New Rotary-specific Mufflers from Borla
 

Just saw these in the catalog today. I called and spoke with Borla, and final pricing has not yet been released, but they expect to start shipping these any day now. The packing inside these has been specifically designed for rotary use.

P/N 400371
Borla XR-1 Multi-core Rotary
3" Inlet / 3" Outlet
16" x 4 1/4" x 7 7/8" Oval

P/N 400372
Borla XR-1 Multi-core Rotary
3" Inlet / 3" Outlet
12" x 4 1/4" x 7 7/8" Oval

P/N 400373
Borla XR-1 Multi-core Rotary
3" Inlet / 3" Outlet
16" x 6 1/4" Round

There is also a P/N 400374, like the 400373 except 4" in/out

Nice.... I hope they are reasonable.

ooo! any pics of said exhaust?

edit: just realized these are mufflers only, nix my request

fyi:

https://www.borla.com/media/prod_images/large/40575.jpg

i cant find them on their website

^--- Or you can just look at my blog too....oops! I said too much... :x

http://www.borla.com/media/prod_images/large/40575.jpg


The round is for import cars and the oval is for muscle cars.

Rotary muscle cars?

if that is the case, it looks like my HKS hi power will be retired soon. I've burned through my Racing Beat dual resonated midpipe and the packing in my hks is going fast.

here is their catalog: page 51 :D

Looks like the guys over at racing beat really fubared up then using oval mufflers on their rx8 specific catback

:wallbash:

No.

lol it doesn't matter...either one can be for any car. -_-;;

Rotary muscle cars... the no torque edition:bootyshak

would these work well as resonators? i have a cat delete test pipe that i'd like to weld on a couple resonators.. but these seem to be a bit large for that purpose. any input as to whether or not these would fit?

ok just found this at summit racing, http://www.summitracing.com/parts/BOR-400371

ships 6/6 and costs $289. not very economical for use as dual resonated mid pipe.

Holy shit $289.00 for just the muffler?

Use a proper rotary resonator http://blackhaloracing.com/?page_id=...product_id=183

Thanks for the link, I can't believe I didn't know they sold just the resonator.

Yep, I got my BHR resonator welded in to a 3" RX7store midpipe I picked up for $80 with a $90 Magnaflow metallic-substrate cat. It takes the midpipe + SP2 noise level down a notch, particularly in the drone zone. Makes a nice improvement, IMO. :ylsuper:

last time i considered this, they were out of stock, i will check stock again. can you elaborate on the noise? are you comparing to a straight pipe? how is the current setup compared to stock cat?

what would be the difference between a proper rotary resonator and a proper rotary muffler if they are of the straight through design? other than size in this case.

We have two resonators left and I can always get more made for us.

My opinion only

The most basic definition of a resonator would be a device placed in the exhaust system prior to the mufflers designed to reduce and alter the exhaust tone.

Resonators tend to reduce the exhaust rasp more then mufflers.

I am not sure why I said Proper except that the resonator I am suggesting was designed as a resonator to be used for rotarys. The biggest issue with using a muffler as a resonator would be size limitations. Heat might be a second, resonators are subjected to higher heat.

Burns Stainless now sells a metal cat/muffler combo, haven't seen much info on it yet though

http://www.dragzine.com/features/pri...ents-cat-back/

Oh, that's tough to elaborate on in a very scientific way, but I'll give you my take on it. I think of exhaust sound as consisting of 3 components:
1) Level: the total energy being radiated outwards which is hearable.
2) Drone: the level of sound identifiable as a distinct tone or pitch.
3) Rasp: the level of sound resulting sympathetic vibrations with the metal in the system. Think "rattle" or "blatt".

My car came with an SR Motorsport ceramic cat + no resonator + 3" midpipe + Greddy SP2 (which is one of the louder muffler setups). All 3 sound components were in the brutal category! This is a total boy-ricer combo, but a good catted flame thower setup.

I swapped in the stock muffler, SR + SP2. This arrangement had a lower sound level overall, but still full of rasp and drone @ ~ 4,000 rpm.

I swapped in the stock cat + stock exhaust. Definitely the lowest levels with no rasp. The drone is there, but at a low rpm ~2500, which one seldom holds for long. Mazda did their homework on this one. It's tame though, and feels "stuffed" at high rpm.

Next was stock cat + SP2. Not a bad combo, but a bit on the loud side for a GT car, IMO. Drone was louder but still at the low frequency, with occasional rasp.

But I want to mess with fuel maps, thinking maybe I can get better mpg for cruising by leaning things out. CW is that it's easy to melt the stock ceramic cat @ $1200 which seems unwise. I'm not going catless because it's environmentally irresponsible, plus, perhaps more importantly, the image of the car with one of my actress/model companions dressed in evening wear was incompatible with the smell of rotten eggs. I tried to find a spare stocker off junk yards or a bad one from the dealer to expriment with, but found that it's a 100% return item with a huge core charge from Mazda. So, time to build my own (BHR's was not on the market then). The Davesport metallic cat has a good rep here, but they were out of stock, so I got a Magnaflow version from Summit for ~$100 and picked up a used RX7store straight midpipe. Previous experience told me this car needs a resonator and I shopped several. However, any high-flow cat is gonna be louder than stock, so I wanted some muffling effect too. Not knowing that BHR was working on the same solution, I got a Moroso sprial-flow "muffler" to server both functions and had the thing welded up.

So, Magnaflow + Moroso + stock muffler: Pretty darn good. Drone was still significant @ 4k rpm, but relatively quiet. No rasp, but still felt "stuffed" by the stock muffler at high rpm.

Magnaflow + Moroso + SP2. Same sound quality as above, more "open" at high rpm, but about 30% too loud inside the car for my taste.

Winter! Different tactic: coat the entire trunk and interior of the car with Second Skin Damplifier which cost 25 lbs, but made the stereo vastly better and gave an acceptable sound level inside. Done? Nope, I read the BHR saga: http://blackhaloracing.com/?p=654 which shows that the Moroso won't live long.

Finally now: Magnaflow + BHR + SP2 + Damplifier. A sweet setup. The test was a 1750 mile trip and return to DGRR this year, about 1250 on freeway and 500 ripping up mountain roads. Very open at WOT with aggressive but pleasing sound. (I left the windows down most of the time just to hear the exhaust bouncing off the cliff faces.) Livable on the freeway, but still drones ~4000 rpm. Muted but it's there.

Next? The stock exhaust would be quieter, but it's stuffed, plus being ugly and heavy and I don't like any of those. I may try the OBX which is rather inexpensive and contains and additional resonator tuned specifically to dampen the 4k drone. I'm happy at present, but still the car is more GTR than GT; depends what you're after. I should mention that sometime in the process, I swapped out the stock exhaust manifold for a port-matched version which added some small amount of sound level, with a bit of airyness to it.

I think I pretty much ended up duplicating the catted BHR midpipe with this setup. Thanks to a very friendly local shop, it didn't cost any more than what they offer, but didn't cost a whole lot less either. It gets you in the right range to vary the sound level by choice of cat-back, say from stock to RB to Greddy to Borla.

As usual YMMV.

Thanks for posting these part numbers!

I tried calling them multiple times today but they are always "on the phone". I left a message and I am hoping they call back sometime.

Did anyone find out if these are being produced yet and if so how much? I need to get one in the next couple of weeks. I have always used the regular XR-1 for the racecars but since they have one specific for the rotary why not give it a try! That is IF it can be purchased :)

Let me know if anyone reaches them or finds out the availability!
Stephen

http://www.summitracing.com/parts/BOR-400371