chassis dyno

Z.hb71

Well-Known Member
Messages
6,399
soo guys, I'm gunna build a chassis dyno @ some time. so question, how do I calculate the proper roller mass or inertia or whatever you're supposed to use? is there a good calculator on it??? article? I'm sure someone who is smart knows. for future reference and over the winter i have some ideas that could improve power and rpm so id like a proper way to prove it vs (like someone on here) just saying "oh yeah it makes such and such power" without numbers to prove. there's a guy who sells the Arduino board and has videos how to set it up, so that's the electronic side, but I just need to know how to calculate the weight, inertia, or mass of the roller,
 
Last edited:

Z.hb71

Well-Known Member
Messages
6,399
http://www.mcpappyracing.com/dyno.php
Most of the home built stuff you read about don't actually put a controlled load on the engine. Making calculating hp and torque impossible. This would be a decent set up for 2wd. I would imagine you could build most of it yourself.
So 4 pound rollers? Load is what I'm concerned about. And I want it rated all the way up to 50hp, for other...things
 

Z.hb71

Well-Known Member
Messages
6,399
I would get the heaviest ones for your application
Yeah but they don't tell y that, they just say their rollers (9inch) are 4lbs. And I'm not trying to buy their system cuz it's literally $1000 when I can build my own for alot cheaper
 

Seandonato73

Well-Known Member
Messages
2,255
You just need something of known resistance so you can figure out the torque its putting out at a given rpm. I did kinda assume you could build the chassis and buy their software and not the rest of it. the free software your talking about doesn't tell you crap except rpm. And how fast that rpm was achieved. Which is great for testing gearing out but worthless for testing engine power. That's why their set up is using a (or 2) brushless motors to add a known resistance to the chassis. The rollers are a static resistance as it takes x amount of power at Y rpm to make them spin if they weigh Z. (don't ask how much I'd have to research the formula) just something to ponder on your quest of home built dyno. And just an fyi it's much easier to build an engine brake dyno.
 

Z.hb71

Well-Known Member
Messages
6,399
You just need something of known resistance so you can figure out the torque its putting out at a given rpm. I did kinda assume you could build the chassis and buy their software and not the rest of it. the free software your talking about doesn't tell you crap except rpm. And how fast that rpm was achieved. Which is great for testing gearing out but worthless for testing engine power. That's why their set up is using a (or 2) brushless motors to add a known resistance to the chassis. The rollers are a static resistance as it takes x amount of power at Y rpm to make them spin if they weigh Z. (don't ask how much I'd have to research the formula) just something to ponder on your quest of home built dyno. And just an fyi it's much easier to build an engine brake dyno.
Simple Dyno is what I'm Gunna use, tells ya up, torque, rpm, vehicle speed and i think how it works is you add in the inertia of the rollers and it calculates it for u? Maybe?
 

cbaker65

Well-Known Member
Messages
899
Yeah but they don't tell y that, they just say their rollers (9inch) are 4lbs. And I'm not trying to buy their system cuz it's literally $1000 when I can build my own for alot cheaper
They don't want you to build one ,they want you to buy theirs ,if that guy is smart ,he should put a PAT on it!
 

Seandonato73

Well-Known Member
Messages
2,255
I'll check it out quick.
He most likely wont patent his design, I doubt he make enough money on it to justify the cost of filing for the patent. It's big money. And it would be simple to build, his software I'd where the money is it. If the stuff z found is any good and can have a dynamic load he could build something simple and cheap!
 

Z.hb71

Well-Known Member
Messages
6,399
. If the stuff z found is any good and can have a dynamic load he could build something simple and cheap!
Which is the goal! Wanna have a decent Dyno setup 👍 ain't gotta be that pretty but it gotta work
 

Seandonato73

Well-Known Member
Messages
2,255
So im.gonna have to bow out of this. The software's forum hasn't had a comment since 2017. And most of the techy end of it is over my head. From what I've seen you would need some big arse rollers to use its simplest version to get a rough hp idea. There was a whole article about scaling your roller for mass for expected hp. There are mush better setups using this software, but not as stand alone. There is mention of an adruino uno board for more accurate inputs. Like I said over my head. May be some of our more tech savvy guys can help out. I'll look up the link for the engine brake dyno when I get some free time. Its far simpler and rpm and a torque guage/ pressure meter in ft/lbs is all that's needed to calculate hp.
https://endless-sphere.com/forums/viewtopic.php?t=53617
This guy did a fantastic job on his dyno using your software of choice. I didnt watch all the vids, but he seems to know how to use it to good extent.
 

Z.hb71

Well-Known Member
Messages
6,399
So im.gonna have to bow out of this. The software's forum hasn't had a comment since 2017. And most of the techy end of it is over my head. From what I've seen you would need some big arse rollers to use its simplest version to get a rough hp idea. There was a whole article about scaling your roller for mass for expected hp. There are mush better setups using this software, but not as stand alone. There is mention of an adruino uno board for more accurate inputs. Like I said over my head. May be some of our more tech savvy guys can help out. I'll look up the link for the engine brake dyno when I get some free time. Its far simpler and rpm and a torque guage/ pressure meter in ft/lbs is all that's needed to calculate hp.
https://endless-sphere.com/forums/viewtopic.php?t=53617
This guy did a fantastic job on his dyno using your software of choice. I didnt watch all the vids, but he seems to know how to use it to good extent.
So the original idea was to follow the steps of 2 stroke stuffing (a moped YouTuber), he built his own Dyno with simple Dyno and made a ardruino board setup and now sells the boards for 10usd, and in his vids he shows how to set it up. He's had good results from it. But do put up the brake Dyno link when you can. My biggest problem is the rollers. I'll look some more
 

cbaker65

Well-Known Member
Messages
899
So im.gonna have to bow out of this. The software's forum hasn't had a comment since 2017. And most of the techy end of it is over my head. From what I've seen you would need some big arse rollers to use its simplest version to get a rough hp idea. There was a whole article about scaling your roller for mass for expected hp. There are mush better setups using this software, but not as stand alone. There is mention of an adruino uno board for more accurate inputs. Like I said over my head. May be some of our more tech savvy guys can help out. I'll look up the link for the engine brake dyno when I get some free time. Its far simpler and rpm and a torque guage/ pressure meter in ft/lbs is all that's needed to calculate hp.
https://endless-sphere.com/forums/viewtopic.php?t=53617
This guy did a fantastic job on his dyno using your software of choice. I didnt watch all the vids, but he seems to know how to use it to good extent.
It looks like he used conveyor belt rollers with pillow block bearings!

I don't have a clue about the software either!
 
Top