Exhaust Resonator Question

[Johnny5]

On my previous 1994 LT1 i deleted the resonator which gave a deeper rumble in the exhaust (sounded very nice). I was thinking of doing the same with my 91 ZR1. Doing this won't throw any codes will it? (the service manual says replacement of resonator assembly will require replacement of both mufflers) And has anyone tried this yet and kept the stock mufflers? How does it sound? I originally wanted to put a corsa on but I'm waiting to do my tuneup first....injectors, coil packs. wires, fuel filter and maybe the fuel pumps.

[GOLDCYLON]

On my previous 1994 LT1 i deleted the resonator which gave a deeper rumble in the exhaust (sounded very nice). I was thinking of doing the same with my 91 ZR1. Doing this won't throw any codes will it? (the service manual says replacement of resonator assembly will require replacement of both mufflers) And has anyone tried this yet and kept the stock mufflers? How does it sound? I originally wanted to put a corsa on but I'm waiting to do my tuneup first....injectors, coil packs. wires, fuel filter and maybe the fuel pumps.


No it wont throw any codes a lot of folks have went to x pipes and switched out the exhaust as well. However you will pick a resonance issue between 1200-1800 RPMs.

I also a spare Corsa resonator if your interested.

[KILLSHOTS]

That was my "STEP 1". I didn't notice any difference. I'm in the minority, though, as a couple of other guys have done the same thing and really liked the extra rumble. My advice: remove the resonator AND the mufflers...it sounds amazing!

[WARP TEN]

Goldcylon is right. The ZR-1 engine has pronounced natural resonance at two rpm points, about 1800 and about 3400. I believe he is right that the center resonator handles the 1800 rpm frequency and the mufflers handle the 3400 rpm frequency, although it might be the reverse; can't remember. Both contain what are known as Helmholtz Resonators, essentially empty containers specifically sized to damp down the resonant frequencies at those rpm points. Deleting the stock 91 resonator should provide a modest performance gain as the early resonators were quite restrictive. See Marc Haibeck's website to more on that.--Bob

[Johnny5]

No it wont throw any codes a lot of folks have went to x pipes and switched out the exhaust as well. However you will pick a resonance issue between 1200-1800 RPMs.

I also a spare Corsa resonator if your interested.

How much did you want for it? And whats the difference if i just get meineke to weld an x pipe?

[Johnny5]

Depending on the price welding thr nex x pipe or resonator i may just buy a used corsa or new obx after i fix my fuel issue. I want it to have a nice deep rumble but not too loud. I love the way my brothers 04 Z06 sounds (stock titanium mufflers).

[GOLDCYLON]

How much did you want for it? And whats the difference if i just get meineke to weld an x pipe?


PM Sent. The difference is you will pick up significant resonance and your exhaust will be louder. The CORSA resionator flows better than stock and you wont have the resonance issue.

[mike100]

I've done it and it sounds good. Still has 90 percent of the factory designed non resonating easy going exhaust sound with a little more growl. I think the mufflers have the bulk of the restriction, but maybe there is a few hp in the resonator also.

Once you take the factory mufflers off though...oh boy does it get loud. You need to have a single outlet muffler scheme to keep it reasonable.

[max76]

I'll like to put an x pipe on my b&b exhaust...the sound is amazing, I love it!!!
Someone have a used 3" x pipe?

[edram454]

the resonator is a power robber. I had a flowmaster force II system and I removed the resonator and the large 3 chamber mufflers and just placed 2 2chamber old school flowmaster 40 series with minimal obstruction. It is very loud. It has mind numbing resonance but I feel much more power and free revving unlike before. the resonator also weighs a ton along with those large stock mufflers. I cut the weight and greatly reduced back pressure. My z sounds very nasty, way nastier than those ls motor cars. when the secondaries open all hell breaks loose. I dont drive it much but when I do I like to be noticed and I am!!

ed ramos #3028

[edram454]

by the way, I have long tube headers and no cats either... very straight free flowing exhaust like they ran at the ft. stockton record run!!

[Okiedoke]

Goldcylon is right. The ZR-1 engine has pronounced natural resonance at two rpm points, about 1800 and about 3400.

Well, that certainly helps explain things. I've been getting these annoying vibrations (okay, maddening vibrations) near these RPMs and my mechanic tracked it down to a busted resonator. So now I need to look for a replacement.

[Okiedoke]

PM Sent. The difference is you will pick up significant resonance and your exhaust will be louder. The CORSA resionator flows better than stock and you wont have the resonance issue.

Goldcylon, do you have the model number of this CORSA resonator? Would it adversely impact smog tests? Do you know if it's still possible to purchase a stock resonator?

[WARP TEN]

Goldcylon, do you have the model number of this CORSA resonator? Would it adversely impact smog tests? Do you know if it's still possible to purchase a stock resonator?

The Corsa resonator would not adversely impact smog tests although visually it is slightly different from the stock one. Lee (LGAFF) has a used Corsa system for sale listed in the parts for sale section. --BOb

[Gunny]

Corsa resonator is 2.5" inlets/outlets. To my knowledge it is not available as a separate part, but I have seen a used Corsa resonator a couple of times over the past 10 years or so.

OEM resonator is 2.75". Again, AFAIK these are no longer available but can sometimes be found used. If you go OEM try to find a 94 or later including the 96 LT4 ... these are the least restrictive and work very well. A good exhaust guy can fab these to whatever setup you have.

Other resonators/X-pipes et al ... I doubt you will find anything in 2.75 diameter but only 2.5" or 3.0". Search for Craig's (Hawaii ZR-1) solution for the center resonator ... I believe he discovered a good substitute.

[RussMcB]

Maybe, as a short term solution, install an H-pipe with 2.75" tubing to put in place of the stock resonator. That will get rid of the rattle. It will be a little louder - Not sure how much, but maybe the stock mufflers will keep the sound level reasonable.

[Gunny]

... install an H-pipe with 2.75" tubing to put in place of the stock resonator ...

this is actually a pretty good idea. in conversations with several Z-owners I'm learning that the H-pipe installed toward the front and eliminating the resonator might produce better results than an X-pipe. sounds like this might be a good time to give it a try ... if you do, please report your findings.

[C4Ray]

The Resonator keeps the drone down, so if you remove that or replace it, then you will have drone and drone is terrible for long term hearing. Those Corvette engineers back in the day did their research with the stock exhaust ... It is a pretty good system as is!

[Okiedoke]

OEM resonator is 2.75". Again, AFAIK these are no longer available but can sometimes be found used.

There seems to be a 1990 complete exhaust system listed in the registry market place. Does anyone know if there are any differences between the '90 and '91 exhaust? If not, would it make sense to swap out the entire exhaust system instead of just the resonator?

[Gunny]

Does anyone know if there are any differences between the '90 and '91 exhaust? If not, would it make sense to swap out the entire exhaust system instead of just the resonator?

Someone more knowledgeable may chime in ... but I think the 90 and 91 systems are essentially identical. I'm fairly certain all the pipe diameters are the same @ 2.75" and that the resonator is the same. Not sure if the 91 still has the twin tip mufflers or not. If so, it would probably be easier to swap an entire exhaust system since it involves no more than unbolting the two pipes from the back of the engine and taking loose 6 hangers ... no need to go to an exhaust shop for welding, etc.

The big advantage is retaining the OEM look without a lot of effort. But, in an effort at full disclosure, the early OEM exhaust systems are rather restrictive (resonator & mufflers) and do not allow the LT5 to breathe as well as the later OEM systems or other, less restrictive 3rd party systems.

[RussMcB]

Not sure how pertinent this is to this discussion, but I'll share: We discovered my original exhaust (67k miles) was extremely restrictive, like maybe clogged cats or something. My HP was a bit below expected on the dyno (even after a Haibeck chip), making it an easier decision to update to headers and a new system. It's nice now - power-wise and sound.

[rkreigh]

the stock 2 3/4 exh with a nice x pipe and magnaflow stainless muffs makes a very nice budget system that has great fitment

also nice is to install the c6 exh tips with the flapper

best of both worlds, quiet when needed for long drives

and aggressive "on demand" with the right setup or a simple on/off if desired

2 3/4 pipes are high quality and kinda too good to throw away.

they will likely support enough flow for a very aggressive build and save a few $$ for the rest of the needed mods.

[Okiedoke]

The Corsa resonator would not adversely impact smog tests although visually it is slightly different from the stock one. Lee (LGAFF) has a used Corsa system for sale listed in the parts for sale section. --BOb

If I go the Corsa route, should I just use the resonator or the entire system, including exhaust? I've PM'd Lee to see if his Corsa system is still available.

[Johnny5]

I bought corsa and really like it. I wish Lee was selling his 3 months ago when I bought mine

[edram454]

i cobbled up my flowmaster system and got rid of that power robbing resonator and felt more power but the drone was completely ridiculous and unbearable. i recently bought a new corsa that was installed in my car and i hope to hear it in the near future. corsa is the best exhaust because it gets rid of drone and has a complete flow thru design that does not rob horsepower.

ed ramos #3028

[WARP TEN]

If I go the Corsa route, should I just use the resonator or the entire system, including exhaust? I've PM'd Lee to see if his Corsa system is still available.

Seems simplest to go with an entire system as you will know everything will fit together without any extra effort. Corse is a good system. I had one on my cars most of the time I owned them until I finally switched to stock with cutouts. --Bob