Tuning tools- tach, temp, mpg etc.

What do you think of a device that could not only take tach an temp, but also estimate mpg, record accurate speed and throttle position? I thought it would be fun to build one, so you could get a throttle/rpm response curve, or test engine temp vs rpms. It would be cool to be able to dump this into a computer so that you could record your build better.

Optimize yo' ride.


Re: Tuning tools- tach, temp, mpg etc.

Sounds epic, but expensive. this mpg what would it be a flow sensor vs mph? rate of consumption vs speed. Hmmm now you got my wheels turning, thought i'm no where near tech savvy enough to figure this out. Would definatly look into investing in this tech though. ^_^ cheers mate great idea.

Re: Tuning tools- tach, temp, mpg etc.

Cool idea if you can make a onboard black box set up for data points of throttle position, tachometer, CHT, EGT in header and flask, crank pressure/vacuum, rpm, ignition advance, ambient temperature, pressure and relative humidity.

I do not see the use of mpg. (edited)

Re: Tuning tools- tach, temp, mpg etc.

Not expensive at all....I've actually been thinking up a system to do some of these things. There is a hardware/software package out there called Arduino...it's for prototyping/programming. It's just the type of tool to do something like this!

Right now I'm working on a box that takes in the following:

EGT - measured by thermocouple

CHT - measured by thermocouple

RPM - magnets epoxied to magneto housing, detected with hall effect sensor

Speed - magnets epoxied to wheel, detected with hall effect sensor

Throttle Position - likely a potentiometer

It may become a fly-by-wire type setup, with the throttle position measured, and the carburetor controlled by a servo. Still up in the air on that.

Ultimately, I want to incorporate timing adjustment into the system.

My primary focus is racing, so fuel calculations are not a big concern for me...but really, it's a simple case of software....with a couple buttons, you could tell the system everytime you fuel up, and how much fuel you put in....after a few tanks, the software could pretty accurately give you a 'distance to empty'.

For a pre-built solution, should you not want to design/build something yourself, check out the Veypor...I have one on my TL1000R, and it's very cool! http://www.veypor.com/

Re: Tuning tools- tach, temp, mpg etc.

Speed could be off engine rpm if you allow the user to input gearing and wheel size.

Re: Tuning tools- tach, temp, mpg etc.

problem with that is the slippage of the clutch (accelerating, off throttle, etc)....engine RPM and speed vary greatly with a moped.

Re: Tuning tools- tach, temp, mpg etc.

Lukas McWhorter /

Tower Hobbies.com has what your looking for. They sell a handheld tach that can read revs off your flywheel, and take temp at the same time.

Costs maybe 40 bucks I think?

Re: Tuning tools- tach, temp, mpg etc.

Salsa Salsa /

hmmm, remember that thread about the guy who was goona make an all in one android app for all of this? what happend to that?

Re: Tuning tools- tach, temp, mpg etc.

Ran out of pot probably...

How can you calculate RPM with arduino? I can get a signal, but the math is fucking me...

Re: Tuning tools- tach, temp, mpg etc.

First count the number of pulses in 1000 milliseconds, then divide that number by the number of pulses per revolution (this depends on how you are measuring the revolution of the crank...if it is say a single magnet then this value is 1, if your using a method that sends 4 pulses per revolution, then divide by 4...etc)...then multiply the whole thing by 60 to get revolutions per minute.

[(number of pulses in 1000ms) / (number of pulses per revolution)] x 60 = RPM

That would be the simple way to work with it (easier to code), but would yield inaccurate results...but likely close enough. Count pulses for maybe 5 seconds and then calculate...would be more accurate.

The better (but harder to code) way to do it would be to drive a hardware interrupt with the 'signal', and count the delay between pulses....add together N samples which is equal to the number of pulses per revolution [if 4 pulses per revolution, then add 4 samples (N=4)] ...and then calculate 60000 ms / (duration of N pulses).

N = number of pulses per revolution

60000ms / [SUM (time between N pulses)] = RPM


So two possible methods for you...hopefully I haven't goofed up the math there....been a long day. Hope that gets you started!


Re: Tuning tools- tach, temp, mpg etc.

Gordon Babbitt /

How do you obtain an accurate magnet pickup signal for obtaining such sensitive information with all the EMFs present?

Re: Tuning tools- tach, temp, mpg etc.

careful, this is the internet.

Dont be spreading sensitive information like RPM's with your cell phones and pedometers in your pockets.

Re: Tuning tools- tach, temp, mpg etc.

I'll be using a hall effect sensor.

In general, careful wire routing (ie away from ignition coil and plug wire), using shielded twisted pairs, and possible filtering (if needed // using RC filters) are all part of working up a successful design.

Re: Tuning tools- tach, temp, mpg etc.

I'd shy away from putting anything on the flywheel, you could get a tiny magnet flying at your head at 1000000 miles an hour, if you are dead set on using the flywheel, i'd look into painting your flywheel alternating black and white and using a non contact photo sensor type deal, that way you're not changing the rotating mass of the flywheel, and you're not risking having a projectile murder you at high rpm.

if you are running a cdi with a trigger wire, you can just read off of that.... food for thought

Re: Tuning tools- tach, temp, mpg etc.

I like the optical/paint option....thanks for mentioning it!

Re: Tuning tools- tach, temp, mpg etc.

One month of over thinking the tach pickup - just get one of these http://tinytach.com/gasoline.php they are not $29 anymore like the ancient one I am still using

Re: Tuning tools- tach, temp, mpg etc.

That takes the fun out of it....if I buy something off the shelf, I've learned nothing.

Re: Tuning tools- tach, temp, mpg etc.

frederickrelyea, how far along are you with the throttle position sensor? Have you done any TP burn rate calculations (for that servo control system)?

I’m almost into testing with an arduino CDI controller but won’t have the TPS or EGT until its next gen. I’m trying to offload all the analog to a second controller to save the overworked ignition controller all that ADC work.

Re: Tuning tools- tach, temp, mpg etc.

I'm going to use a 10k slide potentiometer (linear taper) to sense throttle position. Part: http://www.mouser.com/Search/ProductDetail.aspx?R=RA2043F-20-10EB1-B10Kvirtualkey14860000virtualkey312-219BF-10K

At this point I'll just be logging throttle position and other data, down the road I'll consider servo throttle control, and ignition timing adjustment...if I think I can improve the performance of my machine doing so. It's an evolving project.

The thermocouple amplifiers, and CHT sensor arrived today, so I'll be making some progress soon.

Re: Tuning tools- tach, temp, mpg etc.

I like this idea, I have been thinking of a project like this. Implementing a servo throttle control wouldn't be that hard since you are using a pot to record the value. Since you will have the ADC values you could mess with the throttle curves. You could have an exponential curve to make your throttle super sensitive.

Re: Tuning tools- tach, temp, mpg etc.

one thing to be aware of, with the computer controlling the throttle body directly...be sure the code you write is quick (at least giving priority to the throttle sensing, and servo position)....last thing you want is a slow throttle response when your out there and your life is counting on it. :)

avoid using that awful delay(); function at all costs, as nothing else gets done when delay(); is doing it's thing.

Re: Tuning tools- tach, temp, mpg etc.

Salsa Salsa /

My car is drive by wire(electronic throttle) and I hate it! Its instant. But you can still tell its differnt than a normal car.

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