81silverbullet

I have the factory exhaust still on my 1981, but I am wanting to place a true dual exhaust 2 1/2" system with Flowmaster mufflers. One shop says they can do it no problem for about $400...and another shop says that they cannot change anything before the cat. My question is...if I just change after the cat and go with 2 1/2" pipes and the flowmaster 50 series mufflers, will I see as much improvement as a true dual exhaust system? Are the Flowmaster 50 series mufflers a good choice? I am not looking for super-loud sound, just much better than it is now.

Thanks for the help.

Steve

AGVI

If you want to see a noticeable difference go with the true dual pipes...end of story.:smash:

...and welcome to the forum! :party:


[Modified by AGVI, 9:50 AM 10/14/2003]

1972 Shark

I would go with the true duals with a crossover H pipe, if your car is emisions exempt, then get rid of the cats too. The Delta 50 series is a good choice or the Dynomax Super Turbos sound real good too.
Good Luck and welcome to the Forum!


72, 350, TH400, with a few bolt ons:D
:cheers:


[Modified by 1972 Shark, 10:01 AM 10/14/2003]

81silverbullet

AGVI,

Thanks for your opinion and for the welcome. Your vette looks great! It looks like your front bumper is part of your hood surround. Is that all one piece?

Steve

81silverbullet

Mike,

What exactly is the purpose of the H-pipe? I've read a lot of posts where it is mentioned, but haven't seen a good explaination. Thanks for the welcome. this is my first Corvette and I been dreaming of owning one for many years.

Thanks,

Steve :steering:

Fast81

You already have 2.5" pipes after your cat, so only the mufflers would need to change.

What are you looking for....sound........perf..........both?? ? For just sound the muffler change should be enough. All the other mods satisfy the right foot. If you do go true dual, you're going to want to get rid of the stock exhaust manifolds as well. Ditching the cat will also bump up the sound level a bit -- kind of acts like a pre-muffler.

You can get the entire true dual system from MidAmerica for around $275 plus mufflers.

81silverbullet

Dean,

I didn't know I had 2 1/2" pipes...I should have checked before posting. :sleep: I am looking for a performance increase and sound also, not too loud to draw the wrong attention though. I'm not sure what manifold I have on it now; the car was Bubba'd when I got. The engine is from a 1978 Vette and the exhaust manifolds are not cast iron either. Not sure what they were in '78. How much hp do you think I would gain by going with a true dual exhaust?

thanks,
Steve

Fast81

Most claim 20-30 real HP with the true dual. Of course, the stouter the motor; the more HP you'll see. If your 78 engine is bone stock, the dual will probably feel like 2 more cylinders. As far as the exhaust mans, look em over, if they look like most of the headers in Summit you're in luck. If they look like all 4 pipes merged into 1 about 6" down from the heads, you'll feel less punch than a header would give.
Just remember to check your local emissions dictates before removing the cat by going dual.

UKPaul

Hi Steve,
When I got my '81 the cat had been replaced by a length of pipe, so there was no cat in the system causing a restriction. Fitting a MA true dual system was the biggest seat of the pants power increase that I've so far done to it. I was told anything up to 30hp could be gained with true duals (which I didn't believe), but after fitting them I wouldn't be at all surprised if I got another 30hp out of it. That single pipe (or cat) was a major restiction in the system. With true duals the manifolds are a restriction (assume you've got the later tubular ones?). I fitted Headers a few months back & the power increase was nothing like true duals gave.
An "H" pipe balances the exhaust pulses between the 2 banks of cylinders, giving a slight increase in power. I fitted one purely to quieten the pipes down a bit (my mufflers are Monzas which aren't exactly public friendly). An "H" pipe will also stop the popping & banging that can occur with duals on the overrun (shutdown?).
I initially ran my MA duals with the stock mufflers & they didn't sound to bad. If you want to keep it fairly quiet don't fit Monzas!!
:cheers:

vetteonr

I converted my '80 to a true dual exhaust with a kit from Mid-America.:thumbs: My car has headers so I had to do some modifications :smash: I also went with flowmaster 40 series mufflers. What a difference this makes :eek: I never had it on a dyno so I couldn't give you hard numbers, but you will notice a huge difference :cool: One tip though, if you do this yourself, take it to a good muffler shop and have them weld it together. You won't regret it :hurray:

1972 Shark

The H Pipe balances cylinder pressures, it (by the experts explanation) gives the motor increased HP and Torque and balanced sound. An explanation I've been given is when you don't have an H pipe the motor is acting as two halves separately to produce power, by installing the H pipe you balance the cylinder pressures and engine power in the two sides to increase the effieciency of the motor = increased HP and Torque. It will also make a difference in balanced sound when you are at cruising speeds.
:steering:

Corvette_fetish

I would suggest doing some research because I always hear an "X" pipe configuration is superior to an "H" pipe, or simple dual. The stock 2-1-2 is definitely restrictive and must go. My Corvette mechanic specializes in custom exhaust, and he claims an "X" pipe is the least restrictive because it somehow creates a "suction" to help the flow. but hey, I'm just an owner, not a mechanic or a physics expert, so I'd suggest checking out every type of configuration, ask several specialists their opinions and pick what works best for you considering your needs and local emission restrictions.

vetteonr

Very good explanation 1972 shark :iagree: It makes all the sense in the world. I'm going to find a way to put an "X" pipe in mine. I'm convinced. :thumbs:

Fast81

UKPaul - are yours the Monza mufflers or the Monza twin-tip pipes ??

UKPaul

"X" is better than "H" for flow (if you think of gas hurtling down the pipes then the angle to turn through on an "X" pipe is a lot gentler than the 90* required with an "H"). With the MA system a custom made "X" pipe would be the easiest option to fit as the pipes run very close together under the x-member. Another advantage of doing this is that it will hold the pipes rigidly in place. If I could think of a gripe with my MA system, it's that the pipes were so close together that they'd sometimes hit each other over large bumps.
:cheers:

UKPaul

They're the twin tip type with not a lot in the way of silencing. They're very good at discouraging tailgaters :D

jrzvette

Am I right in assuming that neither an H pipe or an X pipe can be used with chambered exhausts? Or is there some way to weld either one in without destroying the exhausts?


[Modified by 6t9l4t6, 5:30 PM 10/14/2003]

mvftw

I just replaced my exhaust with true duals, but I went with 2.25" not 2.5" because 3 exhuast pros said stock Vettes like ours will run better with 2.25", not enough hp for 2.5", you ask them yourself. As far as the H v. X pipes. I went with the H (X is better) because the X-pipe should as close to the front (collectors) as possible. Because of the tranny location, you can not get that close to use the X-pipe at it's best. I also went with Stainless Flowmaster Delta 50's. Very happy with everything, sound and hp.

1972 Shark

When you say chambered exhaust I assume you are talking about the mufflers (example- Flowmasters, Dynamax Super Turbos), right? According to the folks at Flowmaster Mufflers Inc., they advise using an H pipe with their mufflers, for the reasons stated above. They also suggest putting the H or X pipe configuation as close to the vertical point where the exhaust come down from the manifolds or on headers it would be as close to the Headers as possible. I have not heard anything negative about the use of H or X pipe configuations with chambered (mufflers) exhaust.

:seeya


[Modified by 1972 Shark, 3:18 PM 10/14/2003]

mvftw

A Chambered Exhaust does Not use mufflers. The pipe itself has baffles in it. It's also loud. You can use a H-pipe with it.