| Author | Message | ||
     Englishman119 |
Just to keep you all updated. I have 3 confirmed participants in the Velocity Stack Challenge and I’m now receiving parts. All of the Vendors are well known on this board. For the tests, my XB9 will be using the Buell Race ECM, as this something we all have access to. I will gear my chain drive to that of the stock belt drive system. I am trying to make the data as relevant as possible to the mainstream Buell community. The tests will be in 2 parts. a) At the Dyno; I should be able to do all the dyno testing on the same day to minimize the effects of humidity and ambient temperature across all the tests. b) At the Track; I will be renting Blake and Scullys favorite piece of Texas pavement to evaluate real world riding (lap times, general rideability, etc). I will then write up the results, allow each vendor to comment (not edit) on their test data and publish. All being well, I hope to be wrapped up mid-late June. 119 | ||
| M1combat |
You're a scholar and a gentleman Englishman  . Thank you. | ||
| Oconnor |
Hip Hip Hooray!! Hip Hip Hooray!! Hip Hip Hooray!! | ||
| Misato |
sweet. I owe you a beer | ||
| Ortegakid |
We all owe you a beer!,i'll supply the first mcewans scotch ale!(my all time favorite!) | ||
| Xb9er |
Excellent. Can't wait for the results. Mike. | ||
| Blake |
Please be sure to allow the AFV to adjust between changes. Suggest taking a 15 minute ride at the requisite engine speed before dyno testing each configuration. And then be sure to do enough runs to achieve repeatability. And please have them log A/F. New spark plugs might be a good idea too. Final drive gear ratio wouldn't concern me, but the 5th gear runs are most accurate due to their longer duration and improved efficiency. No sitting on the bike, just gentle consistent pressure, ideally from tie downs. Call me "Blake the Anal one." Henrik would be proud. | ||
| Slowby |
O blake the anal one  (i couldn't pass that open shot up. i think that's raising the roof. i say we join mark on the day. i'm sure it'l be on the open weekend. non race day. and i've been meaning to take the kids up to the track to ride their bikes. hey mark give us a call. sorry i missed you at cresson. will you be using different air box covers and base's? maybe i'll see skully's xb on the track finally! i have spare wheels w/track tires if desired. | ||
| Englishman119 |
Blake; All the vendors have asked for 20 minutes minimum at 3500 to 4000 RPM to reset the AFV, so thats what each one will be getting. New sparkers already in hand. "No sitting on the bike, just gentle consistent pressure" - What are you saying, my 200 lb butt is not so gentle ?  Slowby; Yes there will be dramatic variations on the airbox arrangements as required by each vendor. Everyone else; I'll post the shipping address for the beer later  119 | ||
| Aaron |
Make sure you understand the heat soak effect and how it affects dyno numbers. It ain't subtle at all, and if you don't understand and manage it, you'll most certainly get fooled. Temperature management is the key to repeatability. | ||
| Buckinfubba |
aaron hit the nail square on the head.... and yes BLAKE THE ANAL ONE!!!!!!!!! damn that felt good  | ||
| Blake |
Whe the hell is this "Aaron" joker who thinks he knows something?  Good to see you post old man. Bubba, you and Toby are scarin me. Especially Toby. | ||
| M1combat |
How do you deal w/ heat soak? | ||
| Aaron |
"Heat soak" refers to an effect you get with engine temperature while dynoing a bike. Gary Valine from Buell did an excellent write-up about it in a Battle2win issue sometime back. It's very real, I see it all the time, and it can have a pretty significant impact on dyno numbers. I don't pretend to understand the physics behind it. All I really know is that if you have an engine fully warmed up, hot enough in fact that power is dropping slightly on back to back pulls, and then you shut it down for say 6-7 minutes with the fans running, and pull it again, you'll almost always get a result that's a couple hp higher than you had been seeing. Subsequent pulls will drop in power. Cool it down and do it again and you'll see it jump back up. In general, looking for potentially small differences in horsepower (which is what I would personally expect from these stacks) is a difficult thing to do with a dyno, and it takes a lot of careful attention to procedures to do it with any level of confidence in your results. I don't think it's really the dyno's repeatability so much as an engine's repeatability. Every time you pull a motor, you're getting a different temperature, and a different distribution of temperature, and it tends to act a little differently. Throw in some cool downs in between sets of pulls and everything really moves around on you. Proving some small difference in performance can be tough with so much inherent variability in the measured results. Careful management of the temperature, lots and lots of pulls, and lots of A-B-A type rechecking of results is essential if you really want to get to the accurate answer. I once read an article where a guy had used a dyno to supposedly prove the worth of a fuel treatment device. He tried to show that there was a small gain from it. I always look at that kind of stuff skeptically because I know how easy it is to get fooled and how much work it really takes to prove a small difference. This guy described enough of his procedures that it was obvious to me he had made a critical mistake and didn't even know it. His procedures had set up the ideal conditions for heat soak, and he missed it because he never went back and rechecked his baseline. He was obviously a rookie with a dyno. | ||
| Buckinfubba |
Dang aaron you makin up for lost band width there but once again tellin it like it is | ||
| M1combat |
Thank you for the response. How do you work around it? | ||
| Wyckedflesh |
You work around it by accounting for it. Do a couple pulls, let it cool then redo the pulls. IF your numbers match you are good to go. If not, let it cool and do the pulls again. That is if I read what he said correctly but that was how it was described in school when the subject came up, I may have been in Theory for one week, but damned if I didn't pay attention in that one week. Plus my intructor has his own dyno and used to write for one of the old cycle magazines. He said he had written a similar article when bike dynos first came available. | ||
| Blake |
Do enough pulls on each config so that they cease changing (don't change from pull to pull); perform the same procedure for all configurations. | ||
| M1combat |
Sounds logical... Thanks. | ||
| Englishman119 |
Thanks for all the input guys. In terms of establishing the repeatability of each vendors product, I had planned on multiple dyno runs (and track runs for that matter) to establish this. I had not specifically considered “heat soak” (But I will now)however, I believe that establishing a repeatability criteria would have ultimately achieved a similar result or at least have given me a reason to investigate why I could not achieve repeatability. I have the ability to monitor the various sensors on the bike while at the dyno. Does anyone have a suggested temperature span (like +/- say 40 degrees or whatever) for the head temperature ? That way I may at least have some measure of heat soak while dyno testing. Thanks Mark | ||
| Skully |
Hey Mark and Toby - I missed you guys at Hallett this weekend. Blake - Thomas was surprised you were not there and said to tell you "hello" Keith | ||
| Mikep |
119, You might try monitoring the cylinder head temps while you repeat Aaron's description of Heat Soak. Then try to repeat those same temps for each of the different configurations. +/- 40 degF seems like too great a tolerance to me. mikeyp |
