[Diy_efi] Strain gauge on engine mounts

[niche at iinet.net.au]

At 11:32 PM 19/04/05, you wrote:
>My papa called this ''Educated beyond your intelligence''
>
>Randy 

Sure as far as intelligence is a measure of enlightened effort,
in so far as we know which form of intelligence we are dealing with...

Dealing with nonlinearities of rubber engine mounts (amoung other
things) is asking for trouble (as in huge wasted time relearning
whats already been arrived at), far far more direct, efficient, effective
and less invasive to measure the twist of the tailshaft :o)

Regards from


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






>-----Original Message-----
>From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org] On
>Behalf Of niche at iinet.net.au
>Sent: Tuesday, April 19, 2005 11:23 AM
>To: hugh at sol.co.uk; diy_efi at diy-efi.org
>Subject: Re: [Diy_efi] Strain gauge on engine mounts
>
>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.