Guest bastaad525 Posted December 22, 2003 Share Posted December 22, 2003 Long post here you have been warned! just wanted some input and info on this. Been giving a lot of thought to my exhaust setup recently, especially after I went and dynoed the car... just thinking of how much power and responsiveness I"m losing there and how much lag I'm putting up with that I shouldn't have to. I really made some bad choices with my exhaust system... they were made out of desperation and a lack of funds, and being in a hurry to get something, ANYTHING on there. First I was just running the open DP... which as far as I can remember, surprised me in that it didn't create nearly as bad a problem with exhaust smell in the car as I would have thought it would have. However, it was a bit loud... not TOO loud... comparable to a big V8 running thru glasspacks only... at idle and cruise it was tolerable, and really roared when floored... but, wanting more of a sleeper car that no one would notice, I wanted to quiet it down, but with as little restriction as possible, and again, on a limited budget (like those two things go together!). So I followed some other peoples steps, and decided to just add a section of 3" pipe, extending from the DP to right where the differential is, and had the end pointed down. No muffler, no nothin, just pipe. To my dismay this actually made the car LOUDER, and created a real problem with exhaust fumes in the car, like eye-wateringly bad. So... not wanting to return to the shop that had done the 3" pipe (they had done a crappy job along with being real jerks), and being even more limited on funds, I looked around but couldn't find another shop that would do 3" for anywhere near a reasonable price... in the meantime the exhaust smell was killing me... so I got desperate, ponied up another $100 to get the rest of the exhaust proper put on, from the diff, thru those two 90* bends, into a glasspack and out the back of the car. Unfortunately I had to settle for having this done in 2.5" pipe, adding yet more restriction and I didn't have enough cash at the time to get the mandrel sections to throw in there. Then I just recently realized that the glasspack I bought is the less desirable kind, it has the 'fins' that stick up into the exhaust flow and created turbulence and backpressure... as opposed to the straight thru kind. So I can only imagine how this is really robbing performance and killing the turbo's response. The only benefit is that it did quiet it down very nicely for not even having a true muffler. Now... I"m still relatively short on cash (especially being x-mas time), and have other more necessary things that need to be done on the car first, so getting a mandrel bent, 3" system with a good muffler is out of the question for a while. Yet... the lure of extra power and responsiveness is making me think some crazy/stupid thoughts I'm thinking of going to the muffler shop and having a section of pipe removed from the middle of the exhaust system. Cut right at the DP, to about the middle of the car where the first exhaust hangar is. This will cost about $20. I know it may make more sense to some to just remove the whole thing, but just cutting a section from the middle like this can possibly serve several purposes. For one, it will leave an exhaust tip sticking out of the back of the car... less chance of getting pulled over for not running a proper exhaust, and again, it's quiet enough at light throttle (okay... EXTRA light throttle) as to not arouse much attention. Secondly, it would be just as easy to reverse, weld the section back up, for the same cost, should I decide I'm not happy with it or run into any problems. I'm much more open to dealing with the extra noise (of which was the main reason I DIDN"T want to keep running the open DP...) than I was before, so that shouldn't be an issue... BUT, I'm not sure I'm remembering right about the problem of exhaust fumes. Even as it stands now with a full exhaust exiting from the back of the car, fumes can sometimes be a problem, and this is with a new hatch seal (checked for areas not sealing properly) new tail light seals, and some extra sealing around openings in the body in the back. I figure having just the open DP dumping right there in front of the drivers seat shouldn't be any more of a problem if I seal up all the holes in the firewall... again... I dont remember it being any worse before with the open DP than it is now, even though none of those firewall holes was properly sealed. I just really hope I"m remembering right about that..... I think I only drove with the open DP for about a week if that. Third, I'm thinking of possibly welding flanges onto the whole thing where I removed that section, it's not that expensive, and would give me the option of removing it when I want the power, like at the track or whatever, giving performance close to that of a good 3" system when I want it, while not costing nearly as much, and putting it back when I want to be quiet. What do you guys think? Bad idea? I have some power questions... it's well documented that a 3" mandrel bent exhaust and good muffler will pick up a good amount of power (Jeffp documented some 20hp and ftlbs increase on a stock Turbo ZX after changing ONLY the exhaust) and tons of responsivenes will be gained. What I want to know is, will an open DP perform as well as/even better then/any worse than a proper 3" exhaust? Also, I remember someone recommended something to me for sealing the holes in the firewalls... I believe he said it could be easily applied and also, if needed, easily removed (I think he said you could just peel it right off) but I can't remember what he recommended... you guys no any good stuff I can use that would be cheap and fit the above description? Quote Link to comment Share on other sites More sharing options...
spacecoastz Posted December 22, 2003 Share Posted December 22, 2003 Self inlicted hot foot? Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted December 22, 2003 Share Posted December 22, 2003 That WAS a long post. I still get exhaust fumes in my car whenever the windows are down. They almost completely go away when I pop up the sunroof. I think your fumes are getting in the same way, by being sucked in from the back from the forward motion ofthe car. You may get some benefit from extending the exhaust tip further out the back, but it may look funny. I don't think you will get many fumes from the firewall area - sorry I don't have any suggestions for sealing it up. If you are still using a crush-bent 2-1/2 at the back, you will realize a huge benefit by just replacing those bent sections with 2-1/2" mandrel bends. Your glasspack is not restricting that much I bet. A pair of 90 degree bends will probably only cost $50. If you can do the cutting and clamping or welding, it should only cost you $10-$20 more. Quote Link to comment Share on other sites More sharing options...
Jersey Posted December 22, 2003 Share Posted December 22, 2003 525 - I think you should either wait a little more, save enough money or whatever else is holding you up, and do it right the first... well... this time You see what you're about to do - cut off pipe that you've spent $ on no more than a year ago that could've been applied toward the right setup now. And i know you were hard pressed at the time but it always winds up costing more in the long run by cutting corners early. Ask me, i've made that mistake plenty of times!!! haha. Oh yeah... and what's this - Yet... the lure of extra power and responsiveness is making me think some crazy/stupid thoughts ??? LOL. See how the brain works! MORE POWER! lol. Anyway, this is what i did with my exhaust and currently doing to my cousins 280 - JCWHITNEY TWO OF THESE - 90° Mandel-bent Aluminized Tubing, (A/B)=12", ©=6", ID=2-7/8", OD=3" Each 81ZX2954Y $20.99 SUMMITRACING TWO OF THESE - SUM-640030 Aluminized, 3 in. x 4 ft. exhaust tubing. Today $13.39 AND ONE OF THESE - WLK-24222 3 in. center inlet/outlet, Bullet muffler Today $35.95 If you can weld, it'll cost you nothing more than the cost of the equipment and if you can't, i wouldn;t think it would cost that much for a shop to do it. Then again, i don't know what shops charge becuase i dont take any of my cars/trucks to anyone unless absolutely neccesary. Guess it's a trust issue with me Oh yeah, money is the other big part Just an idea and opinion. Adding it up... $20.99 x 2 = $42 $13.39 x 2 = $26.80 Muffler = $36 ----------------------- Total = $104.80 + shipping + install Not the best of the best, but it'll get you basically a full 3" mandral bent system from DP to muffler and it should last a while. The cheap muffler is a straight through design also. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 22, 2003 Share Posted December 22, 2003 Sleeper - hence the warning The weird thing with my exhuast fume problem is that it had almost completely gone away for quite some time, and just over the last week or two has been coming back. I went to the usual suspects... loosening bolts on turbo/downpipe flange, exhaust manifold... checking the rear hatch seal. Funny you mention about the firewall thing... I've actually always thought that no matter how many unsealed holes there were in the firewall that it wouldn't contribute to the odor in the car. Just thought I'd try to seal them up ... I mean... couldn't hurt, but I don't expect it to help much either. It just baffles me how I could still be getting fumes in from the back. Again, the hatch seal and tail light seals are new. I also sealed all around the rear trim panel, the one that is right below the rear windshield on the hatch itself. Today I also went and used silicone to seal up some of the holes where the fuel tank vent hoses pass into the cabin. I'll see if that helps tonite on the ride to work... unfortunately the car now reeks of silicone sealant . Otherwise I really dont know where it could be coming from. As with everyone else it does usually go away with the windows up but not always. I've wondered about installing a sunroof to help this problem, and also because the roof of my car is so badly dented and wrinkled taking out a large section of it would help the look of the car immenseley I've also always wondered about installing a rear spoiler, in hopes that that would alter the air flow over the back of the car and not suck exhaust back inside. No one that has a wing installed seems to be able to confirm this or not. How much you think it would cost to install a sunroof? If it will help the smell with the windows down I may put that on my to-do-in-the-near-future list. I did extend the exhaust tip a few inches and it didn't help. I also tried a suggestion of Tim240z's, getting a tip welded on that pointed out and to the side of the car, blowing the exhaust out into the air stream... oddly, that didn't help either. So you dont think that the kind of glasspack with the fins that stick up into the exhaust flow are restricting? It almost looks like an inverted pine cone... I read somewhere that those can be even more restrictive than a stock muffler... really ticked me off when I went and looked and sure enough that's what i had. I agree that those two 90* bends at the end are really bad. They look crushed down to even less than 2". I had kinda figured the whole exhaust for a loss... but if you think just those two bends could make a big improvement... Unfortunately I dont have the tools for doing any of that work, I'd have to pay a shop to do it... judging by other work I've had done it could run anywhere from $50 to $100, but if you really think it would make a big difference I'll try to get that done asap too... Anyways I went back and read some of my ollllllld posts from when I first got the car to see if I could jar my memory about running with the open DP... seems I really disliked it and thought it was just way too loud, though I saw NO mention of exhaust fumes in the car until after I added the 3" pipe that dumped at the diff. I guess I'll leave it the way it is and save up for some mandrel bends... much less of a compromise to do it that way. Thanks for the sense-talking Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 22, 2003 Share Posted December 22, 2003 Jersey thanks for posting that info... was just going thru old posts trying to find the names of places people recommended me to for mandrel bends... that muffler looks like it'd be a better option than my current glasspack too and lord it is cheap. Thinking it might be loud by itself though... amazingly the glasspack quites the car VERY well by itself. Those prices are REALLY good too. I may just do the whole thing using those exact parts... I'm thinking I may just have to install a cat this time too... I know performance guys hate them but I'm really thinking I'd rather sacrifice some performance for a less stinky car, and if I went with this setup you showed it would still be worlds better than what I have now even with the cat. Question is, WILL a cat get rid of the 'typical exhaust smell' of the car?? By the way Jersey... I know I'm way late here... I JUST found out about what happened to your car I'm really sorry dude that friggin SUCKS so bad... I'm always a little on edge worrying that some idiot is gonna plow into my car... sux even more that yours got screwed due to a friggin wet road... no one to vow revenge on Well I'm very glad for you though that it's nothing un-fixable... since that was almost two months ago have you had any repair work done on it yet? Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 22, 2003 Share Posted December 22, 2003 And btw Jersey... you caught me okay well not really! I'm still thinking of little mods like this because they still fall in the range of my 250hp goal, and still fall in the range of what I can pull off with the stock EFI. But you ARE correct in that I am thinking of more ways to spend money, which I really shouldn't be... but I guess the exhaust just bothers me because I really feel you are right in that I should have done it right the first time. Also, asides from what extra power it might free up, I'm more into the idea of a better exhaust for the response... I really dislike how much lag there is now compared to how snappy it was when I had just the DP on there. Just makes the car feel like such a slug sometimes. Quote Link to comment Share on other sites More sharing options...
Jersey Posted December 22, 2003 Share Posted December 22, 2003 It's really not bad at all. With a N/A motor, i'm sure it would be a bit too loud for me. The only reason i really went with that muffler was because i was headed to the track that weekend and they required a muffler. I was going to swap it out afterword but never did. If i could get a good sound clip of it, i would but, you know how sounds change transferring them over the wire. Yeah, the crash sucked. It's all straighted out, bought a '77 vented hood, in the process of picking up "new" front/rear bumpers and fiberglass headlight buckets. I still have it on the road with the smashed hood, no bumper or grill but when the snow is finally here to stay, i'll rebuild her better than before for the spring Oh yeah, i would ditch the CAT idea. Your Z didn't come with one and you're going to add it because of the smell? NONononoo... I would start by replacing the exhaust form front to rear, making sure there are no laeks at all, then go from there. I also wouldn't cut your '72 apart by adding a sunroof just to fix a problem. Is your BOV vented back in or is it venting to atmosphere - i.e., through the holes in your firewall into the cabin? Just a thought. Quote Link to comment Share on other sites More sharing options...
fl327 Posted December 23, 2003 Share Posted December 23, 2003 you could always get one of those exhaust cutoff things they sell at summit and jegs that uses choke cable to uncork the exhaust at will. Im thinking about using one in the future-I love turbo noises.. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 23, 2003 Share Posted December 23, 2003 Jersey - I dont think I'll ever get 100% rid of the smell w/o installing a cat. No matter how well designed the system is. I've already checked and double checked and had other people check for leaks and there are none to be found. I will keep looking for places that the smell is entering the car... personally I think the smell just envelopes the car sometimes and is coming in thru the open windows as much as anywhere else. My BOV is recirculated. I really do like the idea of a sunroof... I dont really do or NOT do anything on this car based on it being a '72... it's already in bad enough shape that I dont worry about taking down the value of the car by doing those types of things. And the benefits seem to be great and would outweigh any potential 'loss'. Anyways the roofline is already really badly dented up... to ever have it fixed would require large amounts of bondo I'm sure. Anyways.... it will probably just remain on my list of "Things I'd LIKE to do if I could spend the $$$" and never actually get done. Glad to hear your car is well on the way to recovery. If you're not gonna get the new hood painted to match right away, just paint it flat black... I've seen a few Z's like that and they look pretty nice you could always get one of those exhaust cutoff things they sell at summit and jegs that uses choke cable to uncork the exhaust at will. Im thinking about using one in the future-I love turbo noises.. I was thinking of doing something like that after I thought about adding a flanged section of pipe in the middle of the exhaust. That is one of the few things I really miss about the open DP... the great sound of the turbo spooling... very cool sounding. Quote Link to comment Share on other sites More sharing options...
Guest szlash280z Posted January 9, 2004 Share Posted January 9, 2004 what I am going to do is get the 3" U bends that summit has for sale. summit part numbers: sum-622004 or 622005. it's just $20 for the U and you would get two 90* bends out of it right? if you cut them in the middle. that saves $20 right there. the only thing the muffler shop screwed up on my car was the placing of my muffler, they recommended what I didn't want and ended up taking anyway (muffler hanging direction), but when he welded it into place he had to pull on the muffler to attach the hanging brackets. this causes the pipe to rattle against my diffy when I accelerate. I am going to fix it when I put in my mandrel bends, so I'll have this huge amount of 3" pipe as the rest of the setup is still useable. Now I just need to get a turbo flange so I can make my downpipe as well. anyone want to help me with the flange? Quote Link to comment Share on other sites More sharing options...
mobythevan Posted January 9, 2004 Share Posted January 9, 2004 anyone want to help me with the flange? I just made my own out of 3/8 mild steel and a lot of time at the drill press and using a metal file. Quote Link to comment Share on other sites More sharing options...
Guest szlash280z Posted January 9, 2004 Share Posted January 9, 2004 did you just drill a bunch of holes in the center to make the big hole? do you have the plans/drawing for the flange? Quote Link to comment Share on other sites More sharing options...
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