[Diy_efi] Strain gauge on engine mounts

[niche at iinet.net.au]

This is by far the hardest way you could measure torque...

Mike


At 11:16 PM 19/04/05, you wrote:
>Milosz,
>
>I have accelerometers on the vehicle as well, but the two axis
>accelerometers will not resolve for bumps in the road / hills etc. A three
>axis accelerometer set-up might be better as it would resolve out the
>unknowns.
>
>I beleive airbag accelerometers are very cheap to buy and might provide a
>reasonable and complete solution.
>
>I also have a digital speed measurement which is easier to use, but also
>does not allow for bumps in the road / hills etc.
>
>Thanks
>
>Hugh
>
>
>Original Message:
>-----------------
>From: Milosz Kardasinski miloszk at gmail.com
>Date: Tue, 19 Apr 2005 05:23:14 -0400
>To: diy_efi at diy-efi.org
>Subject: Re: [Diy_efi] Strain gauge on engine mounts
>
>
>>Using one on each mounting point will, I hope, allow you to delete the
>>effects of bumps in the road.
>
>It's a bit more complicated than that because the loading on your engine
>mounts
>is combined loading...axial, lateral, bending and torsion. Don't forget that
>strain
>gauges have a temperature drift that you need to account for and lastly,
>they are
>fragile devices, when I played with them 10yrs ago you could break them
>pretty
>easily not to mention that it was a pain in the but to get them to bond
>well.
>
>>Going over a bump, each strain gauge will be compressed by the weight of
>>the engine, but the difference should I think still equal the engine
>torque.
>
>Probably not, the reason is that I have seen very few engines that have
>their
>CG colinear with centerline, but you might be lucky something you have to
>check. You'll have to figure what the weigh distribution is side to side and
>front to back if the mounts are not on the same plane.
>
>>There will obviously be calibration issues, but I am looking for a tuning
>>aid rather than a definitive torque number.
>
>Complicated way of going about it...but that shouldn't stop you. How about
>using an accelerometer instead? You could zero all the extra variables
>introduced
>by using systematic and methodical approach to your testing. A one axis
>accelerometer
>will give you acceleration, braking....with a 2-axis you could measure your
>lateral
>accel (cornering) as well.
>
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Regards from


Mike Massen
Perth, Western Australia
VL Commodore Fuse Rail that wont warp or melt !
http://niche.iinet.net.au