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Posted on 08/07/10 21:59:16 |
zoltechx
 Posts: 220 Reply  |
MAKING OF A RPM DYNO
This aint nothing new to slot cars i guess  but i had brain wave and thought ide give it ago..Checking the internet and finding many ways of counting stuff..electronics was almost the obvious  pic micro controllers ..wel i aint going to go out and buy a whole heap of parts and learning to programe the damm thing..BUT then i found a story on industrial counting using an ENCODER..kind of sounded familiar..SO HERE GOES.. i wanted to do basic rpm tests under load..so i got some stuff out of the shed..and threw this together in about 5 hours between smokes  A few parts from an old tape player for rollers and a couple of ir's and some laptimer software...THINKING THIS IS CHEATING AND TO EASY..  Once all the minor adjustments were established and i had the right ratio"s as this is critical in getting the " read rate right "...im not to bright in the gearbox area .I POWERED IT UP...yep it did the job..  IT DOES ONLY TEST UNDER LOAD WITH OUT DOWN FORCE MAGNETS..BUT IAM GETTING ABOUT 116 RPM out of a turbo car running for a-- minute..  cooling is optional as this might have some bearing on any true readings..its all only in the experimental stages..Running the laptimer software along side a software countdown timer for a minute..the laps count up..RPM..we will eventually use track start in the laptimer with a relay and set for short 1 minute race hopefully with the same result..RUNNING THE CAR FLAT OUT ON FULL VOLTAGE GIVES MAX RPM..  no controller used..
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Posted on 08/07/10 22:04:12 |
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zoltechx
Posts: 220 Reply |
Re: MAKING OF A RPM DYNO
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Posted on 08/07/10 22:08:22 |
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zoltechx
Posts: 220 Reply |
Re: MAKING OF A RPM DYNO
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Posted on 08/07/10 22:11:16 |
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zoltechx
Posts: 220 Reply |
Re: MAKING OF A RPM DYNO
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Posted on 09/07/10 11:39:15 |
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Dave in Perth
Posts: 873 Reply  |
Re: MAKING OF A RPM DYNO
dammit you stole one of the ideas floating around in my brain!! very nice work. Something aint right though - if the encoder wheel is turning at the same rate as the car wheel, then there is no need to account for it's different size ie you'd only need one light transmission hole.. The other thing that seems odd is the low value of the rpm.. I work on a rough motor revs of 20,000rpm for a typical turbo car, so with standard 7/23 gearing, the wheel rpm should be about 6086rpm. Crunch a couple more numbers and that equates to an actual track speed of about 12.5kph.. which is in the ballpark range and is also verified by speeds given on my dragstrip. At wheel revs of 6086rpm, the wheel turns once every 10milliseconds (.010secs), so maybe check Laptimer's minimum lap (Debounce) setting, and also set your timer resolution setting to the minimum 1millisecond.. You've got a great ssetup, just something needs to be tweaked to output what you're after 
Much admired handiwork, onya fella
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Posted on 09/07/10 17:21:17 |
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zoltechx
Posts: 220 Reply |
Re: MAKING OF A RPM DYNO
Thanks buddy your compliments are appreciated yea mathmatically it dont add up..i wasnt even sure if it would even work in practice..i actually had toyed with the idea in my mind a while ago, cause i think id seen afx years ago made a dyno type system,,and id seen on here some where one of the blokes made one that measured the currents and voltages of the motors electrical preformance..THATS ALSO IN THE PIPE LINE But unloadeed and loaded motors do preform differently, but my mechanical days of having my xb gs 302 panel van dynoed..it was always load tested<,160 bhp> at 3/4 power.The encoder wheel i gathered <in my mind> was twice the size> and according TO some gearing reasurch id done T1/speed=t2/speed>>this is abit involved as to do the damm equations for another project a micro mini bike using 4 sets of gears as a reduction type setup to be fed from 23 cc motor>blah blah..  so i automatically came up with this stoopid principle ..SOME HOW ?yea the revs do seem a bit low, perhaps the rear wheels are actualy bouncing off the dyno rollers cuase its only the front thats chocked down with rubber clamp.But 6000 revs seem pretty high..but your probably right But i will only use 116 as bench mark between cars ..not a true scale.. BUT TWEEK I WILL  .. i have seen digital taco's some of the yanks i worked with use..at about $500-$2000 a pop , some with roller and some with infared I WILL RECALIBRATE this engineering marvoule and pay special attention to the lap timer settings..GOOD ONE BLOKE.. give it shot dave seen what you come up with.get to biuldin .. CROSS POLLENATION RULES..i may go an see if i can find some specs on afx motors on the net right now
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Posted on 09/07/10 21:59:16 |
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Dave in Perth
Posts: 873 Reply |
Re: MAKING OF A RPM DYNO
an easier way is to buy a Tamiya Mini 4WD Speed Checker, it'll give you a readout of wheel speed in kph 
I've got one, works well http://www.hobbylinc.com/gr/tam/tam15183.jpg |
Posted on 09/07/10 22:18:15 |
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zoltechx
Posts: 220 Reply |
Re: MAKING OF A RPM DYNO
is it expensive ..mr davo ill sneek a peek.. i sat aptitude test for a job at capral aluminium as a production worker..The first question was ..if wheel A turns clockwise..which way does wheel b turn..as they were meshed.. i did the test and rang the bloke back and asked how i went..HE SAY YOU GOT AN OVERAL SCORE 13% and i didnt get the job..2 weeks later i got a gig with lockheed martin for a years contract on an aussie post upgrade..the contract blew out to 2 years..I DID LEARN ALOT FORM THE YANKS..technicaly..but is true wat they say about the yanks..they were going to sack me cause i didnt know how to send an email.. i asked 1 of the local lads how it all worked ..aussie aussie iin 2 minutes i was sending emails to new york telling them they suked.. |
Posted on 09/07/10 22:24:42 |
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Dave in Perth
Posts: 873 Reply |
Re: MAKING OF A RPM DYNO
haha onya for the email story should be able to find those speed checkers for about $30 ? Haven't looked for ages, check ebay and also Google for prices |
Posted on 09/07/10 22:55:22 |
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zoltechx
Posts: 220 Reply |
Re: MAKING OF A RPM DYNO
encoders arent cheap..so we thought we could kind make 1 ..and we kinda did ahh ya can kinda buy any thing now days..even MINI BOB JANE RIMS AND TYRES..poor bob surprised he didnt think of it..he lives just around the corner from us ..well up the road..AHH UP THE HIGHWAY ABOUT 10 KMS..LOL..ill have look any ways thanks dave.. |
Posted on 10/07/10 13:49:19 |
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zoltechx
Posts: 220 Reply |
Re: MAKING OF A RPM DYNO
ATTENTION ANY GEOMETRY EXPERTS IN THE AUDIENCE .....round things go around an around, but somethings need calculation...im perplexed by this equation..my encoder needs further analisis..boing...if small wheel is attached mechanicllay to big wheel..THE BIG WHELL MUST TAKE LONGER oor shorter time to revolve? any opinions..JOKE ..PINEEEEON ..
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Posted on 10/07/10 21:48:29 |
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zoltechx
Posts: 220 Reply |
Re: MAKING OF A RPM DYNO
revamped dyno 
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Posted on 10/07/10 21:56:22 |
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zoltechx
Posts: 220 Reply |
Re: MAKING OF A RPM DYNO
reset laptimer settings..RPM at the moment about 400..? is there any how i can post a video of this here in mp4 or wmv ?  |