Off Road Exhaust

[Vette66AirCoupe]

I've seen off road exhaust mentioned as an option in a lot of old specs but I don't have a clue what that means. What did you get when you opted for off road exhaust? :confused

 

[67HEAVEN]

Edited to allow for better information.

 

[Vette66AirCoupe]

The only thing better than getting a prompt response is getting one I understand that includes a picture! Thanks!

 

[nick67vette]

uhhhhh, maybe John Z could help this thread a bit...

 

[Lucy64]

I have this Mid America chambered system on my 64. I have my Hookers going straight into this system and it is louder than any sidepipes I have ever heard. I do get the attention of all of my neighbors when I fire her up.

 

[Vette66AirCoupe]

I have this Mid America chambered system on my 64. I have my Hookers going straight into this system and it is louder than any sidepipes I have ever heard. I do get the attention of all of my neighbors when I fire her up.

Do you have less cabin noise as the result of the fact that they terminate at the rear of the car?

 

[Lucy64]

Yes, at least with it exiting in the rear it is not right in you ear. But with the rear exit I have had friends following me that commented how loud it is when I jump on it. It also may be a bit louder because of the headers and not stock manifolds.

 

[61 Silver]

I've seen off road exhaust mentioned as an option in a lot of old specs but I don't have a clue what that means. What did you get when you opted for off road exhaust? :confused

I purchased a set of aluminum coated exhaust from Allen's for my 63 project. The exhaust are 2 1/2" and are welded like the originals. On the mufflers in stencil are the words off road . I have been going to call Allen's to to get information on the difference between what I received and standard exhaust. In todays world it might be just the stencil.

Ray

 

[ChuckG]

To the best of my recollection, the off road exhausts are identical in outward appearance to the "regular" under the car exhaust.

The only difference is that the muffler is less restrictive, having 3 internal baffles instead of 5 as I recall.

I've never seen original chambered pipes. Those are some aftermarket creation. Chuck

 

[Fuelie]

Chuck is 100% correct. The original off road option was for the 3 baffle mufflers instead of the quieter stockers. The Off Road mufflers have a nice sound without being obnoxious.

The only chambered pipe application on midyear vettes was the side exhausts.

The General did offer a chambered under car exhaust from the factory, but only on the '68 and '69 Camaro

Take care,
Brian

 

[67HEAVEN]

uhhhhh, maybe John Z could help this thread a bit...

Nick,

Please jump in with corrections when you have better information.

 

[nick67vette]

I suggested John Hinckley get involved because in the back of my mind I think I recall GM installing a chambered style under car exhaust... but on the early Z28 Camaro?

Chuck is correct, the original RPO N-11 Corvette exhaust was nearly identical to original standard exhaust system except for 2 fewer baffles in the muffler.

I spent stupid money for an original N-11 system for my yellow coupe. Once I heard it on the car I became convinced It was a good investment. There is no sound today that can mimic the sound of an original N-11 system.

 

[435er]

Purchased a set of N11 from GM in the early 90s for my previous car,a 66
390 hp roadster.I found them to be quieter than hoped for at idle and low
speeds,this may have been due to the mild character of the 390 hp engine.
At higher RPM or on acceleration they were much louder and sounded great.
There is a supposed set of reproduction set on my 435 and i will say things
are definitely busier at the rear.

435er

 

[JohnZ]

The original factory N-11 Off-Road mufflers had a wonderful, authoritative sound; unfortunately, the reproduction N-11 mufflers don't have the same sound, as their internal construction is completely different than the originals. Nobody makes a duplicate of the originals - too much tooling expense, not enough market to justify it.