Rotary Shack Muffler?
Rotary Shack Muffler
05-07-10, 12:16 AM
#61
Sounds like a stock flywheel too.
I finally got a chance to drive mine today. It's decently quiet when at part throttle but any time you open the throttle for even minor stuff it gets really loud inside the car. I don't like it. Seems I should have used a slightly thicker pipe between the header and the first muffling device. Heck even stock FBs had a thickwall pipe between the manifold and the first cat. I found a place online that sells 3" in .120 wall so I might give that a try. It's only like one foot. I've made this mistake before on my bro's RX-4 with a piece of thinwall between the header and the presilencer (it already ahd the right slant cut/curve when I grabbed it from the pile). The only fix was to chop it out and replace with thickwall. Cured it just fine.
I finally got a chance to drive mine today. It's decently quiet when at part throttle but any time you open the throttle for even minor stuff it gets really loud inside the car. I don't like it. Seems I should have used a slightly thicker pipe between the header and the first muffling device. Heck even stock FBs had a thickwall pipe between the manifold and the first cat. I found a place online that sells 3" in .120 wall so I might give that a try. It's only like one foot. I've made this mistake before on my bro's RX-4 with a piece of thinwall between the header and the presilencer (it already ahd the right slant cut/curve when I grabbed it from the pile). The only fix was to chop it out and replace with thickwall. Cured it just fine.
05-07-10, 12:47 AM
#62
Moderator
iTrader: (3)
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,796
Received 2,574 Likes
on
1,830 Posts
Sounds like a stock flywheel too.
I finally got a chance to drive mine today. It's decently quiet when at part throttle but any time you open the throttle for even minor stuff it gets really loud inside the car. I don't like it. Seems I should have used a slightly thicker pipe between the header and the first muffling device. Heck even stock FBs had a thickwall pipe between the manifold and the first cat. I found a place online that sells 3" in .120 wall so I might give that a try. It's only like one foot. I've made this mistake before on my bro's RX-4 with a piece of thinwall between the header and the presilencer (it already ahd the right slant cut/curve when I grabbed it from the pile). The only fix was to chop it out and replace with thickwall. Cured it just fine.
I finally got a chance to drive mine today. It's decently quiet when at part throttle but any time you open the throttle for even minor stuff it gets really loud inside the car. I don't like it. Seems I should have used a slightly thicker pipe between the header and the first muffling device. Heck even stock FBs had a thickwall pipe between the manifold and the first cat. I found a place online that sells 3" in .120 wall so I might give that a try. It's only like one foot. I've made this mistake before on my bro's RX-4 with a piece of thinwall between the header and the presilencer (it already ahd the right slant cut/curve when I grabbed it from the pile). The only fix was to chop it out and replace with thickwall. Cured it just fine.
05-07-10, 03:13 AM
#64
I keep taking two steps forward, then take two steps back on this thing. Sorry for making you remember that song. I think it's 20B time. I'm just spinning my wheels otherwise. I'll have to get a video when it's in and running.
05-08-10, 06:37 PM
#66
Environmentally-Hostile
Sounds like a stock flywheel too.
I finally got a chance to drive mine today. It's decently quiet when at part throttle but any time you open the throttle for even minor stuff it gets really loud inside the car. I don't like it. Seems I should have used a slightly thicker pipe between the header and the first muffling device. Heck even stock FBs had a thickwall pipe between the manifold and the first cat. I found a place online that sells 3" in .120 wall so I might give that a try. It's only like one foot. I've made this mistake before on my bro's RX-4 with a piece of thinwall between the header and the presilencer (it already ahd the right slant cut/curve when I grabbed it from the pile). The only fix was to chop it out and replace with thickwall. Cured it just fine.
I finally got a chance to drive mine today. It's decently quiet when at part throttle but any time you open the throttle for even minor stuff it gets really loud inside the car. I don't like it. Seems I should have used a slightly thicker pipe between the header and the first muffling device. Heck even stock FBs had a thickwall pipe between the manifold and the first cat. I found a place online that sells 3" in .120 wall so I might give that a try. It's only like one foot. I've made this mistake before on my bro's RX-4 with a piece of thinwall between the header and the presilencer (it already ahd the right slant cut/curve when I grabbed it from the pile). The only fix was to chop it out and replace with thickwall. Cured it just fine.
05-09-10, 04:16 PM
#68
Sorry about the welds. Best I could do with a flux core welder.
The lump you see at the bottom is a nut to allow different inserts held with a bolt.
Over the axle part worked out pretty well. Those are air pump brackets. Lots of good metal in them. Special thanks to Lloyd for doing the welding on the 3" flanges.
Magnaflow Magnapack 4" round 3" core. Two welded together to make it 22" long. Bullet end.
Large RB universal presilencer. Nice 30° collector into 3". This collector is temporary while the 2 rotor is in there. I'll swap to thickwall later on when I redo it for the other engine.
The lump you see at the bottom is a nut to allow different inserts held with a bolt.
Over the axle part worked out pretty well. Those are air pump brackets. Lots of good metal in them. Special thanks to Lloyd for doing the welding on the 3" flanges.
Magnaflow Magnapack 4" round 3" core. Two welded together to make it 22" long. Bullet end.
Large RB universal presilencer. Nice 30° collector into 3". This collector is temporary while the 2 rotor is in there. I'll swap to thickwall later on when I redo it for the other engine.
05-09-10, 04:33 PM
#69
I have to say at idle and part throttle it is nice. But as soon as you give it just a tiny bit of gas, it goes HMMMMM way more than I wanted. Inside. Droning. Haven't taken it on the freeway yet because there's still no cooling system, but I suspect it will be even worse. Just a drive around the block is all I can do.
The main areas for noise to leak into the passenger space is in front of the first muffling device, which it only has 14 gauge pipe. Then at the lengthened Magnaflow because the outer shell is 16 gauge. Had I known at the time, I'd have replaced it with 14 gauge like an RB presilencer. I still can swap them if I was keeping it 2 rotor, but hopefully the 20B will run quieter. More pulses which apparently helps with noise.
I snapped a couple pics during the Magnamods.
I'm kind of affraid to go any further right now on things like a cooling system (electric fan conversion), DLIDFIS (again, electrical work), relocate the battery (more electrical work) until the beast goes in with EFI, which will require all that stuff to be redone on top of a huge amount of additional electrical work.
However there is one temp possibility. I'll explain it next.
The main areas for noise to leak into the passenger space is in front of the first muffling device, which it only has 14 gauge pipe. Then at the lengthened Magnaflow because the outer shell is 16 gauge. Had I known at the time, I'd have replaced it with 14 gauge like an RB presilencer. I still can swap them if I was keeping it 2 rotor, but hopefully the 20B will run quieter. More pulses which apparently helps with noise.
I snapped a couple pics during the Magnamods.
I'm kind of affraid to go any further right now on things like a cooling system (electric fan conversion), DLIDFIS (again, electrical work), relocate the battery (more electrical work) until the beast goes in with EFI, which will require all that stuff to be redone on top of a huge amount of additional electrical work.
However there is one temp possibility. I'll explain it next.
05-09-10, 05:06 PM
#70
The current engine is an old R5 13B with a Camden supercharger. On its maiden voyage, after the exhaust upgrade, I attempted to boost it and because it still has a stupid foam triangle air filter, it fell on its face at 6k. Ok, not too suprising. It also didn't seem as crisp as it did with the 2" system. Maybe 3" is hurting low end performance a little? Maybe a little. A perfect exhaust for that engine would have been 2.5" I think. No matter as it's all coming out.
This leaves the car empty until I can rebuild the 20B. Or I'll test it in the car first to make sure it's all hooked up and able to run, then rebuild it.
But then I realized I have enough, or nearly enough parts to build a half bridge 12A, and I've wanted to try something like this for a long time. Just never an oppurtunity until now. Let's see here I'll need to make a list.
RB modified Holley 600 (for SP 13B)
high flow 1970s Nikki manifold with Holley adaptor plate (or I'll get an RB intake manifold)
'83-'85 12A rotating assembly with new springs good seals etc ready to go
side plates ready for porting
housings with slight missing chrome (probably the best I'll find these days)
110gph Carter fuel pump already installed.
Holley pressure reg
adjustable ROPR for 85 to 90 psi
Various flywheels from stock (26pounds) to light steel to aluminum
Hockey puck motor mounts
20Bs are all about torque. Supercharged 13Bs have great torque. 12As do not. I really like something peejay said in the NA forum, something about his half bridge has as much torque at 3k as his streetport did at peak. That's for me! Of course I suspect he's 13B-only these days, but was a real supporter of 12A stuff for a good long while. An SP 12A can make how much HP at peak? Anyway I could do a 13B, but at a far greater cost, so I think a 12A is fine. Plus I have a 12A road race header just sitting, waiting.
So what do you guys think? Half bridge 12A to tide me over and justify the existance of a loud exhaust? Then sell it to fund the 20B rebuild? It'd give me an excuse to wire up DLIDFIS, electric fan and maybe relocate the battery.
This leaves the car empty until I can rebuild the 20B. Or I'll test it in the car first to make sure it's all hooked up and able to run, then rebuild it.
But then I realized I have enough, or nearly enough parts to build a half bridge 12A, and I've wanted to try something like this for a long time. Just never an oppurtunity until now. Let's see here I'll need to make a list.
RB modified Holley 600 (for SP 13B)
high flow 1970s Nikki manifold with Holley adaptor plate (or I'll get an RB intake manifold)
'83-'85 12A rotating assembly with new springs good seals etc ready to go
side plates ready for porting
housings with slight missing chrome (probably the best I'll find these days)
110gph Carter fuel pump already installed.
Holley pressure reg
adjustable ROPR for 85 to 90 psi
Various flywheels from stock (26pounds) to light steel to aluminum
Hockey puck motor mounts
20Bs are all about torque. Supercharged 13Bs have great torque. 12As do not.
I really like something peejay said in the NA forum, something about his half bridge has as much torque at 3k as his streetport did at peak. That's for me! Of course I suspect he's 13B-only these days, but was a real supporter of 12A stuff for a good long while. An SP 12A can make how much HP at peak? Anyway I could do a 13B, but at a far greater cost, so I think a 12A is fine. Plus I have a 12A road race header just sitting, waiting. So what do you guys think? Half bridge 12A to tide me over and justify the existance of a loud exhaust? Then sell it to fund the 20B rebuild? It'd give me an excuse to wire up DLIDFIS, electric fan and maybe relocate the battery.
05-09-10, 07:41 PM
#72
Moderator
iTrader: (3)
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,796
Received 2,574 Likes
on
1,830 Posts
20Bs are all about torque. Supercharged 13Bs have great torque. 12As do not.
I really like something peejay said in the NA forum, something about his half bridge has as much torque at 3k as his streetport did at peak. That's for me! Of course I suspect he's 13B-only these days, but was a real supporter of 12A stuff for a good long while. An SP 12A can make how much HP at peak? Anyway I could do a 13B, but at a far greater cost, so I think a 12A is fine. Plus I have a 12A road race header just sitting, waiting. So what do you guys think? Half bridge 12A to tide me over and justify the existance of a loud exhaust? Then sell it to fund the 20B rebuild? It'd give me an excuse to wire up DLIDFIS, electric fan and maybe relocate the battery.
oh and we do know it wont get much louder than it is now!
09-09-10, 11:01 AM
#75
I need a new user title
Join Date: Oct 2005
Location: Yaizu, Japan
Posts: 2,646
Likes: 0
Received 0 Likes
on
0 Posts