Mthis goes to the dyno!
01-22-2010, 09:59 PM
#26
Super Moderator Alumni
Join Date: Dec 2009
Location: USA
Posts: 2,189
Likes: 0
Received 6 Likes
on
4 Posts
2011 GLK 350, 2013 GT-R, & 2013 RAM 1500
Mo, I agree with you 100% about one dyno to the next not being comparable (I'm pretty sure my post said most of what you just said 
), but I actually meant run to run variability in the same session on the same dyno. My personal experience on a couple of different dynojets (with different operators) has been that it's hard to get a reliable baseline, even on multiple runs in one session. I can't comfortably say my car has 470 rwhp (just a number) because it's the average of five runs when the variation is from 455-480. I'd rather have five runs that read between 454-457 and say that my car has 455 rwhp. It's a lower number, but statistically valid. And if you know the correction factor on a repeatable dyno, then you have legit numbers to work from. Yeah, I'm a nerd like that, but there's a lot of claims made in this industry based on a single dyno pull and I'm starting to believe there really isn't much validity in that method.
Just saying...
Josh
), but I actually meant run to run variability in the same session on the same dyno. My personal experience on a couple of different dynojets (with different operators) has been that it's hard to get a reliable baseline, even on multiple runs in one session. I can't comfortably say my car has 470 rwhp (just a number) because it's the average of five runs when the variation is from 455-480. I'd rather have five runs that read between 454-457 and say that my car has 455 rwhp. It's a lower number, but statistically valid. And if you know the correction factor on a repeatable dyno, then you have legit numbers to work from. Yeah, I'm a nerd like that, but there's a lot of claims made in this industry based on a single dyno pull and I'm starting to believe there really isn't much validity in that method.Just saying...
Josh
01-22-2010, 10:11 PM
#27
I'm glad I qualified by saying it was my personal experience, but I've heard similar things from others as well. It seems like there's an art to running a dyno properly. Definitely more to it than "just strap it down and run it."
Josh
01-22-2010, 10:15 PM
#28
Super Moderator Alumni
Join Date: Dec 2009
Location: USA
Posts: 2,189
Likes: 0
Received 6 Likes
on
4 Posts
2011 GLK 350, 2013 GT-R, & 2013 RAM 1500
BTW, I really appreciate reading your posts/threads. They are always well written and filled with solid information. It is great to have someone like you on the boards.
01-22-2010, 11:00 PM
#29
MBWorld Fanatic!
Join Date: Nov 2006
Location: California, USA
Posts: 9,137
Likes: 0
Received 4 Likes
on
4 Posts
E63 P30, CL500 Sport
Mo, I agree with you 100% about one dyno to the next not being comparable (I'm pretty sure my post said most of what you just said ), but I actually meant run to run variability in the same session on the same dyno. My personal experience on a couple of different dynojets (with different operators) has been that it's hard to get a reliable baseline, even on multiple runs in one session. I can't comfortably say my car has 470 rwhp (just a number) because it's the average of five runs when the variation is from 455-480. I'd rather have five runs that read between 454-457 and say that my car has 455 rwhp. It's a lower number, but statistically valid. And if you know the correction factor on a repeatable dyno, then you have legit numbers to work from. Yeah, I'm a nerd like that, but there's a lot of claims made in this industry based on a single dyno pull and I'm starting to believe there really isn't much validity in that method.
Just saying...
Josh
), but I actually meant run to run variability in the same session on the same dyno. My personal experience on a couple of different dynojets (with different operators) has been that it's hard to get a reliable baseline, even on multiple runs in one session. I can't comfortably say my car has 470 rwhp (just a number) because it's the average of five runs when the variation is from 455-480. I'd rather have five runs that read between 454-457 and say that my car has 455 rwhp. It's a lower number, but statistically valid. And if you know the correction factor on a repeatable dyno, then you have legit numbers to work from. Yeah, I'm a nerd like that, but there's a lot of claims made in this industry based on a single dyno pull and I'm starting to believe there really isn't much validity in that method.Just saying...
Josh
