Blackjack1

I have a 1981 Vette that I've put a crate motor in and a set of Hooker side pipes. I'm not satisfied with the sound. I'm running antigue tags so it's not a problem with having to have stock exhaust.

slapjack9

You'll lose back pressure with the absence of mufflers...but that being said, any performance exhaust system removes back pressure. I have straight exhaust on my truck and I don't have any issues with it. Obviously that's not a performance engine, but it shouldn't be any different in my opinion.

mobird

Are you saying you are running Hooker Side pipes with no baffles/inserts and you are wanting to know if there is a disadvantage to that?

Or are you asking about switching to an undercar exhaust with no mufflers?

What about the sound are you unhappy with, the volume or the tone?

Easy Mike

You might want to touch base with local law enforcement to determine whether you could be violating noise laws. "Loud mufflers" used to be a generic excuse to write a ticket.

theandies

Oh good grief with some of the Harley and even some new Mustangs (that sound like **** IMO) never get pulled over I don't think open pipes to the rear would set off any police noise warning buzzers.
Good read on the subject:

Exhaust Performance

C3 Stroker

Agree on that.......it is at the discretion of the officer about writing a loud noise ticket. They give tickets for loud music here, so exhaust would be fair game.

naramlee

did we seriously just bring up the backpressure myth? hold on... cross-posting this to the ricer forum...

blue427

what do you mean"back pressure myth"?

mrichi

The back pressure debate intrigues me, you couldn't get any more high performance than a dragster engine and they run pipes straight out , no extractors and no mufflers

Hemi John

And VERY high rpm. Leave the line at high rpm and stay there! Maximum airflow in and out.

Much different application than street driven vehicle.

twinpack

Agree! Scavenging is important to extracting (pulling) exhaust gas from the cylinder allowing more room for a larger charge on the intake stroke resulting in more power. Back pressure assist in the scavenging effect at street RPM, open exhaust has close to no scavenging effect at street RPM. I am no expert but this is how I understand it. Please feel free to correct me if I am mistaking. All this really does not matter much if you have lower compression, restrictive intake,stock CI heads and restrictive exhaust.

Cool95vette

Back pressure? So inhibiting the engine's ability to expel exhaust gases increases horsepower? Who would've thought.

naramlee

the argument of needing a certain number "X" of backpressure to maintain "Y"... aka: proper engine functionality and performance

it's a flat earth argument, it's all about flow, NOT back pressure... yet it always gets brought up on forums about needing proper "backpressure"

twinpack is right, it's about flow and scavenging, which is NOT present when you put duel 3" exhaust on a 300hp engine... small wonder it falls flat on it's face...
IIRC Carol Shelby's famous 427 cobra was only 2.00" exhaust tube due to his calculations of exhaust gas flow/scavenging... and who can argue with the performance of that evil little snake xD

IIRC engine master builders did a test of this on YouTube and found it cost almost 40 f/lbs on a basic ford 5.0 running stock exhaust vs what most ppl do, full length headers and dual 2.5" all the way back... the flow and scavenge went to hell.

BUT... full length headers are the first mod I do to any car I get... I love that sound!

FINWOLF

I was told and don't know how true it is that you lose a little low end torque on a street car with open pipes. I want to run open pipes but cant get the
baffles out of my side pipes. I guess in to long and rusted in.

theandies

I think the article explains the pressure wave pretty good and makes sense to me. Like I said it's a pretty good read.

v2racing

Open pipes often allow reversion waves to travel backwards through the exhaust, back though the open exhaust valve and out the intake valve during overlap, reversing intake flow. This is usually a problem in the low end or mid range. It can be mild and just cause a loss of power in the rpm range it occurs, or if severe it can cause misfires. It has nothing to do with back pressure. Back pressure is always a bad thing!

Mike

71 Vert LS1

Just my .02 from some info from a friend of mine that used to build replica Cobras for a living. Due to the side pipes the sound as you are sitting in the car will not sound as good as some following you from behind. Two dedicated exhaust paths that sound different due to firing orders. Open exhaust on any car or truck on the street is annoying. Typically it's on a beat up truck where they cut off the cats and run the exhaust out the back. Remember the just because it's loud doesn't mean it's fast. Same goes for Harleys.

terrys6t8roadster

Open side exhaust disadvantages: A; tennitis [did I spell that right] ya know that constant ringing you hear caused by loud consistant sounds. B; you cannot hear the passenger or then again that maybe a good thing. C; If you want to play every law enforcement person can hear you for at least 1 to 2 miles. T

naramlee

oh that's cool! I never thought about why they sounded diff, but that makes total sense!!!

car junkie

You can lose power removing exhaust back pressure if the fuel and air intake isn't modified to compensate for the inevitable leaning out condition less back pressure creates.