Dynomometer low cost ?

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Well I am FINALLY getting my real parts in today ( metal bearing blocks and load block ) so I can run this without fear of it falling apart LOL ! , still gotta get the code worked out , need better RPM data , I got the brakes figured out I think ??
 
Ok got my first run in today , not sure about my RPM's I know they are off but it all worked for the most part , this is a Rovan 32 cc ESP race ported top end with DDM Dom V1 Pipe on the Dyno. there are improvement's needed for sure lol
 

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I do not know how the setup reads the rpm in the configuration. But when I used the Eagle Tree setup I had to tell it "1" for the pulse count to read correctly.
 
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ok so heres a run using a Drill lol ! I got my code sorted out now !! THIS IS REALLY GOOD RPM code now , thanks to a guy on the Arduino forums ! IF you want a killer Tach ask me for the code. Im working on adding the Temp sensor to the system so it will store RPM/Load/Temps/H.P. to an SD card and display it on the LCD
 

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Ok I added the EGT sensor code to it as well now , so it logs RPM/Load/EGT I made the Excel sheet to have RPM& LOAD on one chart and HP& Temps on the other so you can compare calculated HP to EGT temps , I'll Post a chart later . Remember this is off the rear axle not the crank , not sure if this setup will want to do 19,000 RPM's
 
New run , need to video it in action next , can someone check the HP numbers for me ?? the math seems correct ? I measure in OZ/FT of torque then divide by 16 to get Ft/Lbs , I use the 5.7 gear ratio to calculate Crank RPM's also , I know Im not getting 12 HP at peak so something is wrong ??? the crank Rpm seem';s close to me
 

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I get 6.2702 hp.
The equation is
torque (ftlbs) x rpm /5252
I may be off with your rpm as the table got really fuzzy when I zoomed in, but I should be rather close for uncorrected hp.
 
Seandonato73 said:
I get 6.2702 hp.
The equation is
torque (ftlbs) x rpm /5252
I may be off with your rpm as the table got really fuzzy when I zoomed in, but I should be rather close for uncorrected hp.
Click to expand...
Ya I use that equation , look at the lower lines on the new PIX I posted it shows up to 12 hp !!
I need to re calibrate my load sensor to make sure I have good Load data ! , I am using 2 Tach;s to make sure I have good #'s on speed
 
12.757 actually. Yeah that doesn't seem realistic but hey if your code is right, and my math is (it is) then that's the uncorrected hp. The engine rpm seems like a believable rpm, you could get a cheap tach to strap to the plug to verify peak engine rpm. What data are you going to use for your correction factor?
 
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Live run on the Dyno , Ill have charts later
Seandonato73 said:
12.757 actually. Yeah that doesn't seem realistic but hey if your code is right, and my math is (it is) then that's the uncorrected hp. The engine rpm seems like a believable rpm, you could get a cheap tach to strap to the plug to verify peak engine rpm. What data are you going to use for your correction factor?
Click to expand...
I will look into a plug tach setup to compare what I calc and what I measure , I have NO correction factors yet.
Duhh I can add a hall sensor to the flywheel in the cover to sense the magnet in the flywheel , ! instant engine RPM's ! no new circuits or code.
 
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Few thoughts for you, first it seems your rpm is rather erratic during the pull. Normally you top out rpm and apply load, seems for some reason your rpm is jumping around a lot. Second thought, and I'm not sure how it effects the readings, did you calculate for the spider gears possibly throwing you off? Idk what the split would be for running just one wheel, or what if any ratio you would use to make sure you have accurate gear ratio. I'll look into it when I get a chance. Other then that i think your set up looks good and seems to be working well, still having a hard time wrapping 12hp out of 32cc engine.
Ok did some digging into driving off one side of the rear. When you stop one wheel completely the rom of the free wheel doubles. So by this it halves your rear (ring and pinion) gear ratio. Is this how you figured your final gear reduction?
 
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Seandonato73 said:
Few thoughts for you, first it seems your rpm is rather erratic during the pull. Normally you top out rpm and apply load, seems for some reason your rpm is jumping around a lot. Second thought, and I'm not sure how it effects the readings, did you calculate for the spider gears possibly throwing you off? Idk what the split would be for running just one wheel, or what if any ratio you would use to make sure you have accurate gear ratio. I'll look into it when I get a chance. Other then that i think your set up looks good and seems to be working well, still having a hard time wrapping 12hp out of 32cc engine.
Ok did some digging into driving off one side of the rear. When you stop one wheel completely the rom of the free wheel doubles. So by this it halves your rear (ring and pinion) gear ratio. Is this how you figured your final gear reduction?
Click to expand...
Thats me manually doing the throttle ! I need to speed up the braking and possibly run the throttle off the same servo signal timing so they are sync'ed up ? the HP is messed up somewhere thats for sure ! I need to get actual engine RPM data like I mentioned.
 
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