Any MECHANICAL/CHEMICAL mileage booster?

[Nereth]

Originally Posted by KiwiBacon

Post up the calcs you used, I'm genuinely interested. I'm assuming it's just torsional vibration and you used the polar moment and torque on a solid block.
I thought it was obvious that engines shake the most at idle.

Damnit, I just did the whole thing really neatly and then lost it because my login timed out before I clicked submit.

Anyway, I'll do it again. Feel free to correct me if I do anything wrong.

---------------------------
Starting assumptions:

Simple harmonic motion

Block has homogenous density, dimensions 0.3 on x by 0.5 on y, weight 250kg

Vibration amplitude is 1/4 inch (ie 1/2 inch side to side)

Vibration frequency is 50hz (3k RPM)

Block vibrates around axis parralel to Z but 0.05m below the CG of the block.

---------------------------
Angular displacement of vibration

Radius from axis of vibration to top of block: 0.3m
Displacement at top of block: 1/2 inch

Angular displacement:
radians=arc/radius
radians=0.0127/0.3
radians=0.04233
---------------------------
Moment of inertia

Moment of inertia of a solid rectangle around its CG, with axis parallel to one of its sides:

i=1/12*m*(h^2+w^2)
i=7.08333

However our block is vibrating around a point 0.05m below its CG.

Parallel axis theorem:

i(o)=i+m*r^2
i(o)=7.08333+250*0.05^2
i(o)=7.708333
---------------------------
Angular acceleration

Position w.r.t time is given by

p=(0.04233/2)*cos(50*2*pi*time)

velocity:

p'=-6.64918*sin(50*2*pi*time)

acceleration:

p''=-2088.901*cos(50*2*pi*time)

Which obviously has a peak of 2088.901 rad/s/s
---------------------------
Torque:

a=t/i

therefore

t=a*i

t=2088.901*7.708333
t=16101.95046

And that is that. 16 kilonewton-meters. Doesn't hold a candle to the figure I got last time (which shocked me a bit, but I couldn't see where I had gone wrong and I had never done something similar before so I didn't have much of a 'feel' for it), but it is still large enough to make it somewhat unfeasible.

Curtis is still right, as I know engines vibrate that much so they need the flexible rubber parts. It's just they don't vibrate back and forth like that every revolution.

[curtis73]

I buy those numbers... but it is 3am

In my line of work, it its not rocking 1/2" you need more cam. If its rocking more than 1/2 you need solid motor mounts

Yeah, at this point (although I really crave a greater grasp of physics like Nereth has) the bottom line is that engines move relative to the frame/body, so somewhere there are soft lines.

[Nereth]

Originally Posted by curtis73

the bottom line is that engines move relative to the frame/body, so somewhere there are soft lines.

This is true.

[KiwiBacon]

Originally Posted by Nereth

Damnit, I just did the whole thing really neatly and then lost it because my login timed out before I clicked submit.

Anyway, I'll do it again. Feel free to correct me if I do anything wrong.

---------------------------
Starting assumptions:

Simple harmonic motion

Block has homogenous density, dimensions 0.3 on x by 0.5 on y, weight 250kg

Vibration amplitude is 1/4 inch (ie 1/2 inch side to side)

Vibration frequency is 50hz (3k RPM)

Block vibrates around axis parralel to Z but 0.05m below the CG of the block.

---------------------------
Angular displacement of vibration

Radius from axis of vibration to top of block: 0.3m
Displacement at top of block: 1/2 inch

Angular displacement:
radians=arc/radius
radians=0.0127/0.3
radians=0.04233
---------------------------
Moment of inertia

Moment of inertia of a solid rectangle around its CG, with axis parallel to one of its sides:

i=1/12*m*(h^2+w^2)
i=7.08333

However our block is vibrating around a point 0.05m below its CG.

Parallel axis theorem:

i(o)=i+m*r^2
i(o)=7.08333+250*0.05^2
i(o)=7.708333
---------------------------
Angular acceleration

Position w.r.t time is given by

p=(0.04233/2)*cos(50*2*pi*time)

velocity:

p'=-6.64918*sin(50*2*pi*time)

acceleration:

p''=-2088.901*cos(50*2*pi*time)

Which obviously has a peak of 2088.901 rad/s/s
---------------------------
Torque:

a=t/i

therefore

t=a*i

t=2088.901*7.708333
t=16101.95046

And that is that. 16 kilonewton-meters. Doesn't hold a candle to the figure I got last time (which shocked me a bit, but I couldn't see where I had gone wrong and I had never done something similar before so I didn't have much of a 'feel' for it), but it is still large enough to make it somewhat unfeasible.

Curtis is still right, as I know engines vibrate that much so they need the flexible rubber parts. It's just they don't vibrate back and forth like that every revolution.

Thanks.
I was surprised to see you working in metric. Looks like the US has finally been assimilated.

[Nereth]

Originally Posted by KiwiBacon

Thanks.
I was surprised to see you working in metric. Looks like the US has finally been assimilated.

Nobody ever said I was American.

[KiwiBacon]

Originally Posted by Nereth

Nobody ever said I was American.

You need to change your handle to "waltzingmatilda" to avoid any confusion.

[curtis73]

You boys enjoy your upcoming winter. I was just 80 degrees here today (that's 26.7 to you guys)

[Nereth]

Originally Posted by KiwiBacon

You need to change your handle to "waltzingmatilda" to avoid any confusion.

How the hell did you know I was australian

Edit: Oh wait it's in my profile.

*sits back down*

[Moppie]

Originally Posted by Nereth

How the hell did you know I was australian

Don't be ashamed, I believe there is now a cure.

[Nereth]

Originally Posted by Moppie

Don't be ashamed, I believe there is now a cure.

I must know more!

[KiwiBacon]

Originally Posted by curtis73

You boys enjoy your upcoming winter. I was just 80 degrees here today (that's 26.7 to you guys)

Sounds pleasant, we're running roughly 10-19 deg C here at the moment. Most Aussies don't know what winter means.