Naturally Aspirated Performance Forum Discussion of naturally-aspirated rotary performance. No Power Adders, only pure rotary power! From the "12A" to the "RENESIS" and beyond.

Long primary length

Thread Tools
 
Search this Thread
 
Old 10-05-12, 06:24 PM
  #1  
Meat Popsicle

Thread Starter
iTrader: (1)
 
TougeMonster's Avatar
 
Join Date: Dec 2004
Location: Missoula, Montuky
Posts: 414
Likes: 0
Received 0 Likes on 0 Posts
Long primary length

Does longer piping (118") boost low end or high RPM? Or shorter (113")
Im shooting for a Helmholtz resonance effect at around 5500 rpm with a half bridge
Old 10-06-12, 01:21 PM
  #2  
Rallye RX7

iTrader: (11)
 
fidelity101's Avatar
 
Join Date: May 2005
Location: MI/CHI
Posts: 2,403
Received 92 Likes on 55 Posts
Shorter for high rpm, longer for low rpm. it just shifts the torque curve over left or right
Old 10-06-12, 02:30 PM
  #3  
Meat Popsicle

Thread Starter
iTrader: (1)
 
TougeMonster's Avatar
 
Join Date: Dec 2004
Location: Missoula, Montuky
Posts: 414
Likes: 0
Received 0 Likes on 0 Posts
So maybe somewhere in the middle? 115" primary? I have 2" runners. Should I collect to a 4"megaphone then 4 inch piping and muff. Or go to 2" , 2.5" 3"? Oooor 4"megaphone with 3" reverse cone at the end. I'm lost
Old 10-08-12, 10:59 AM
  #4  
Moderator

iTrader: (3)
 
j9fd3s's Avatar
 
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,796
Received 2,574 Likes on 1,830 Posts
the difference between 118 and 113 is pretty small, i'd just run whatever fit the chassis best, or even better make it adjustable
Old 10-08-12, 11:20 AM
  #5  
Lapping = Fapping

iTrader: (13)
 
Jeff20B's Avatar
 
Join Date: Aug 2001
Location: Near Seattle
Posts: 15,725
Received 70 Likes on 64 Posts
Agreed on the length - just make it fit the car.

As for individual runner length, over a long span such as that, it doesn't matter as much as it does on a short primary. So make the header runners a comfortable length(shape/angle) for you.

The collector can can begin as a 2.5" smashed down to 2" tall and about 3" wide. The length should be 6" per .5" diameter increase (like a megaphone) but I would only expand to 3", then into a final muffler with a 3" core. You might try a center/offset core muffler so the offset can absorb a little more noise without hurting flow noticeably.
Old 10-20-12, 04:47 AM
  #6  
Meat Popsicle

Thread Starter
iTrader: (1)
 
TougeMonster's Avatar
 
Join Date: Dec 2004
Location: Missoula, Montuky
Posts: 414
Likes: 0
Received 0 Likes on 0 Posts
What's your guys' take on butt welding tubes together.
I purchased a complete long primary road race exhaust but it had to but cut to smithereens to ship.
I doubt I can afford a presilencer and I'm trying to drive it by Halloween
Old 10-20-12, 03:36 PM
  #7  
Senior Member

iTrader: (1)
 
John Huijben's Avatar
 
Join Date: Oct 2010
Location: The Netherlands
Posts: 605
Likes: 0
Received 13 Likes on 10 Posts
no problem if done right, make sure the pipes match up perfectly, and use backing gas
Old 10-20-12, 04:57 PM
  #8  
Meat Popsicle

Thread Starter
iTrader: (1)
 
TougeMonster's Avatar
 
Join Date: Dec 2004
Location: Missoula, Montuky
Posts: 414
Likes: 0
Received 0 Likes on 0 Posts
Cool should be no biggie then. And plus I gotta weekend job that should help me out with buying more car parts
Old 10-25-12, 07:02 PM
  #9  
Moderator

iTrader: (3)
 
j9fd3s's Avatar
 
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,796
Received 2,574 Likes on 1,830 Posts
when i get around to doing mine, im going to use something like these to be able to try a few different lengths. JEGS Stainless Steel Lap Band Exhaust Clamps - JEGS

i'm on exhaust 2.0 and not only was it expensive, its also broken, so 3.0 is going to be simpler
Old 10-25-12, 08:52 PM
  #10  
Meat Popsicle

Thread Starter
iTrader: (1)
 
TougeMonster's Avatar
 
Join Date: Dec 2004
Location: Missoula, Montuky
Posts: 414
Likes: 0
Received 0 Likes on 0 Posts
That's a good idea. I'll hafta start over to do that. Mines collected at the muffler right now.
Kinda long but oh well
Old 11-09-12, 10:44 PM
  #11  
Meat Popsicle

Thread Starter
iTrader: (1)
 
TougeMonster's Avatar
 
Join Date: Dec 2004
Location: Missoula, Montuky
Posts: 414
Likes: 0
Received 0 Likes on 0 Posts
Long primary length-image-1293366399.jpg

I had an old dynomax muffler welded up
It's long. And ghetto
I'm lookin for a 3" strait through muffler that is maybe like 10" round.
Basically as big as I can fit, then ill get better tubes bent
It's not to loud with the presilencer atleast
Haven't measured it yet, but its long
The collector is pretty much part of the muffler.
Ovaled it and has two 2" pipes into a 3" muffler
Old 11-13-12, 11:04 AM
  #12  
Moderator

iTrader: (3)
 
j9fd3s's Avatar
 
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,796
Received 2,574 Likes on 1,830 Posts
that system actually looks pretty good, its good enough you can go work on the intake/ecu.

i've been looking for an 8" round muffler forever, and the seem to be normal in japan, and AUS, but good luck finding one in the us!
Old 11-13-12, 04:06 PM
  #13  
Full Member

 
Laxfreak3557's Avatar
 
Join Date: Jan 2008
Location: Huntington Beach, CA
Posts: 122
Likes: 0
Received 0 Likes on 0 Posts
How loud is that system? It looks really nice!
Old 11-13-12, 04:48 PM
  #14  
Meat Popsicle

Thread Starter
iTrader: (1)
 
TougeMonster's Avatar
 
Join Date: Dec 2004
Location: Missoula, Montuky
Posts: 414
Likes: 0
Received 0 Likes on 0 Posts
It wasn't too loud till I took it on the highway.
Muffler is blown out already and kills my brain it's so loud.
I'm lookin at huge strait through diesel mufflers.
Ill have a whole new rear section made when I get a new muffler.
Should I get a strait through style or the kind with the louvers that keep the sound down?
Too much backpressure for a half bridge?
Old 11-14-12, 12:34 AM
  #15  
Full Member

 
Laxfreak3557's Avatar
 
Join Date: Jan 2008
Location: Huntington Beach, CA
Posts: 122
Likes: 0
Received 0 Likes on 0 Posts
I have heard great things about the flowmaster hushpower series. Might be something worth looking into
Old 11-14-12, 12:05 PM
  #16  
Moderator

iTrader: (3)
 
j9fd3s's Avatar
 
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,796
Received 2,574 Likes on 1,830 Posts
the engine will eat baffles, the exhaust pulses are supersonic, so its probably literally like taking a hammer to the insides of the muffler.
Old 11-14-12, 07:38 PM
  #17  
Meat Popsicle

Thread Starter
iTrader: (1)
 
TougeMonster's Avatar
 
Join Date: Dec 2004
Location: Missoula, Montuky
Posts: 414
Likes: 0
Received 0 Likes on 0 Posts
How about louveres?
Too much of a restriction?
I might end up getting two more resonators put in if I can't find a suitable muffler
Name:  3in.jpg
Views: 255
Size:  30.5 KB
Old 11-14-12, 10:01 PM
  #18  
Banned
iTrader: (40)
 
73rx313b's Avatar
 
Join Date: Mar 2006
Location: North Cackalacky
Posts: 2,023
Received 1,431 Likes on 1,000 Posts
Im using the HushPower 3in with the dump tip, I also have RB dual pre silencers and I love it! sounds deep and throaty...
Old 11-14-12, 10:34 PM
  #19  
Full Member

 
Laxfreak3557's Avatar
 
Join Date: Jan 2008
Location: Huntington Beach, CA
Posts: 122
Likes: 0
Received 0 Likes on 0 Posts
I read about the hushpower on the improved touring website. It isn't your standard flowmaster 40 series . . .
Old 11-14-12, 10:57 PM
  #20  
Banned
iTrader: (40)
 
73rx313b's Avatar
 
Join Date: Mar 2006
Location: North Cackalacky
Posts: 2,023
Received 1,431 Likes on 1,000 Posts
No! not anything like the Flowmaster series... I talked to the Cheif design guy at HushPower and he stated that the HushPower mufflers with hold up to ovedr 2000 degrees and not blow out like flowMaster... They are built pretty well from what i can tell
Old 11-15-12, 02:28 PM
  #21  
Meat Popsicle

Thread Starter
iTrader: (1)
 
TougeMonster's Avatar
 
Join Date: Dec 2004
Location: Missoula, Montuky
Posts: 414
Likes: 0
Received 0 Likes on 0 Posts
Are you hush power guys running a bridgy?
How loud is it?
Any sound clips?
Old 11-15-12, 03:12 PM
  #22  
Banned
iTrader: (40)
 
73rx313b's Avatar
 
Join Date: Mar 2006
Location: North Cackalacky
Posts: 2,023
Received 1,431 Likes on 1,000 Posts
Im running a large street ported 13b with a RB Holley here is a sound clip
Pictures by mazdasandcoffee - Photobucket
Old 11-19-12, 05:06 PM
  #23  
Meat Popsicle

Thread Starter
iTrader: (1)
 
TougeMonster's Avatar
 
Join Date: Dec 2004
Location: Missoula, Montuky
Posts: 414
Likes: 0
Received 0 Likes on 0 Posts
Still sounds pretty loud tho eh.
Do you have a presilencer or resonators?

I wish I could find sumthin like the rotaflo mufflers.
US currency is crap and worth less than AUD.
So one rotaflow muffler would be $411.15 USD then add shipping from Australia .... not cool
Old 11-19-12, 05:52 PM
  #24  
Lapping = Fapping

iTrader: (13)
 
Jeff20B's Avatar
 
Join Date: Aug 2001
Location: Near Seattle
Posts: 15,725
Received 70 Likes on 64 Posts
Make your own muffler. Get the materials. Weld everything together. Can't be that hard. You'll save a ton of money and learn something too.

Here is a link to get you started.
3" Stainless Steel Tube Perforated Pipe Exhaust 0 25M Long Straight 76mm OD Perf | eBay
Old 11-19-12, 07:22 PM
  #25  
Meat Popsicle

Thread Starter
iTrader: (1)
 
TougeMonster's Avatar
 
Join Date: Dec 2004
Location: Missoula, Montuky
Posts: 414
Likes: 0
Received 0 Likes on 0 Posts
I would if I had a TIG
I was thinkin maybe I should just get a universal power pulse muffler
Seems like it would get the job done, especially if I get two more resonators
One for each tube before it collects at the muffler but after the presilencer

Apparently I have unequal length headers so I wanna try to put the two seperated resonators at equal lengths, so I guess they would look staggered slightly.
Would that even matter?


Quick Reply: Long primary length



All times are GMT -5. The time now is 02:13 AM.