Datsun Roadster Forum-311s.org

In April I participated in the Touge California rally, you can read about it here:
http://www.311s.org/phpBB3/viewtopic.php?f=4&t=25985

In preparation for the rally my navigator would join me only on one condition: I put a quieter exhaust system in.

I agreed and we both concluded it was time for a more "adult" sound for the roadster. I was running a Borla XS muffler with 3" outlet to a megaphone style tip:



I ran this setup for ~9 years. It was awesome. It was loud. 102.5db at Laguna Seca with a short shift! Even around town just slowly decelerating from 10 mph and 2500rpm it set off car alarms with a sort of booming tone. Again, it was fun but long trips left a ringing in my ears.

The solution? Replace the Borla with a larger muffler and add a resonator in the factory spot next to the gas tank.
In this picture below, the straight pipe would be replaced by a small resonator:


We went with a much longer Magnaflow muffler and a resonator, as many of Z-builds at the shop use them with nice results:


Here are some closer shots:




I am tempted to paint the resonator black

I was shocked how much quieter it was, while still maintaining the throaty sound. The booming was gone and I could hear things like the intake, and my passenger
Here is comparison of the two setups:

https://youtu.be/UcaLl_LReGc

https://youtu.be/UcaLl_LReGc

Alvin,

Where does one get the material like yours between the gas tank and the straps?

Congratulations on the dent free exhaust pipe!

Mike,

I used 1/4" exercise mat material on my car's straps. It's closed cell foam, used black silicone on the edges to seal out any moisture. Any luck finding a new tank?

Pat

Much better! As I posted yesterday, I was considering changing out the dynomax turbo, looking for that more "adult" sound as you put it (and exactly what my thoughts were!). As I said, my carbs (with foam socks on) are louder than my exhaust at the moment, so I'll wait to see how she sounds with the airbox on (whenever that happens).
The change sounds great Alvin... Very throaty without rasp. Exactly what I'm looking for.

Gregs672000 wrote:Much better! As I posted yesterday, I was considering changing out the dynomax turbo, looking for that more "adult" sound as you put it (and exactly what my thoughts were!). As I said, my carbs (with foam socks on) are louder than my exhaust at the moment, so I'll wait to see how she sounds with the airbox on (whenever that happens).
The change sounds great Alvin... Very throaty without rasp. Exactly what I'm looking for.

Consider a tamer Borla model or Magnaflow....or if possible add a resonator to existing setup?

New exhaust sounds really good Alvin-- well done!

I put a Borla muffler on my 67 Roadster and it sounds amazing.

Alvin wrote:I am tempted to paint the resonator black

Do it... It will disappear..

harlankatz01 wrote:solvang roadster classic 4222016 046.JPGI put a Borla muffler on my 67 Roadster and it sounds amazing.

I should have demanded an audio demo in Solvang!

RCMike wrote:

Alvin wrote:I am tempted to paint the resonator black

Do it... It will disappear..

Weekend project here I come!

Alvin,
Would you have part numbers for the Magnaflow muff and resonator? I'm going shopping for a muffler and resonator soon!
Thanks.

Karl

TurboRagtop wrote:Alvin,
Would you have part numbers for the Magnaflow muff and resonator? I'm going shopping for a muffler and resonator soon!
Thanks.

Karl

Karl,
Sorry I do not have part numbers.

Alvin wrote:

TurboRagtop wrote:Alvin,
Would you have part numbers for the Magnaflow muff and resonator? I'm going shopping for a muffler and resonator soon!
Thanks.

Karl

Karl,
Sorry I do not have part numbers.

Alvin,
If you can measure length and width I can get Karl the part numbers

Thanks Pjackb!
I appreciate the info Alvin, sorry for any inconvenience.

I am friends with one of the guys at Magnaflow (engineers a lot of the systems you see on some really well known builders projects) and had a long discussion about an exhaust for my car based on my planned use of the car and mods it has (40 over 1600 w/ higher compression, mild cam, weber carb set-up, header) based on that, here was his suggestions: "I would start the system wa a 2.5" to 2.25" taper and keep it 2.25" until the frame and maintain 2.0" after for a balanced system. If more for peak power of track racing I would keep the 2.25 throughout. Because every ft-lbs is noticeable on small bore cars, I would personally stick to 2.0" for street and low rev drivability. Go with a smaller reso 4" round x 14" long, primary 4x9 14" long both with 2" internals, 2.25" internals if you decide to go more track/ peak hp. I ultimately decided to go with the 2" system as the car is going to see a lot more street use than track. once I get everything installed I will post photos.