally Posted by vrago
I have and FCR on my 640 (hear that, cult of the BST)

Don't believe the hype...

This came up on another thread; why would Weber put dual CV carbs on his custom rally twin bike? For $68,000 I expect nothing to be "second rate"

http://www.rallytwin.com/

Specifications

Engine:
Kawasaki EX 500, liquid cooled
parallel twin, 498cc, DOHC,
4 valves per cylinder, threaded
adjusters, electric start
74mm x 58mm
10.8:1
375 Watt
Wet sump, 3.6 quart capacity
50hp (approx)
35ft-lb (approx)
Dual 34mm Keihin CV
6 speed
Chain, 520 X-ring
Aluminum air box with dual foam
element filters
Custom tuned stainless steel headers
and mid-pipe, with 86dB USFS spark
arrestor
45-50 mpg (dual sport use)

Frame:
4130 Chrome Molybdenum, TIG welded, single
backbone, double cradle
4130 Chrome Molybdenum, TIG welded, removable
Aluminum, KTM, linkage suspension
WP 4057 upside down cartridge, adj. comp/rebound,
11.8” travel
Ohlins, adj. pre-load, comp/rebound, 12.6” travel
27.5 degrees
62”
39.5” (unlaiden, 4” less with rider)
12.5”
6.1 gallons
KTM hubs, Excel rims, 21” front, 18” rear
Brembo, 290mm disc (fr) 210mm disc (rr)
350lbs (wet, without gas or aux. components)

Controls:
Answer hi-carbon steel, with Enduro Engineering
aluminum hand guards
Magura
Magura
Honda
custom instrumentation

(This message paid for by the Cult of the BST)
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Old 01-12-2005, 03:58 PM   #3
Jinx
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Quote:
Originally Posted by vrago
OK, I may be a sucker, but nothing ventured.

Since I have and FCR on my 640 (hear that, cult of the BST), I figured I'd do some extensive research on more response from the FCR. I checked out some of the reviews on the Power Now intake baffles.

Maybe Snake oil, like the perpetual motion machine spinners in this months Cycle World.

Vendor says, baffle on intake side of carb reduces turbulence at less than half throttle and improves responsiveness on lower end. The also have a power now plus which is a baffle for the head end, which reportedly acts much like porting and polishing in that it aids top end.

I will give it a try. I'll even have some witnesses at this weekend's tech event. Look for a report to follow.

Turbulence is the result (or is rather predicted by) the Reynold's Number of the gas flowing through your intake tract.

I won't bore you with the math, but let's just say that all intake flow is turbulent all the time, and there is not a damn thing you or anyone else can do about it, because you can not have laminar flow at the velocities, pressures, temperature, and density combinations that we are dealing with.

But WTF, Dirt Bike Magazine loved it.

But all is not lost. If it isn't the next great thing, get your money back and send for my latest leaflet:

"How not to be a sucker" by sending $49.95 +$6.95 S&H to

Jinx
c/o Cardboard Box near Statue of Lenin
Seattle, WA 98112

Sorry, mate.
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Old 01-12-2005, 04:11 PM   #4
Mack
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They are quite popular and seem to wake bikes up on the bottom end. I gave a lot of thought about trying one, but decided to go with an FCR-39 rather then a FCR-41 and a Power-Now. No way to know without trying one, but I think I will get just about the same results for less money. The two factors that made me decide against one, were the fact that IMHO, the LC4 already has plenty of grunt down low, and I noticed that it was advised that you drop down one main jet size. This lead me to believe it might slightly reduce airflow at higher engine rpms, and on an LC4 I felt more need for top end then more bottom end.

It seems to me these make a lot of sense on a MX or Hare Scrambles bike, where power output is becoming less and less of an issue, but throttle control seems to be paramount, but not so much so on a big honk'en D/S........... (Heck I've groundlooped my ADV a few times, by getting a bit more grunt then I needed for the available traction)

It would be nice to have some seat of the pants real world experience with one of these. So why don' you try it out for us? Cheers, Mack

PS: I know some guys on KTM talk installed them on their LC4's, and a large number of EXC owners as well.
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Old 01-12-2005, 04:20 PM   #5
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I believe the idea of the Power Now is not so much to direct air flow, as to reduce the turbulence that occurs when the column of intake air contacts the exposed face of the partially open slide.
As the “vane” resides very close to the slide face, turbulent air above it (at part throttle openings) is restricted from mixing with the relatively laminar air flow below the vane.
In theory, the flow is improved at throttle openings where the slide cutaway is below the vane (potentially the best available flow is when the cutaway is parallel or in line with the vane) and this is why they recommend a slightly leaner mixture.
The less turbulent, more laminar, higher velocity air flow creates a stronger than usual vacuum signal (negative pressure), pulling more fuel thru a given jet size.

Or… I am completely full of shit, and made all this up as I went.
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Old 01-12-2005, 04:45 PM   #6
viverrid
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oh no not here too...

Power Now caused the most vicious flaming session I ever saw on the New England Dirt Bikes site. Some guys love them and run them and claim it makes their bikes livelier, and others ridicule them and say there is no way it could work and point out that dyno tests show no improvement.

Only way I can see, is get a few bikes together, lets somebody take them into a garage and put Power Nows in some of them but not tell anybody which ones (that person goes out the back door so he can't even give away the answer unintentionally with a non-poker face). The riders go ride them and declare which ones have it and which don't. (They can all ride their own bikes). Then a lunch break, back into the garage, some get it taken out or in, some are left alone - and back out again and let the riders say if they still have it or don't.

Then we'll see if it really does anything.
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Old 01-12-2005, 05:03 PM   #7
vrago OP
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Location: Occidental, CA - Sonoma County
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Mack,
I'm runnin the FCR-39.

Quote:
Originally Posted by Mack
They are quite popular and seem to wake bikes up on the bottom end. I gave a lot of thought about trying one, but decided to go with an FCR-39 rather then a FCR-41 and a Power-Now. No way to know without trying one, but I think I will get just about the same results for less money. The two factors that made me decide against one, were the fact that IMHO, the LC4 already has plenty of grunt down low, and I noticed that it was advised that you drop down one main jet size. This lead me to believe it might slightly reduce airflow at higher engine rpms, and on an LC4 I felt more need for top end then more bottom end.

It seems to me these make a lot of sense on a MX or Hare Scrambles bike, where power output is becoming less and less of an issue, but throttle control seems to be paramount, but not so much so on a big honk'en D/S........... (Heck I've groundlooped my ADV a few times, by getting a bit more grunt then I needed for the available traction)

It would be nice to have some seat of the pants real world experience with one of these. So why don' you try it out for us? Cheers, Mack

PS: I know some guys on KTM talk installed them on their LC4's, and a large number of EXC owners as well.
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Old 01-12-2005, 05:12 PM   #8
Gregg Wannabe
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Reminds me of that infomercial product for cars called Tornado or something like that. Its a vane that goes in the intake just BEFORE the filter supposedly to increase power and MPG. My local TV news guy (consumer watchdog dude) did a test on a variety of cars and MPG was DECREASED.
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Old 01-12-2005, 07:23 PM   #9
potatoho
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I put an intake vane on my bst40 intake. It was nice. Mainly an improvement on 1/4 throttle. Then one day I gave it some good throttle and it sucked my vane loose. I had to stop and fish it out through the airbox. I used very thin brass for the vane and it caved due to the pressure.

Without the vane, I just couldn't ride the bike the same. I got used to creeping around turns, and without the vane I always felt like falling over. The off-idle torque was gone.

So instead of making a bigger/stronger vane, I ordered a pumper. I got an oversized 42mm since I plan on putting both intake and engine side vanes. So that should leave me with 40mm give or take and dual vanes. Sweet.
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Old 01-12-2005, 07:41 PM   #10
ChrisC
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Quote:
Originally Posted by creeper
Or… I am completely full of shit, and made all this up as I went.
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Old 01-12-2005, 07:48 PM   #11
dagwood
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Quote:
Originally Posted by creeper
I believe the idea of the Power Now is not so much to direct air flow, as to reduce the turbulence that occurs when the column of intake air contacts the exposed face of the partially open slide.
As the “vane” resides very close to the slide face, turbulent air above it (at part throttle openings) is restricted from mixing with the relatively laminar air flow below the vane.
In theory, the flow is improved at throttle openings where the slide cutaway is below the vane (potentially the best available flow is when the cutaway is parallel or in line with the vane) and this is why they recommend a slightly leaner mixture.
The less turbulent, more laminar, higher velocity air flow creates a stronger than usual vacuum signal (negative pressure), pulling more fuel thru a given jet size.

Or… I am completely full of shit, and made all this up as I went.

My idea on that (back talking to Gumbydave and flanny was to go with the fcr39 or even the fcr34 for excatly that reason. higher velocity air flow at lower throttle opening.
same results with a cheaper and more readily used carb than the 40/42.
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Old 01-12-2005, 08:54 PM   #12
vrago OP
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Joined: Mar 2002
Location: Occidental, CA - Sonoma County
Oddometer: 898
I'm in learning mode now,

What do velocity stacks do exactly?

Tuned for what?
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Old 01-12-2005, 10:16 PM   #13
Jinx
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Quote:
Originally Posted by vrago
I'm in learning mode now,

What do velocity stacks do exactly?

Tuned for what?
Velocity stacks are used to smooth the flow, and prevent the inlet stream from separating from the inlet tract walls on entry. Which would actually reduce the effective area.

This is a typical piece of crap velocity stack beloved of Harley riders and VW builders. Note the sharp entry. Avoid them.



Now here is the business. Note the fully radiused lip. That's what you want. This allows the full inlet area to be used, and as the diameter gets smaller downstream, the gas flow is gradually accelerated.



Tuned length is a different subject, Sort of, as velocity stacks are often used to vary the tuned length of an inlet system. My own preference is to see the inlet tract either shortened or lengthened downstream of the carb or throttle body, but to each his own. But either way, every inlet should have a full radiused entry, or as close to one as we can get.

An inlet system is tuned as follow: When the inlet valve opens there is (hopefully) a lower pressure in the combustion chamber. When you open a valve and there is a pressure differential in the adjacent chamber, a wave is created. In this case, the higher pressure inlet tract creates a negative, or suction wave that travels back up the inlet tract. At full throttle, as long as the inlet tract is otherwise unobstructed, this negative pressure wave travels right through the carb or throttle body, and to the end of the inlet tract where we have just installed our velocity stack.

So what happens when a negative wave reaches an open end? It also reflects back, but this time as a positive pressure wave. And what we want is to have the length of the inlet tract just long enough so that this reflected wave arrives at the valve just before it closes and shove a little extra fuel/air mixture in, where the closing valve traps it. The math is pretty straight forward, the speed of sound (which is the speed that all our waves travel, which is why it is often called acoustic tuning) is @1100 ft/sec. All you have to do is figure out your cam timing, and what RPM you want this effect to happen.

The waves are pretty much a full throttle only thing. Waves will move quite nicely through smooth cross sectional changes, but a throttle slide sticking halfway through the bore will kill them dead.

And there are two big flies in the ointment. The first is this only works at specific RPM, or multiples thereof.

The second problem is that there is not always room for a single pulse to travel up and back. Inlet tracts tuned for that tend to be pretty long. But you can always cut them in half. A system tuned for 16000 RPM will also work at 8000 (the waves just travel twice up and down, but the pressure phasing is almost the same), and it will fit a lot better.

The effect of all this is great at 8000 RPM if that is what we have tuned for. But it pretty much sucks at 6000 because it is now out of phase (though it may be back on the job at 4000). But there is hope.

Modern airboxes are also frequency tuned (the term is Helmholtz Resonator if you want to do some more reading), and they are tuned to take out the flat spots created by inlet length tuning. Waves resonate in an airbox system just like they do in the inlet tract. And these can be tuned to have the airbox have it's highest pressure at any RPM you want. Modify a modern airbox at your own peril. There is a lot of engineering behind them these days.

Pretty much the same thing happens on the exhaust side, except everything there is tuned to give the lowest pressures (as opposed to our inlet example where we want the highest pressures). But, in general, longer primary pipe lengths work at lower RPM, and shorter ones at Higher RPM. In fact, a two stroke's expansion chamber is nothing but a bunch of tuned lengths with diffusers and convergent tapers designed to amplify and lengthen the effect of these waves bouncing back and forth.

But watch that wave speed. Due to temperature, the speed of sound, and of our waves, in the exhaust system is @1700 ft/sec.

If you space these events out (inlet tuned for 8000 RPM, Airbox tuned for 6000 rpm, exhaust tuned for 7000 RPM) you get a nice wide powerband with few flat spots. If you bring them together (everything tuned for 8000 RPM) you get a rocket with no powerband at all. It's like turning on a light switch. And it will have a flat spot you could shoot pool on.

Lot's of good info in books and on the web if you want to dig into the subject in depth. Cheers.
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Jinx screwed with this post 01-12-2005 at 10:51 PM Reason: removed double quote
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Old 01-17-2005, 02:58 PM   #14
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vrago's power now...

Hi all,

I was there for the installation of this on vrago's bike. To say the least I was skeptical as well of this, but given that he seems to have his gear pretty well sorted and it was his C note on the line, I was very curious about it's effects.

Frankly I do not recall if I rode his bike prior to instll or not, but I was able to ride it after install.

WOW!

I cannot verify any hp increase or otherwise, but what was VERY impressive was the INSTANT power upon throttle! With my FCR41 I have to get into it a bit before wicking it up rapidly. That was eliminated with Power Now.

I will definitely be adding this to my list of to-do's for my bike.

Thanks for being the guinea pig vrago

M
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Old 01-17-2005, 10:09 PM   #15
vrago OP
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Sooooooooo...

I put the nicely machined matte gold anodized intake bell witha a vane down the center of it onto my FRC-39 carb equiped LC4.

I had dyno runs from jetting (Factory Eddy current dyno) indicating it had 40+ HP at 7000 RPM. I was very pleased with the jetting and found the power fine. I did notice that the FCR did not seem to like to be "thwacked" open, for lack of better term, instead it seemed to respond better to a more linear roll on.

Since I'm a bit uptight and edgy, I wanted my throttle response to be that way as well. THat's why I tried the Snake Oil out.

Sicne I do not have a dyno handy and am ot sure how you would run a test on such a modification since its purpose is not really to add any hp. But You all will just have to take my subjective assessment.

IT ROCKS!

No really, it does change things a bit, like instantaneous throttle responsiveness. My favorite sensation on a bike (OK, tractor, truck, or anything else powered ) is torque and It made the torque come on earlier and possibly longer.

Say what you will, but that c note made me smile. I'd recommend the device to any other heretics who have abandoned the much championed BST.

Oh yeah, Since there is so much energy on this topic, I made creeper ride it so he could get dragged into the drama.

Jokes aside, I think it did move the start of the torque rise down a bit and am very pleased with the result.

The unit is just slightly longer than the intake bell I got from sudco when I got the fcr for conversion. It made no diffrence on install.
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