Q&A Forum
This system allows you to apply as much downward force you need as per application , no need to seat 100 people in the back seat of the vehicle being dyno tested !
Some chassis dynos might need some form of alterations/fabrication engineering work to adapt DD's strapping system to work on another chassis dyno style.
Ok , chassis dyno design will influence how you tire the vehicle down but you will get the idea.
This is the method i use on my DD650max chassis dyno.
It's very self explanatory view DD's utube link
How to use the Dyno Dynamics HP Traction Control!
https://m.youtube.com/watch?v=Z_k9mu3Q_1I&t=183s
This works for me! And my style of chassis dyno!
What do you think will be the correct way of strap cars on dyno? it is something i wonder a lot.
Ok , you tell me what chassis dyno you're using. Full roller dyno length , two rollers, one roller , four rollers coupled front and rear rollers , independent front and rear rollers un_coupled..... then i will go into what works on my DD650max chassis dyno.
Tell me how you tire your solid rear axle vehicle down. Then i will tell you my system " as i stated already copied DD's system' " no secret!
What do you think will be the correct way of strap cars on dyno? it is something i wonder a lot.
PMSFL ..... why does everything have to turn into a pissing contest ?
Think about it people in the back seat equals downward force of what " the sum of the peoples weight" im sure if you put 100 people in the back seat you won't get tyre slippage ! " I'm being sarcastic here!" i see so many people tie vehicles incorrectly on chassis dynos!
if i say i can believe me i can hold it on my DD650max chassis dyno. Don't know what your dyno is ? Maybe you can shed some information on you unit you use ?
Setting mixtures on carburetors on WOT on 700Bhp engines on steady state mode for the last 30 years is a no biggy.
If i shifted gears down the quarter mile drag_strip at my engines maximum torque_rpm ? I would be losing all my races! LOL !
I'm not into dyno competition's I'm into drag_racing !
Hp is a function of torque they both affect traction.
Thanks for the clarification, I'll make a note of that
I can hold it in st(r)eady state and ramp rate mode re(g)(d)ardless no traction issues.
Well, maybe then you need to educate the OP on how to hold 700hp, steady state ...... by extrapolation he's struggling holding a lot less, unless his 'diesel BMW' is pulling 8308 rpm ..... strapped down, full of people !
[442.5 lbs ft (~600nm) x rpm :- 5252]
And with that, I'm out ...... 🤪
Hp is a function of torque they both affect traction. I can hold it in stready state and ramp rate mode redardless no traction issues.
i just copied DD's system for solid axle differential and have no issue holding 700BHp+
Steady state ?
Sweep is a whole different ballgame ....... and doesn't cover everyone's needs ......
It's not uncommon for RWD cars to light the rollers up at 300lbs ft against the brake, even strapped down and with a handful of people in the hatch
It's torque that breaks the traction, not bhp per se
Be careful about pulling the vehicle down with too much strap, and running for any length of time
These are my direct observations, and the long post above is a reasonable synopsis ...... your results may vary
There are many ways of strapping and tying down vehicles with big RWHp/torque.
i just copied DD's system for solid axle differential and have no issue holding 700BHp+ cars running 9 seconds quarter mile.
Without slippage. As most of my vehicles are rear wheel solid differential happy to share information if you require it.
Have also a good system for front wheel drive cars too.
Thanks
Good resource for understanding the issues :
https://www.dynomitedynamometer.com/dyno-tech-talk/roll_diameter.htm
and i had to strap it a lot sit people inside the car, and spraying adhesive to rollers, only possible to make runs without slips on no brake mode
I've had three rolling roads over the years, the first one a water cooled HP Anderson 30+ years ago, and the problem you always run into with the 'standard' small twin roller European type designs is that eventually traction becomes a problem
Depending on the vehicle weighting, higher powered rwd cars are the worst in this respect, traction problems can onset surprisingly early
Coatings will eventually come off, even the factory applied ones, and the various knurls & grooves can help, but aren't usually cost effective to do on an already installed roller set
Rolling roads are convenient, but with that convenience comes compromise, as you've found out ...... I'm not saying they can't be made to work, especially if you split the load between both rollers, or maybe go to the large drum designs, but most people don't have that as an option and have to work with what they have
Hence my decision some time back to build a hub dyno ...... with it's own particular set of compromises ...... although there are tentative plans to maybe build a twin brake roller set sometime going forward
Good luck with your project
All kind of them, i have run front and rear wheel drive, and solid differential and not.
Now i can just strap cars on the rear, no place for strap it on front ( i am working on it), so maybe problem could be there, on the other hand i make run on a diesel bmw with 600 nm, and i had to strap it a lot sit people inside the car, and spraying adhesive to rollers, only possible to make runs without slips on no brake mode.
i have no paint on wheel path on my roller, maybe with good grip painting will be better, but no idea how much time will stay the paint on it.
Hi ivanro_jo , what sort of vehicles rear wheel drive or front wheel drive ? Solid axle differential or IRS diferential rear wheel drive vehicles?
What method to you employ to secure the vehicles down to the chassis dyno rollers ?
ivanro_jo
ON the other hand i am having some troubles with slipping with high torque cars, could you guys advise me some kind of grip paint for rollers?
BR
@tutuur, i use 6 seconds for sweep stabilization just works very well normally i have start rpm arround 1200 for turbodiesel engines and 1500 for fuel engines, works quite ok.
ON the other hand i am having some troubles with slipping with high torque cars, could you guys advise me some kind of grip paint for rollers?
BR
I'll give that setting a try aswell, for now with the 1.6/0.7 it works fine, but could be better.
Only thing I seem to struggle with is the moment the stabilisation is over, and it goes into the sweep, it releases the brake to get the rpm rise going, but then has to cut back in to maintain the speed. Maybe this would've been better with lower inertia rollers, I don't know.
I seem to remember there has been an update on this?