Miata Mailing List: March 1997, Message #1384



     



   From: (none)

Subject: Re: Help! Do I Need Resonator on Exhaust?

   Date: (none)



Abbreviated Problem Statement:



Exhaust rework for Spare-tire relocation cause exhaust ring at 2.5-3.5k RPM.



Latest update:



Just got back from the muffler shop.  Replaced the resonator with an oval 

glasspack for a MGB.  This sort of solved the problem. The 2.5-3.5k ring 

is still there, but the extra glass-pack quiet it down to an acceptable 

level.  The final test will be if I have to sleep on the couch tonight ;-) 

Here is a quick recap of the muffler work.



* Installed the Kaleva Spare-tire bracket with original muffler. 

* talk/visited half dozen muffler shop that either wouldn't do the work or 

charges an arm and leg with no gurantees.

* Found A & B muffler shop on web page. Call Store #2 in Holtom City, spoke 

with owner Doug Palmer and stopped by same day after work.

* Miata put on lift and measured for fit.  Look through all the muffler 

catalogs and found 2 muffler under 12" long (Chevette - gas was one of them).

* Ordered the 11" - long 4"X9" oval with 2" offset inlet and 2" offset 

(other side) outlet muffler (not turbo muffler).

* Installed the muffler at lunch the next day.  $50 parts and labor. I 

also added a chrome tip for an additional $10.  Current total $60.

NOTE: spare was a perfect fit on Kaleva spare bracket.

* Return to shop after work.  Exhaust too boomy.  Ringing problem at 

2.5k-3.5k RPM.  Installed ANSA tip for $30 ($40 - $10 credit for chrome 

tip).  New tip lower overall sound level but did little for the 3k boom.

Current total $90

* Return to shop again for the ~20" oval glass-pack to replace the ~12" 

factory resonator.  The glass-pack was for a MGB. This lower the entire 

sound level to a very acceptable level.  The 3k boom is still there but 

now at a tolerable level.  Glass-pack cost $30.  Total cost $120.

* While the car was on the rack, I bought a can of gray engine paint to 

paint the MBG muffler (it was originally orange) and the exhaust pipe 

that were rusted. (paint $3)

NOTE:  this system seems to have better torque at the low range but less 

(?) power at the high RPM.  Doug claims the back pressure should not 

be much different than factory.  Maybe I'm imagining this because it 

is louder at low RPM and quiter at high RPM?



John

'96M



> 

> At 08:04 PM 12-03-97 -0500, you wrote:

> .......

> >  I keep you guys posted on the results.  BTW, I intend to do 

> >a full write-up on this muffler shop (in the Dallas/Fort Worth area) and 

> >the Kalveta Spare Tire Bracket.

> >      ^^^^^^

> >

> >  John T. Yang         [ jyang@ftw.mot.com ]  

> >'96M - rumbling along with UT Austin personalized plate og "BOMBIE"

> >

> ...........

> John (and all):

> Hope the install goes well!  Let me know if you have any problems with the

> bracket.  Also, it's:  Kaleva   Kalveta sounds cheesy    ((you know:

> Velveeta (tm)))

> The muffler I used, which doesn't ring at 3k RPM, but is loud by itself

> (until I put a resonator tip on) is a Walker "ultra-flow" : low loss, small

> and readily available.  

> The trouble with 'glass-packs' that I had back when my MGB was a way of

> making me take public transportation, the fiberglass blew out of the 'cans'

> about 6 mos. after install. So good luck 

> As usual, YMMV.

> Robert Ullrich

> 

> 

>