Jeff20B

iTrader: (13)

Need to start piecing together an exhaust system for the 20B in an FB. It will be NA and no bigger than 2.5".

I'm thinking about Magnaflow components in 2.5" and the hardware from Racing Beat such as a 4 foot length of 1/8" wall tubing, a couple of U-bends, and four flanges with two gaskets, all in 2.5".

Knowing what I need from Racing Beat is a start. Now what do I need as far as mufflers and/or presilencers? Is Magnaflow good enough? Will it die or get louder in time?

I thought about a 4x9 center/offset in either 14 or 18 length (whichever fits) in the cat location. Then a 4" round 14 or 18 or 22 (whichever fits) right before the axle. Then maybe a 5x8 oval in the back with either single or dual outlet in whatever tip size looks good.

There will be one flange between the header and first muffler, and the other flange before the rear end. Basically in the usual places for convenient service in the future.

What can you guys tell me about Magnaflow in 2.5"? How noisey will it be in the car? Will engine noise eminate though the outer shell?

The car currently has a 12A with the Racing Beat dual pipe "street port" system, and it is super excellent in sound control and power. Unfortunately it is too small and restrictive for a 20B (the collector in the muffler pipe is only about 2.25"). I want something basically as quiet and powerful as the RB system, but in 2.5" and I'm hoping three mufflers will do it.

Oh, and for future noise production I could always add an exhaust cutout with an electric valve from Summit. For now though, it has to be as quiet as three mufflers will allow. Any Magnaflow users in the audience?

Jeff20B

iTrader: (13)

Here's the Magnaflow website with pictures and specs. http://www.magnaflow.com/02product/s...ne=main&id=301

I have no need for polished chrome, except maybe for the rear muffler.

kgray

i's say go with at least one borla... I have 2.5" exhaust with 2 magnaflows and it is still too loud for my liking.
-=One 4" round 20" long
-=one 6" round 20" long FYI

trochoid

iTrader: (6)

I have 2 Magnaflows on the 1/2bp, along with a full 3" exhaust, way too loud. Borla will do a better job. I have heard the difference on a 3" TII exhaust, w/wo the Borla and with it's a very sweet sound.

Jaime Enriquez

I was using Magnaflow 4" diameter rounds for presilencers in a long primary setup and they blew out in 5 months. They were a good 2 1/2 feet from the header flange and cooked 'em anyway.

I agree with the Borla or customize some RB muffs.

Directfreak

iTrader: (2)

I am suprised by these responses. I have had nothing but good luck with my Magnaflows.

kgray

well my magnaflows have held up but dont muffle a great deal

broke7

iTrader: (1)

I know you want a 2.5 but isc racing has a 3" manderal bent rear section that uses a mangaflow and the rear section minus the muffler was about $100 when i purchased it awhile back which is about the same price for the materials to fab it and it didn't fit to bad but I had to cut it to work with my muffler

dean7

The only muffler that I have ever seen stand up to the rotary engine (after years of being around newly installed systems ) was the Monza muffler, friend had that on his car since I knew him and after over 8 years, it was still dang quiet... His intake (minuki) was about 6 times louder than his exaust, with headers, presilencer (not sure brand, and Monza)... I loved my dyno max, but after 4 years, died lol.

Jeff20B

iTrader: (13)

Thanks for the responses.

Well I love the RB "streetport" system currently on the car. Can't get a better system for a 2 rotor as far as I'm concerned (NA or supercharged).

I wanted to go with a 4" round Magnaflow as a presilencer but not if it'll blow out in short order. What's his name with the green REPU in his sig had a Magnaflow get loud on him after a while too.

Hmm... It's over twice as expensive, and doesn't really muffle, but it's guaranteed to work and not blow out. Of course I'm talking about a real RB presilencer in 2.5" meant for the T2. http://www.racingbeat.com/resultset....rtNumber=16406

I like the part where it says:The 1987-91 RX-7 Turbo Power Pulse Presilencers are manufactured with a large diameter 2.5-inch I.D. core pipe for improved exhaust gas flow.

So what if I bite the bullet and get the RB presilencer in 2.5, then a Magnaflow 4" round, then some kind of Borla main muffler in the back? Think that would be quiet enough? Yet still allow enough flow at mid and high RPM?

What I'd really like to do is build a system that's quiet like the RB "streetport" and add an exhaust cutout with electric valve so I control when and where it gets loud and quiet, regardless of RPM or load. Sound like a 'sound' plan?

Check these out on Summit's site. The cutout: http://store.summitracing.com/partdetail.asp?autofilter=1&part=SUM%2D670136&N=70 0+115&autoview=sku

The electric valve: http://store.summitracing.com/partdetail.asp?autofilter=1&part=QTP%2DQTEC25&N=70 0+115&autoview=sku

Hmm, all I'd need to do is get the electric valve and fab the cuttout thing itself. No need to buy that kit (with the clamps and everything) from Summit.

The 20B has such a unique exhaust note character, why not let it be heard at opportune times?

Jeff20B

iTrader: (13)

Let me know what you think about this parts list.I may not need the 4 foot length of pipe. I've got some really old stuff kicking around. I'll have to measure it and see how thick it is. Hopefully I can save $28.00.

Jaime Enriquez

In Oz, many people have been making their own mufflers...lotsa stainless scouring pads and high temp rockwool. I may give it a try one day, gotta get the welding skills up to par tho.
http://www.ausrotary.com/viewtopic.php?t=109236&start=0

Check this thread on the 2nd page....a very nice job...the round one that is...not sure about those boxes!

trochoid

iTrader: (6)

If you are dead set on buying a Magnaflow, get the cheaper oval for a pre-silencer, (14-19X9"). Go to Magnaflows website and pick out the part # you want, then search eBay for that part#. I found a couple of sellers that will take a 'best offer' instead of their listed price. From experience, if you make a best offer that's 10% less than their listing price, the seller will often accept it, along with free shipping. That's how I bought the 2 Magnaflows on the widebody. Net cost was around 60% off list.

If you can find a Borla oval XS or XR model in your price range, that's the best route to go. XS is the street version, XR is the race version. Race version is more of a straight through shot, the S is quieter and has a bit of an internal wiggle.

dbragg

iTrader: (7)

borla or RB

Jeff20B

iTrader: (13)

Jaime Enriquez, I read through that thread. Wow that's some cool stuff! The round one in 8" x 18" would be perfect for a 1st gen.

I looked up perforated tubes inc and found some info on rock wool too. With those components and some decent guage sheet metal for the shell, anyone can make their own rotary-capable mufflers it seems.

I did some more digging on Borla's site and came across the new Pro XS units. It seems they're all 14" shell length except for the 19" length single in/dual out. http://www.borla.com/proxs/pages/muflrdual.php

Check out the 40348. I wonder how splitting a 2½" inlet into dual 2½" would hurt flow? It would double the cross section and reduce, by 50%, the velocity, wouldn't it? Does it matter so near the end of the system? Would it quiet the exhaust more than a single outlet could?

I like the look of dual tips on a 1st gen, and would prefer this muffler over a single tip. Also the shell length is 19", which should muffle better than 14".

I'm just a bit concerned that the 9½" width would be tough to fit within the heat shield, but MosesX605 appearantly got a Pro XS to fit his car. Gotta go search for his famous Borla thread...

Siraniko

iTrader: (13)

Jeff
PM 61620b for exhaust idea. He did my bros 3-rotor turbo RX-3 SP. Maybe one of these days, i will do a video clip while idling and taking off for the hell of it.

Jeff20B

iTrader: (13)

Wacky, Rene doesn't like Borla, if I remember correctly. That's ok. I didn't really know anything about them until yesterday. Now I likes what I sees (spent a few hours reading their site, including the FAQ).

Thanks for the suggestion. My 20B will start NA though, so velocity rules apply. That's why I'm going with 2.5" straight-through (2¼" was too small, 3" was too big and 2¾" was too hard to find). The only thing that concerns me is the Borla 40348 single in/dual out, all in 2½". That screams NO to me, but it's at the end of the system, and I was definitly looking into dual tips as an add-on at the end anyway. Why not save some money and get the tips incorprated in the muffler like the stock/RB? It's just that stock/RB is a smaller diameter inside the tips and the Borla isn't. Now if I was going with 3" in/dual 2½" out, that muffler (40349) would work.

trochoid, I'm not set on anything at this point. Just making a list to help you guys see what I'm thinking about getting. So far I've been able to find a cheaper muffler so that cuts around 50 bucks off the total cost. I also don't think I'll need the 4 foot length of pipe from RB, so there's another 28.00.

I'd really like to replace the RB presilencer with a Borla if I could. It would be cheaper, for one thing. I was reading what some 2nd gen guys were saying and the Borla appearantly makes a better presilencer than the 2nd gen type. Very Interesting! All the 2nd gen type are 2.5" as far as I know.

trochoid, you've been recommending Borla XR-1 as a presilencer for some time now. Has anyone actually used one on a 1st gen? How well do they fit in the cat location? Better yet, has anyone used an XS as a presilencer yet? I'm very interested in the XS since they don't have that funny oval baffle thing like the XR-1s, that likes to burn out.

It looks like MosesX605 didn't use a Pro XS in the back, but it was still 9½" wide, and it fit ok.

trochoid

iTrader: (6)

Jeff, If you're going to turbo the 20B, go 3" from the beginning. A 3" exhaust is the 1st/best upgrade for a stock TII engine. NA, 3" is hard to quiet down, the turbo does some quieting, then a good pre silencer. With that 3rd rotor, you're going to need flow, NA or Turbo.

Jeff20B

iTrader: (13)

I don't know if/when I'll ever do a turbo. Having so many projects will do that to a person.

At least those Borla Pro XS I was just looking at also come in 3".

So you think a 3" system on an NA 20B will be ok? I'm not going for loud. The car has a nice quiet RB "streetport" dual pipe system and I love it. They collect into a single 2¼" right before the muffler and it's great for at least 200HP even with the restrictiveish Primaflow muffler. Too small for the 20B, but a proper tune, port job, and a 2.5" system will get me to 300HP, I tell you what (like Rotary20B and his ITB setup). Gotta learn how to tune NA before taking the next step into boosted territory. Remember I came from the world of carbs. The 20B was my first fuel injected engine. Never even owned an EFI car.

How about this. Since the 2.5" system will be nice and quiet and not too expensive, I think I'll run it for the 20B while NA. Then if and when (IF) I ever go turbo, I'll definitely get a full 3" system. I know a place that sells and can bend 3" stainless .063" thickness (like what RB sells) so I'm golden. The turbo will keep things quiet enough for me with the thinner wall pipe.

For now I want the quieter thick wall .120 1/8", 2.5" pipe and a couple Borlas.

Will the Borla Pro XS 40358 (offset/center) or 40364 (center/center) fit in the cat location? http://www.borla.com/proxs/pages/mufflers.php