Dual muffler drone experiment.

I guess the combo of aluminized 2.5" exhaust and 2.25" tail pipes must have hit some magic formula to make it sound off like an organ pipe. Changing mufflers didn't change the resonant RPMs much if any

 

Where do your tailpipes exit? Mine are straight out the back.

 

Angled down some at the rear valance. Thinking they might be too close to the valance, I slipped some 4" extensions on them to get the exhaust exits well past the valance. No difference. Straight back would probably be quieter but I like the almost-hidden tail pipes.

Haven't done it yet, 'cause its really not a problem now, but I might put insulation on the trunk floor and drop downs. I think the sound was/is coming from the trunk area. As I said, its OK now with the Thrush Turbos and additional insulation in the quarters and under the package shelf.

 

:16suspect ..All this complaining.. I hope to have this problem soon

 

Those of you with the same exhaust system but one has drone and one does not are forgetting something. The Engine! The compression ratio and cam will have alot to do with when and if you get drone. My exhaust sounded totally different when I put on the new heads and raised the compresison from 9:1 to 10.5:1.

 

Engine has '86 5.0 flat top pistons that appear to come even with the deck, E7 heads shaved .005. I'm guessing 9+:1. Stock HO roller cam.

Don't think Craig and I have the same exhaust system. Mine has 2.5" exhaust pipes and 2.25" tail pipes, had 3-chamber mufflers, and X-pipe vs H-pipe.

 

That is very true. I have a 347, 10:1 Compression / 64cc Chamber, Comp Cams Ford 351W Xtreme Energy Retro-Fit XR270RF-Hydraulic Roller Cam and RHS Pro-Action heads.

Here is my exhaust:

 

I have magnaflows, my exhaust dumps behind the rear wheels, and I have no drone....

 

Nice looking exhaust, Craig!

 

so what conclusions have been reached from these experiments?

 

Umm... we learned that guys with 40 year old cars with aftermarket exhaust systems built to perform and sound cool are concerned about exhaust drone.

What a crazy bunch.

 

or is it 40 year old guys are too old for cool sounding exhaust?

 

I like an exhaust that makes hp. It has to be quiet for my comfort but it has to help the engine make all the power it can.

 

My conclusion is that i cant afford a non-droning setup right now.

But i can afford to screw around with this one for a couple more weeks.

 

That could be it. At 16, I thought louder was better. Then, it might have been fun to see passengers using ear protection.