POLL: C3 True Dual Exhaust

[Glensgages]

... A non-heated sensor won't get a correct reading at the collector.

Anybody got a Part Number on a heated O2-sensor for my '82? I'm thinking headers, true duals, & FlowMasters, or 3.73 gears (maybe BOTH?) over the coming winter. Anybody with headers/duals on a other-wise stock Cross-Fire? Did the free-flowing exhaust mess-up the stock ECM??? THANKS in advance.....GLEN!!!!!

 

[Crickett]

I'd say either way. As long as the exhaust system doesn't run into 1 pipe.

 

[Doug78]

Arizona tests cars 1967 and newer. I planning on true duals with 2 cats, they don't look under the car, however did a 1978 L82 have an AIR pump. Mine doesn't and no fittings on the exhaust manifolds + emissions lable is missing. I would hate to have to install a complete AIR system, $$$.

 

[mvftw]

Yes, a '78 L82 had the air pump, but the L48 (non cal.) did not. Maybe it's a L48. What's the 5 digit in your vin? L=L48, 4=L82. I just put in true duals, no cat in my '78.:cool

 

[Doug78]

The fifth digit is a 4, it's the original L-82 engine. Why would someone put L-48 manifolds on it and remove the AIR pump? I could see getting rid of it to put on headers, but why remove it if not modifying the engine?

 

[mvftw]

Why Not...someone else put on headers on their car and the next best & cheapest thing is to remove the smog and put on maybe free manifolds. Not a crazy idea...

 

[LanceB]

Smell

I have true duals on 81, no cats and in response to someone elses thread, there is an exhaust smell. Wife hates it and often won't ride in it because she says it makes her clothes smell like it also. I have thought about putting high flow cats on it but man it sure does run and sound good.

 

[JJS]

I have true duals on 81, no cats and in response to someone elses thread, there is an exhaust smell. Wife hates it and often won't ride in it because she says it makes her clothes smell like it also. I have thought about putting high flow cats on it but man it sure does run and sound good.

HA! I sure can relate to that. If there's a down side to having duals (and I can't think of one), it's the exhaust smell that clings to your clothes. I have to use the higher octanes in my LT-1, and the exhaust sure does seem to cling to my clothes. Only happens if you hang around inside the garage as it warms up. Something about it smells really sweet, though. Not as sweet as those duals sound, but sweet none the less!

 

[74bigblock]

I haven't read any of the other posts in this thread.

"True Dual Exhaust" Specifically means that there is one exhaust pipe for each exhaust manifold, and that they do not scavange off each other. Therefore I voted no.

 

[venom94558]

I would say check for an exhaust leak, thats what it sounds like to me....

 

[ruby76]

to me, "true duals" simply means the exhaust from the driverside of the engine never touches exhaust from the passenger side, two complete separate pipes, Cats are just more stuff to go through., so I voted "EITHER WAY"

IMO an x-pipe or h-pipe isn't "True duals" but are still considered regular "duals"

 

[Doug78]

All Corvettes have had dual rear outlets, so unless you have an exhaust leak the only other thing to consider is that maybe the catalytic convertor serves a purpose. If you go to a "true dual" exhaust running dual cats as well should not hinder performance very much. Keep in mind that L-82 Corvettes were putting 200+ HP thru a single cat that had very poor flow. Help clean up the air and run some high flow cats.

 

[Koop]

My early '69 350/300 came new with a smog pump.

 

[Paul Borowski]

I've had "1974 style" true dual exhaust on my Silver '75 L-82 coupe since 1991. In Ohio, anything you register as either "collector's vehicle" or "antique vehicle" has no emission testing required.

 

[Eddie 70]

I don't have to do emissions testing so I would say either way is true duals. If you must have cats, use high flows and the car should never know they are in place as far as flow is concerned.

 

[Evolution1980]

Woohoo! Another thread resurection!...

"True Dual Exhaust" Specifically means that there is one exhaust pipe for each exhaust manifold, and that they do not scavange off each other. Therefore I voted no.

You aren't considering one cat on each side.

Right now, I'm running "true duals" as most like to say here. No where do they meet. However, because it's about getting more power, I am likely going to put in an X-pipe this year.

RE: X-pipe versus H-pipe... From what I've been reading, there's actually little difference in terms of what they are supposed to do. I thought one improved HP while the other improved torque. The more I read, they are about the same, but that the X-pipe is better because it impedes the flow less than an H-pipe. The logic being that when you are going for the best air flow, an H-pipe requires a 90° corner for airflow to split into, versus a smoother 45° bend where the two sides join, then split back out.
I think I read this from one of the Corsa engineers. However, only dyno results would give the truth. And not many of us have the resources to test 3 different sets of exhaust.
If/When I do mine, I will be sure to have a recent baseline dyno run and then an "after" test to see what comes up.

 

[grapeknutz]

Half true...'74 had duals and smog. Smog started everywhere in '71 and just got worse...

Actually the smog controls started in 1966!

 

[zachh]

I got Hooker Sidepipes with Glasspacks.... I love 'em!
zachh

 

[Jerrylee]

Duals...

The cats however small are a restriction.....It shouldn't be to hard to find a garage who will give u a sticker....good luck...Jerrylee///

 

[Twin_Turbo]

Absolutely do like the man says... A non-heated sensor won't get a correct reading at the collector.

Joe

Why not? It will get plenty warm there, the stock O2 sensor is all the way back in front of the cat and it's the cat con that provides most of the heat for the sensor there. A heated O2 will result in a somewhat faster closed loop engagement but it should be hot enough in the collector area.

Here's a system I built for a friend's 82, tig welded true dual 2.75" stainless w/ 2 cat cons, equal length system.