FAQ: The Exhaust Thread

crlombardi69 wrote:

I have a commercial account available to me at NAPA and they have a 3" thrush glasspack w/20" body for pretty cheap.I was gonna run that on the end of my 3" run off the headers and then "Y" into 2.5" tails w/aftermarket grand prix type tips.Then if it is to loud I will put two small bullet style resonators where the stock mufflers were originally!What do you think rick?I have a similar set-up engine wise as you have pretty much.

I think you really need to wait for the turtle's feedback.
I like the sound of it on face value, but like everything else, especially when it comes to exhaust work, you have to be sure it is going to satisfy your ears.
I think you should try it and see. I like the combination on paper, and let me know what you think when your done and how much you've spent.
The 20" resonator has to be a good start and the ability to add a couple of muffler later is a plus.

I will wait because I want to do the cat-back once and that's it.As far as help goes I wish I were closer to you guys because I talked to derek about tuning and I really want him to do my pcm but I can't down the car right now until I fix my F-350's oil leak.I think w/his tuning experience my car would be running even better than it is.I'm really happy with the current set-up now though.

I used to have a spare 98 PCM that could be used for this purpose, But I sold it, Sorry.

Rickw wrote:

I used to have a spare 98 PCM that could be used for this purpose, But I sold it, Sorry.

I don't think it will work on a '97.

We both have 98's though.I was talking to rick about wanting you to do my programing but I can't down the car right now.

crlombardi69 wrote:

We both have 98's though.I was talking to rick about wanting you to do my programing but I can't down the car right now.

whoops, sorry. I was talking to somebody else about a '97.

Hi
Someone can tell me if the exhaust parts for GTP or Regal are the same than the riviera likes Headers downpipe and catback??

The headers and the DP are the same. If you are going to buy headers, you would buy them for a GP/Regal. Everything is the same except for the way the exhaust hangs near the cat....

Uh, you don't have your car's specs listed in your signature line, but as far as just replacing the downpipe on at least the 97+ Rivieras, I'm afraid that Scott is mistaken here...

This is the Hogan 3" downpipe that many of us have used, and it is in the H-body/Bonneville section, not the GP section.
http://www.hoganperformance.com/DP8S.htm

Also, our board-thread is here:
https://rivperformance.editboard.com/series-ii-engine-transmission-f4/hogan-downpipe-t1142-90.htm?highlight=hogan

Ty Eldo, once again, for your infinite wisdom.....I was referring to the header kit in general being the same and the DP that comes with it. Sorry for the confusion.

The difference being that the exhaust parts available for the GP/Regal/W bodies don't take into account that on the G-bodies (Riv, PA, etc and H-bodies (bonneville etc) the rear exhaust outlet is about an inch and a half to one side. It doesn't seem to make much difference on the headers, as whoever welds your cat-back onto the outlet flange probably won't even notice the difference. But a standalone downpipe probably needs to account for that spacing difference.

My exhaust work here:
https://rivperformance.editboard.com/series-i-engine-transmission-f13/write-up-custom-y-split-exhaust-pipes-t7396.htm#113932

Dynomax VT mufflers.

Ok, I have a noob question. As some of you know, I do not have a scan tool. I am also not trying to do anything to crazy with the Rivi because it's supposed to be my reliable (yet fun) daily driver. The crazy stuff happens to the Talon. I have spoken with other members, and so far I have installed a FWI I made my self, AL 104's, 180 SuperStat, and new AL wires. The only supercharger mod I want to make is a 3.5" pulley. I am therefor not purchasing a MPS simply because once finished I have no plans on changing it. I'll get it where I want it, and then continue to concentrate on the Talon. From what I've come to understand, although there is always a chance of KR, given the current mods plus some exhaust work, realistically I should probably be ok with out being able to scan.

The question I now have is the exhaust, in all of your "expert" opinions, would simply a larger pipe from the cat back and two high flow mufflers be enough? Or would I be forced to also do headers, down pipe, high flow cat or eliminate cat, etc etc.

I understand more is better, I'm just unsure of what will happen to theses engines with little to no back pressure. The only experience I have is with the Talon and since it's turbo, by definition it has back pressure and wants NONE after the turbo. What about these cars? I would prefer not to have to buy headers, but since I'll be under there already it's not to much harder to eliminate the cat if needed. While I'm on the subject, (I'm sure I could figure it out if I searched but I'll ask now simply because I'm thinking about it) does removing the cat on our cars throw a CEL? And if so if anyone could point me in the right direction for a mod of some type regarding the issue it would be much appreciated.

So....

Can i just do cat back and mufflers given the mods I have/want?

Does eliminating the cat throw a CEL?

And if someone would be kind enough to point me in the right direction for a write up/mod as far as eliminating the cat without a CEL it would be very appreciated.

Oh and Karma, did you ever get any sound clips? Is everything still working/holding up ok? It looks fantastic! I envy your skills.... lol

quick answers:

- of course, eliminating the cat throws a CEL.

- the stock exhaust flows pretty well, look way back on this thread and you will see some calculations. If your exhaust is sound, you might/should not mess with it just yet -- see the earlier posts.

- you ought to reconsider tunign with a smaller pulley permanently installed. Maybe another list member in your area has a tuner, you could meet up for a day to work it out.

Albertj

And if you really want to reduce back-pressure, the post right above yours is probably the best option...

Eldo wrote:

And if you really want to reduce back-pressure, the post right above yours is probably the best option...

YEP, Karma did a first class job at straightening out the bends without miserably cluttering the underbody. I think the only problem he's going to have is heat buildup above the mufflers (heating up the tire in the spare tire well), but there's heat shielding he can get/apply if that's an issue.

Albertj

albertj wrote:

Eldo wrote:

And if you really want to reduce back-pressure, the post right above yours is probably the best option...

YEP, Karma did a first class job at straightening out the bends without miserably cluttering the underbody. I think the only problem he's going to have is heat buildup above the mufflers...
Albertj

To be absolutely honest, I suspect that he also gave up some ground clearance...

Come on Karma, we need some more porn, in the form of video and NOISE.

Must hear these mufflers growl and idle, before pulling the trigger and budgeting for some exhaust work.

BTW, do you still have the stock resonator, or have you removed that already.

Wondering if leaving the stock resonator and cutting the pipe where you did and then having a custom "Y" made and pipes bent to the VT Muffler's will be a good option for the Riv. Considering I have Headers and a 3" Cat.

I have had a nice set of exhaust Tips for over a year that I haven't installed yet either. They will look good on the VT's as well.
Thanks, Rick

oh yea i agree!

oh yeah,and dont forget to sneak in some canadian titties...

Rickw wrote:

Come on Karma, we need some more porn, in the form of video and NOISE.

Must hear these mufflers growl and idle, before pulling the trigger and budgeting for some exhaust work.

BTW, do you still have the stock resonator, or have you removed that already.

Wondering if leaving the stock resonator and cutting the pipe where you did and then having a custom "Y" made and pipes bent to the VT Muffler's will be a good option for the Riv. Considering I have Headers and a 3" Cat.

I have had a nice set of exhaust Tips for over a year that I haven't installed yet either. They will look good on the VT's as well.
Thanks, Rick

Got some family stuff to take care of first. Also I'm still chasing the low RPM KR I have. Stock resonator is still in place. I'll get some vids as soon as possible. The car is at the shop though, and its a 2 hour drive, so I can only get there on weekends.

Eldo wrote:

albertj wrote:

Eldo wrote:

And if you really want to reduce back-pressure, the post right above yours is probably the best option...

YEP, Karma did a first class job at straightening out the bends without miserably cluttering the underbody. I think the only problem he's going to have is heat buildup above the mufflers...
Albertj

To be absolutely honest, I suspect that he also gave up some ground clearance...

Heat buildup is something I've been watching, but its just the metal form for the spare tire there, and is never to warm to touch after blasting around in the car.

For ground clearance, I didn't measure, but it seems to be the same. The mufflers do sit a bit lower than the stock ones, but they also aren't the lowest point in the car by a long-shot. I like to keep the back jacked up with PSI in the air shocks for better corners and launches, so its really a non-issue for me anyway.

So, I had to get a new exhaust. My DynoMax Super Turbo's I had decided to rust through . I bought 2 SS Pypes M80's with 3" inlet and outlet (they're tubes) to mount right after the DP. These are advertised as mufflers, not resonators. They lie.......bastards And after looking at this pic, it appears I'm missing a clamp?!


It was ridiculously stupid f*@king loud, and I was embarrassed to drive it. Now, I like a good sounding loud exhaust, but these things are ridiculous. They do sound cool by themselves, just about 50dB too loud. I couldn't hear the S/C, I couldn't hear the radio......So, I ended up ordering 2 DynoMax 2 chamber welded mufflers the next day. I had to drive the stupid thing for 2 days until they arrived. Made a trip back to the Exhaust shop. The guy that did it met me in the parking lot before I could make it to the door. The first words out of his mouth were "Change of plans"?....with a little grin. This is what we ended up with.


I missed a spot cleaning the tips on the left inner pipe.....
It sounds pretty cool IMO. It's not that loud until you hammer the gas. I left the other mufflers on there, so I have 4 total lol. It's still louder than I thought it would be, but whatever.....The cruising drone is less than my old mufflers, which is surprising. Apparently, even 4 performance mufflers can't tame the raspiness this 3800 emits. It's different, but that may be why I like it....

I actually got to make a video for 'ya. The woman let me borrow the camera that I bought her All that hissing you hear is a fountain in the pond to the left. I took this vid in a subdivision that has 3 occupied homes (8,000 sq ft +) and 7 not finished. It's been like that for 4 years.....


I also posted this in Abaddon's Riv in the Showcase. I'm using that thread as like a diary of the car I spose, so, sorry for the double posting of this.
I'll edit this post and include the P/N's for everything when I get home tonight....

Longer mufflers would probably fix the raspies. If you're flush, replace one of the SSPypes with the next longer or shorter size to change the resonant frequency of the system. Longer will move the resonant note down, in general, but depends on the system harmonics. Kind of like a longer organ pipe give lower notes.

The thing I learned when working on my exhaust is the 3800 engine has a raspiness that makes the Riv's cabin drone like a wasp nest. I got rid of it but basically the exhaust I got pushes the fundamental frequency below normal audible range--using a meter you can see the sound is there, but you just can't hear it. I got the GM exhaust for the Park Avenue - the muffler cans are HUGE. The resonator is the same as that on the Riv system bug the muffler cans are taller and longer than the OE Riv cans, and fill the space between the spare tire well and the rear bumper cover. They make essentially no sound; a meter is required to revela that the sound pressure is actually rather high below the first audible octave band, indicating to me that the GM engineers succeeded in pushing the resonant frequency below the bottom audible band.


Albertj

Albertj

I agree with albertj. Also, keep in mind the entire exhaust system works together as a single unit. This means the 3" pipes are part of the equation. So, another way to lower the resonant frequency (make the exhaust quieter) is to lesson the diameter of the 3" pipes. In effect, it's the same thing as lengthening them.

If you go to Abaddon's Riv thread, you'll see that I said the noise doesn't bother me. The resonance inside the cabin is less than the mufflers I had before, and the cruising drone is less also. I'll chalk that up to the 2 mufflers down the center tunnel. They just seem to be louder out the back of the car.....I like it. Robo and I were discussing it in a diff thread. Sorry if you were mislead into thinking I want it quiet.....