shanehutton Posted October 4, 2022 Report Share Posted October 4, 2022 We have been having issues with mufflers on our K20 powered civic. Every couple of events we end up with holes in our muffler and / or loose baffles. The last muffler was a baffled muffler from flowmaster or dynomax and it had a baffle come loose. The current muffler is a straight through dynomax muffler with packing and at its first event a hole appeared in the top of the case and we welded a patch of sheet metal over the entire top to get back out in the track. Now, two races later, the bottom has let go and all the packing blew out the massive hole. The system has a flex joint after the header, a resonator and small bullet muffler followed by the case muffler at the back. Everything after the flex is hung on rubber hangers but back just before the large muffler there is one hanger that is a 1.5” or so rubber filled square with not much movement. No abnormal pops and bangs on overrun and no large rich or lean issues. Any ideas on what is causing it and any ideas on mufflers that are quiet and would survive whatever is doing this better? Quote Link to comment Share on other sites More sharing options...
mender Posted October 4, 2022 Report Share Posted October 4, 2022 (edited) Looks like metal fatigue on the flat surfaces due to pulsation. A round muffler or one that has baffles internally welded to the flat surfaces might keep those surfaces from flexing and failing. Looks like fairly thin stainless on the case, a thicker mild steel case might survive. On our B18C Civic we run a round muffler about three feet after the header then a cheap box muffler under the rear bumper cover that dumps directly out the back. No issues so far. Edited October 4, 2022 by mender 1 Quote Link to comment Share on other sites More sharing options...
enginerd Posted October 4, 2022 Report Share Posted October 4, 2022 (edited) 38 minutes ago, shanehutton said: We have been having issues with mufflers on our K20 powered civic. Every couple of events we end up with holes in our muffler and / or loose baffles. The last muffler was a baffled muffler from flowmaster or dynomax and it had a baffle come loose. The current muffler is a straight through dynomax muffler with packing and at its first event a hole appeared in the top of the case and we welded a patch of sheet metal over the entire top to get back out in the track. Now, two races later, the bottom has let go and all the packing blew out the massive hole. The system has a flex joint after the header, a resonator and small bullet muffler followed by the case muffler at the back. Everything after the flex is hung on rubber hangers but back just before the large muffler there is one hanger that is a 1.5” or so rubber filled square with not much movement. No abnormal pops and bangs on overrun and no large rich or lean issues. Any ideas on what is causing it and any ideas on mufflers that are quiet and would survive whatever is doing this better? We have had great success with vibrant round/oval mufflers and resonators on our K24. We use two of these: https://www.summitracing.com/parts/vpe-1142?seid=srese1&gclid=CjwKCAjws--ZBhAXEiwAv-RNL6UKEdJ153SNXrbSDaaWFquu77ELnzi1R83prhIw17G4IWdhRc7i2RoCoZQQAvD_BwE Close to 100 hours on one, and we added the 2nd one because we were too loud about 30 hours ago. Edited October 4, 2022 by enginerd 2 Quote Link to comment Share on other sites More sharing options...
shanehutton Posted October 4, 2022 Author Report Share Posted October 4, 2022 Mender - I was thinking vibration but I was picturing it coming from the car to the muffler and your comment makes more sense. Enginerd - How quiet is the "ultra quiet"? I hate loud race cars and for 2hr stints even more, I am looking for something that car really cut the sound down. Quote Link to comment Share on other sites More sharing options...
enginerd Posted October 4, 2022 Report Share Posted October 4, 2022 (edited) 8 minutes ago, shanehutton said: Enginerd - How quiet is the "ultra quiet"? I hate loud race cars and for 2hr stints even more, I am looking for something that car really cut the sound down. We were mid-pack? on sound at Road America two weeks ago and nobody was loud enough to fail the sound checks that Bill Strong did that weekend. That probably doesn't help a lot... but I can't think of a different way to quantify it. Edited October 4, 2022 by enginerd Quote Link to comment Share on other sites More sharing options...
shanehutton Posted October 4, 2022 Author Report Share Posted October 4, 2022 Thanks Quote Link to comment Share on other sites More sharing options...
Ian Posted October 4, 2022 Report Share Posted October 4, 2022 1 hour ago, enginerd said: We have had great success with vibrant round/oval mufflers and resonators on our K24. We use two of these: https://www.summitracing.com/parts/vpe-1142?seid=srese1&gclid=CjwKCAjws--ZBhAXEiwAv-RNL6UKEdJ153SNXrbSDaaWFquu77ELnzi1R83prhIw17G4IWdhRc7i2RoCoZQQAvD_BwE Close to 100 hours on one, and we added the 2nd one because we were too loud about 30 hours ago. Same on our VQ. Good sound reduction, and haven't had any issues in over 100 hours. Quote Link to comment Share on other sites More sharing options...
Team Infiniti Posted October 4, 2022 Report Share Posted October 4, 2022 Borla of the same construction has given 5 years of trouble free operation, up till the case cracked from my lack of tailpipe hanger... while ordering another set I was reminded of their million mile warranty, a couple of pictures, and proof of purchase emailed to them, a week later a new set arrived in the mail FREE, no strings, they did not care the cracks were my fault. 9 2 Quote Link to comment Share on other sites More sharing options...
Technical Advisory Committee mcoppola Posted October 4, 2022 Technical Advisory Committee Report Share Posted October 4, 2022 1 hour ago, Team Infiniti said: Borla of the same construction has given 5 years of trouble free operation, up till the case cracked from my lack of tailpipe hanger... while ordering another set I was reminded of their million mile warranty, a couple of pictures, and proof of purchase emailed to them, a week later a new set arrived in the mail FREE, no strings, they did not care the cracks were my fault. I also recalled that Borla mufflers are lifetime warranteed. In fact, I may have gleaned this form 1 of Ed's previous posts. We've run borlas on all the Focus' we've built. Quality and looks are great - the sound is awesome too. A well sounding 4 cylinder engine, not a fart can. 2 Quote Link to comment Share on other sites More sharing options...
hotrod Posted October 4, 2022 Report Share Posted October 4, 2022 Cherry Bombs all the way! Quote Link to comment Share on other sites More sharing options...
TimS Posted October 5, 2022 Report Share Posted October 5, 2022 Spin tech is my choice. No packing Quote Link to comment Share on other sites More sharing options...
shanehutton Posted October 5, 2022 Author Report Share Posted October 5, 2022 I ordered a Borla as I like the idea of the warranty in case it keeps happening . Will report back when I have some testing. Being in Canada, that will be a while. 3 Quote Link to comment Share on other sites More sharing options...
Fetterhund Posted October 6, 2022 Report Share Posted October 6, 2022 Timely thread. Our rear muffler blew out at Harris Hill. The front was OK and thus we stayed within sound, but it was noticeably louder. 2 Quote Link to comment Share on other sites More sharing options...
ETR Posted October 6, 2022 Report Share Posted October 6, 2022 34 minutes ago, Fetterhund said: Timely thread. Our rear muffler blew out at Harris Hill. The front was OK and thus we stayed within sound, but it was noticeably louder. You guys were backfiring all weekend, oh that poor muffler. The first time I experienced it coming up behind your car I thought I was taking rocks to the windshield. You might have a decent exhaust leak (and O2 intake) upstream. 1 Quote Link to comment Share on other sites More sharing options...
Fetterhund Posted October 6, 2022 Report Share Posted October 6, 2022 1 hour ago, ETR said: You guys were backfiring all weekend, oh that poor muffler. The first time I experienced it coming up behind your car I thought I was taking rocks to the windshield. You might have a decent exhaust leak (and O2 intake) upstream. The off the shelf tune is marked as "includes burble" but I think it is just dumping extra fuel when lifting. Switching to stock ECU with an OEM-ish tune doesn't do it. Might need to get a different tune or have custom tuning done 2 Quote Link to comment Share on other sites More sharing options...
FrumRoll Posted October 6, 2022 Report Share Posted October 6, 2022 On 10/4/2022 at 11:58 AM, enginerd said: We were mid-pack? on sound at Road America two weeks ago and nobody was loud enough to fail the sound checks that Bill Strong did that weekend. That probably doesn't help a lot... but I can't think of a different way to quantify it. You guys were definitely fine, I didn't know they were doing any testing but there was at least one car (maybe a white Miata) that I'm surprised would have passed. Noticably louder than anyone else as he passed pit out. 1 Quote Link to comment Share on other sites More sharing options...
shanehutton Posted October 6, 2022 Author Report Share Posted October 6, 2022 10 hours ago, Fetterhund said: Timely thread. Our rear muffler blew out at Harris Hill. The front was OK and thus we stayed within sound, but it was noticeably louder. This is the exact same make and model of muffler that we had fail. I will say that the metal seemed awfully thin. 1 Quote Link to comment Share on other sites More sharing options...
Team Infiniti Posted October 6, 2022 Report Share Posted October 6, 2022 (edited) 15 minutes ago, shanehutton said: This is the exact same make and model of muffler that we had fail. I will say that the metal seemed awfully thin. Not sure if it’s thin metal or packing not tight enough, we once cut open some Borla to re-pack them and realized they are assembled with a hydraulic press before welding. Unrelated but: We did succeed in getting it back together with one of us standing on it as the other welded, sounded good, Grass roots even commented on it in one of their little crap can racing blurbs …still have it laying somewhere. I miss ChumpCar Edited October 6, 2022 by Team Infiniti 2 Quote Link to comment Share on other sites More sharing options...
Todd K Posted October 7, 2022 Report Share Posted October 7, 2022 We have an Integra with B18A1. I ditched the resonator and just have exhaust piping from a flex joint after the header collector all the way to the rear. I have a cheap - I think it was $45 - 2.5 " Thrush turbo muffler that I put in place of the ebay "phart can". Works well and meets the sound requirements - no issues with fatigue, cracking, or other failures. Quote Link to comment Share on other sites More sharing options...
Ian Posted October 8, 2022 Report Share Posted October 8, 2022 On 10/6/2022 at 7:55 AM, FrumRoll said: You guys were definitely fine, I didn't know they were doing any testing but there was at least one car (maybe a white Miata) that I'm surprised would have passed. Noticably louder than anyone else as he passed pit out. Yah, that one and the purple RX7 were super loud. That would drive me nuts. 1 Quote Link to comment Share on other sites More sharing options...
Administrators Bill Strong Posted October 12, 2022 Administrators Report Share Posted October 12, 2022 holy poop. I use the same muffler on the MR2s. I have never had that issue. I would have the glass blow out after about 8 or so race weekends. But never every the metal blow out. Have you guys contacted Dynomax? 1 Quote Link to comment Share on other sites More sharing options...
Team Infiniti Posted October 12, 2022 Report Share Posted October 12, 2022 (edited) 54 minutes ago, Bill Strong said: holy poop. I use the same muffler on the MR2s. I have never had that issue. I would have the glass blow out after about 8 or so race weekends. But never every the metal blow out. Have you guys contacted Dynomax? Eight Races?!? That’s a crap Muffler! Edited October 12, 2022 by Team Infiniti 1 Quote Link to comment Share on other sites More sharing options...
Black Magic Posted October 13, 2022 Report Share Posted October 13, 2022 13 hours ago, Team Infiniti said: Eight Races?!? That’s a crap Muffler! I would guess having the engine in the back forces them to put the muffler closer to the heat machine.... 2 Quote Link to comment Share on other sites More sharing options...
Administrators Bill Strong Posted October 13, 2022 Administrators Report Share Posted October 13, 2022 17 hours ago, Team Infiniti said: Eight Races?!? That’s a crap Muffler! Mid-Engined. It's a lot of heat. Quote Link to comment Share on other sites More sharing options...
Team Infiniti Posted October 13, 2022 Report Share Posted October 13, 2022 1 hour ago, Bill Strong said: Mid-Engined. It's a lot of heat. From what I’ve learned during the early days of ChumpCar coupled with working at an exhaust shop early in my years…Dare ya to try my favorite brand, even if it fails sooner than I think, I bet you it’ll work longer then a dynomax 2 Quote Link to comment Share on other sites More sharing options...
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