Pendulum Outlaw, Build, Adventures and Misadventures

[Tom Elder]

Hi, Dan

I did a spring shake down run out to the Markham Airport. This is really subjective, too many changes to the car since last fall, but the muffler seems to have a deeper richer sound at idle, it does not seem to be any louder at speed in the car. I will confirm this later in the week, I took some sound measurements last fall but this will not be a true A - B test as there were other changes that would effect the interior sound. For the video, camera was held approximately to the SAE Sound Test Spec 0.5 meter back from a muffler tip, 45 degree offset and at the height of the tip. Hope this helps with your decision.



Video did not upload, I will try again

[will hung]

Originally Posted by Tom Elder

...I like the purposeful look of the 904 cookie cutter tips,
and the unexplained science of them...

I love the look of this muffler, can't wait to hear it.

The history behind the tips is pretty cool too. While running at the Nurburgring, Porsche found that as the cars got airborn, with their rear weight bias, they would smack the tail pipes off the road, bend the tips straight up and flatten the pipes. So they made these tail pipes so that they wouldn't bend when hitting the ground.

[Tom Elder]

Pendulum Outlaw 904 tips - YouTube

Crank it up!

I took some sound measurements last fall because I wanted to track the sound quality as I changed the car. Unfortunately I did not get too many data points before the weather turn. I will the post the results but it is really not quality data. Over the winter I changed the muffler, changed the seats, added a roll bar removed some of the rear padding, the exterior mirror is presently off the car. Speed was measured with a gps unit and and the sound meter is a Omega unit.
2012, 50kph - 75dB, 80kph - 78.5dB
2013, 50kph - 74.3dB, 80kph - 77.5dB
So with all the changes the car got a little bit quieter. I would say the muffler did not increase in sound level but the tone appears to me to be lower. I think the biggest contributor to the noise level is powertrain noise, I have street urethane bushings on the spring plate and old original rubber engine / trans mounting, which I will update next.

[Tom Elder]

Small update, a step forward in mono chromatic exterior look, changed the front lenses from amber to clear. I realize from a thread on clear signal lights there are some pretty strong opinions on whether they should be installed on a long nose. The Italian front signals back in the day were about 3/4 clear so I think that establishes some precedent before the tuner crowd went to clear. My thought at this point, the car will be painted a dark gunmetal grey which I saw on a late model 911 GT3. I think when clear lights step over the bing line is when there is too much contrast between the body color and the lights, The current Prius clear rear taillights look, like large slabs of chrome, but some other OE's, on some of their models have rear clear lenses with grey behind the lens which makes the light assembly less pronounce and less of a distraction from the body form.

Progress has been slow, summer yard work and deck build, vacation (Montreal GP) but I have started a complete rubber bushing refurbish. Noticeable difference just installing new engine mounts and top front strut rubber, less structural borne noise. So I am now looking for a 901 trans mount I can cut off the fixed rubber mounts and install the two extra engine mounts I bought from our host, and have a minimal down time. Also looking for an extra 901 gear lever so I can send it out and have it de chromed (de blinged) and looking for a through the body front sway bar as well to complete the suspension update. I will post a WTB in the classifies.

Installed the 935 mirrors, I will post more pictures later.

[lateapex911]

Keep it coming, and enjoy the process and driving !

[Reiver]

Enjoying your work and vision....fun to personalize 911's IMO.
Did you notice any change in torque with the muffler change? Is the sweet spot higher or lower in the rpm range.....in my short 911 experience I've found the torque to be easily influenced by muffler tuning and lots of the aftermarkets (M&K in my case) reduce mid range grunt to a higher rpm...fine if you are always running at high rpm but not so traffic friendly.

[andy_uranium]

Tom car looks very cool! Subbed for future progress.

[Tom Elder]

Reiver, no I did not notice any change in the mid range torque. I did think about this when I built the muffler not to make it too free flowing. You do make a good point, my goal is have a good daily, streetable, driver which will be a good 3 season commuter, in traffic, and good for the occasional long distance driving holiday and hopefully some what capable for an occasional track day.

[urseppos]

Wow, absolutely love the rear deck lid, nice work !

[Tom Elder]

Installed a set of used 935 mirrors, picked at Hershey Swap Meet a couple of years ago. Pretty straight forward install. Put some tape on the door and window frame to mark the spot for mounting holes. Made a couple of transfer screws up by cutting the heads off a #10 - 32 screws and sharpening to a point, on the grinder. Put the screws all the way in the mirror. Positioned the mirror to the door, then pressed hard to mark the tape. Drilled the holes. This was where I ran out of a bit of craftsmanship talent. On the driver's side, one of the tapped mounting holes in the mirror was not perpendicular to the mounting surface. So after drilling a hole perpendicular in the window frame, I had to open it up a bit to get the mirror to sit flat. The mirrors also require some filing of the housing to sit flat, there was some fouling at the bottom edge of the quarter window frames. The door trim needed to be cut shorter as well. The end of the door trim fits only partially under the trailing edge of the mirror.
Visibility with the mirrors is good, adjust them up for your blind spot. They definitely are not truck mirrors!

[jakz]

Congrats on the mods your car is looking awesome, love the decklid and the exhaust, i was just starting to research that mod and your post helps a lot, do you think that the baffles you added kept the db's low? I want a loud exhaust but not too loud on the DD i have some welding skills and a great mig welder do youthink i can get away with it?
Bes regards

[safe]

Originally Posted by jakz

Congrats on the mods your car is looking awesome, love the decklid and the exhaust, i was just starting to research that mod and your post helps a lot, do you think that the baffles you added kept the db's low? I want a loud exhaust but not too loud on the DD i have some welding skills and a great mig welder do youthink i can get away with it?
Bes regards

Just do the sport muffler conversion, sounds great and is not to loud.

[Tom Elder]

Hi, Jakz / Magnus

Yes I do think adding the baffles kept the sound level low or pretty much the same as the stock muffler but the tone seems to be deeper due to the megaphones. I am ok with having erred on the quiet side as I want to be able to do long distance trips in it.
What influenced me to do something different over the sport muffler mod described, was talking to a person who had completed the mod on an early long nose car and found it too loud for a long distance drive. He was about the same age as myself, north of fifty, so maybe we are a bit less tolerant of noise.

Magnus, I am curious to learn more about your car and driving habits. What is the set up on your car, year, engine size, type of driving, sound deadening material in or not? Your opinion is opposite of the guy I talked to, and that does not mean yours or his opinion is wrong, there is no, one right answer on this subject, way too many variables in the drivers and cars.

I may change my mind in the future, once the rubber bushings have been refreshed and new interior sound deadening has been installed to get rid of the high road noise.

I would really like to hear one of mufflers which have had the modifications completed as described in the 1974 print.

Cheers

[PaulGeudon]

Great thread, lovely looking project. Will be following with great interest!

[safe]

Originally Posted by Tom Elder

Hi, Jakz / Magnus

Magnus, I am curious to learn more about your car and driving habits. What is the set up on your car, year, engine size, type of driving, sound deadening material in or not? Your opinion is opposite of the guy I talked to, and that does not mean yours or his opinion is wrong, there is no, one right answer on this subject, way too many variables in the drivers and cars.

Cheers

Hi
It's the 77 Targa in my signature.
My driving habits are 3000+ miles a year, some driving around town but mostly driving to and from auto-x and track days.
I have all original sound deadening, except in the engine bay, that disintegrated last week...
After the sport conversion the exhaust sound quite a lot louder outside and behind the car, but it's not very loud I still pass under 95db on track days.
Inside the car while driving It's not that different from before the conversion, unless your in a tunnel .
I have noticed on other cars that loud exhausts doesn't actually make that much more noise in the car.

My engine has a very open intake with big ITBs, they make a sweet racket @5000 inside the car, a lot more than exhaust megaphones would do.

A side note after the sport conversion:
I haven't been on a dyno but since I have a wideband lambda and an EFI capable of closed loop feedback I have seen that the engine wants about 10% more fuel to maintain the same AFR as before on WOT above 4000 rpm (and other places along the fuel map).
That tells me that the exhaust breathes a lot better than before, my butt dyno is useless so I can't tell a difference, but it sure sounds faster!!

[Tom Elder]

Paul, thanks, Love your car! I really like SWB cars, in particular the rear fender shape / rear wheel openings, very subtle. I like the colour of your car, very well co ordinated, body, wheel colour.

Magnus, thanks for the excellent feedback! This is what makes this forum so good.

I was doing a little light reading on controlling Noise, Vibration, Harness (NVH) issues in a vehicle. I mentioned before the interior cabin noise in my car is a bit high due to structural borne noise, 78 dBa. Came across this passage in a book, Vehicle Refinement, Controlling Noise and Vibration in Road Vehicles by Matthew Harrison. I thought some of you might find it interesting when making a decision on the loudness of your muffler.

"When the intelligibility of the female voice is of particular importance, this target might be lowered to 60 dBa" (From 65 dBa)






Where does your better half think the sound target should be set at.

[Flieger]

Lol!

[Lapkritis]

Great work- nice job putting your own touches on the car. Look forward to future updates.

[safe]

Originally Posted by Tom Elder

I see that you also have the "Scientific design of...", I have read that 3-4 times and understand less and less (well, its getting a little better 3rd time).
It's not an easy book to read and understand, but it is one of the best book I have ever bought.
It's always on my nightstand, if I have trouble sleeping, with too many thoughts in my head, I read from it and within 30 minutes I'm asleep... I kid you not !

[scootermcrad]

Wow! Looking great! I bet that exhaust sounds great as well. I would love to see/hear a video showing that off... (hint hint)

Aaaaa.... I love to see people still using drafting machines! I still use mine all the time.

I was recently looking for a book on exhaust AND intake manifold design. First I've heard of that one. I just might have to pick that one up!