Is this sound knocking/pinging or something else?

[CS310]

I need some help identifying a sound.  It's a high pitch rattling that happens under hard acceleration.  I uploaded a quick video to YouTube.  The link is below.

 

 

[banzai510(hainz)]

Hard to hear

 

some times I jack the car on all 4s and has some gas it while under car

 

alternator loose

if 4 speed the plate cover under the trans loose
 

something simple I bet

[CS310]

The rattling sound starts at 1, 3 and 6 seconds into the video.

 

I've been all over the car checking to make sure nothing is loose.  I only hear the sound under hard acceleration.

 

Specs are below.

72 510

L18

5spd Z trans

32/36 Weber

 

[datzenmike]

Engine torque under load moves the exhaust pipe or muffler against something. Climb under and give the exhaust pipe a big hard shove.

[Crashtd420]

11 minutes ago, CS310 said:

The rattling sound starts at 1, 3 and 6 seconds into the video.

 

I've been all over the car checking to make sure nothing is loose.  I only hear the sound under hard acceleration.

 

Specs are below.

72 510

L18

5spd Z trans

32/36 Weber

 

 

Does it happen at low rpms as your getting on the throttle? 

What about if your up in the rpm range already and give it full throttle?

 

There is also something called lugging..

Internet definition....

 

[CS310]

Mike: I had previously checked around the exhaust for any signs of rubbing and I couldn't find any, specifically around the rear cross-member.  The entire exhaust system is firmly mounted.  It doesn't move at all when you push on it.  Not sure if that's a good thing.  I'll check the exhaust system again to confirm.

 

 

[CS310]

Crash: I haven't noticed it at low RPM's under hard acceleration.  I'll check later to confirm.  I would say it happens around 2500-3500K RPM and continues until I lift.

[banzai510(hainz)]

Like I said

Jack up on all 4 and have somebody go under the car and act like your driving and shifting the gears.

I did this on my 521.  bolts were coming loose