Will I burn out a glass pack?
 

I am making a straight through exhaust on my mostly stock '87 TII, so no cats. I ported the wastegate and I have a 2.5" downpipe and 2.5" y-pipe to cans. My plan is to put a 28" Thrush glass pack in between the y-pipe and downpipe, but will the exhaust heat damage the glass pack? I also want to know if anyone's listened to such a setup, I'm doing this really cheaply, but I really would like to make it sound the best for my money. I don't want it to have that hollow, breathless, rattling sound that I've heard from hollowed cats with all stock components. I'm also considering putting a muffler between the dp and y-pipe, however the current plan is for the glass pack and it's sitting in my garage ready to be welded.

Yes absolutely. Probably within the first 30 minutes of driving. ;)

Even though there'll be almost no restriction?

Yes.

Well crap...

Anyone know how would the car will sound with a muffler in there or should I get a cheap resonator or something instead?

dude you will be unhappy with your ghetto exhaust, take it from someone who has gone through several exhaust systems.

buy a good one and you will be satisfied with the performance and sound quality. corksport is a good low restriction exhaust

well I can't afford much right now so if I'd be better off not wasting time and money with an intermediate muffler and saving for a free flowing presilencer then I would do it, but I just need it quieted down for 3 reasons:
1) cops
2) I don't go deaf
3) my wife will willingly ride in the car again

why dont you just wait and spend some decent cash on a good exhaust set up? fuck doin what you are talkin about that shit is ghetto , you have a T2 not some shitty ricer. Make your car nice and use good parts man, good sound costs good money

Regular glasspacks won't last very long, maybe a week for the good ones.

If you can find some of the old Rotary Engineering glasspacks, they hold up for quite a while and sound very nice. Jeff20B used to have a huge stash of them, but we've been using them on a bunch of rotary projects and he's almost out now. :D

If you're curious, here's some clips of my 13B-powered GLC with two short RE glasspacks (one of them is in good shape, the other is almost dead; I'll replace it with a Magnaflow one of these days):
http://media.putfile.com/13B-streetp...zda-GLC-reving
http://media.putfile.com/13B-streetp...zda-GLC-in-car

Jeff20B's red REPU with a single long RE glasspack (it now has two):
http://media.putfile.com/REPU-with-fresh-engine-rebuild

Go with a Borla.

I had my tii with the main cat and got some glasspacks with 3 inch tips on the end and it sounded pretty good. I was going for a deep sound instead of that fart can sound and it worked good. I have heard the glasspacks don't last for some reason though. temp wise.

Try a 2.5"x14" turbo muffler installed between the dp and y-pipe. They are relatively cheap, freeflowing and tend to have a low tone. I don't think the sound will come out raspy.

http://store.summitracing.com/partde...5&autoview=sku

that was my initial plan, then GLASSPACK entered my mind and I ran with it. y'know it's cheap enough I might as well try it out.

hopefully I can have this bad boy fabbed up by the end of the week.

Rule of thumb to determine the suitability of something for RX-7 exhaust:

Will it melt below the melting point of thick stainless steel? If yes, don't use it. Rotaries *eat* cheap exhaust systems for breakfast.

-=Russ=-

^true. i got a magnaflow hi flo cat i can sell ya for cheap...its basically new. mellows out exhaust noise some ..but if your going straight through then i guess no need...let me know

yeah I want to avoid all serious restrictions, and I'm giving up the air pump for good, so any cat, if I used one, would have to be able to flow without fresh air supplied. I'm not sure if that exists, but I don't care too much to look for one since they're usually just an extra expense in Iowa.

Yes; you will burn the the shit out of it in days, if not hours or even minutes.

We got Rotaries, only a few very GOOD items will last
Try Racingbeat!

well, for now I'll be trying a cheap 2.5" inlet by 2.5" outlet, 14" long muffler. what will happen when the glass melts though? will it be expelled or will it collect in the bottom? flames? I don't mind if the glass melts out, I just don't want the structure destroyed because that's the whole point of the muffler in this case: baffles.

There are a bunch of cheap yet high quality resonators on the market. I have one from Vibrant Performance ( http://www.vibrantperformance.com ) on my car and I'm quite happy with it. The key is to get a unit that is stainless packed.

maybe once I have more money to toss at exhaust I'll do it. $60 + shipping on a resonator falls under low priority items right now, but I'll definitely consider those.

well in that case throw the wify some ear plugs were some yourself and go with a test pipe...oh yea throw the car in neutral when by the cops...:lol2:

I dont know jack shit about mufflers but I can tell you this. When I bought my n/a it had 12" or 14" blue glass packs on it. I ran it like that for 5 yrs untill I spend the dough on a complete setup. I have no idea if they were blown or what but it gave a deep throaty sound kinda like a fart cannon but deep. Never had a problem with them rusting through or anything.

I met a guy who said he likes to buy glass packs, run the car so theyre hot, then spray them down with water to purposely blow them out or something. He said they will sound better.

if you're thinking of a "well i'll do X for now until i get money" setup, don't waste your time. unless your car is illegal right now (as in you just might get a ticket for noise violation), save your money and do it right. wait until you can get a full system from exhaust header back to the muffler. if you spend the money to put in a system that is half-assed "temporarily," you're just going to have to wait that much longer until you get something that you're really proud of

Ok think of it this way, guys: IF I continue driving the car as it is, I WILL get fined for noise violation and maybe for not having a cat or mufflers. Probably the only things that's kept me from that issue thus far is the fact that the mufflers are still hung on the car, just not being used. I NEED to quiet it down, and while the car is technically illegal they don't even have emissions stations in Iowa. If they ever do, the car will probably be old enough by then that they still won't care.

Buying this cheap muffler instead of using straight pipe is costing about $15 more, and I'm convinced enough to try it in the aim to keep it from sounding too buzzy. I can also reuse the flanges I'm making when I buy better components, and these flanges cost about $8 in parts and some labor, then about $34 for the muffler and pipes. It'll just have to do.

borla is really the way to go. ansa and even magnaflow make some quality products, recently vibranperformance has been putting out quality stuff. Good luck, and remember you get what you pay for.

hey hows that FCD workin out for ya

Is this muffler a glass pack? Just curious. Anyway glass packing is best at muting the high frequencies.

As the glass packing melts out, the high frequencies will become more and more dominant. The raspy harsh tones will overpower the low tones and your ears will begin to bleed.

Your wife will not ride in this car as female ears are much more sensitive and delicate.

Look, when I bought my S5 vert it had a Rotary Performance Bonez Superflow Cat. This is basically 2.5" downpipe with a high-flow cat and a 'resilencer' that is basically a glass pack design packed with stainless steel. The exhaust system then went into the 'Y' and out straight pipes. Nothing else. Man, it would make your Heart Sing and your ears ring! I put in 2-2.5" 14" turbo mufflers into the oem spots. They were basic galvanized steel turbo mufflers from a local muff shop. They sound great with the presilencer and the cat. Deep and low toned, they currently have about 20,000 miles on them with no burnout or any other problems even though the exhaust behind the cat is a lot hotter than in front of the cat.

I cannot believe that you will have any durability issues with a true turbo muffler used as a resonator. Turbo muffler design is high flow and low back pressure. BTW, you will see 'Turbo Mufflers" that have glass packing. This is not a true turbo muffler and is unlikely to either perform or last like a true turbo design.

You do not need an uber-expensive muffler for a budget exhaust as long as you stay away from anything that is glass packed.

Actually I've decided not to use it so I sold it to someone else. I've found that even with just the downpipe I only creep up to about 7-8 psi floored in 4th around ~110mph. I figure with exhaust finished I'll be hard pressed to creep like that even in 5th WOT. However, I am curious, at what psi of intake pressure does the stock ECU cut rear rotor fuel?

As for this 'turbo muffler' I got, it's a cheap Thrush turbo muffler and I think it does have glass in it. I don't think anyone has answered my question about what my exhaust temps will do to glass packing, what happens? Will it clog? Burn? Cause any exhaust leaks? I'm not worried it the glass leaves the exhaust as long as it does so without harm to the car or stalling the motor.

The "turbo" style mufflers are only good for a few miles. Some may last a little longer, some may last minutes.

The significant EGTs melt the fiberglass packing, then it blows out.

I'm still confused. By 'blows out' do you just mean the packing leaves the exhaust or that the muffler will burst and create a big leak? An unpacked yet sealed muffler would still silence more than a straight pipe of the same length.

The packing itself blows out of the muffler outlet.

It'll do then. Thanks, guys! I'll try to get some video of before and after, though at the rate crap is falling from the sky I may not be able to finish the exhaust for yet another week. Or two.

You should take a video of it so we can post it when people ask this question. :)

yea...under the section of what not to do to your car.

my opinion is if you can't afford to spend $60 on your car for a better setup...then you don't need a rotary....but whatever.

The glass will melt. Then it depends on the temperatures. The glass will either sag to the lowest part of the muffler and stay in useless but harmless slug of glass. But if the exhaust is a little higher temp, the glass will liquefy and be 'blown' out the back of the muffler in little droplets. These will reform into small glass beads and will basically be dispersed in the exhaust setup that you are describing. If however you used a glass packed muffler in front of another muffler or a catalytic converter, the little beads would potentially clog the next unit in the system creating back-pressure or component failure.


A true turbo design muffler has no packing of any kind, nor does it need packing. The word Turbo is often used as a marketing term to describe any kind of muffler the marketer deems as suitable to sell to someone that wants to drive fast.

A poorly designed turbo muffler sucks and proper turbo muffler works well. Cherry bomb turbo mufflers have a poor rep and Walker Dynomax has a great rep. These reps are based both on flow bench and dyno testing. Funny cause the dynomax has fiberglass packing and the cherrybomb does not.:)

A proper turbo muffler has 3 tubes and two baffles. The inlet and the outlet cannot be along the same line. In between the baffles, the tubes are perforated, like a glass pack. The inlet goes through the end, through the first baffle then teminates at the far baffle. The exit does the same from the opposite direction. The intermediate tube extends only from baffle to baffle. Properly designed and sized, this design is reversible in flow, cuts the high freq sounds, is pretty quiet at low rpms/flow and gets fairly loud when you get up into higher rpms/flows.

I think it is a great design for real life, including avoiding police attention/getting 'civilized' women to ride with us.

Good luck and I hope everything works out with your car.

^^^ what you pictured there is exactly how my 'turbo' muffler is designed. not that it won't melt out any glass, but that's ok. if I didn't mention it before, I will now: I won't have any cats on the system, only pipes and mufflers :D

the po of my car removed everything from the exhaust except the mufflers and put a glasspack in. Of course it's melted by now, so when people ask, I'm just like 'yeah, it's got a straight pipe :lol:

Hey Aaron - I was looking at Vibrant's stuff and contacted them about their Ultra-quiet resonator...they didn't recommend using it with a rotary (because of the heat). How long have you been running yours? No degradation yet?

Thanks.

I've put a few thousand miles on the Vibrant resonator this summer and it seems fine. I can't see how there would be heat issues since it's all stainless.