Car is too loud, but only mild mods - why?
08-24-15, 07:50 PM
#1
Full Member
Thread Starter
Car is too loud, but only mild mods - why?
My FD is too damn loud, but I bought it in roughly its current state of modification so I'm not sure what the culprit is. At the same time, I thought most of what was done should be pretty mild as far as volume goes, so I'm a bit confused. Here's what I've got:
GReddy Airinx intake > "full" nonsequential stock twins > stock y-pipe and crossover > GReddy SMIC > stock intake elbow/TB > stock UIM w/ double throttle removed > stock port engine > aftermarket catless downpipe > SR motorsports high flow cat pipe > RB dual catback
I actually put the RB on in place of a PFS exhaust. It helped but not nearly as much as I expected.
Everything is loud. WOT is loud, sure, but the car is pretty loud at idle (embarrassing in my quiet suburban 'hood) and even just cruising around at part throttle 2500-3000rpms it's boomy and resonant. The car is unpleasant after 15-20min. I know some of you guys like em as loud as you can get, but I'm a thirty-something professional and I've had my loud fun already, with some mild tinnitus to remind me. At this point in my life I'd like to be able to hear some exhaust note and not much more than that. Somewhere there's a happy spot between Camry-silent and rolling up like Dom Torreto when i take the 7 into the office.
Questions:
1) The RB is supposed to be among the quietest exhaust choices, so where is the noise coming from? At this point I'd be willing to go back to the stock catback but if the RB didnt even dent the noise then maybe the catback isnt the issue? Also, I'd rather not give away all my flow benefits if I can help it. The NS twins are laggy enough already.
2) Is it the nonsequential mod? I've read this increases noise but I'm not sure how much. Seems like removing some flapper doors shouldnt make the car intolerable?
3) Would going back to the stock airbox help? I was going to do that for cooling reasons anyway, but I'm assuming it wont be a huge help with sound.
4) What if I put on the stock cat vs the SR high flow?
5) Could I have an exhaust leak? How do I tell? Two rotary specialists have looked over the car in the last two years, including to inspect and tune it, and although I didnt ask anything about noise or leaks, they didnt note any issues. Car seems to run just fine.
GReddy Airinx intake > "full" nonsequential stock twins > stock y-pipe and crossover > GReddy SMIC > stock intake elbow/TB > stock UIM w/ double throttle removed > stock port engine > aftermarket catless downpipe > SR motorsports high flow cat pipe > RB dual catback
I actually put the RB on in place of a PFS exhaust. It helped but not nearly as much as I expected.
Everything is loud. WOT is loud, sure, but the car is pretty loud at idle (embarrassing in my quiet suburban 'hood) and even just cruising around at part throttle 2500-3000rpms it's boomy and resonant. The car is unpleasant after 15-20min. I know some of you guys like em as loud as you can get, but I'm a thirty-something professional and I've had my loud fun already, with some mild tinnitus to remind me. At this point in my life I'd like to be able to hear some exhaust note and not much more than that. Somewhere there's a happy spot between Camry-silent and rolling up like Dom Torreto when i take the 7 into the office.
Questions:
1) The RB is supposed to be among the quietest exhaust choices, so where is the noise coming from? At this point I'd be willing to go back to the stock catback but if the RB didnt even dent the noise then maybe the catback isnt the issue? Also, I'd rather not give away all my flow benefits if I can help it. The NS twins are laggy enough already.
2) Is it the nonsequential mod? I've read this increases noise but I'm not sure how much. Seems like removing some flapper doors shouldnt make the car intolerable?
3) Would going back to the stock airbox help? I was going to do that for cooling reasons anyway, but I'm assuming it wont be a huge help with sound.
4) What if I put on the stock cat vs the SR high flow?
5) Could I have an exhaust leak? How do I tell? Two rotary specialists have looked over the car in the last two years, including to inspect and tune it, and although I didnt ask anything about noise or leaks, they didnt note any issues. Car seems to run just fine.
08-24-15, 08:16 PM
#2
Constant threat
If you have the stock catalytic converter still, put it on. IMHO, the excessive noise you hear is from the high-flow cat. The RB Dual exhaust is NOT loud...it is just right. No droning, no excessive exhaust note. Decent sound when you get on it, otherwise it just sounds "healthy". Good luck if you have to try and buy a stock cat...they are stupid expensive, like over two grand.
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08-25-15, 08:03 AM
#8
Too funny Matt. First thing I thought as well when reading the subject line 
Seriously though, I would bet you have an SR Motorsports resonated midpipe, which looks like a pregnant midpipe with Cherry Bomb muffler style body. If you truly have the SR highflow cat, then it may come down to checking for exhaust leaks and putting a stock cat back in. Guaranteed that will quiet her down. A friend of mine used to have stock exhaust on his Red '93 and it was uber quiet. Best of luck!
Seriously though, I would bet you have an SR Motorsports resonated midpipe, which looks like a pregnant midpipe with Cherry Bomb muffler style body. If you truly have the SR highflow cat, then it may come down to checking for exhaust leaks and putting a stock cat back in. Guaranteed that will quiet her down. A friend of mine used to have stock exhaust on his Red '93 and it was uber quiet. Best of luck!
08-25-15, 08:12 AM
#9
All out Track Freak!
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If you are not used to these cars a DP, HF cat and any exhaust even RB will sound somewhat loud but not crazy loud. Something is wrong.
I'm betting the HF cat is gutted or old. If you put a stock midcat on it will likely be super quiet.
I'm betting the HF cat is gutted or old. If you put a stock midcat on it will likely be super quiet.
08-25-15, 09:04 AM
#11
Spray some seafoam in the engine via a vacuum line and see where the white smoke comes out. If its pouring out under the car/exhaust manifold etc, there's your leak.
My guess is with the others, the "high-flow" cat is just a little louder than factory.
If there is no exhaust leak then unfortunately you have little baby ears haha. I've been cruising around open cut-out over here, now that's what you call loud.
My guess is with the others, the "high-flow" cat is just a little louder than factory.
If there is no exhaust leak then unfortunately you have little baby ears haha. I've been cruising around open cut-out over here, now that's what you call loud.
08-25-15, 10:26 AM
#12
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Spray some seafoam in the engine via a vacuum line and see where the white smoke comes out. If its pouring out under the car/exhaust manifold etc, there's your leak.
My guess is with the others, the "high-flow" cat is just a little louder than factory.
If there is no exhaust leak then unfortunately you have little baby ears haha. I've been cruising around open cut-out over here, now that's what you call loud.
My guess is with the others, the "high-flow" cat is just a little louder than factory.
If there is no exhaust leak then unfortunately you have little baby ears haha. I've been cruising around open cut-out over here, now that's what you call loud.
haha.
08-25-15, 11:40 AM
#14
I also have a Bonez/RB twin combo, coming from a PFS exhaust. I live near Laguna Seca and the allowed noise levels for the track keep going down and down. I began to get meatballed every weekend!
You know what really quieted my car down? when I 86'd the Tripoint intake and did Adam C's cheap bastard intake.
I have nothing to back up my claim and I'm definityely no technican, but maybe give your stock intake a try and see if it helps. I sure did for me.
Cheap Bastard: cheap stock airbox mod - RX7Club.com
...and that's why ya gotta do the seafoam thing at night, l00katme!
You know what really quieted my car down? when I 86'd the Tripoint intake and did Adam C's cheap bastard intake.
I have nothing to back up my claim and I'm definityely no technican, but maybe give your stock intake a try and see if it helps. I sure did for me.
Cheap Bastard: cheap stock airbox mod - RX7Club.com
...and that's why ya gotta do the seafoam thing at night, l00katme!
08-25-15, 12:16 PM
#15
Spray some seafoam in the engine via a vacuum line and see where the white smoke comes out. If its pouring out under the car/exhaust manifold etc, there's your leak.
My guess is with the others, the "high-flow" cat is just a little louder than factory.
If there is no exhaust leak then unfortunately you have little baby ears haha. I've been cruising around open cut-out over here, now that's what you call loud.
My guess is with the others, the "high-flow" cat is just a little louder than factory.
If there is no exhaust leak then unfortunately you have little baby ears haha. I've been cruising around open cut-out over here, now that's what you call loud.
Last edited by jetlude; 08-25-15 at 12:39 PM.
08-25-15, 02:00 PM
#16
It should be real simple to get your car on a lift and start it and check for exhaust leaks, takes 30 seconds to walk from front to back of the car and listen, it will be obvious.
As far as I know an air intake doesnt affect exhaust noise levels much, but it will make you hear the turbos spool in the car a lot, and others can hear it outside, if that bothers you then you know the cause now.
I agree that you may have a straight through midpipe instead of high flow cat or that your RB catback is worn out and the noise reducing material is gone if it's been on a car that was driven hard and with high HP.
Lastyly, non sequential sucks, if you've just wired it temporarily go back to sequential and your car will be slightly quieter and actually entertaining to drive instead of laggy and low powered.
It's not really reasonable to remove the intake or downpipe and your catback is the quietest aftermarket. I'd say put on a stock cat system and that will make your biggest improvement in quieting things down. But it will also lob you of a ton of power. If instead you put on a stock catback it may have similar noise reduction and rob you of less power.
As far as I know an air intake doesnt affect exhaust noise levels much, but it will make you hear the turbos spool in the car a lot, and others can hear it outside, if that bothers you then you know the cause now.
I agree that you may have a straight through midpipe instead of high flow cat or that your RB catback is worn out and the noise reducing material is gone if it's been on a car that was driven hard and with high HP.
Lastyly, non sequential sucks, if you've just wired it temporarily go back to sequential and your car will be slightly quieter and actually entertaining to drive instead of laggy and low powered.
It's not really reasonable to remove the intake or downpipe and your catback is the quietest aftermarket. I'd say put on a stock cat system and that will make your biggest improvement in quieting things down. But it will also lob you of a ton of power. If instead you put on a stock catback it may have similar noise reduction and rob you of less power.
Last edited by Snook; 08-25-15 at 02:02 PM.
08-25-15, 03:23 PM
#18
Do you have any other rx7 friends to compare to?
Racing Beat exhaust is pretty quiet compared to most all the others no matter what the rest of your exhaust looks like. Mine for example, I have down pipe and high flow gutted cat running to the Racing Beat dual tip. There is no drone at any rpm range. I can hear the exhaust under pretty much all driving conditions but it's far from what anybody I know would call loud. It will get loud at full throttle and high rpm, that's it.
Now I don't know how much difference non sequential makes in terms of noise, but I would be surprised if it is enough to really matter. Intake would be similarly small impact to noise, but maybe the combination of NS and intake can add up to an annoying sound level. May as well try swapping the intake, that's easy.
If it was exhaust leaks you would hear that from the side or in front of your car and know that's what your problem is. Can you hear leaks? If so they certainly need fixed. You could wrap the exhaust, would make it quieter from inside the car or outside next to the car, but could be louder behind you.
Racing Beat exhaust is pretty quiet compared to most all the others no matter what the rest of your exhaust looks like. Mine for example, I have down pipe and high flow gutted cat running to the Racing Beat dual tip. There is no drone at any rpm range. I can hear the exhaust under pretty much all driving conditions but it's far from what anybody I know would call loud. It will get loud at full throttle and high rpm, that's it.
Now I don't know how much difference non sequential makes in terms of noise, but I would be surprised if it is enough to really matter. Intake would be similarly small impact to noise, but maybe the combination of NS and intake can add up to an annoying sound level. May as well try swapping the intake, that's easy.
If it was exhaust leaks you would hear that from the side or in front of your car and know that's what your problem is. Can you hear leaks? If so they certainly need fixed. You could wrap the exhaust, would make it quieter from inside the car or outside next to the car, but could be louder behind you.
08-25-15, 04:34 PM
#19
Full Member
Thread Starter
Car is too loud, but only mild mods - why?
Thanks everyone for a ton of thoughtful replies. Here are some thoughts:
- I'm confused about how much diff nonseq makes to noise. I've read threads where people say its the biggest drawback and others where people claim no apparent difference. Long term I'd like to go back to sequential, but as my setup is "full" nonseq I have to souce everything from rats nest to new twins/y-pipe to go back, which is a daunting project. I hate the lag but I can live with it to just enjoy the car for now. But if I'd take a big chunk out of the noise, going sequential would move up the priority list.
- Pretty sure the SR high flow is actually a high flow. I have the receipt from prev owner. But it's also pretty old. Maybe '07 IIRC. So maybe pretty well blown out by now?
- I have the stock cat pipe, though I'm not sure what shape the catalyst is in. Sounds like job 1 should be throwing that back on.
- Stock airbox is going on anyway because my IATs are stupid with the Greddy hot air intakes. Fingers crossed that helps too.
- the RB exhaust is brand new. Doubt it's somehow defective.
- I like the idea of putting the car in the air or even doing seafoam to check for leaks. But really I think I'm just old.
- I'm confused about how much diff nonseq makes to noise. I've read threads where people say its the biggest drawback and others where people claim no apparent difference. Long term I'd like to go back to sequential, but as my setup is "full" nonseq I have to souce everything from rats nest to new twins/y-pipe to go back, which is a daunting project. I hate the lag but I can live with it to just enjoy the car for now. But if I'd take a big chunk out of the noise, going sequential would move up the priority list.
- Pretty sure the SR high flow is actually a high flow. I have the receipt from prev owner. But it's also pretty old. Maybe '07 IIRC. So maybe pretty well blown out by now?
- I have the stock cat pipe, though I'm not sure what shape the catalyst is in. Sounds like job 1 should be throwing that back on.
- Stock airbox is going on anyway because my IATs are stupid with the Greddy hot air intakes. Fingers crossed that helps too.
- the RB exhaust is brand new. Doubt it's somehow defective.
- I like the idea of putting the car in the air or even doing seafoam to check for leaks. But really I think I'm just old.
08-26-15, 07:13 PM
#20
Now I am single turbo and it is a whole different level of annoyance at cruise. I'm thinking the V-bands may not be sealing as good as they should be. But at the same time going single changes the exhaust side of things radically, so it is not surprising that I have extra noise either. **** it is probably the vented wastegate now that I think about it lol...
Last edited by Montego; 08-26-15 at 07:19 PM.
08-27-15, 12:42 AM
#21
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this makes me laugh. We had a car that was not starting, so we sprayed a ton of seafoam into the engine to decarbonize it while it was running. We shut it off for a while and restarted it. The smoke that emitted form the car was insane. We (5-10 people) were engulfed in smoke like it was a smoke bomb in vietnam hiding from our enemies and we kept running the car to burn it all off. It just kept smoking and smoking and it was so bad that people called the fire dept on us and thought something was on fire.
haha.
haha.
Just a few experiences to share (all with the stock cat unless noted):
-stock seq twins with stock intake but changed to catless DP caused no change in exhaust noise level but SIGNIFICANT increase in turbo whine
-stock seq twins but changed to apexi intake with catless DP caused no change in exhaust noise leveL
-stock seq twins with apexi intake with catless DP but changed to greddy exhaust significantly increased exhaust noise level but still comfortable
-stock seq twins with apexi intake with catless DP but removed stock cat and greddy exhaust and noise WAS DEAFENING
-stock seq twins with apexi intake with catless DP but changed to racing beat exhaust reduced exhaust noise level compared to greddy exhaust
I think your culprit is the high flow cat. Go back to stock cat and you will probably see a big noise reduction at the expense of some power with some extra weight lol.
If you need a stock cat I've got one.
08-27-15, 02:31 AM
#22
I don't agree with the stance that a few people are taking with regards to the non-sequential mods creating your noise problem as it should create a tone difference rather than a dB difference. Now this bears to question, is the car actually too loud, or just unpleasant?
08-27-15, 09:06 AM
#23
Full Member
Thread Starter
Car is too loud, but only mild mods - why?
It's a bit of both volume and "unpleasantness." And frankly my tolerance for the noise changes with the day/what I'm doing/how tired I am. I'll also say that the older I get the less tolerant I am of loud noise over time. Plain road noise can bother me on 4+ hr highway drives in even factory stock sedans, so I think I'm probably a bit noise sensitive.
However, the nature/quality of the noise is also problematic. It's like there's a vibration or resonance that goes beyond the volume. Drove home over an hour the other day and threw in thick -30db earplugs and it was still unconfortable; like it was vibrating inside my head at certain RPMs anyway.
BTW, checked PO's records and there are ten years and 40k mi on the SR high flow (which is a high flow - I looked under the car to verify). I guess the typical lifespan of these aftermarket cats varies with conditions of use, but I bet that's getting kinda up there. Will swap to stock when I have a moment.
However, the nature/quality of the noise is also problematic. It's like there's a vibration or resonance that goes beyond the volume. Drove home over an hour the other day and threw in thick -30db earplugs and it was still unconfortable; like it was vibrating inside my head at certain RPMs anyway.
BTW, checked PO's records and there are ten years and 40k mi on the SR high flow (which is a high flow - I looked under the car to verify). I guess the typical lifespan of these aftermarket cats varies with conditions of use, but I bet that's getting kinda up there. Will swap to stock when I have a moment.
08-27-15, 09:37 AM
#24
The stock cat is going to make a world of difference. It'll probably take care of all of your issues. However the car is going to feel like you have the ebrake partially up under boost...
You can also check to see that your exhaust is installed tight. Check all screws and the hangers to make sure nothing is loose and rattling.
I don't think you're crazy, nobody likes road noise from bad tires on the highway or droning in their exhaust.
You can also check to see that your exhaust is installed tight. Check all screws and the hangers to make sure nothing is loose and rattling.
I don't think you're crazy, nobody likes road noise from bad tires on the highway or droning in their exhaust.
08-27-15, 10:32 AM
#25
The stock cat can be easily modified to flow better without losing its intended effects.
If you look at the flange welds, you will find that they are on the the inside of the inlet and outlet of the OEM cat. These welds effectively reduce the inside diameter of the piping from 2 1/2 inches to 2 1/8 inches. Do the math. Thats a 28% restriction in flow.
The fix is easy.
** IMPORTANT**
**FIRST STEP** Have the flanges welded on the outside. You MUST do this first. Once this is done,
Then ** SECOND STEP** you can simply grind down the inner welds until you have a full 2 1/2 inch opening.
I have done this on two oem cats, with great success. This will leave you with a nice oem high flow cat!!!! Your butt dyno will notice the difference
If you look at the flange welds, you will find that they are on the the inside of the inlet and outlet of the OEM cat. These welds effectively reduce the inside diameter of the piping from 2 1/2 inches to 2 1/8 inches. Do the math. Thats a 28% restriction in flow.
The fix is easy.
** IMPORTANT**
**FIRST STEP** Have the flanges welded on the outside. You MUST do this first. Once this is done,
Then ** SECOND STEP** you can simply grind down the inner welds until you have a full 2 1/2 inch opening.
I have done this on two oem cats, with great success. This will leave you with a nice oem high flow cat!!!! Your butt dyno will notice the difference