| Author |
Message |
    
Blake
| | Posted on Friday, April 06, 2001 - 09:08 pm: | 
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Jose:
It's very tough to even measure torque in a dynamic system. The inertial dynos actually physically only measure drum rotation, elapsed time, and if desired, your engine's rpm. The dyno software knows the rotational inertia, rolling resistance, and geometry of it's drum; from those known constants it calculates RWHP, equivalent land speed (mph), and (if it's monitoring engine rpm) engine torque referenced to the crankshaft. |
Clydeglide
| | Posted on Friday, April 06, 2001 - 09:09 pm: |
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Blake,
Your'e a sick man.
I learned more here today than I did in both years of 4th grade!
Clyde |
Ralph
| | Posted on Friday, April 06, 2001 - 10:10 pm: |
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Actually Blake I never had a problem with the contact patch theory Aaron presented. It was more of a word game as far as I could see.
I'd have to take some time to work out the equations to be sure, but I'm guessing that the HP used to spin up the rear wheel will be identical for each gear. That'd be easy enough to prove, now wouldn't it?
All of this stemmed from Rocket (thanks alot poop head) and his estimation of the difference between British and American horses. As you bought up in your love letter above, you can figure how much horse power Rocket used in his drag runs. Pretty much common knowledge, as are the formulas. So here's all we have to do, have some of the nice gentlemen with the high pony bikes go down to the drag strip so we can figure out if they really have that much power.
Oops, darn doesn't work. You only get the power utilized, not the capability.
Just had to point that out before Rocket launched.
bighairyralph |
Tripper
| | Posted on Friday, April 06, 2001 - 10:12 pm: |
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And this is the same guy that professes he can't do web programming. Probably because there is no advanced mathematics involved. Jeeeeezz Louise. My eyes burn. Can someone verify for me, is what Blake posted above on the level, or is he blowing smoke just to have fun at my expense. i feel so inferior |
José_Quiñones
| | Posted on Friday, April 06, 2001 - 10:20 pm: |
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Blake,
Vette vs Diesel,
I didn't say same torque/weight ratio, I said same power (hp)/weight ratio. Of course if one is making it's torque at twice the rpm of the other it would be faster, that's simple math, as you point out.
_________________________________________________
The way I understand a dyno to work is as follow:
The rear wheel of the bike will make the drum accelerate from one rpm value to another. The dyno will measure the start and end rpm and the time it took to get between them (starting when the operator hits the button and ending it when he hits it again).
The software, as you mentioned, knows how much mass (the spinning drum) was accelerated and how long it took to accelerate that mass from one rpm spot to another.
So it knows the work (making the drum spin from one rpm to another rpm) and how long it took (the time between operator clicks on the button). So P=W/t and you get power, which is converted to Horsepower.
So it is really measuring mass, acceleration, time, and rpm. So it is more accurately called an accelerometer instead of a dyno.
As you say, the Horsepower is CALCULATED, and the torque is CALCULATED based on a measured variable (rpm) and a calculated one (the HP)
Are we agreeing? |
S2no1
| | Posted on Friday, April 06, 2001 - 10:40 pm: |
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Tripper,
Blakes calcs check very well. You can find a drag et calculator at the following link:
http://www.nightrider.com/biketech/calc_estimatehp.htm
It shows the HP at 91.6 for the ET.
All that, and we could show Rocket getting 91HP at the rear wheel. With a 15% loss, that means about 104 at the crank. Sounds good to me.
Blake, I'd estimate the drag coefficient at about 0.45 with his head down. Course that's without the brick, needs to be 0.54 with the brick and his head up. Oh wait, the new CF wheels have raised surfaces, will that increase or decrease the drag?
Arvel |
Hoser
| | Posted on Friday, April 06, 2001 - 11:39 pm: |
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MikeJ:
Here's that Mtn. Bike "dyno pull"
Keep in mind this was after 4 beers , tire slippage was also a problem getting the drum up to speed.
Jeff |
Blake
| | Posted on Saturday, April 07, 2001 - 12:01 am: |
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Jose:
Oops, I totally missed your power to weight ratio comment, and I agree. I still disagree with the aforementioned torque/HP web article though in that it asserts that "Torque is the only thing that a driver feels, and horsepower is just sort of an esoteric measurement ..." and that "...horsepower has nothing to do with what a driver *feels*." I think I get what he is trying to say, and it's in the context of the acceleration/kick in the pants of one car versus that car's own torque and HP curves. It does not in any way hold true for a comparison of two different vehicles. I mean obviously a GSXR750 will flat out smoke a Buell, even if it had some extra mass to equalize weights between the two, the relatively low torque but smokin high HP will win every time except possibly for the very first 40m of a drag race where the high revver has not yet hit it's power (err torque) band and the jixer pilot is afraid of smoking his clutch.
I did like his comment about how (neglecting aerodynamic drag) acceleration in any one gear will track identically (same relative magnitudes) to the torque curve (versus rpm). That coincides with needing twice the power to maintain constant acceleration at double the speed (the energy conservation thing).
The workings of an inertial dyno:
Quote:The rear wheel of the bike will make the drum accelerate from one rpm value to another. The dyno will measure the start and end rpm and the time it took to get between them (starting when the operator hits the button and ending it when he hits it again) continuous (bunches of times every second) time indexed drum rotation.
The software, as you mentioned, knows how much mass inertia (the spinning drum) was accelerated and how long it took to accelerate that mass inertia from one rpm spot to another.
So it knows the work (making the drum spin from one rpm to another rpm datapoint/position to the next) and how long it took (the time, calculated as the difference between consecutive elapsed time data points) between operator clicks on the button aquisition of each dataset. So P=W/t and you get power, which is converted to Horsepower for the infinitesimal interval between all consecutive sets of drum position and time data.
So it is really measuring mass, acceleration, time, and drum rotation, and (if desired) engine rpm. So it is more accurately called an accelerometer instead of a dyno.
As you say, the Horsepower is CALCULATED, and the torque is CALCULATED based on a measured variables (time, drum position, and engine rpm) and a calculated one (the HP) known constants (inertia and geometry of drum, geometry being the drum's outer radius).
An accelerometer is a device that actually measures acceleration directly. They oftem employ calibrated crystal assemblies which when subject to acceleration (force) produce a measurable voltage that is proportional to the magnitude of the acceleration.
Yeah, I basically agree amigo. I'm just a picky SOB. 
I sure do enjoy the opportunity to blather on about this stuff though. My wife will have none of it! I can make her eyes glaze over faster than a fish can drink. LOL!
oao,
Blake (heading to apt for a few hours sleep, perchance to dream, of... PHYSICS!???) |
Mikej
| | Posted on Saturday, April 07, 2001 - 02:07 am: |
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Allright Jeff,
A little spikey, but considering that you had tire slippage and were running on a fuel/alcohol blend I'd say it looks pretty good. Anything over 24mph is good when not going downhill. |
Al_Lighton
| | Posted on Saturday, April 07, 2001 - 02:13 am: |
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Yep, yer right Blake....just goes to show a couple things:
1) always write the equation before making assumptions based on intuition
1) you really do lose it if you don't use it...I gotta stop being just a manager...
I had myself convinced about the linear physics, I thought my lack of understanding was do to the conversion to rotational physics.
humbly, Al |
Al_Lighton
| | Posted on Saturday, April 07, 2001 - 02:15 am: |
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wierd duplicate post deleted...... |
José_Quiñones
| | Posted on Saturday, April 07, 2001 - 08:03 am: |
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Blake,
I don't disagree with any of the "revisions" you made to my explanation, but jeez, I think mine is easier to understand because it's what you can observe when you see a bike run on a dyno.
This is great, but can we get back to the 2002 motor speculation? |
Tripper
| | Posted on Saturday, April 07, 2001 - 09:20 am: |
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Hoser - Check the ASB and TwinSport web sites for an ECM that will raise the rev limit on your motor! |
Axtell
| | Posted on Saturday, April 07, 2001 - 10:08 am: |
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Blake: I don't think we can cross out mass and substitute inertia when describing this accelerometer. Both certainly exist and that is one problem the dyno has on sweep tests.
I believe these dyno systems use a blanket inertia correction factor and that is one of the reasons changing the gear used on the run can change the amount of hp that is reported to being produced at the crank. |
Hoser
| | Posted on Saturday, April 07, 2001 - 10:04 pm: |
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Here's Bullzebub's 97 S1
* Stock lightning heads / flat top pistons
* Pro series air cleaner
* Pro series header
* White Bro's "E" series muffler
* "Tweaked" carb
Jeff |
Jmartz
| | Posted on Sunday, April 08, 2001 - 07:44 am: |
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Jeff you are somwhat of a magican! Over 87 HP on a very slightly modified S1, I just wonder what you could do with mine if you got your hands on it 107?
Jose
PS How far is the ride to Calgary? |
Hoser
| | Posted on Sunday, April 08, 2001 - 02:43 pm: |
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Jose:
I have seen similar numbers before on pre thunderstorm engines . Nothing special was done to get to this point either. The reason I posted this was the White Bro's "E' series muffler has a 2.5" inlet and necks down to 2" , so I was a bit surprised myself to see those numbers. Exhaust plays a huge!! role in quest for horsepower / torque , lots of guys (harley) make bad decisions often buying an exhaust system that looks or sounds cool rather than a system that may look odd (to them) but makes 10 or more HP and 15 ft/lb more TQ . We once built a 113" w/ nitrous for a guy , he then went through 6 or 7 different exhaust systems , finally settling on a set of ridiculous long upswept fishtail drag pipes and in doing so wound up with 15 HP less than what he would have had with the pipes I wanted him to use.
Ya it looked cool and sounds badass , but it was what he wanted and he went home smiling. All those other exhaust systems , he bought all of them and gave them to his friends ! making them happy too.
Some guys just have too much money to throw around.
Jeff |
Hoser
| | Posted on Sunday, April 08, 2001 - 02:59 pm: |
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Jose:
It's about 2400 miles to Calgary
This thursday myself and another staff member are riding to Las Vegas for a Dynojet course ( 1300 miles ) and do some exploring / sightseeing in Arizona / California . We recently updated our dyno room to model 250 spec , had to wait a couple of months to get our training, now we will be an authorized tuning center.
Jeff
S2T packed and ready to roll !!!!!
PS: Anybody in Vegas wanna get together for a beer and bullshiitt session ? |
Aaron
| | Posted on Sunday, April 08, 2001 - 09:05 pm: |
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Here's a Buell I had on the dyno the other day:
Stock displacement. Good head work and a good tune-up and a few other go-fast parts.
Like Rocket sez, there's horses and there's HORSES. This one has HORSES 
AW |
Hoser
| | Posted on Sunday, April 08, 2001 - 09:19 pm: |
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A sample a bad exhaust
This is not intended to piss anyone off or slam any manufacturer , so here it is "just the facts"
This is a 97 S3T , stock lightning heads , stock 2" header and the following changes.
It has been rejetted
It has a Pro series air cleaner
It has a Pro series ignition module
We ordered a set of slipons ( D&D ) for a Triumph 1200 Daytona and one of the parts guys thought he should order a slipon muffler for a buell , "because they work well on Triumph" .
That D&D hung on the showroom wall for a very long time before my curiosity made me try it on a bike. I was stunned by what happened when I did a few dyno pulls , the engine would not rev beyond 4500-5000 RPM!! , it would stumble and break up causing me to abort and end the sampling.
What I did next was install a V&H slipon , no other changes and the problem disappeared.
After a bit of tuning the graph looked like this.
Jeff |
Clydeglide
| | Posted on Sunday, April 08, 2001 - 09:20 pm: |
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Aaron,
"a few other go-fast parts"
a TURBO perhaps?
Clyde |
Tripper
| | Posted on Sunday, April 08, 2001 - 09:29 pm: |
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THAT'S A REAL STUD! Must be one of those Western Mustangs that run wild out in Aarons back yard. Seriously now, what was that?
Met a guy last night with a Busa that pulled 259.8 HP and his wife rides on the back. I understand him, but she must be nuts. |
Aaron
| | Posted on Sunday, April 08, 2001 - 09:55 pm: |
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Jeff: actually, you're not the first one I've heard that from, about a D&D on a Buell.
Clyde: No, no turbo.
Stock cylinders, cases, etc. It does have good heads, and they've been professionally prepared. Lots of cam and compression, too. Mikuni HSR42 & a good air cleaner.
I don't have the owner's permission to tell what's in it, I better stop. Everything I've said is 100% true, though. I just posted it to show what you can accomplish with a few well-chosen pieces and a good thorough tune-up.
I bet Rocket's bike would smoke this one, though, with all he's got in it. I'd be afraid to even put his bike on my dyno, might break the dyno!
Tripper: 260hp Busa? MC express kit?
AW |
Blake
| | Posted on Sunday, April 08, 2001 - 11:32 pm: |
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No Turbo... Hmmm... then it's gotta be NO2 or blown? I hate secrecy. Get that guy's permission would ya already? Otherwise we'll have to spank you for teasing us this way!
Blake (thinking of sending Rocket a couple of intercontinental ballistic bricks) |
Tripper
| | Posted on Monday, April 09, 2001 - 12:37 am: |
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Tripper: 260hp Busa? MC express kit?
No, Mr. Turbo kit. The guy was on his 4th engine getting it right. Ouch. |
Aaron
| | Posted on Monday, April 09, 2001 - 09:23 am: |
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Well, I didn't lie, but I didn't tell the whole story ... two HSR42's and good air cleaners. Also, notice the gearing on that bike. |
Mikej
| | Posted on Monday, April 09, 2001 - 09:51 am: |
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Uh, hmmm, ummm, well, nevermind, I'd better not say anything. Aaron, you got mail.
MikeJ (peeking into the kitchen)
Gotta somehow get me a play bike, S1 or RR
=====
wow, that posted without the "preview" |
Clydeglide
| | Posted on Monday, April 09, 2001 - 10:16 am: |
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Aaron,
yeah, I saw the gearing and hanging an extra carb on the equation still won't compute. Whats up the lack of a torque curve?
Come on, let's have it. Inquiring minds want to know!
Clyde |
Aaron
| | Posted on Monday, April 09, 2001 - 10:52 am: |
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Go ahead, Mike, say it ... I'm waiting for someone to do it.
BTW, unless you e-mail me at work, I won't see it until tonight.
AW |
Mikej
| | Posted on Monday, April 09, 2001 - 11:01 am: |
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Aaron,
I could be wrong, email forwarded to your work. I took a personal day today because Blake scared me last night about taxes being due.
MikeJ (an imagination coupled with observation can be a dangerous thing.) |
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