v6 pullies
Member
Joined: Dec 2001
Posts: 177
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From: sf bay area
'03 C320 coupe-manual, '07 530i
Ben, how about a quick lesson on reading a dyno graph.
For instance, what is so magic about looking at the hp differential at 28.16 mph?
Why the dramatic dip and equally dramatic recovery around 60 mph?
Why is there an apparent "leftward" shift between the two curves so that the new pullied run seems to lag the original run?
Why is there so much variation in the hp differential over the speed spectrum?
Thanks.
For instance, what is so magic about looking at the hp differential at 28.16 mph?
Why the dramatic dip and equally dramatic recovery around 60 mph?
Why is there an apparent "leftward" shift between the two curves so that the new pullied run seems to lag the original run?
Why is there so much variation in the hp differential over the speed spectrum?
Thanks.
Out Of Control!!
Joined: Nov 2001
Posts: 35,855
Likes: 3
From: Southern CA
Originally posted by Wheens
Ben, how about a quick lesson on reading a dyno graph.
For instance, what is so magic about looking at the hp differential at 28.16 mph?
Why the dramatic dip and equally dramatic recovery around 60 mph?
Why is there an apparent "leftward" shift between the two curves so that the new pullied run seems to lag the original run?
Why is there so much variation in the hp differential over the speed spectrum?
Thanks.
Ben, how about a quick lesson on reading a dyno graph.
For instance, what is so magic about looking at the hp differential at 28.16 mph?
Why the dramatic dip and equally dramatic recovery around 60 mph?
Why is there an apparent "leftward" shift between the two curves so that the new pullied run seems to lag the original run?
Why is there so much variation in the hp differential over the speed spectrum?
Thanks.
That particular dyno displays the first 3 gears. 28.16mph is right before the car shifts into 2nd gear. The 2 large dips is the car changing gears. The "leftward shif" is simply the car developing power sooner, thus it is displayed at a lower speed. If that graph was in RPMs, then you would see the HP as being higher at each RPM.
The variation at speed is how the car naturally is. We do not play with the "smoothing" to make graphs look flat and unnatural.
Thanks,
Ben
MBWorld Fanatic!
Joined: Feb 2002
Posts: 1,038
Likes: 1
C32 AMG
A bit more tech info on this graph. Since UD pulleys reduce rotational inertia and accessories speed they allow more power to get to the wheels. Due to TQ converter "flash" on automatic cars we typicaly see the biggest gains in 1st and 2nd gears, there are some gains in the 3rd and smaller ones in the 4th.
This is what you see on the graph. It shows an acceleration run in the first three gears. The dip at 38 mph and the spike at 61 mph are transmission shifts. Red is stock W210 E320 SW and blue right after the UD pulleys.
This is what you see on the graph. It shows an acceleration run in the first three gears. The dip at 38 mph and the spike at 61 mph are transmission shifts. Red is stock W210 E320 SW and blue right after the UD pulleys.
Almost a Member!
Joined: Jun 2003
Posts: 59
Likes: 0
From: Huntsville, Al
I have done a lot of dyno runs, helped intall a Dynojet and used it very often. This dyno graph is actually pretty clean. Most dyno run graphs are very rough. It is caused by unclean air paths to the intake and through the intake, condition of ingition system....etc.
It is a amazing how you can change the "look" of a graph by doing simple things like taking off the cold air intake. I am not doughting the results here, the look good and honest, but it is easy to show great results to sell a product. Remember the throttle body spacers. Ran many of them and NONE increased HP and most made a mess out of a dyno graph. A lot of exhaust systems decrease HP. We dynoed cold air systems, different mufflers/exhaust systems...every product we could find. I quit messing with dynos before the pulley thing came out.
Also, these new computerized dynos don't lie. Guys would come in and show, say, 360 HP from calculations doing 1/4 runs. The dyno would show 300 HP and the customer would be pissed. It did not set well with the red necks here in Alabama. If they could just get passed the numbers and use the dyno for a tuning tool, they would be faster.
If you are moding a car, even putting pulleys on, I would spend the money and dyno it. With these new dynos becoming popular the prices are coming down for runs on them. Running a car on a dyno is worth the money just in entertainment. It is a hoot! Find a place that will let you drive (if you can call it that) your own car on the dyno. The guy that owned the dyno had the fasted injected car in the nation. A streetable, licensed Ford Mustang at 850 HP. It was cool to see that thing run on the dyno!
It is a amazing how you can change the "look" of a graph by doing simple things like taking off the cold air intake. I am not doughting the results here, the look good and honest, but it is easy to show great results to sell a product. Remember the throttle body spacers. Ran many of them and NONE increased HP and most made a mess out of a dyno graph. A lot of exhaust systems decrease HP. We dynoed cold air systems, different mufflers/exhaust systems...every product we could find. I quit messing with dynos before the pulley thing came out.
Also, these new computerized dynos don't lie. Guys would come in and show, say, 360 HP from calculations doing 1/4 runs. The dyno would show 300 HP and the customer would be pissed. It did not set well with the red necks here in Alabama. If they could just get passed the numbers and use the dyno for a tuning tool, they would be faster.
If you are moding a car, even putting pulleys on, I would spend the money and dyno it. With these new dynos becoming popular the prices are coming down for runs on them. Running a car on a dyno is worth the money just in entertainment. It is a hoot! Find a place that will let you drive (if you can call it that) your own car on the dyno. The guy that owned the dyno had the fasted injected car in the nation. A streetable, licensed Ford Mustang at 850 HP. It was cool to see that thing run on the dyno!
