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Testing my DIY Dynamometer

Old 04-06-16, 04:11 PM
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Question Testing my DIY Dynamometer

What's up guys. Usually I'd stick to lurking in the 1st Gen forum, but I've been working on something and want y'alls opinion on it. I'm a BS student in the Mechanical Engineering program down here at Clemson, and ever since I got the '7 a few months back I've been working on my own home-brew method to calculate HP accurately (Some of us don't have access to a Dyno!). I've come up with a fairly interesting Excel program that can calculate (somewhat accurately) your HP and Torque based on every small detail in your car: Weight reduction, rim and tire size, flywheel, drive-line, aerodynamics, etc. SO my question is, are you guys interested in seeing this and is this the best place to make this information easily accessible or would a different part of the forum be best? Let me know and I'll post the program file so you guys can get it!
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Old 04-06-16, 05:11 PM
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This already exists in the form of Virtual Dyno and Airboy.

We've found that both can be fairly accurate compared to a real dyno, assuming you enter the parameters accurately in the first place. You could always test your version again the existing and see how close you are.
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Old 04-06-16, 05:20 PM
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I never knew that this even existed. Noted :/
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Old 04-06-16, 07:01 PM
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Just out of curiosity, how do these programs build the power curve for your car? Do you have to tell it where you think the power peaks?
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Old 04-06-16, 07:38 PM
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no, the curve it what it reads. the values of the highs and lows of the curve is what is doesn't know. even on the dyno you have to enter accurate weight..
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Old 04-06-16, 07:44 PM
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Originally Posted by lastphaseofthis View Post
no, the curve it what it reads. the values of the highs and lows of the curve is what is doesn't know. even on the dyno you have to enter accurate weight..
Ah now I understand. To be clear, The program I made builds an independent power and torque curve in Excel. All you have to do is give it some info that you gather yourself from your car.
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Old 04-07-16, 11:43 AM
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The key thing is to make sure the road where you do the "pull" is as flat as possible... not so easy to find in Clemson. Definitely stay away from roller coaster road :P
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Old 04-07-16, 01:10 PM
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Ah I love RCR! Took the '7 out on it the first day I got it XD. Have you been on 76? I love that road. And yes, I've developed a good technique to get the most accurate curve with my program. All I have to do is time my Tachometer.
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Old 04-12-16, 11:17 AM
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The best DIY dyno would be jacking up the drive wheels and using the ebrake to set you up in load zones as you vary RPM with your right foot. It's driveway tuning for a basemap so you can figure out transient throttle AFR before jumping right onto the street untuned.
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Old 04-14-16, 11:01 AM
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For vehicles with high weight and low power, I use a stretch of highway with a long steep mountain climb. I make a baseline run and note peak mph. Then I make my changes, and run it again and note new (hopefully) higher peak mph. I am not worried about absolute horsepower numbers, I just want to see what % faster my change did to the vehicle.
On the race track, it doesn't matter what the horse power number my car has. All that matters is that it is faster than the guy I am trying to beat. Don't get me wrong, occasionally I take my low weight and high power peripheral port road race RX to a chassis dyno to do some testing, but I don't get too caught up in the magnitude of the numbers, I just look for % better or % worse with each change.
The only number that I pay really close attention to is my lap time around each track I run, and my finishing position number at the end of the race.
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Old 04-15-16, 09:55 AM
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Originally Posted by Ricardio Frenz View Post
Ah I love RCR! Took the '7 out on it the first day I got it XD. Have you been on 76? I love that road. And yes, I've developed a good technique to get the most accurate curve with my program. All I have to do is time my Tachometer.
For you some of those big straight hills on hwy 11 by Keowee would be ideal to load the engine for testing.

BTW we have a ton of Clemson interns here at work designing turbos, and we race a first gen RX7 ChumpCar…
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