Dynojet dyno- Mustang dyno ----Whats the difference????
07-16-2003, 07:00 AM
#1
Honda-Tech Member
Thread Starter
Join Date: Feb 2002
Location: In the sticks, Tn, U.S.
Posts: 843
Likes: 0
Received 0 Likes
on
0 Posts
Dynojet dyno- Mustang dyno ----Whats the difference????
I am just wondering why the mustang dyno shows such low #'s. I talk to all the muscle heads around my area at the shops and they tell me that the dynojet dyno are really called egojet dyno's. Whats up with this? Can someone shine some light on the situation please.
07-21-2003, 07:32 PM
#3
Re: Dynojet dyno- Mustang dyno ----Whats the difference???? (dwilson)
Google is your friend....
http://www.activeautowerke.com...t.asp
Ok... cliff's notes...
The mustang dyno adds load when it's spinning to simulate true load that the car would be subject to on the street...
dyno jets do not impede the drum that the wheels spin so it's MUCH easier to spin and get high numbers... but the truth is you're nowhere near that number because in the real world your car weighs something... and it's constantly trying to overcome that weight...
http://www.activeautowerke.com...t.asp
Ok... cliff's notes...
The mustang dyno adds load when it's spinning to simulate true load that the car would be subject to on the street...
dyno jets do not impede the drum that the wheels spin so it's MUCH easier to spin and get high numbers... but the truth is you're nowhere near that number because in the real world your car weighs something... and it's constantly trying to overcome that weight...
07-22-2003, 12:25 AM
#4
Honda-Tech Member
Thread Starter
Join Date: Feb 2002
Location: In the sticks, Tn, U.S.
Posts: 843
Likes: 0
Received 0 Likes
on
0 Posts
Re: Dynojet dyno- Mustang dyno ----Whats the difference???? (NonovUrbizniz)
Thanks for the link. I never knew this was the difference between the dynos. Guess you learn something everyday. 
07-22-2003, 04:50 AM
#5
Honda-Tech Member
Join Date: Oct 2001
Location: Eindhoven, Netherlands
Posts: 1,756
Likes: 0
Received 0 Likes
on
0 Posts
Re: Dynojet dyno- Mustang dyno ----Whats the difference???? (NonovUrbizniz)
I guess the Mustang dyno puts an extra load on the drum to simulate "real world conditions", but whether one is more "real world" than the other, IMO vehicle weight and air resistance and all that bs should have no effect on horsepower at the wheels. If the number that the dyno spits out is supposed to be purely horsepower at the wheels, these variables have no place in calculating that value.
07-22-2003, 10:58 AM
#6
Re: Dynojet dyno- Mustang dyno ----Whats the difference???? (Lsos)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Lsos »</TD></TR><TR><TD CLASS="quote">I guess the Mustang dyno puts an extra load on the drum to simulate "real world conditions", but whether one is more "real world" than the other, IMO vehicle weight and air resistance and all that bs should have no effect on horsepower at the wheels. If the number that the dyno spits out is supposed to be purely horsepower at the wheels, these variables have no place in calculating that value.
</TD></TR></TABLE>
When you drive you have the weight of the car on the wheels... that is resistance... on the dyno the drum spins pretty freely NOT AT ALL like truely driving your car... the mustang dyno gives a much more accurate "real world" number.
</TD></TR></TABLE>
When you drive you have the weight of the car on the wheels... that is resistance... on the dyno the drum spins pretty freely NOT AT ALL like truely driving your car... the mustang dyno gives a much more accurate "real world" number.
07-22-2003, 11:01 AM
#7
Junior Member
Join Date: Oct 2002
Location: Pa, 15401
Posts: 941
Likes: 0
Received 0 Likes
on
0 Posts
Re: Dynojet dyno- Mustang dyno ----Whats the difference???? (NonovUrbizniz)
I agree with Lsos, I want to now what my car is putting down, on a windy day, a hot day, winter day, any day. I'm not trying to run the quarter mile on one, then I could understand the use of a Mustang dyno. If your just looking to see what kind of power your making, it doesn't matter how much your car wheighs, since it's not making the power for you. Just my opnion.
Trending Topics
07-22-2003, 11:57 AM
#8
Honda-Tech Member
Join Date: Oct 2001
Location: Eindhoven, Netherlands
Posts: 1,756
Likes: 0
Received 0 Likes
on
0 Posts
Re: Dynojet dyno- Mustang dyno ----Whats the difference???? (NonovUrbizniz)
After reading that link again, I'm thinking that the Mustang dyno allows you to keep the engine at a steady rpm because it can put a load on the wheels. Therefore, it should not be affected by things such as lightened flywheels and wheels....variables that an inertial dyno is sensitive to.
07-22-2003, 03:42 PM
#9
Join Date: Feb 2002
Location: Hell
Posts: 265
Likes: 0
Received 0 Likes
on
0 Posts
Re: Dynojet dyno- Mustang dyno ----Whats the difference???? (Lsos)
.<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Lsos »</TD></TR><TR><TD CLASS="quote">After reading that link again, I'm thinking that the Mustang dyno allows you to keep the engine at a steady rpm because it can put a load on the wheels. Therefore, it should not be affected by things such as lightened flywheels and wheels....variables that an inertial dyno is sensitive to.</TD></TR></TABLE>
lightened flywheels and wheels affect a mustang and dynojet the same. the motor is still having to spin the flywheel and wheels regardless of the dyno you're using.
the mustang dyno loads the drum so that your vehicle has to keep working to keep it spinning as opposed to using the drums own momentum to help it spin.
however the HP number you get from any given dyno, mustang or dynojet, doesn't REALLY matter. what matters is that while you're tuning or adding parts is that your HP number increases on that particular dyno on that particular day. due to differences in elevation, atmospheric conditions, even dynos from the same manufacturer you're not going to be able to truely compare HP figures from one car to another unless you hook them both up to the same dyno right after each other
lightened flywheels and wheels affect a mustang and dynojet the same. the motor is still having to spin the flywheel and wheels regardless of the dyno you're using.
the mustang dyno loads the drum so that your vehicle has to keep working to keep it spinning as opposed to using the drums own momentum to help it spin.
however the HP number you get from any given dyno, mustang or dynojet, doesn't REALLY matter. what matters is that while you're tuning or adding parts is that your HP number increases on that particular dyno on that particular day. due to differences in elevation, atmospheric conditions, even dynos from the same manufacturer you're not going to be able to truely compare HP figures from one car to another unless you hook them both up to the same dyno right after each other
07-22-2003, 06:01 PM
#10
Honda-Tech Member
Join Date: Oct 2001
Location: Eindhoven, Netherlands
Posts: 1,756
Likes: 0
Received 0 Likes
on
0 Posts
Re: Dynojet dyno- Mustang dyno ----Whats the difference???? (00CIVICwB18C1)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 00CIVICwB18C1 »</TD></TR><TR><TD CLASS="quote">lightened flywheels and wheels affect a mustang and dynojet the same. the motor is still having to spin the flywheel and wheels regardless of the dyno you're using.</TD></TR></TABLE>
A flywheel doesn't take much power to keep it spinning, it just takes power to accelerate it. That's why it affects the numbers on inertial dynos, more so in the lower gears. I can bet that on a dyno where the rpms are held steady, you couldn't even see the effect of a lightened flywheel in the numbers.
A flywheel doesn't take much power to keep it spinning, it just takes power to accelerate it. That's why it affects the numbers on inertial dynos, more so in the lower gears. I can bet that on a dyno where the rpms are held steady, you couldn't even see the effect of a lightened flywheel in the numbers.
07-22-2003, 08:41 PM
#11
Re: Dynojet dyno- Mustang dyno ----Whats the difference???? (Lsos)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Lsos »</TD></TR><TR><TD CLASS="quote">
A flywheel doesn't take much power to keep it spinning, it just takes power to accelerate it. That's why it affects the numbers on inertial dynos, more so in the lower gears. I can bet that on a dyno where the rpms are held steady, you couldn't even see the effect of a lightened flywheel in the numbers.</TD></TR></TABLE>
Are you serious?
Lightened flywheels dramatically increase whp... you notice it through the range... EVERYWHERE it's a big difference... my buddy just got one on his gti and that thing revs up WAY faster and ALL that extra power that would've gone to spinning the flywheel is now spinning the wheels.
It does depend on how much weight is dropped and the weight of the stock unit but flywheels and ANY lightened rotating mass in the engine/drivetrain increase hp by freeing up torque.
A flywheel doesn't take much power to keep it spinning, it just takes power to accelerate it. That's why it affects the numbers on inertial dynos, more so in the lower gears. I can bet that on a dyno where the rpms are held steady, you couldn't even see the effect of a lightened flywheel in the numbers.</TD></TR></TABLE>
Are you serious?
Lightened flywheels dramatically increase whp... you notice it through the range... EVERYWHERE it's a big difference... my buddy just got one on his gti and that thing revs up WAY faster and ALL that extra power that would've gone to spinning the flywheel is now spinning the wheels.
It does depend on how much weight is dropped and the weight of the stock unit but flywheels and ANY lightened rotating mass in the engine/drivetrain increase hp by freeing up torque.
07-23-2003, 03:31 AM
#12
Honda-Tech Member
Join Date: Oct 2002
Location: Dallas, PA, 18704
Posts: 180
Likes: 0
Received 0 Likes
on
0 Posts
Re: Dynojet dyno- Mustang dyno ----Whats the difference???? (NonovUrbizniz)
One thing a Mustang Dyno can do is simulate the real acceleration of the car. So, my understanding is you can input the weight of the car and run a 1/4 time on the Mustang Dyno. You can't do that on a Dynojet.
But horsepower is horsepower, at the wheels or crank. Either can do horsepower.
Chris
But horsepower is horsepower, at the wheels or crank. Either can do horsepower.
Chris
07-23-2003, 05:01 AM
#13
Banned
Join Date: Jun 2001
Location: Youngstown, OH
Posts: 1,992
Likes: 0
Received 0 Likes
on
0 Posts
Re: Dynojet dyno- Mustang dyno ----Whats the difference???? (ChrisShen)
i personally like the mustangs better. i got dynoed on a mustang 4 at speednation in pittsburgh. speednation.com
well anyways the dynojet was going to GIVE him a dyno because he writes all sorts of honda books and stuff. but he declined and BOUGHT a mustang because its a better dyno. That speaks worlds to me. also the quarter mile stuff is pretty slick, except you can still get wheel hop on those thing
ps - mustangs dynos are also MUCH more repeatable when compared to a dynojet
well anyways the dynojet was going to GIVE him a dyno because he writes all sorts of honda books and stuff. but he declined and BOUGHT a mustang because its a better dyno. That speaks worlds to me. also the quarter mile stuff is pretty slick, except you can still get wheel hop on those thing
ps - mustangs dynos are also MUCH more repeatable when compared to a dynojet
07-23-2003, 08:05 AM
#14
Honda-Tech Member
Join Date: Oct 2001
Location: Eindhoven, Netherlands
Posts: 1,756
Likes: 0
Received 0 Likes
on
0 Posts
Re: Dynojet dyno- Mustang dyno ----Whats the difference???? (NonovUrbizniz)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by NonovUrbizniz »</TD></TR><TR><TD CLASS="quote">Are you serious?
Lightened flywheels dramatically increase whp... you notice it through the range... EVERYWHERE it's a big difference... my buddy just got one on his gti and that thing revs up WAY faster and ALL that extra power that would've gone to spinning the flywheel is now spinning the wheels.
It does depend on how much weight is dropped and the weight of the stock unit but flywheels and ANY lightened rotating mass in the engine/drivetrain increase hp by freeing up torque.</TD></TR></TABLE>
Yeah I'm serious. Lightening a flywheel will not have any effect on torque or horsepower, except maybe for whatever frictional losses are reduced from the lower weight.
It will rev up faster, and the car will accelerate faster in first gear, not so much in second, less in third....and the higer gear you're in/ slower you are accelerating, the less of an affect the lightened flywheel has. This means it will not effect top speed. If no acceleration is taking place, the flywheel makes no difference. You could slap on a thousand pound flywheel and a dyno that keeps the engine at steady rpms will not tell the difference.
What I'm getting at is that saying that a lightened flywheel affects power is like saying that lightening the car affects power. It might make it faster, but it's not making more power.
Lightened flywheels dramatically increase whp... you notice it through the range... EVERYWHERE it's a big difference... my buddy just got one on his gti and that thing revs up WAY faster and ALL that extra power that would've gone to spinning the flywheel is now spinning the wheels.
It does depend on how much weight is dropped and the weight of the stock unit but flywheels and ANY lightened rotating mass in the engine/drivetrain increase hp by freeing up torque.</TD></TR></TABLE>
Yeah I'm serious. Lightening a flywheel will not have any effect on torque or horsepower, except maybe for whatever frictional losses are reduced from the lower weight.
It will rev up faster, and the car will accelerate faster in first gear, not so much in second, less in third....and the higer gear you're in/ slower you are accelerating, the less of an affect the lightened flywheel has. This means it will not effect top speed. If no acceleration is taking place, the flywheel makes no difference. You could slap on a thousand pound flywheel and a dyno that keeps the engine at steady rpms will not tell the difference.
What I'm getting at is that saying that a lightened flywheel affects power is like saying that lightening the car affects power. It might make it faster, but it's not making more power.
07-23-2003, 10:24 AM
#15
Join Date: Oct 2002
Location: TX, USA
Posts: 192
Likes: 0
Received 0 Likes
on
0 Posts
Re: Dynojet dyno- Mustang dyno ----Whats the difference???? (dwilson)
A mustang dyno uses an eddie current brake that adds resistance to the rollers. A dynojet has rollers like a mustang dyno but does not have the eddie current brake. The easiest way to picture it is to imagine a bicycle with the rear lifted off the ground. Start pedaling. Once you've turned the wheel over 2 or 3 rotations, it is almost effortless to spin it even faster. Now try the same but with the brake engaged. You start to pedal and the wheel starts to spin, but because the brake is engaged you need to keep the same amount of effort or more in order to get the wheel spinning faster. Because the dyno jet is like the bike w/o the brake, the dynojets hp/trq readings will be exaggerated.
HTH, let us know if you dont understand.
Modified by tmc racing at 8:27 PM 7/23/2003
HTH, let us know if you dont understand.
Modified by tmc racing at 8:27 PM 7/23/2003
07-23-2003, 11:43 AM
#16
Honda-Tech Member
Join Date: Oct 2001
Location: Eindhoven, Netherlands
Posts: 1,756
Likes: 0
Received 0 Likes
on
0 Posts
Re: Dynojet dyno- Mustang dyno ----Whats the difference???? (tmc racing)
You should be able to get an accurate tq reading if you measure how fast the bicycle wheel gets accelerated...especially since on the dynojet it weights like 3000lbs. There's a simple equation for how much torque angularly accelerates a mass how fast.
The problem is that along with this 3000lb drum, the flywheel and the wheels and any part that rotates has to be accelerated. So...the lighter the drum, the lower the gear, and the more powerful the car, the more it <U>appears</U> that a lighter flywheel/wheel produces more power. The number has no meaning though, especially since the 3000lb drum has an arbitrarily chosen weight.
The problem is that along with this 3000lb drum, the flywheel and the wheels and any part that rotates has to be accelerated. So...the lighter the drum, the lower the gear, and the more powerful the car, the more it <U>appears</U> that a lighter flywheel/wheel produces more power. The number has no meaning though, especially since the 3000lb drum has an arbitrarily chosen weight.
07-23-2003, 01:12 PM
#17
Junior Member
Join Date: Jul 2002
Posts: 23
Likes: 0
Received 0 Likes
on
0 Posts
Re: Dynojet dyno- Mustang dyno ----Whats the difference???? (Lsos)
Lsos, I agree with everything you've said 100%. good job.
I have a question for anybody who may happen to know. On a mustang dyno where you're accelerating through the entire RPM range (ie not constant RPM) how does the mustang dyno calculate HP. Does it only consider the torque required to overcome the eddie current brake, or does it also take into consideration the torque required to accelerate the roller inertia? If it neglects the roller inertia, than the error introduced will be a function of how quickly the car can accelerate the roller, which can change from one run to the next (for example if you have two runs back to back, one without nitrous and one with)
FWIW, I think dynapack dyno's are the best. they can apply a load to keep the car at a constant RPM, but they eliminate sources of error caused by alignment, tire slippage etc
I have a question for anybody who may happen to know. On a mustang dyno where you're accelerating through the entire RPM range (ie not constant RPM) how does the mustang dyno calculate HP. Does it only consider the torque required to overcome the eddie current brake, or does it also take into consideration the torque required to accelerate the roller inertia? If it neglects the roller inertia, than the error introduced will be a function of how quickly the car can accelerate the roller, which can change from one run to the next (for example if you have two runs back to back, one without nitrous and one with)
FWIW, I think dynapack dyno's are the best. they can apply a load to keep the car at a constant RPM, but they eliminate sources of error caused by alignment, tire slippage etc
08-28-2003, 01:45 AM
#18
Member
Join Date: Nov 2000
Location: Bay Area, CA
Posts: 1,132
Likes: 0
Received 0 Likes
on
0 Posts
Re: Dynojet dyno- Mustang dyno ----Whats the difference???? (Lsos)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Lsos »</TD></TR><TR><TD CLASS="quote">
Yeah I'm serious. Lightening a flywheel will not have any effect on torque or horsepower, except maybe for whatever frictional losses are reduced from the lower weight.
It will rev up faster, and the car will accelerate faster in first gear, not so much in second, less in third....and the higer gear you're in/ slower you are accelerating, the less of an affect the lightened flywheel has. This means it will not effect top speed. If no acceleration is taking place, the flywheel makes no difference. You could slap on a thousand pound flywheel and a dyno that keeps the engine at steady rpms will not tell the difference.
</TD></TR></TABLE>
you have no idea what you're taking about..
one of the ways a motor loses power to the wheels is because of the energy lost in the drivetrain
having a lighter flywheel means that you will have less energy loss through the drivetrain
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Lsos »</TD></TR><TR><TD CLASS="quote">
What I'm getting at is that saying that a lightened flywheel affects power is like saying that lightening the car affects power. It might make it faster, but it's not making more power.</TD></TR></TABLE>
the weight of a car DOES affect power.
weight of the car is a load on the motor..
if you use a dyno that can simulate weight (say, the weight of your vehicle), your car will put down MUCH less power.
Yeah I'm serious. Lightening a flywheel will not have any effect on torque or horsepower, except maybe for whatever frictional losses are reduced from the lower weight.
It will rev up faster, and the car will accelerate faster in first gear, not so much in second, less in third....and the higer gear you're in/ slower you are accelerating, the less of an affect the lightened flywheel has. This means it will not effect top speed. If no acceleration is taking place, the flywheel makes no difference. You could slap on a thousand pound flywheel and a dyno that keeps the engine at steady rpms will not tell the difference.
</TD></TR></TABLE>
you have no idea what you're taking about..
one of the ways a motor loses power to the wheels is because of the energy lost in the drivetrain
having a lighter flywheel means that you will have less energy loss through the drivetrain
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Lsos »</TD></TR><TR><TD CLASS="quote">
What I'm getting at is that saying that a lightened flywheel affects power is like saying that lightening the car affects power. It might make it faster, but it's not making more power.</TD></TR></TABLE>
the weight of a car DOES affect power.
weight of the car is a load on the motor..
if you use a dyno that can simulate weight (say, the weight of your vehicle), your car will put down MUCH less power.
08-28-2003, 05:26 AM
#19
Honda-Tech Member
Join Date: Oct 2001
Location: Eindhoven, Netherlands
Posts: 1,756
Likes: 0
Received 0 Likes
on
0 Posts
Re: Dynojet dyno- Mustang dyno ----Whats the difference???? (Mr.Integra)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mr.Integra »</TD></TR><TR><TD CLASS="quote">having a lighter flywheel means that you will have less energy loss through the drivetrain</TD></TR></TABLE>
That may be so, but it's not even close to as much as an inertial dyno will have you think.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote »</TD></TR><TR><TD CLASS="quote">the weight of a car DOES affect power.
weight of the car is a load on the motor..
if you use a dyno that can simulate weight (say, the weight of your vehicle), your car will put down MUCH less power.</TD></TR></TABLE>
Neither the weight of a car nor the load on a motor affects its output!! How do you think dynos measure the output in the first place? By putting a HUGE load on it! In an inertial dyno it's a 3000lb drum and in a Mustang dyno they add eddy currents on top of that!
The only thing I can see is more weight = more friction (rolling resistance, in wheel bearings), and there's no way to escape that anyways when you're measuring whp. In fact, nowhere in the link
http://www.activeautowerke.com...t.asp
does it say anything about simulating the weight of the car. It just says "real world conditions", which I imagine means air resistance.
That may be so, but it's not even close to as much as an inertial dyno will have you think.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote »</TD></TR><TR><TD CLASS="quote">the weight of a car DOES affect power.
weight of the car is a load on the motor..
if you use a dyno that can simulate weight (say, the weight of your vehicle), your car will put down MUCH less power.</TD></TR></TABLE>
Neither the weight of a car nor the load on a motor affects its output!! How do you think dynos measure the output in the first place? By putting a HUGE load on it! In an inertial dyno it's a 3000lb drum and in a Mustang dyno they add eddy currents on top of that!
The only thing I can see is more weight = more friction (rolling resistance, in wheel bearings), and there's no way to escape that anyways when you're measuring whp. In fact, nowhere in the link
http://www.activeautowerke.com...t.asp
does it say anything about simulating the weight of the car. It just says "real world conditions", which I imagine means air resistance.
08-28-2003, 10:23 AM
#20
Member
Join Date: Nov 2000
Location: Bay Area, CA
Posts: 1,132
Likes: 0
Received 0 Likes
on
0 Posts
Re: Dynojet dyno- Mustang dyno ----Whats the difference???? (Lsos)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Lsos »</TD></TR><TR><TD CLASS="quote">
Neither the weight of a car nor the load on a motor affects its output!! How do you think dynos measure the output in the first place? By putting a HUGE load on it! In an inertial dyno it's a 3000lb drum and in a Mustang dyno they add eddy currents on top of that!
The only thing I can see is more weight = more friction (rolling resistance, in wheel bearings), and there's no way to escape that anyways when you're measuring whp.
</TD></TR></TABLE>
sorry it wasn't clear. what i meant to say is that weight on the car doesn't affect power. If we want to move at 50 mph, the heavier the car the more "power" it takes to move it. You're right in the fact that the weight of the vehicle doens't change the "power" output.
HOWEVER, the weight of rotations masses ON the car WILL affect the power delivered to the wheels. why? because it's the drivetrain losses. Why do you think if we take off the powersteering belt we automatically free up 3 whp?
If a stock ITR is rated at 195 @ the crank and puts down 168 to the wheels, rotation masses such as flywheel and tire won't affect the crank hp, but it WILL affect the power delivered to the wheels.
more weight = more friction..? That is absolutely wrong wrong wrong. weight has no effect on friction.
Neither the weight of a car nor the load on a motor affects its output!! How do you think dynos measure the output in the first place? By putting a HUGE load on it! In an inertial dyno it's a 3000lb drum and in a Mustang dyno they add eddy currents on top of that!
The only thing I can see is more weight = more friction (rolling resistance, in wheel bearings), and there's no way to escape that anyways when you're measuring whp.
</TD></TR></TABLE>
sorry it wasn't clear. what i meant to say is that weight on the car doesn't affect power. If we want to move at 50 mph, the heavier the car the more "power" it takes to move it. You're right in the fact that the weight of the vehicle doens't change the "power" output.
HOWEVER, the weight of rotations masses ON the car WILL affect the power delivered to the wheels. why? because it's the drivetrain losses. Why do you think if we take off the powersteering belt we automatically free up 3 whp?
If a stock ITR is rated at 195 @ the crank and puts down 168 to the wheels, rotation masses such as flywheel and tire won't affect the crank hp, but it WILL affect the power delivered to the wheels.
more weight = more friction..? That is absolutely wrong wrong wrong. weight has no effect on friction.
08-28-2003, 11:23 AM
#21
Re: Dynojet dyno- Mustang dyno ----Whats the difference???? (Lsos)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Lsos »</TD></TR><TR><TD CLASS="quote">
That may be so, but it's not even close to as much as an inertial dyno will have you think.
Neither the weight of a car nor the load on a motor affects its output!! How do you think dynos measure the output in the first place? By putting a HUGE load on it! In an inertial dyno it's a 3000lb drum and in a Mustang dyno they add eddy currents on top of that!
The only thing I can see is more weight = more friction (rolling resistance, in wheel bearings), and there's no way to escape that anyways when you're measuring whp. In fact, nowhere in the link
http://www.activeautowerke.com...t.asp
does it say anything about simulating the weight of the car. It just says "real world conditions", which I imagine means air resistance.</TD></TR></TABLE>
It's funny that this got brought back up cuz I was origonally going to argue back but I had like 5 threads of me TOTALLY disagreeing with people at the time and this was not one that I felt I could explain well....
HOWEVER...
Lsos.. you are wrong...
weight IN the car does not affect output... weight of rotating internal components DOES.... The lighter the rotating mass of or tied to the engine... the less loss there is... The reason AT cars have lower WHP then their manual counterparts is because there is MORE to an automatic and it absorbs some of the power before it gets to the wheels...
Think of it simply... If you dyno your car (whp) with the A/C on you will have a lower output then if it were off... That's because there is more drag with it on... the power used to turn it is power that would otherwise go to the wheels...
My buddies shop just got a mustang dyno installed and it's NOT a 3000lb drum and it takes NO effort to get it rolling... or keep it rolling... it's a drum on VERY good bearings... it takes a certain amount of torque to get it going but once it's overcome it's own mass it spins VERY freely... the only way the mustang dyno creates load is through the electric brake...
The realworld conditions it's talking about IS "load" on the engine (simulates the drag created by weight of the car..) it is also refered to as a "load bearing" dyno...
Ok I just found a TERRIFIC write up on this... Dyno jets measure horsepower... where as mustang dyno's measure torque and derive HP which is more accurate.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote »</TD></TR><TR><TD CLASS="quote">A Loading Dynamometer applies resistance to the dyne's roller(s) , typically using either a water brake or a current eddy brake. In either case, the amount of force is measure using a strain gauge. The measured force is torque which is a real, indisputable measurement of the actual output at the wheel. Horsepower than can be calculated: Hp = Trq * 5252 / RPM.</TD></TR></TABLE>
taken from...
http://www.germanmotorcars.com...1.htm
That may be so, but it's not even close to as much as an inertial dyno will have you think.
Neither the weight of a car nor the load on a motor affects its output!! How do you think dynos measure the output in the first place? By putting a HUGE load on it! In an inertial dyno it's a 3000lb drum and in a Mustang dyno they add eddy currents on top of that!
The only thing I can see is more weight = more friction (rolling resistance, in wheel bearings), and there's no way to escape that anyways when you're measuring whp. In fact, nowhere in the link
http://www.activeautowerke.com...t.asp
does it say anything about simulating the weight of the car. It just says "real world conditions", which I imagine means air resistance.</TD></TR></TABLE>
It's funny that this got brought back up cuz I was origonally going to argue back but I had like 5 threads of me TOTALLY disagreeing with people at the time and this was not one that I felt I could explain well....
HOWEVER...
Lsos.. you are wrong...
weight IN the car does not affect output... weight of rotating internal components DOES.... The lighter the rotating mass of or tied to the engine... the less loss there is... The reason AT cars have lower WHP then their manual counterparts is because there is MORE to an automatic and it absorbs some of the power before it gets to the wheels...
Think of it simply... If you dyno your car (whp) with the A/C on you will have a lower output then if it were off... That's because there is more drag with it on... the power used to turn it is power that would otherwise go to the wheels...
My buddies shop just got a mustang dyno installed and it's NOT a 3000lb drum and it takes NO effort to get it rolling... or keep it rolling... it's a drum on VERY good bearings... it takes a certain amount of torque to get it going but once it's overcome it's own mass it spins VERY freely... the only way the mustang dyno creates load is through the electric brake...
The realworld conditions it's talking about IS "load" on the engine (simulates the drag created by weight of the car..) it is also refered to as a "load bearing" dyno...
Ok I just found a TERRIFIC write up on this... Dyno jets measure horsepower... where as mustang dyno's measure torque and derive HP which is more accurate.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote »</TD></TR><TR><TD CLASS="quote">A Loading Dynamometer applies resistance to the dyne's roller(s) , typically using either a water brake or a current eddy brake. In either case, the amount of force is measure using a strain gauge. The measured force is torque which is a real, indisputable measurement of the actual output at the wheel. Horsepower than can be calculated: Hp = Trq * 5252 / RPM.</TD></TR></TABLE>
taken from...
http://www.germanmotorcars.com...1.htm
08-28-2003, 01:57 PM
#22
Honda-Tech Member
Join Date: Oct 2001
Location: Eindhoven, Netherlands
Posts: 1,756
Likes: 0
Received 0 Likes
on
0 Posts
Re: Dynojet dyno- Mustang dyno ----Whats the difference???? (Mr.Integra)
Friction = Weight * coefficient of friction.
Weight: It's right there in the formula. Look it up in any physics book.
All else equal, that is the ONLY reason it takes more power to move a heavier car at 50mph: the fact that weight affects friction. There is no other reason. There's air resistance slowing it down, rolling resistance, and friction in the drivetrain. If it wasn't for those, it would take NO power to move a car at 50mph, no matter how much it weights. Rolling resistance and drivetrain friction will increase with a heavier car, but air resistance won't.
You guys' arguments about rotating masses are invalid simply becasue AC, power steering, and an automatic transmission are not the same as a flywheel. By design, AC requires power to run it, as does power steering. An automatic robs power because of the slushbox. The weight of these components has very little to do with how much power they rob. If they could reduce them to .1 lb apiece, they would still rob pretty much the same power simply because of thermodynamics. It takes power to cool air, it takes power to run a pump, and it takes power to spin a fan through thick oil. It DOES NOT take power to turn a disk.
Just as you said NonovUrbizniz:
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote »</TD></TR><TR><TD CLASS="quote"> it's a drum on VERY good bearings... it takes a certain amount of torque to get it going but once it's overcome it's own mass it spins VERY freely...</TD></TR></TABLE>
If it wasn't for frictional losses, the flywheel/drum would keep on spinning forever! No power required!
NonovUrbizniz, thank you for the explanation on how the mustang dyno works. Just as I suspected, it is not an inertial dyno. I can gurantee that a flywheel's weight would have no effect on the reading of a mustang dyno, as long as the engine is kept at a steady rpm.
Weight: It's right there in the formula. Look it up in any physics book.
All else equal, that is the ONLY reason it takes more power to move a heavier car at 50mph: the fact that weight affects friction. There is no other reason. There's air resistance slowing it down, rolling resistance, and friction in the drivetrain. If it wasn't for those, it would take NO power to move a car at 50mph, no matter how much it weights. Rolling resistance and drivetrain friction will increase with a heavier car, but air resistance won't.
You guys' arguments about rotating masses are invalid simply becasue AC, power steering, and an automatic transmission are not the same as a flywheel. By design, AC requires power to run it, as does power steering. An automatic robs power because of the slushbox. The weight of these components has very little to do with how much power they rob. If they could reduce them to .1 lb apiece, they would still rob pretty much the same power simply because of thermodynamics. It takes power to cool air, it takes power to run a pump, and it takes power to spin a fan through thick oil. It DOES NOT take power to turn a disk.
Just as you said NonovUrbizniz:
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote »</TD></TR><TR><TD CLASS="quote"> it's a drum on VERY good bearings... it takes a certain amount of torque to get it going but once it's overcome it's own mass it spins VERY freely...</TD></TR></TABLE>
If it wasn't for frictional losses, the flywheel/drum would keep on spinning forever! No power required!
NonovUrbizniz, thank you for the explanation on how the mustang dyno works. Just as I suspected, it is not an inertial dyno. I can gurantee that a flywheel's weight would have no effect on the reading of a mustang dyno, as long as the engine is kept at a steady rpm.
08-28-2003, 02:21 PM
#23
Re: Dynojet dyno- Mustang dyno ----Whats the difference???? (Lsos)
Just to make it easy...
I started out my interest in cars with classic cars...
One thing that is ALWAYS the case with classic cars with stock drivetrains (as in driveshaft rearend)... Is that they have WAY higher drivetrain loss then new cars do... be it auto or manual... Why you ask? because the components are MUCH heavier... there by taking more work to turn them..... heres another quote/link...
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote »</TD></TR><TR><TD CLASS="quote">
Independent testing by a leading automotive magazine (Turbo, October, 1996) showed rear wheel horsepower gains of more than 5% with the simple switch to an ACPT carbon fiber driveshaft. This significant increase is primarily due to lower rotational mass of the driveshaft. Carbon fiber offers you more strength to resist extreme torque than steel with about half the weight. Just like the common use of lightweight clutch and flywheel units, a lightweight driveshaft allows more of you engine's power to be applied to the ground. </TD></TR></TABLE>
taken from...
http://www.acpt.com/driveshaft/driveshafts.html
If that's not enough....
A lightweight wheel is a rotating disk...
So by your theory (explination whatever)... light wheels won't increase wheel hp either huh?
No fan spinning in a fluid... no pump... just reduced spinning weight...
When I went from my borbet t's to konig heliums... I can ASSURE you the car got MUCH faster... not just off the line either.. it's all over...
Lightend engine components absolutely increase power output of an engine... givin IDENTICAL specs a lighter weight cam or valves or any other moving component of the engine WILL increase power... and in ALL of those cases not only will it increase WHP but also crank HP...
I started out my interest in cars with classic cars...
One thing that is ALWAYS the case with classic cars with stock drivetrains (as in driveshaft rearend)... Is that they have WAY higher drivetrain loss then new cars do... be it auto or manual... Why you ask? because the components are MUCH heavier... there by taking more work to turn them..... heres another quote/link...
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote »</TD></TR><TR><TD CLASS="quote">
Independent testing by a leading automotive magazine (Turbo, October, 1996) showed rear wheel horsepower gains of more than 5% with the simple switch to an ACPT carbon fiber driveshaft. This significant increase is primarily due to lower rotational mass of the driveshaft. Carbon fiber offers you more strength to resist extreme torque than steel with about half the weight. Just like the common use of lightweight clutch and flywheel units, a lightweight driveshaft allows more of you engine's power to be applied to the ground. </TD></TR></TABLE>
taken from...
http://www.acpt.com/driveshaft/driveshafts.html
If that's not enough....
A lightweight wheel is a rotating disk...
So by your theory (explination whatever)... light wheels won't increase wheel hp either huh?
No fan spinning in a fluid... no pump... just reduced spinning weight...
When I went from my borbet t's to konig heliums... I can ASSURE you the car got MUCH faster... not just off the line either.. it's all over...
Lightend engine components absolutely increase power output of an engine... givin IDENTICAL specs a lighter weight cam or valves or any other moving component of the engine WILL increase power... and in ALL of those cases not only will it increase WHP but also crank HP...
08-28-2003, 03:29 PM
#24
Honda-Tech Member
Join Date: Oct 2001
Location: Eindhoven, Netherlands
Posts: 1,756
Likes: 0
Received 0 Likes
on
0 Posts
Re: Dynojet dyno- Mustang dyno ----Whats the difference???? (NonovUrbizniz)
Of course lighter components will make your car faster, and lighter rotating components all the more so. If you look at my earlier posts that's exactly what I said. I understand that a light flywheel can have the same effect on a car as removing 200lbs (in first gear). And yes, they will show power gains on inertial dynos because of an inherent flaw that inertial dynos have, which I also described. I bet if you dyno your car in first gear, the effect of the flywheel will show up as many horsepower. If you dyno it in fifth gear, it will be hardly nitceable. I also bet if you use a 100000lb drum instead of a 3000lb drum, it will be hardly nitceable. It's not because the engine puts out more/less power in these different situations, but because the engine is being asked to accelerate a weight faster or slower.
Just like can't say that a 100hp engine in a bike puts out more power than a 100hp engine in a car, you can't say that an engine with a 20lb flywheel puts out less power than one with a 10lb flywheel.
Just like can't say that a 100hp engine in a bike puts out more power than a 100hp engine in a car, you can't say that an engine with a 20lb flywheel puts out less power than one with a 10lb flywheel.
08-28-2003, 07:38 PM
#25
Re: Dynojet dyno- Mustang dyno ----Whats the difference???? (Lsos)
It will have more wheel horspower... and it'll be MUCH faster. and not just at launch... it'll just be faster...
And to explain why you're wrong about the whole "maybe initialy" arguement...
accelerating is ALWAYS overcoming your weight to go faster... you are CONSTANTLY fighting the weight of the car to not just keep moving but to move faster... Sure maintaining speed doesn't take as much work as getting moving does but it still takes work. as does accelerating from that point. which a car with a lighter flywheel (or crank or pistons or any other rotating/reciprocating part of the engine) will do faster...
To use someones analogy before about pushing a car... sure it's easy to keep it rolling but it's NOT easy to keep INCREASING the speed of it... you need to overcome the weight of it AGAIN.... till it's rolling at the new speed... then to accelerate again you would need to put in MORE work...
And the whole once it's rolling thing isn't even remotely logical... sure it has momentum but that momentum NEVER accelerates anything... it just keeps it moving (slower and slower the less work is put into it to turn it at either the same speed or speed it up.) eventually stopping.
If you've ever pushed a car uphill or even long distance on a FLAT road you'd be well aware that it DOES take CONSTANT work to keep it rolling.... much less to accelerate it...
here's another analogy cuz I know you're just going to keep dis-agreeing...
If you have lighter shoes on... you can move your feet faster... there is less drag in the form of weight... however if you hit something with them they won't hit as hard as they would if you were wearing big heavy boots... that's about as simple as I can explain it...
And to explain why you're wrong about the whole "maybe initialy" arguement...
accelerating is ALWAYS overcoming your weight to go faster... you are CONSTANTLY fighting the weight of the car to not just keep moving but to move faster... Sure maintaining speed doesn't take as much work as getting moving does but it still takes work. as does accelerating from that point. which a car with a lighter flywheel (or crank or pistons or any other rotating/reciprocating part of the engine) will do faster...
To use someones analogy before about pushing a car... sure it's easy to keep it rolling but it's NOT easy to keep INCREASING the speed of it... you need to overcome the weight of it AGAIN.... till it's rolling at the new speed... then to accelerate again you would need to put in MORE work...
And the whole once it's rolling thing isn't even remotely logical... sure it has momentum but that momentum NEVER accelerates anything... it just keeps it moving (slower and slower the less work is put into it to turn it at either the same speed or speed it up.) eventually stopping.
If you've ever pushed a car uphill or even long distance on a FLAT road you'd be well aware that it DOES take CONSTANT work to keep it rolling.... much less to accelerate it...
here's another analogy cuz I know you're just going to keep dis-agreeing...
If you have lighter shoes on... you can move your feet faster... there is less drag in the form of weight... however if you hit something with them they won't hit as hard as they would if you were wearing big heavy boots... that's about as simple as I can explain it...