All: I know there are many YT videos on the subject of muffler deletion, but I decided to post what I have done very cheaply as compared to commercial muffler delete systems. My intent is to help others who might be considering this simple mod. It can be done for $64.

The car is my '84 C4 with an all-new Y-pipe and mufflers. I had a local Corvette shop do the under-car work as I prefer not to lay under the car while dealing arthritis. I've had the C4 with the new pipes for a week, all was well until yesterday when one of the freakin' mufflers fell off. They failed to properly secure the muffler clamp to the tip of the Y-pipe. It wiggled loose and dropped to the ground. I was not happy, but it would have taken less time to reconnect it properly myself than calling the shop much less bringing back. I realized that the car had a very cool growling sound with one muffler removed. That motivated me to consider removing the mufflers. After watching some YT videos, I quickly learned that removing the mufflers was a widely done mod plus there were commercial kits available to replace the muffler.

My approach was to acquire two 45-degree elbows and one turn down tip, I connected the elbows together as seen in the pix and mounted them to the Y-pipe end. The tip just touches the hanger. I will weld the turn down tip to the elbow and weld that elbow to the elbow that connects to the Y-pipe. Welding will be done off the car in my shop. (Note the car is not jacked up.) I will weld a tab to the tip so it can be bolted to the hanger. I will u-bolt the elbow to the Y-pipe so it can be removed. In other words, the muffler was replaced by two 45-degree elbows, and one turn down tip. The elbows are Nickerson #548754, 2 1/4" diameter ($9.99/each at O'Reilly Auto Parts), the turn down tip is Nickerson #548604, 2 1/4" diameter ($11.99 O'Reilly Auto Parts).

If your car's Y-pipe and/or mufflers are rusted together then you might have to jack the car up to cut them loose. Your call on that.

Two 45-dgree elbows connected together with a turn down tip end. The right-side elbow slips over the Y-pipe end and will be u-bolted. A tab will be welded to the tip (at the black mark) so it can be bolted to the existing hanger.

The tip just touches the hanger. The tab will slip between the sides of the hanger and will be secured by a bolt. The tip is not visible from the rear looking at the bumper. The purist might consider connecting a chrome tip extension which will make it visible. I might do it myself, otherwise, I don't think it's that big of a deal. Note the car is not jacked up.

 

84s were supposed to have turndowns anyway. Nice job.

 

These photos show the weld connections as described. I brought the muffler with me to my local O'Reilly's then asked the counter guy to bring out some elbows. We tried a 90-degree elbow first and it clearly would route the tip way off center. We then tried a 45-degree elbow which showed a much better orientation of the tip. A second 45 elbow was then added to bring the tip to overlay the center line of the muffler. Success!! The turn down tip was then installed and was a near perfect replacement for the muffler from the Y-pipe to the hanger. The elbows and the tip are inserted completely into each other so there are several inches available to extend the entire pipe. What is shown here works for the '84, other year models of the C4 might need more length in the pipe. If it requires less length, then you would have to cut one or more section shorter.

I forgot to mention that I will paint the entire visible portions of the Y-pipe and the exhaust extensions with "high temp" black paint. Seeing all that shiny aluminum under the body from the rear is tacky.

The sections will be totally inserted into each other then welded at their joints. That leaves several inches which can be used if other year models of the C4 require a longer replacement pipe.

One-inch slots will be cut into the elbow that mates with the Y-pipe so the u-bolt clamp securely crimps onto the Y-pipe.

This is the 'straight' pipe overlaying the muffler. The turn down tip is slightly longer than the muffler but is not an issue when mounted, in fact, the straight portion of the tip is where a tab will be welded for the hanger. The black hash mark is where the tab will be welded. The turn down tip is centered at the cutout on the 'bumper' but not visible.

All this shiny piping will be painted black with high temp engine paint rated at 500F. Fingers crossed it does not burn off. If it does, oh well...

 

Did you delete your cat also?? I deleted my 84 cat and had a true dual exhaust system installed with original style mufflers.

 

No, cat still there. I got involved with the muffler delete project when one of the new mufflers fell off. When I got home and heard the sound of the car with one muffler, it hit me that no mufflers would be very cool. I now will have two very expensive, like new mufflers not being used. I might post them on Craigslist and see if there are any takers.

My goal with this C4 is to make it more comfortable to drive. It has been mostly idle in my garage since 1999. It belonged to my wife who died in 2001. I bought it for her in 1997 when she became ill with cancer. She was able to drive it for two years then was not able to drive as her health deteriorated. My daughter, age 19 at the time gave me orders not to sell her mom's Corvette so there it sat for 23 years. I get it on the road a few times per year but in the last year it just sat unused. I decided to get it road ready and have been upgrading it since early July. Replaced the starter solenoid, four new shocks, greased joints, changed oil/filter, repaired and replaced the interior light timer, replaced rear tires, installed new Y-pipe and mufflers, adjusted steering (toe in/out). I have new weather stripping ready for install.

My primary car is a '98 C5, secondary ride is a 2012 Dodge Durango SUV. Also have a 1987 Dodge "Raider" 4X4 and a Ford E250 Van.

 

Done!! I removed the right-side muffler, fab'd the straight pipe, added tab to bolt up to the hanger, painted everything in Black Engine High Temp semigloss. This paint is rated at 500F which I take with that proverbial 'grain of salt'. I ran the engine, so the coolant read 195F on the instrument panel. I then shoved a K thermocouple into the left side pipe about 12" deep. The display on the Fluke 52 Thermometer read 291F. This, I admit, is an entirely crude measurement but does show that if these numbers are accurate, the "500F" paint will hold up to normal operating temperatures while driving the car.

Left side pipe exhaust read 291F when the coolant temp was 195F. The instrument is a Fluke 52 Thermometer with K type thermocouple inserted into the pipe by about 12".


Left side pipe.

Right side pipe.

Y-Pipe connected to left and right pipes. All pipes painted with Engine High Temp Black.

The very low-lying Y-pipe has been corrected, see post #12 below.

 

Update: I drove the Vette yesterday and noted the sound wasn't nearly as loud as you would expect without mufflers. My guess is only a few dB over the muffled sound. The route was only 8 miles so it's possible a much longer time on the road would be a better of test of elevated drone induced fatigue.

The bottom line: If you are considering new exhaust and/or mufflers, don't waste your money on mufflers, go straight pipes.

nnnn

 

Probably dropped a lot of weight off the rear by losing the mufflers. Nice work, sir.
I may try this on my 91.

 

I just checked and one muffler comes in at 14lbs. One side is held up by the hanger while the other is attached to the Y-pipe. This design is totally nuts. There is no hanger to grab onto the Y-pipe at or near the cat. The pipes are 3" off the ground, totally stock. I don't think that is even legal. If you run over road debris, you can really mess up the Y-pipe. What am I missing? I've watched videos and checked photos of the C4 and it ain't just mine.

 

There is supposed to be a hanger on the inlet side of the cat.

 

When I get motivated, I'll get under it and check. I assumed the Corvette shop who did the Y-pipe and mufflers ensured hangers were in place and connected.

 

Got motivated this morning. Put the front end on ramps and snapped pix of the pipe going into the cat's inlet. As seen in the pix, the pipe is parallel with the underside and snuggly fits. So, the hanger is in place and supports the pipe and catalytic converter. The Y-pipe is sloped downward from the outlet of the cat going rearward. It was obvious to me that the mufflers (removed) and my straight pipes needed to be adjusted so the Y-pipe is raised higher. I loosened the u-bolt clamps and pipe hanger tabs. I used a mini floor jack to raise the Y-pipe up about one inch then tightened all bolts. It now is much higher and snuggly connected to my straight pipes and their hangers. I'm OK with it now. The design engineers weren't nuts after all, I failed to properly align the Y-pipe and my straight pipes.

This shows show the exhaust pipe off the manifolds into the cat's inlet and the Y-pipe hanging off the outlet of the cat. The Y-pipe clearly should be running parallel with the underside like the front pipe.

The camera flash did not cooperate, but the Y-pipe can be seen raised up by about one inch. I loosened the u-bolt clamp connections to the Y-pipe and the hanger tabs I welded to the straight pipes. With the Y-pipe jacked up into correct position, the straight pipes were securely clamped to the Y-pipe and the hangers. This kept the Y-pipe in its elevated position. I should have done this when I installed the straight pipes.

 

Congrats for getting her back road worthy. I acquired my mom's '84 years after she passed of cancer. It's just about done as well.

 

One thing I strongly encourage '84 C4's owners do is to change the interior lights into LEDs. The reason is the incandescent bulbs (floor well, door, cargo) draw 5 amps which flows through the delay timer. They used a transistor in the output of the timer which that 5 amps flows. I don't know the specs of that transistor (its labeled as GE8516 and doesn't show up in any search or in any of my literature) but it has failed in both of my '84 C4's. (I mention in my various postings that I also have a '98 C5 but never mention the other C4 I had). Anyhow, by changing to LEDs you get much brighter lighting with much less current, truly win-win. I measured 1/2 amp with LEDs so the transistor will not overheat and fail, an alternative is to use the delay timer's output transistor to pull in a relay making the relay pass those 5 amps.

 

LEDs are nice. Just not for me. To fatiguing even with a 4300k temperature in interior lighting. Forward lighting doesn't bother me for some reason. They've switched the roadway lighting to 5500k and it's horrible for night driving. Just glares off everything. The only thing I run LEDs on is my boat. I paid a lot for them but they aren't fatiguing even on for hours.

 

I think you missed my point in replacing INTERIOR incandescent bulbs with LEDs. The primary reason is to reduce the current flowing through the delay time output transistor. It has nothing to do with exterior lights, color temperature, fatigue, etc...

 

No that's exactly what I was saying. I hate LEDs in cab, out of cab anywhere. They are annoying and blinding in dome, map, courtesy lights whatever. It's great to lower the amperage for sure. I just clearly stated that for me, I don't like them but they are nice. Particularly for what you are accomplishing, they are by far the best option to do exactly that. I should've been a little clearer rather than going off on a tangent as to why I personally don't like them in most situations. Sorry.