Drone between 2500-3500 RPM
01-15-05, 11:48 AM
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Drone between 2500-3500 RPM
ok i have a T60-1 turbo with 3" exhaust all the way through and a Blitz NUR Spec catback. i like the way it sounds when driving around but when i cruze on the highway there is a really bad drone between 2500-3500 RPM that just drives me nuts. So i went out and bought a resonator and installed that into the midpipe and the sound of the exhaust got even deeper and not all that loud at idle but the damn drone is still there, not the same drone but noe a deeper drone. Please help i really like driving my FD a lot but this is almost getting rediculous. After about 20 min. yesterday my girlfriend got a headache and started getting nausiated. how ever you spell that. anyway please help
01-15-05, 12:17 PM
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Blitz NUR Spec catback. as far as the DP and midpipe go i'm not sure but it's a complete straight through system. i even bought some dynomat last night and put it in the trunk. did nothing though. i guess i didnt have enough. i think i might wind up dynomatting most of the car. might add a little weight but cant be that much.So what your saying is by wrapping the DP(with what)that may quiet the drine? if so how would that do anything?
01-15-05, 12:29 PM
#4
I'm thinking that the heatwrap will quiet the exhaust down some it comes in a roll
I don't think the dynomat really helps in the back that much I would try going underneath the car and putting it above the exhaust on teh floorboard of the car and transmission tunnel etc.
I don't think the dynomat really helps in the back that much I would try going underneath the car and putting it above the exhaust on teh floorboard of the car and transmission tunnel etc.
Last edited by Snook; 01-15-05 at 12:34 PM.
01-15-05, 02:57 PM
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the nur spec is loud and drony even with the stock main cat. it's just a very loud exhaust. wrapping the DP and MP might help a little but i wouldn't expect that to overcome the design of the CB. i'd love to trade mine out. i'd go rb dual or custom from a good muffler shop.
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01-15-05, 03:03 PM
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Originally Posted by particleeffect
the nur spec is loud and drony even with the stock main cat. it's just a very loud exhaust. wrapping the DP and MP might help a little but i wouldn't expect that to overcome the design of the CB. i'd love to trade mine out. i'd go rb dual or custom from a good muffler shop.
01-15-05, 05:19 PM
#9
Originally Posted by SurgeMonster
I have a greddy sp catback and a borla xr-1 in the midpipe its hard to get the car quiet on the highway I'm going to try wrapping my downpipe. and midpipe I figure it couldnt hurt.
01-15-05, 05:38 PM
#10
I have a fuel single turbo setup and it's not even half as loud as when I had the dual N1 exhaust on my stock twins car non seq. But have you heard a racing beat or different catback on the highway? I think I'd be willing to go for a racing beat or other quieter catback if it would help a lot. lmk thanks
01-15-05, 05:44 PM
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i use to have the dual N1 and i sold it because iwanted something quieter. so i bought the nur spec and it is a lot nicer sounding IMO, but this thing has a worse drone. i dont think the N1 drone was as bad it was just a lot louder all the time. i think i'm going to put in another resonater and and spray some sound dedning stuff under the car the length of the exhaust. if there is anything else i can do please let me know
01-15-05, 08:08 PM
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ok, so not much i can do than. i was thinking about putting a high flow cat on but if you still have the stock cat and it's still drony than i guess all i can do is dynomat the hell out of the car and see what happens from there. if anyone has done this or knows someone please let me know before i go spend a lot of money on all this crap and all i have left at the end is a loud heavy *** FD.
01-16-05, 07:33 AM
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Originally Posted by particleeffect
just get an rb dual and resonated mp. you'll be out a few $ but it should be much better in the end.
01-16-05, 12:19 PM
#17
I had a similar drone when I installed a PFS catback. It was totally unsatisfactory, so I set out to fix it without impairing exhaust flow, since the catback was a big performance improvement.
Basically, the drone is a result of the exhaust system resonating and acting like an organ pipe. The reason chambered mufflers (like stock) are so effective is because they kill any tendency for the exhaust to resonate. Note that the drone is related to the total length of the exhaust system (about 11'), its diameter, and the frequency of excitation (or rpm in our cases).
What I decided to do was attempt to break up the exhaust pipe further by adding a [Magnaflow] resonator ahead of the catback. Turns out this was a good location for the resonator as the results were huge. (Note that different locations along the pipe will filter out different frequencies or modes.) The drone dropped by about 20db with no impact on flow at all (as determined on a flow bench). It's not as quite as stock, but pretty damn close under cruise.
See attached pics.
Basically, the drone is a result of the exhaust system resonating and acting like an organ pipe. The reason chambered mufflers (like stock) are so effective is because they kill any tendency for the exhaust to resonate. Note that the drone is related to the total length of the exhaust system (about 11'), its diameter, and the frequency of excitation (or rpm in our cases).
What I decided to do was attempt to break up the exhaust pipe further by adding a [Magnaflow] resonator ahead of the catback. Turns out this was a good location for the resonator as the results were huge. (Note that different locations along the pipe will filter out different frequencies or modes.) The drone dropped by about 20db with no impact on flow at all (as determined on a flow bench). It's not as quite as stock, but pretty damn close under cruise.
See attached pics.
01-16-05, 08:27 PM
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My single car with a straight midpipe and GReddy SP catback drones really bad. Almost to the point were my 100% aftermarket stereo setup is almost useless to have in the car. The open atmosphere wastegate isn't any help either but atleast I can fix that.
01-18-05, 09:31 PM
#19
Originally Posted by KevinW
ok i have a T60-1 turbo with 3" exhaust all the way through and a Blitz NUR Spec catback. i like the way it sounds when driving around but when i cruze on the highway there is a really bad drone between 2500-3500 RPM that just drives me nuts. So i went out and bought a resonator and installed that into the midpipe and the sound of the exhaust got even deeper and not all that loud at idle but the damn drone is still there, not the same drone but noe a deeper drone. Please help i really like driving my FD a lot but this is almost getting rediculous. After about 20 min. yesterday my girlfriend got a headache and started getting nausiated. how ever you spell that. anyway please help
The turbo is a Turbonetics T61.
01-18-05, 10:21 PM
#20
Just to underscore an important point from my last post (above) is that the LOCATION of the resonator along the exhaust is very important and can make a big difference in noise performance. I'll spare you the physics lesson, but depending upon what frequency the exhaust is resonating at, a resonator in the midpipe my help quiet the exhaust but will not necessarily kill the drone. The most effective locations to reduce the lowest (fundamental) frequency of the drone are going to be at or near the ends of the exhaust system. This means the cat-back, just ahead of it AND at the downpipe. A combination of resonators at these locations will "swamp" the pipe and reduce it's tendency to resonate and drone.
The good news is that resonators, at least the ones I've tested, actually flow better than and equivalent piece of straight pipe. In fact, a 2.5" ID core resonator flowed as good as a straight 3" piece of pipe of the same length. This is because there is less friction in them due to construction--at least on the better ones. You could build an entire exhaust system out of these with no penalty in flow.
I've also notice that many cat backs are tuned loud and aren't very effective. Something like the RB would definitely help these situations.
The good news is that resonators, at least the ones I've tested, actually flow better than and equivalent piece of straight pipe. In fact, a 2.5" ID core resonator flowed as good as a straight 3" piece of pipe of the same length. This is because there is less friction in them due to construction--at least on the better ones. You could build an entire exhaust system out of these with no penalty in flow.
I've also notice that many cat backs are tuned loud and aren't very effective. Something like the RB would definitely help these situations.
Last edited by Speed of light; 01-18-05 at 10:23 PM. Reason: correction (sp)
01-19-05, 12:04 AM
#21
Originally Posted by Speed of light
I've also notice that many cat backs are tuned loud and aren't very effective.
If you are are adding 10-30 lbs of sound deadening material to combat the noise of an aftermarket exhaust, you have to ask yourself why you put the exhaust on in the first place. The weight is going to nullify any performance gain that the exhaust has given you.
Not saying that this is the case here, but I'm getting the strong feeling that many people buy an aftermarket exhaust because it is louder, with the performance gain being almost incidental. The irony is, the only people who are impressed by a loud exhaust are driving Civics.
Any exhaust that drones is poorly designed and should be sold on eBay.
01-19-05, 06:53 AM
#22
Originally Posted by KevinW
ok, so not much i can do than. i was thinking about putting a high flow cat on but if you still have the stock cat and it's still drony than i guess all i can do is dynomat the hell out of the car and see what happens from there. if anyone has done this or knows someone please let me know before i go spend a lot of money on all this crap and all i have left at the end is a loud heavy *** FD.
I have the same issue with my setup. I believe it's resonation. I'm on my way now to Pettit Racing for my final tuning and this (droning) is first on my list for Cam to fix. I'll let you know how it turns out.
01-20-05, 12:44 PM
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Originally Posted by moconnor
Very interesting claim. Any data?
If you are are adding 10-30 lbs of sound deadening material to combat the noise of an aftermarket exhaust, you have to ask yourself why you put the exhaust on in the first place. The weight is going to nullify any performance gain that the exhaust has given you.
Not saying that this is the case here, but I'm getting the strong feeling that many people buy an aftermarket exhaust because it is louder, with the performance gain being almost incidental. The irony is, the only people who are impressed by a loud exhaust are driving Civics.
Any exhaust that drones is poorly designed and should be sold on eBay.
If you are are adding 10-30 lbs of sound deadening material to combat the noise of an aftermarket exhaust, you have to ask yourself why you put the exhaust on in the first place. The weight is going to nullify any performance gain that the exhaust has given you.
Not saying that this is the case here, but I'm getting the strong feeling that many people buy an aftermarket exhaust because it is louder, with the performance gain being almost incidental. The irony is, the only people who are impressed by a loud exhaust are driving Civics.
Any exhaust that drones is poorly designed and should be sold on eBay.
01-20-05, 01:01 PM
#24
Originally Posted by moconnor
Very interesting claim. Any data?
If you are are adding 10-30 lbs of sound deadening material to combat the noise of an aftermarket exhaust, you have to ask yourself why you put the exhaust on in the first place. The weight is going to nullify any performance gain that the exhaust has given you.
Not saying that this is the case here, but I'm getting the strong feeling that many people buy an aftermarket exhaust because it is louder, with the performance gain being almost incidental. The irony is, the only people who are impressed by a loud exhaust are driving Civics.
Any exhaust that drones is poorly designed and should be sold on eBay.
If you are are adding 10-30 lbs of sound deadening material to combat the noise of an aftermarket exhaust, you have to ask yourself why you put the exhaust on in the first place. The weight is going to nullify any performance gain that the exhaust has given you.
Not saying that this is the case here, but I'm getting the strong feeling that many people buy an aftermarket exhaust because it is louder, with the performance gain being almost incidental. The irony is, the only people who are impressed by a loud exhaust are driving Civics.
Any exhaust that drones is poorly designed and should be sold on eBay.
I'm with KevinW, I like a somewhat louder-than-stock exhaust. But being loud(er) and droning are two different characteristics IMO. I don't have data for the performance of my Greddy SP, but from the overall design and quality of construction I'd say there is a performance difference with minimal weight gain. I also don't think it should be lumped in with ebay cat-backs.
