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Re: 4" straight through exhaust being obnoxiously loud to anyone around or near the car... I think he kinda already knows that!
Another opinion on header wrap - a Pacesetter Header I bought for my 80LS didn't last more than a few hundred miles after I wrapped it, after having been on the car for years and thousands of miles prior to the wrapping. Pacesetter was known for using thin, mild steel tubing which didn't help and certainly accelerated the damage caused by heat retention due to the wrap.
It did quiet it down for those few hundred miles, but more than made up for it after burning a hole through the rear rotor exhaust pipe where it makes the 90deg turn - this is also the tightest turn on the Pacesetter design which is not equal length. I no longer consider wrap to be a good idea...
Yeah, sorry I should have known that it was a fairly modified car with no mind to noise.
Anybody know how well a ceramic coating holds up on exhaust? I've heard it offers the benefit of heat wrapping but no word on if it holds up long term.
GSLSEforme, yeah i.m familiar with sportbikes, the full Yoshi exhaust on my last bike was too pretty to wrap! Not so much with my RB header. Ugly crappy chrome... It does reduce underhood temps which were a problem with my setup on really hot days, It also makes the exhaust sound a little less tingy, if that's a word? I'll try and get some pics for ya when I dig the car out of the garage for spring. Cant wait!
Yeah, sorry I should have known that it was a fairly modified car with no mind to noise.
Anybody know how well a ceramic coating holds up on exhaust? I've heard it offers the benefit of heat wrapping but no word on if it holds up long term.
I have no 1st hand experience on rotary application but ceramic coated headers on my Tacoma described above have near 100k miles on them with no rust and only slight dulling of silver color of header tubes closest to cyl head. Truck used for towing and surf fishing exposed to salt/sand with no ill effects. Metal air intake tube to throttle body passes about 2.5" over top of header and it's possible to hold your hand comfortably on bottom of air intake tube indefinitely as coating knocks radiant heat down to almost nothing when truck is running. They were expensive but have lasted all this time with original gaskets. I bought another set of long tube coated headers with 7/16" flanges and 14 gauge metal tubes for a Ramcharger restore/repower i'm working on and expect them to last the life of the truck.
Inquired of Racing Beat about acquiring a streeetport header of theirs before chroming and then take them to be ceramic coated to see how it would hold up to rotary heat. They were not interested in the idea.I think with ceramic coatings now good for 2k degrees it's viable.
RB headers don't look like this for long after install...
Two observations here. One, wrapping does cause degradation of the header to accelerate, I have a header to prove it. Had to replace it a few years ago. No more wrap for me. Two, Skeeses car has a turbo which acts like a giant muffler already, that 4 in won't be that loud.
Wow, quite a bit of info has gone through this thread. Thank you everyone for sharing your thoughts and opinions on various exhaust matters. My new exhaust is still a little ways off, but I will eventually get that done and update accordingly.
Originally Posted by Maxwedge
Ben, do you "need" a CAT? To meet emissions obviously, but is it your DD? I titled/registered mine as a Classic Car and it is totally exempt from emissions - both visual inspection and sniffer testing. I could have also tagged it as antique, but then I'm supposed to keep it mostly original equipment, which is getting harder by the year. With Classic plates in PA, it just has to "look" like an '85 RX7.... I could have anything under the hood I want.
Unfortunately the mileage limitation is an issue for me being that it's my daily and all. If that weren't a problem I'd do it in a heartbeat, but alas it's not an option for me - that's why I need a cat. Our smog is sort of a joke, but you still have the pass the sniffer at either idle or 2k free rev.
Originally Posted by LongDuck
Sidenote: OP may want to put his Magnaflow Cat in front of the Presilencer for best effectiveness, as the catalysts rely on high temperature to work properly, and the thermal mass of the heavy (20lb?) presilencer will suck up a bunch of that heat if placed in front of the cat.
And yeah, I had planned on putting the cat before the presilencer for that exact reason. I would assume that sound won't take too much of a hit, if any, due to that?
Hi flow cat will restrict exhaust flow least and muffle sound least. Not rotary,but when i did header retrofit and used a Magnaflow hi flow cat behind on my Tacoma it ended up with a pleasant exhaust note it didn't have previously. Was looking for more tq/hp for towing,sound came with it.
Well it looks like it's been exactly a month since the last update, but I'm just now getting ready order some parts, hopefully this weekend. I have all the major exhaust components settled on (RB 83-85 PP Muffler, RB Universal Presilencer, RB thick wall pipe, etc). The one bit that's still up in the air, though, is the cat. I thought I had it figured out, but after some more investigating it looks like the one I was planning on wouldn't pass the sniffer (which is the only test I have to pass - just idle or 2k if you fail idle, no rolling road). That said, I plan on making the cat on a replaceable section so it can be swapped in for smog testing or drives where I care more about smell, although also allowing it to not be installed 100% of the time hurting performance, getting worn out, shattered, etc. Does anyone have some suggestions in terms of cat's for these cars?
Passing here for smog is less than 220ppm on HC and that's usually the only thing I've had an issue with. For this case, high flow is far less important - so long as it won't get blown out on one drive - to me than passing smog is since it will be removable. Now I'm looking at some of the 'OE Universal' Magnaflow cats such as the 53006, 94006, and similar. It would seem that the larger the volume the better chance I'd have of passing smog everything else being equal. Suggestions or thoughts? Does anyone know the internal differences between the cali vs federal models (are the cali one's more efficient or are they just certified?), or whether a pre-OBD2 cat would be filthier than a OBD2 one? I might need to reach out to Magnaflow on this one.
...I plan on making the cat on a replaceable section so it can be swapped in for smog testing or drives where I care more about smell, ...
I can't help you pick a good CAT for CA smog tests, but wanted to comment on smell. My '85 with all emissions removed, full RB exhaust and a Holley has zero offensive exhaust smell. My '17 Subaru with a hi-flow CAT stinks bad but passes emissions every year.
Use this Magnaflow # MPE99005HM Oval shaped,Heavy metal loaded cat,good for engines up to 6.2 L. I have this cat on my SE for many years and passed emissions easily,though fuel injected run cleaner than carbed by nature. This is certain to do what you need it to,indefinitely and for a good price Summit has it listed for $117.85. I replaced the down pipe from manifold,replacing all three cats with this one. The converter is a clamp on type but you can weld flanges on each end to make it a bolt on affair. I did this on my Tacoma when i installed a header and can post a pic for you to visualize what it looks like. I used same cat on SE and Tacoma. Tacoma also easily passes emissions testing with @100k miles on cat since install.
Awesome, thanks for the quick replies. I was actually looking at the 2.5" version of that one, GSLSEforme, which is the 99006HM. Same price as the 99005HM on Summit, just a step up in pipe size to match my system. Someone left a review on one of the 'spun' type converters I was eyeing at first mentioning that Magnaflow suggested the 99006HM for passing smog after he had issues getting any emissions improvement from the spun cat. As of now I'd say that's my top pick unless anyone has another option to present or I find something else promising.
Two observations here. One, wrapping does cause degradation of the header to accelerate, I have a header to prove it. Had to replace it a few years ago. No more wrap for me. Two, Skeeses car has a turbo which acts like a giant muffler already, that 4 in won't be that loud.
When you feed your engine with a 💪nikki your slightly modded oem heatshield works good with the RB header.
Just the polished stock one. Waterpassages modded feeding semi ports☠ BTW i like cleaning, polish and chrome parts.
Very nice. Everything looks absolutely awesome. Curious how you chrome plated some of those parts. I've re-zinc/chromate plated some of my Nikki parts, but the chrome looks good too. The chrome wasn't factory, yeah? Or am I crazy? All of those chrome pieces you have are yellow zinc plated on everything I've seen.
Having just gone through the bi-ennial (*every 2yrs) ritual of swapping the stock SE 3-cat system for the RB header and PP Presilencer, it can all be swapped in or out in 45min. There are 8 bolts: 2x14mm at the tailpipe, 2x12mm at the airline, and 2x14mm at the exhaust manifold. Leave all of the existing rear tailpipe rubber donuts in place and keep the 3-cat system bolted together, moved around as one piece. Same with the RB parts. What's surprising to me is how heavy the stock system is; easily 2x the weight of the RB parts.
State requires idle test and rolling dyno test up through 3rd gear following a map set previously. Also, a gas tank pressure test as done through the gas cap with clamped charcoal canister vacuum lines - but this is hit or miss - they pass it if they cant get a good suction reading. Here are some quick figures and my notes:
2020: HC1.43 limit of 2.40, CO 12.20 limit of 20.00, NOX1.04 limit of 3.50, all in grams per mile under load, air pump missing 1 vane...
2018: HC1.51, CO6.90, NOX1.06, same limits, 100% functional air pump, all vanes working
2016: HC1.65, CO10.43, NOX0.91, same limits
I also tried the test using the RB system and it failed. Miserably. I paid another $17.50 for a retest with the stock cats, and it passed easily.
Point being, if you're willing to put in the time and effort, you CA use your stock system like this and never have to worry as it's only seeing 40mi of use every 2yrs. I put about 6k miles on the car annually, and I'd rather not move to collector car plates.
I would swap in and out the stock system except that... well, I don't have a functional one anymore (never really did). The SA didn't have cat's to start with, and combined with the engine swap the po did and now I have done as well, the stock system wouldn't have worked anyway due to missing passageways on the center iron. I do still have my air pump and ACV, which I assume I'll need to reinstall to pass smog (all mechanical bits are S2/S3 now, and I can just rig the rats nest like last time), but hopefully with the new cat all should go smoothly. I may have mentioned it previously, but we have free retests (which I made very good use of the first time around; I went through 11 times I believe?) so if I need to change something and redo that's not a huge complication.
I am however planning on removing the cat when not testing so, like your stock system, it will see limited wear and hopefully last a long time. The ported engine has me slightly concerned on the smog aspect, although nothing is too radical (everything is essentially to 74 spec, although I made a couple minor deviations).
Point being, if you're willing to put in the time and effort, you CA use your stock system like this and never have to worry as it's only seeing 40mi of use every 2yrs. I put about 6k miles on the car annually, and I'd rather not move to collector car plates.
in CA you almost have to do this, that cat linked above is not legal here, they won't even ship it to CA
in CA you almost have to do this, that cat linked above is not legal here, they won't even ship it to CA
Convenient that I'm not in CA then; didn't realize how stringent that all was. Here in Oregon smog testing only applies to a limited region, which unfortunately I reside within (Portland and Medford Metro areas I believe). Regardless, I don't think I'll have any legal issues unless I can't clean up the tailpipe enough. Visual doesn't really exist here either.
Convenient that I'm not in CA then; didn't realize how stringent that all was. Here in Oregon smog testing only applies to a limited region, which unfortunately I reside within (Portland and Medford Metro areas I believe). Regardless, I don't think I'll have any legal issues unless I can't clean up the tailpipe enough. Visual doesn't really exist here either.
if the air pump and ACV are working as they should be you don't need much cat to have a really clean running car.
i would love to have a smog that wasn't so strict, ours is such a waste of time
Thanks everyone for all the posts - a lot of interesting info.
I got curious and decided to see how loud my exhaust really is - turns out that decibel meter I have actually is useful for once. While at the moment I have little to compare to, if anyone feels like getting some numbers on their setup as well I'd be grateful. There are mobile apps that can supposedly measure sound intensity, although I don't know how accurate they are. Anyway, here's some numbers.
Interior idle: 60dBA, 79dBC
Interior 2k (no load): 68dBA, 88dBC
Exterior idle ~24" from tailpipe: 80dBA, 96dBC
That's all the data I've got for now, although perhaps I'll eventually get some additional scenarios tested.
I take my tablet 100 cm from the exhaust. The app told me 88 db 12 A Bp at idle 1600 U / min. 30 years old RB system like the one in the vid
I take my tablet 100 cm from the exhaust. The app told me 88 db 12 A Bp at idle 1600 U / min. 30 years old RB system like the one in the vid https://youtu.be/nX1u9qARTC4
1600 U/min Bridgeport
Awesome! Thanks for the data. Even now that I've committed to the "RB" system it's still cool to see info on other folks setups.
That being said, I have now ordered all* the parts needed for the exhaust. By Monday I'll have everything but the RB parts as the muffler is on backorder - should be here within a couple weeks. Only thing left to do is pick up the steel plate to machine the flanges from. Exhaust work will be happening sometime over the week of the 23rd, at which time I will also be looking further into my clutch issues that I have another thread concerning such here.
As of now that last bit of the exhaust that is still uncertain is the connection between the RB 83-85 muffler and the mid-pipe. According to the folks at Racing Beat, the muffler uses a 60mm pipe and has a bolt hole spacing of 82.5mm. So far I have had little luck finding a gasket to fit that, and the one provided on their site with the correct bolt spacing appears to be a 2" gasket, not 60mm which is far closer to the 2.5" of the rest of the system. The gaskets I bought for the remainder of the system use a 100mm hole spacing (as does the flange I designed) and they are easy to come by. I'm debating whether to slot the holes/weld and drill new holes on the RB muffler, to weld on a new flange, or to try and cut the gasket holes further in (there is practically no room to do so however). For now I'm waiting to decide until I see the muffler in person, but if anyone has some thoughts I'd be open to them. The only reason I see to not alter the muffler is if I were to resell it sometime in the future. But even then, I would think that if someone wanted just the muffler and they weren't connecting it to an RB system, the more typical bolt hole spacing might be appreciated.
The other part that I'm still wondering about is the placement of the cat and presilencer. I'm figuring the cat should be as close to the header as possible to keep it running efficiently, but then there's the presilencer. Should it be placed a little further back from the cat in order to avoid some of the heat the cat introduces? Does a cat actually heat up the exhaust significantly (I would assume it would to some degree) or just the cat itself? Does the placement of the presilencer affect sound characteristics? I've never really dove into the specifics of exhaust design before and so far the web has not been too helpful in those regards. If anyone has any advice it is welcome. Note that the cat will not be present most of the exhaust's life.
The non-collected SP muffler surprises me as well. Uncollected pipes into the muffler is the same configuration as the stock 81-82 mufflers, supposedly the most free flowing OEM muffler.
Hopefully it's packed well enough. Over 10 years ago I bought the headers and SP presilencers, but used my stock 82 muffler since I figured OEM = quieter. It was loud and tinny, fart-can sounding. I completed the system with the RB muffler soon after that.
How does it sound now? right now my car sounds like a shitty honda civic with that EXACT set up. its embarassing, i swear i can smell rice from my exhuast pipe when i walk by it idling.
That's exactly what I've read happens - the tinny sound with a stock muffler gig. Apparently the stock muffler does just fine until you add a header, or replace the midpipe, etc. It's my guess that you just need a new muffler and that'll fix it, but like I mentioned before, I'm just going off what I've read. I think someone actually mentioned this earlier on in this thread, not sure though.
EDIT: Oh wait, I think I read your post wrong, did I? Perhaps I misinterpreted what system you currently have? Also that post you quoted would be the one I was referring to.
01-28-20, 10:27 AM
