[decipha]

just curious if anyone has any experience with the dyna-shaft? if so can you post your experiences/thoughts/review?


the idea seems pretty nifty and im tempted to have full integrated support with the d.e.c.


http://www.aemelectronics.com/30-4856-d ... eries-1280

[cougarnut281]

We debated one for a second at the shop but it doesn't really tell you anymore than a gmeter and driveshaft speed sensor do.

[vristang]

I'd be curious on feedback on these things as well...

[99gmq]

We debated one for a second at the shop but it doesn't really tell you anymore than a gmeter and driveshaft speed sensor do.

I've used these (strain gauge torque meters) in laboratory dyno applications. The win you get over shaft speed and G meter is that you're measuring the independent variable, and not the dependent variable, so it doesn't matter how much wheelspin you have, how much power you're losing behind the shaft, what the coefficient of friction is today, or if somebody forgot to take the starting battery out of the trunk, or you have a passenger and you didn't when you weighed in (throwing off your weight estimate ruins your instantaneous TQ and HP calc). You have an instantaneous RPM number and an instantaneous TQ number at each data point, and your resolution is probably good down to five shaft revs or so, so you have a really good idea of just what is going on within a couple of milliseconds.

Strain gauges are also really easy to calibrate. You pretty much set a zero value and one span value and you're done. We did ours with a torsion beam torque wrench when shaft was vertical and with a weight and arm when horizontal.

It's a lot like the difference between mixture tuning with a colortune versus a WB EGO. Both will get you useful information, but the WB is usually going to be much more accurate and precise.

If I were setting up something like an offshore boat or a Bonneville car I'd be all over one of these - you generally can't simulate the running environment on a dyno well enough, and having known values about just what torque caused how much wheel spin or just where the engine hit some weird harmonic at a RPM sustained for minutes or hours can be very helpful.

[cougarnut281]

I should have been more specific, add the words in a drag race setting to the beginning of my first post. I work for a shop with a narrow focus and my answer was based on that.

In general the cars we build motors for have more power than tire, our shop car included. Because of this "issue", knowing how much power we are making at a given time going down the track is not very important to us. Knowing how close to wheel spin we are and optimizing how fast we bring in the power for the track conditions is what matters on race day. I don't care what the actual hp number is as long as I show more G's, my driveshaft shows a faster rate than the last pass, and the timeslip shows improvement.

We were looking at the strain gauge to add to this data in hopes of helping us find the "magic" tune up with fewer test passes but saw no benefit, especially for the money. Instead we invested in a traction control unit and it has been a tremendous help.

[decipha]

tell me more about this traction control setup


is it just a 4 wheel speed monitor that adjust ignition timing to reduce engine output?

[cougarnut281]

http://www.moretraction.com/

[EDS50]

I think its a neat device but the selling price may price most customers out of it since there are cheaper alternatives. If I had money to throw away I would be all over it though.

[dualdj1]

tell me more about this traction control setup


is it just a 4 wheel speed monitor that adjust ignition timing to reduce engine output?

in general they look for rpm spikes and drop spark (ie doesn't fire for a cylinder). so it basically flattens a cylinder temporarily to take out power. (on some systems). I think some take timing out too.

[cougarnut281]

Our unit uses the MAP function in the MSD box and we adjust the sensitivity of the unit to send a different voltage to the MSD thus pulling out different amounts of spark based on the severity of the rpm spike.

It is really a cool unit and gives a ton of data in a short amount of time when used properly.