What did you do to your FB today?
06-28-12, 06:32 PM
#901
love the braaaap
Well I cut open the front magnaflow muffler I cut out of my exhaust system a few days ago for inspection. It had gotten quite noisy inside the car, noise radiating from the case of the muffler. Rule 1, never put an oval muffler near the header, the strong exhaust pulses will vibrate the outer casing and radiate sound into the car. Rule 2, make sure you use a very high quality muffler near the header.
The magnaflow I had literally right at the exit of the header. It always radiated sound out of the case, but after my track day and the extreme head the exhaust likely saw, the muffler got quite a lot louder and actually started rattling a bit. Decided to just cut it out and put a straight pipe in place (don't worry, still 2 more good mufflers in the system, yes I was going for very quiet on a budget lol). Interior noise greatly reduced, I barely hear the exhaust inside the car at a cruise now. Its definitely louder outside the car, which was not a surprise.
I cut the Magnaflow open today, figured I would have a look at the innards and find out what happened exactly. I think its safe to say some very high temperatures were reached inside the muffler. Discoloring of the stainless steel outer shell showed that quite well. I found that about a third of the packing material was burned away, not as much as I expected. But the way the stuff burned it looked like some of it had stuck together in clumps. This isn't a fiberglass packing, some sort of high temperature packing, much higher quality than fiberglass. It is not impervious to open flame though, would not light on fire just simply slowly condense into a smaller and harder mass. The muffler's construction is quite good, heavy stainless steel used for the shell and stainless steel wool around the perforated tube. On any other car or even a position further from the header on a rotary, this muffler would last a long time.
Here are a few pics too see the destruction.
The magnaflow I had literally right at the exit of the header. It always radiated sound out of the case, but after my track day and the extreme head the exhaust likely saw, the muffler got quite a lot louder and actually started rattling a bit. Decided to just cut it out and put a straight pipe in place (don't worry, still 2 more good mufflers in the system, yes I was going for very quiet on a budget lol). Interior noise greatly reduced, I barely hear the exhaust inside the car at a cruise now. Its definitely louder outside the car, which was not a surprise.
I cut the Magnaflow open today, figured I would have a look at the innards and find out what happened exactly. I think its safe to say some very high temperatures were reached inside the muffler. Discoloring of the stainless steel outer shell showed that quite well. I found that about a third of the packing material was burned away, not as much as I expected. But the way the stuff burned it looked like some of it had stuck together in clumps. This isn't a fiberglass packing, some sort of high temperature packing, much higher quality than fiberglass. It is not impervious to open flame though, would not light on fire just simply slowly condense into a smaller and harder mass. The muffler's construction is quite good, heavy stainless steel used for the shell and stainless steel wool around the perforated tube. On any other car or even a position further from the header on a rotary, this muffler would last a long time.
Here are a few pics too see the destruction.
06-29-12, 01:02 AM
#902
Holy surgery batman!
That accoustic material is probably rock wool.
I'm kinda worried because I used a Maganflow 5x8 as a presilencer on the GLC. It sounds fine in the car but I haven't pushed it yet. Once it gets loud I'll throw in a Racing Beat 2.5" presilencer. Like yours, I've got two other mufflers in the system so I'm fine, but I do not want noise inside the car.
That accoustic material is probably rock wool.
I'm kinda worried because I used a Maganflow 5x8 as a presilencer on the GLC. It sounds fine in the car but I haven't pushed it yet. Once it gets loud I'll throw in a Racing Beat 2.5" presilencer. Like yours, I've got two other mufflers in the system so I'm fine, but I do not want noise inside the car.
06-29-12, 07:26 AM
#903
That's impressive! I will keep the muffler placement in mind when I get to the exhaust system this winter. RB header and Magnaflows planned (on a serious budget) and I'll remember to place them a little farther back to avoid melting them. Thanks for the pics, I appreciate them.
06-29-12, 03:51 PM
#905
Lives on the Forum
Thread Starter
I put her back on the road again, finally! 
I also started work again today now that the cancer battle is nearly finished (I win!).
First race will be this Sunday.
.
I also started work again today now that the cancer battle is nearly finished (I win!).First race will be this Sunday.
.
06-29-12, 04:59 PM
#908
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06-29-12, 05:00 PM
#909
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haven't touched the FB, but i'm picking this up sunday
06-29-12, 05:04 PM
#910
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mike #2 is picking this one up saturday. Pro7 car, plenty of spares, $1800.
under the hood it turns out to be a U2 blue 82 model, so its the same as peepers, how could not make him buy that?
of course the only thing better than ONE U2 blue Rx7 race car is TWO U2 blue Rx7 racecars!
under the hood it turns out to be a U2 blue 82 model, so its the same as peepers, how could not make him buy that?
of course the only thing better than ONE U2 blue Rx7 race car is TWO U2 blue Rx7 racecars!
06-29-12, 05:17 PM
#911
love the braaaap
Holy surgery batman!
That accoustic material is probably rock wool.
I'm kinda worried because I used a Maganflow 5x8 as a presilencer on the GLC. It sounds fine in the car but I haven't pushed it yet. Once it gets loud I'll throw in a Racing Beat 2.5" presilencer. Like yours, I've got two other mufflers in the system so I'm fine, but I do not want noise inside the car.
That accoustic material is probably rock wool.
I'm kinda worried because I used a Maganflow 5x8 as a presilencer on the GLC. It sounds fine in the car but I haven't pushed it yet. Once it gets loud I'll throw in a Racing Beat 2.5" presilencer. Like yours, I've got two other mufflers in the system so I'm fine, but I do not want noise inside the car.
Given this information, I think real rock wool insulation that you can buy at any home improvement store these days may be a viable alternative to other more expensive acoustic or insulation materials and also offers excellent sound absorbing ability. I plan to use the perforated tube from the magnaflow, rock wool insulation, and stainless steel wool to build a custom 4" round presilencer.
As for putting a magnaflow up near a header, I would highly suggest you don't do this. The muffler did put up with quite a bit of abuse and even lasted nearly 6000km before finally getting too loud, but the shape of the muffler also had a lot to do with the way it radiated sound out from the shell. I would only suggest round mufflers/presilencers be placed near the header on a rotary. For the price though, magnaflow probably still is the best bang for your buck as its a very well constructed unit.
06-30-12, 01:27 AM
#916
bored **)
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Today i pulled the clean 4port 13b from my rx7 series 2 fb.
The engine has only 30,000 miles on it and a fresh holley carb including many racing beat products. I am keeping the engine handy incase my gsl-se decides to have any problems soon. Hopefully i don't have to change the original gsl-se engine to a 4 port carby though. that would be a shame if i do.. hmm.. any suggestions or requests?
there's a photo when the 4port 13b was ready to be pulled out of the car. i did all the work by myself. this was my first engine pull and it was much easier than i imagined it would be. it only took me a couple of hours including the lunch break. I will be sleeping well tonight!
The engine has only 30,000 miles on it and a fresh holley carb including many racing beat products. I am keeping the engine handy incase my gsl-se decides to have any problems soon. Hopefully i don't have to change the original gsl-se engine to a 4 port carby though. that would be a shame if i do.. hmm.. any suggestions or requests?
there's a photo when the 4port 13b was ready to be pulled out of the car. i did all the work by myself. this was my first engine pull and it was much easier than i imagined it would be. it only took me a couple of hours including the lunch break. I will be sleeping well tonight!
06-30-12, 08:53 AM
#917
Senior Member
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The acoustic material could be a version of rock wool, but according to my research on the stuff, rock wool (also called stone wool or mineral wool) is generally capable of withstanding temperatures of over 2000F without being affected. I put a propane torch up to the Magnaflow acoustic material and it would melt quite easily. Rock wool does not do this even with a large torch.
Given this information, I think real rock wool insulation that you can buy at any home improvement store these days may be a viable alternative to other more expensive acoustic or insulation materials and also offers excellent sound absorbing ability. I plan to use the perforated tube from the magnaflow, rock wool insulation, and stainless steel wool to build a custom 4" round presilencer.
As for putting a magnaflow up near a header, I would highly suggest you don't do this. The muffler did put up with quite a bit of abuse and even lasted nearly 6000km before finally getting too loud, but the shape of the muffler also had a lot to do with the way it radiated sound out from the shell. I would only suggest round mufflers/presilencers be placed near the header on a rotary. For the price though, magnaflow probably still is the best bang for your buck as its a very well constructed unit.
Given this information, I think real rock wool insulation that you can buy at any home improvement store these days may be a viable alternative to other more expensive acoustic or insulation materials and also offers excellent sound absorbing ability. I plan to use the perforated tube from the magnaflow, rock wool insulation, and stainless steel wool to build a custom 4" round presilencer.
As for putting a magnaflow up near a header, I would highly suggest you don't do this. The muffler did put up with quite a bit of abuse and even lasted nearly 6000km before finally getting too loud, but the shape of the muffler also had a lot to do with the way it radiated sound out from the shell. I would only suggest round mufflers/presilencers be placed near the header on a rotary. For the price though, magnaflow probably still is the best bang for your buck as its a very well constructed unit.
06-30-12, 11:31 AM
#919
Gave it a second heat cycle yesterday. Everything worked flawlessly. The compost bin thermometer in the dip stick hole said it idles at 192F. Nice! I've seen 220+ with full flow oil squirters. Glad I have checkball squirters, keeping some heat in the rotors where you want it on an NA.
Next step: use up all the old gas in the tank, then fill with fresh gas and go for a test drive.
Next step: use up all the old gas in the tank, then fill with fresh gas and go for a test drive.
06-30-12, 06:18 PM
#921
What's that smell?
Join Date: Jul 2007
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06-30-12, 08:00 PM
#923
Well I got my new tires. The car rides so much more amazing, I lost a little play in the steering, and I feel some of the acceleration coming back. So far total investment in the car $1100.
Also I started hunting down some of the original chrome license plate lights, but I have had no luck.
Also I started hunting down some of the original chrome license plate lights, but I have had no luck.
06-30-12, 10:19 PM
#925
Sin City Rotary
well wasn't my first gen ... well kinda .... swapped wheels onto mama's car a 83 GSL and am on break from buffing it ...
then a stereo install .... should FINALLY (long story I won't get into) be on the road in the next few days
then a stereo install .... should FINALLY (long story I won't get into) be on the road in the next few days