True dual exhaust

[eants]

Let’s say I have a friend who owns a car very similar to mine. It is a stock ’76 L48 with the infamous 2-1-2 exhaust system. This friend is looking at going to a true dual exhaust system. Being environmental conscience, this friend knows of the adverse effects caused by removing the factor, very restrictive, cat-converter from the exhaust system.. However, this friend would really like to improve the performance of his L48 without having to do any major modifications to the engine. He thinks if he were to improve the exhaust flow, this would meet his desired results. He is also wondering about the other environmental components on his vehicle and would like to know how to deal with those. I.e. EGR, PCV……

Please take it easy on my friend as he is new to the corvette community.

 

[78SilvAnniv]

Hi eants!
How strict is your friend's state about vehicle modifications, like what sort of testing or inspections are done?
I don't have the knowledge to answer the questions you posed, but someone will be along shortly who can.
Heidi

 

[74bigblock]

Here's a low restriction replacement cat:
http://www.ecklers.com/product.asp?dept_id=157&pf_id=31769&mscssid=8L6EFMTA3THG9G6M4QNU31A99FPKFESA

Or you could take it to a local exhaust shop. They can custom make new pipes for you... either from your current manifolds, or you can pick up some performance headers (will give you a significant performance inrease over stock manifold). Just let the shop know you want to retain emissions (i.e. cats and smog controls).

Header example:
http://www.ecklers.com/product.asp?dept_id=160&pf_id=43505&mscssid=8L6EFMTA3THG9G6M4QNU31A99FPKFESA

Since my car did not have cats to start with, I went with Hooker headers and sidepipes:
http://www.holley.com/HiOctn/ProdLine/Products/ES/ESHHSCH/Sidemnt.html

 

[Copdogcorvettes]

As to the EGR and PCV, They are not hurting the perforance and do help make the motor run cleaner. You can leave them alone unless you plan on make other major changes to the motor, (cam
heads, intake & carb, etc.)

Gary

 

[bossvette]

In my part of Ohio we can get away with most anything so I run Hooker Header sidepipes for a nice SOUND

You can get chambered exhaust from most of the Corvette Suppliers which will bolt up to your stock exhaust or headers.
you have many options to choose from including "stock sidepipes"

If you want to stay "enviornmental correct" you can do as 74bigblock said and take to a muffler shop for a custom job
check out Cruise-fest 2004 we should be getting the registration page up any day now.
Craig sr

 

[Bob Chadwick]

I have true duals on my 77 with 2 1/4 inch pipes and free flowing cats.

 

[Stallion]

In my part of Ohio we can get away with most anything so I run Hooker Header sidepipes for a nice SOUND

:eek :eek WOW!!!!!! That sounds amazing. So you just run the side pipes right down then? That is great. I wish I could get away with side pipes in NJ. I would love that roar.

 

[74bigblock]

Craig,

I'm glad you talked me into the Hookers a few months ago. I still don't have them completely installed (drivers side is touching front fender), but if she sounds as good as yours :dance Hehhehe OMG I have 454 bored 30 over. It is going to sound insane.

Are you running those open, or do you have the Muffler insert or the glass pack insert in there? I'm anxious to hear back!

Dave

 

[bossvette]

Dave
I have the glass pack insert about 4+ years and 30,000+ miles through them your big block should sound meaner yet and be worth the effort. I will try the STS baffles next.
Craig sr

 

[Stallion]

Why would you have to put inserts in the pipes? Does it make them sound better? What does that do to back pressure?

 

[Copdogcorvettes]

All most all states require some sort of noise reduction device installed on the exhuast system for street use. That is why you install a muffler or baffle device in the side pipes.

Gary

 

[Stallion]

I see. Do you think you could get away with one without the insert(s)?

By the way, NICE VETTE, Copdogcorvettes!!!

Stallion

 

[74bigblock]

It's all legal until you get pulled over or get your emissions test notice With that said...

From what I understand on these side pipes, you need something to quiet them down a bit .... the exhaust port is next to your ear, so unless you want to go deaf or wear plugs... best put sompin in there.

 

[bossvette]

Stallion
check with some other jersey Vette owners, you may be able to slip the stock side-pipes from an earlier shark thru using "historic" plates or whatever they call them since your 78 is 25 years old now.
I had sidepipes on a Sunbeam Tiger and got them thru NJ inspection many years ago by telling them they were factory installed. Since none of the inspectors had ever seen a Tiger they didn't know any better.
Good Luck
Craig sr


ps as far as no inserts I really doubt it our local Corvette Club runs an autocross and one year they forgot to specify "mufflers" and several showed up with the inserts out and they were LOUD

 

[atmmac]

just give the guy a large tip it wont be a problem.

 

[Mike Carter]

I have the JBA CATS with chambered exhaust , no mufflers, sounds good, performs excellent.

Mike

 

[Stallion]

But for historic plates, don't you need to be of certain age to drive the car? I think I remember reading about them, you have to be over 21 to drive a car with historic plates. And I'm only 17. Or maybe that was something else?

Because if I can, I will get the historic plates on her.

 

[MaineShark]

I have stainless dual pipes from Mid-America, with stainless Dynomax UltraFlow mufflers. I'm very happy with that set-up.

As to the EGR and PCV, They are not hurting the perforance and do help make the motor run cleaner. You can leave them alone unless you plan on make other major changes to the motor, (cam heads, intake & carb, etc.)

Actually, not only don't they hurt, but the PCV significantly increases engine performance. Applying a vacuum to the crankcase (up to maybe 15 inches or so) will improve performance and make the engine last longer.

Joe

 

[74bigblock]

ps as far as no inserts I really doubt it our local Corvette Club runs an autocross and one year they forgot to specify "mufflers" and several showed up with the inserts out and they were LOUD

Hehehe... I am so tempted to run them open!

We sent my headers back to Hooker. We are still waiting to hear back from them. They totally did not fit on the drivers side, pressing up against the fender. We found that the engine mounts were original stock by comparing to another '74 454 in town. If Hooker decides not to replace them, how much clearance you think I would need to prevent my fender from melting? Should I shave a little out?

Dave

 

[eants]

I appreciate everyone’s help on my friend’s dilemma. I think he has made up his mind to go to a true dual exhaust. Since he will not be driving it day in and day out, there will be little impact on the environment.
Now if I can just get away with dumping my old oil into the ditch I will be happy.
JUST KIDDING!!!!! I religiously take spent oil to the proper facilities.

Bossvette, Tell me more about the Cruise-Fest 2004?