Could someone please tell me any negatives associated with running pipes only and no mufflers out the back of a 71? I don't see many with just pipes, and I was thinking that I would just skip the mufflers - would it be too loud or something, do you lose horsepower?

 

Yea, too loud.

Most places have laws against it also because of the noise.

 

Vette would look horrible with pipes out the back with no mufflers... Btw i will be doing this shortly, I am taking my mufflers to my dads friend and he said he will cut them up take al the insides out an dmake it a straight pipe inside.... So theres no muffler but the housings still there

 

Ahh come on - have you ever seen chambered exhaust on an old vette - they don't use a muffler...

 

I'm just guessing here but I think you might have some problems with excessive resonance inside the car if you put a couple of large hollow cans in the exhaust. There are easier ways of getting a free-flowing exhaust system. All of the major muffler manufacturers have low restriction mufflers available. Even with mufflers many folks find that a crossover pipe helps eliminate the resonance inside the car.



Rick B.

 

That's what I don't get. Harleys are loud as hell and they get to drive around like that. I know it's 2 cylinders vs. 8 but I've ran my car with open exhaust and it wasn't louder than a Harley IMO.

 

How about straight pipes then a couple of those buzz cans at the ends?

I drove to the muffler shop once with nothing on but the exhaust manifolds--now that was loud.

 

open-headers on the street rock!!!!!

 

You could be in for a shock!! I've got "mufflers" like this on my bike (Tulips/Trumpets) that have no guts in them. The noise is unreal, extremely loud if you want it to be & can be much louder than the same bike with no mufflers at all. A mate runs just straight pipes on the same type of bike & I can't hear them over the sound of mine (nor can he!!). The resonance that's set up is a deep tone (cops have commented on how nice it sounds, even thought they're completely illegal!), but I'd expect doing the same with a pair of Vette mufflers would make driving it seem like you've got your head inside a PA bin at a Motorhead concert
What I'd suggest, and it's only a suggestion as your dad's mate is going to be cutting them about anyway, is to rip out the guts & replace them with a tube (2 1/2" diameter) that's full of small holes (1/8"? 3/16"?). If you've got anywhere near you where you can look at old Brit bikes (esp 60's Triumphs), have a look down their mufflers & you'll see what I mean. I think they were called absorbtion baffles(?) & there was usually some sort of wadding around the tubes inside the mufflers (which eventually disintegrated - often after owner persuation). These types of baffle take out the harsh high pitch sounds & leave the lower frequencies to give a nice deep burble/rumble, but don't restrict the exhaust in any way.

 

The inspection shop told me to put glass packs on my '78 because I was running 2 1/2" side pipes I made, with no baffels. They said it was too loud, and they wouldn't pass it until I quieted it down. It is alot queter in the car with the glass packs, but I still have a good exhuast tone, and no noticeable change in performance. The total cost on pipes I welded up was $85.00.

 

what about the back pressure? Isn't that needed for optimum engine response?

 

I once had a '69 big block mustang mach I and I ran the exhaust out the back with no mufflers. It was very loud and I really didn't care for the sound, kinda like a high pitched crackle. It wasn't the low pitched rumble that I like from a good set of glass packs.

BTW, I know it would be hard to do on our vettes, but for some reason, with rear exiting exhaust, the closer you can put the mufflers to the headers, the better they sound.

 

Response? Maybe, but not for all out power.

 

IMHO:
If you are running headers with a 3" flange then reduce the pipe down to say 2 1/2" that should create enough back pressure to not affect response.

 

Fixed - Did that last week...

 

home made glass packs... just a collector off the header with mesh and fiberglass cloth wraped and screwed in.... really just to get to the exhaust shop but sounds pretty damn good

 

i run headers and chambered on my BB with no mufflers...sounds awesome

 

I had a '69 Firebird 400 w/ glass packs and all the fiberglass burned out. Sounded real good! I got a ticket once though. No fee if you got it fixed (or "said" it was fixed by a inspection certified garage) No cost Wish that car NEVER go away.

 

I was told by more than one exhaust specialist that the cats on my '78 were so restrictive you could remove the mufflers and sound just fine. I wanted to retain a stock look though and wanted the mufflers underneath. I decided to go with hi-flow cats;convert to true duals and that gave a nnice moderate rumble and still remain legal. I was told that I could get more sound with resonators instead of mufflers, but the stock look at the rear would be lost.

 

You just described Magnaflow and Dynomax UltraFlo mufflers. I have three vehicles with Magnaflows fitted. They are great sounding mufflers...and offer completely legal sound levels.