Exhausting the issue
11-06-2016, 09:52 AM
#1
Zen Vet Master Level VII
Thread Starter
Exhausting the issue
So, not being able to leave well enough alone, I'm beginning to think of making a few mods to my 91.
I typically make an exhaust modification for both sounds and power. Everything from headers, to cat back to resonator deletes depending on the car.
I've been reading up on the ZR1 and can only find generic information on the factory exhaust (66k on mine) I do not know how good the factory exhaust is compared to aftermarket and/or if it is even worth messing with?
I've done enough You tube watching and listening to have confused myself
Does anyone have experiences (good and bad) to share so that I don't "step in it"?
Thanks!
I typically make an exhaust modification for both sounds and power. Everything from headers, to cat back to resonator deletes depending on the car.
I've been reading up on the ZR1 and can only find generic information on the factory exhaust (66k on mine) I do not know how good the factory exhaust is compared to aftermarket and/or if it is even worth messing with?
I've done enough You tube watching and listening to have confused myself
Does anyone have experiences (good and bad) to share so that I don't "step in it"?
Thanks!
11-06-2016, 09:55 AM
#2
Race Director
Member Since: Feb 2002
Location: Compound in the Grove, Ga.
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2020 C3 of the Year Finalist - Unmodified
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St. Jude Donor '16
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11-06-2016, 11:03 AM
#4
Zen Vet Master Level VII
Thread Starter
11-06-2016, 12:12 PM
#5
Drifting
Hi Bill--
Mods are something that are hard to stay away from with a ZR-1. There are many threads on the subject of exhaust systems on both this forum and the ZR-1 Net Registry forum. Best thing to do is get together with some ZR-1 buddies who have different exhausts and listen to and ride in the cars. Probably the best place to do this would be the Bowling Green Spring gathering or at a local Texas gathering. Lots of Texas ZR-1 owners. A key thing to remember is that the LT5 engines produce considerable resonance under moderate throttle at two rpm points, about 1,800 and 3,400 rpms. The factory system and the Corsa system do a good job of eliminating this through the use of Helmholtz resonators in the mufflers and the center resonator. On some aftermarket systems the resonance (or "droning") is quite intense and annoying, but not everyone is bothered by this. Though much dyno testing Marc Haibeck concluded that the Corsa systems produced the most horsepower gains, although that may have changed more recently. In 20-odd years of ZR-1 ownership I tested about a half dozen systems and ended up with Corsas for most of that time. I liked the sound and did not like resonance, so Corsa worked for me for many years. Finally ended with a stock '95 system and QTP electric cutouts to get silence when I wanted it and anything up to a straight exhaust at other times. But sound and loudness are both personal choices. Best thing to do is research all the posts and threads on the two forums and most importantly try a few on for size with friends. As noted on Marc's webpage, early stock center resonators are very restrictive, as are all year stock mufflers. Good luck! --Bob
Mods are something that are hard to stay away from with a ZR-1. There are many threads on the subject of exhaust systems on both this forum and the ZR-1 Net Registry forum. Best thing to do is get together with some ZR-1 buddies who have different exhausts and listen to and ride in the cars. Probably the best place to do this would be the Bowling Green Spring gathering or at a local Texas gathering. Lots of Texas ZR-1 owners. A key thing to remember is that the LT5 engines produce considerable resonance under moderate throttle at two rpm points, about 1,800 and 3,400 rpms. The factory system and the Corsa system do a good job of eliminating this through the use of Helmholtz resonators in the mufflers and the center resonator. On some aftermarket systems the resonance (or "droning") is quite intense and annoying, but not everyone is bothered by this. Though much dyno testing Marc Haibeck concluded that the Corsa systems produced the most horsepower gains, although that may have changed more recently. In 20-odd years of ZR-1 ownership I tested about a half dozen systems and ended up with Corsas for most of that time. I liked the sound and did not like resonance, so Corsa worked for me for many years. Finally ended with a stock '95 system and QTP electric cutouts to get silence when I wanted it and anything up to a straight exhaust at other times. But sound and loudness are both personal choices. Best thing to do is research all the posts and threads on the two forums and most importantly try a few on for size with friends. As noted on Marc's webpage, early stock center resonators are very restrictive, as are all year stock mufflers. Good luck! --Bob
Last edited by ZR1Bob; 11-06-2016 at 12:12 PM.
11-06-2016, 01:18 PM
#6
Safety Car
Whatever happens, keep the stock pipes. They are pretty good and have a unique diameter of 2.7 inches. If you end up with a really loud cat-back, it is good to have the choice to go back to stock for long trips or if you get pulled over too many times with loud mufflers.
The problem with the stock exhaust is a restrictive resonator and mufflers- the pipes are good. I've had tried pretty much all types of pipes on the LT5. The best thing for me was homemade vacuum actuated muffler flaps rather than going with a bolt-on system. Corsa was ok because it does not drone, but is just plain loud all the time. The 3" systems with x-pipes are loud as hell too. you have to get creative with the mufflers.
The problem with the stock exhaust is a restrictive resonator and mufflers- the pipes are good. I've had tried pretty much all types of pipes on the LT5. The best thing for me was homemade vacuum actuated muffler flaps rather than going with a bolt-on system. Corsa was ok because it does not drone, but is just plain loud all the time. The 3" systems with x-pipes are loud as hell too. you have to get creative with the mufflers.
Last edited by mike100; 11-06-2016 at 01:22 PM.
11-06-2016, 08:59 PM
#8
Zen Vet Master Level VII
Thread Starter
Originally Posted by mike10
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0;1593408739
The 3" systems with x-pipes are loud as hell too. you have to get creative with the mufflers.
I ask as I have a '15 Dodge Challenger Scat Pack that is my "daily driver" and one of the mods that is popular is to replace the the center section mufflers and remove the resonators. Here is my video that the muffler shop guys used as a promo:
BTW... The Challengers are stupid fast
Last edited by billschroeder5842; 11-06-2016 at 09:04 PM.
11-06-2016, 09:44 PM
#10
Zen Vet Master Level VII
Thread Starter
11-07-2016, 08:58 AM
#11
Tech Contributor
No resonator ='s Drone. If you want to keep your exhaust but want a better flowing OEM resonator put one in from a 96 LT4. Those are supposed to flow better than the ZR-1 factory resonators
11-07-2016, 11:10 AM
#12
Safety Car
Resonatorless it will grumble a little at 1900 rpm, but nothing like when you have a full aftermarket kit that doesn't have any acoustic engineering put into the design. If you get the chance, take a ride in any C4 with aftermarket pipes before you do anything.
11-08-2016, 07:22 AM
#14
That's the first mod I did with my 91..Headers and exhaust.....It doesn't seem like cost is an issue based on your toys so I would swap out both...
I'm running the OBX system......Its probably the least expensive of all the systems I priced and I am very happy with it.....It has a nice low rumble at idle, nothing too loud...Never heard a Corsa up close personally but they are very loud, yet, they do make the most horsepower but it's not a big difference in numbers as compared to other systems...The OBX I find will drone in sixth gear at 70-75 miles an hour......I really don't find myself in sixth gear all that much unless I'm doing 80-85 MPH, but there is a drone somewhat.....
The whole system was around 1,100 dollars shipped......I have not heard many other systems on the ZR-1 but the OBX sounds great when you get on it......
I would buy a complete system if I were you. when you see the stock manifolds up close you will see how restrictive they really are which will make that decision a good one.....
Another very good mod to do on the ZR1 is porting the plenum, injector housings and air horn to 36mm........Pete from Chicago did mine....He's on the ZR1 registry as Pete.......You remove the parts and mail it to him....
It was a 1,000 dollars to do the work plus the shipping which was 400 and it was money well spent.....Definate increase in power....
From what I understand the LT-5 is chocked from the factory....Pushing more air into them like any other engine will give you noticeable increase in performance....
I'm running the OBX system......Its probably the least expensive of all the systems I priced and I am very happy with it.....It has a nice low rumble at idle, nothing too loud...Never heard a Corsa up close personally but they are very loud, yet, they do make the most horsepower but it's not a big difference in numbers as compared to other systems...The OBX I find will drone in sixth gear at 70-75 miles an hour......I really don't find myself in sixth gear all that much unless I'm doing 80-85 MPH, but there is a drone somewhat.....
The whole system was around 1,100 dollars shipped......I have not heard many other systems on the ZR-1 but the OBX sounds great when you get on it......
I would buy a complete system if I were you. when you see the stock manifolds up close you will see how restrictive they really are which will make that decision a good one.....
Another very good mod to do on the ZR1 is porting the plenum, injector housings and air horn to 36mm........Pete from Chicago did mine....He's on the ZR1 registry as Pete.......You remove the parts and mail it to him....
It was a 1,000 dollars to do the work plus the shipping which was 400 and it was money well spent.....Definate increase in power....
From what I understand the LT-5 is chocked from the factory....Pushing more air into them like any other engine will give you noticeable increase in performance....