Crashtd420 Posted February 23, 2019 Author Report Share Posted February 23, 2019 (edited) The insert in the stack acts like a resonator, I might even reuse it some where else when I redo things.... Now when you say get a bigger muffler are you saying its physical size and stay with 2" in/out ? Or bigger chamber and the 2.5 in/ out? Edited February 23, 2019 by Crashtd420 1 Quote Link to comment
datzenmike Posted February 23, 2019 Report Share Posted February 23, 2019 Datsun cars usually have a resonator about where the transmission is. It looks almost like a smaller muffler (empty) and is a straight through with perforations in it. I would imagine a glass pack thrush would do about the same, added to what you have now, but won't last as long. It should be ahead of the 'muffler'. Resonators are designed to remove objectionable drones at certain RPMs and what works on one engine and system probably won't work on another. The take away is that any resonator is better than no resonator and car makers probably run the smallest they can get away with so larger is likely better. I'd like to try and make my own. A large-ish chamber with a perforated straight through pipe. The exhaust pulses have more room to expand into and slow before finding an exit. I was thinking of filling with stainless steel scrubbing pads rather than fiberglass that could potentially be pounded apart by vibration. The easiest/best/cheapest quieting is done by restricting flow so that the individual pulses are forced to find their way out over a longer time. Higher amplitude (short duration pops (fart cannon)) become lower amplitude (longer duration thumps) If only engines ran at the same RPM all the time. Restricting flow would work but as engine load and RPMs go up the restriction is unacceptable. I kept my Nissan resonator but replaced the damaged stock muffler with a larger one. Again the intent was to allow the pulses to expand and slow more before exiting and I assume there are more holes or larger holes in the baffles inside so less restriction. This is a true muffler.... just larger. My pipe was 1 7/8 or 2" and the muffler inlet was 2 1/4" so I had to add an expander? I have no tail pipe but a 45 degree down bend. It's not at all loud, after all it's got a muffler... but you can hear the exhaust. A tail pipe would be quieter but add more bends. The sound probably reflects back off the pavement also to some extent and enters the car. 1 Quote Link to comment
Crashtd420 Posted February 23, 2019 Author Report Share Posted February 23, 2019 Thanks this is some of the info I was hoping for.... I might trying adding a resonator next to the trans as a temporary trial/ solution... just to see if it helps the sound.... Either way I wanna redo the system, but it sounds like I could benefit from a resonator.... I would still need a new muffler so I'll be looking at these .... Probably something with 2 1/4 in/out.... Should I also go bigger on the resonator or would 2" be better? 1 Quote Link to comment
Crashtd420 Posted February 23, 2019 Author Report Share Posted February 23, 2019 This is the stuff I'm currently using.... This is the insert, fit the inside of a 2.5 exhaust pipe.... 1 Quote Link to comment
thisismatt Posted February 23, 2019 Report Share Posted February 23, 2019 What about an oem for a similar motor/displacement? eg a 4 banger Accord, Camry, Altima, etc 1 Quote Link to comment
DanielC Posted February 23, 2019 Report Share Posted February 23, 2019 See this thread. https://ratsun.net/topic/61167-how-i-replaced-a-521-exhaust-system/ 1 Quote Link to comment
wayno Posted February 23, 2019 Report Share Posted February 23, 2019 Keep on mind that your exhaust is exiting right in back of your head right now, it's going to be noisy, even with the muffler you have right now it will be much quieter to you if it is exiting back at the rear of the truck out the side, and even quieter if it exits straight back, but exiting straight back tends to cause the tailgate to get soot on it when out the rear side keeps the back of the truck cleaner. I farther away from you the exit is the quieter it will be to you in the cab. 1 Quote Link to comment
datzenmike Posted February 23, 2019 Report Share Posted February 23, 2019 Super turbo Yes, all the others are straight through design, some with a kink so you can'r exactly see through them. I imagine this style with two 180 kinks would be slightly quieter then them. It would be better with sound absorbing inner shell. Resistance to flow is the easiest, then there is resonance tuning but it works best at set RPMs and then there is sound absorption. Some makers use all three. Corvettes, Mustangs? and others use a vacuum operated gate in the mufflers to by-pass most of the sound deadening resistance if not all of it. I drove a Shelby Super Snake and when active you have to shout to be heard inside. It's friggin' loud 2 Quote Link to comment
Crashtd420 Posted February 24, 2019 Author Report Share Posted February 24, 2019 Thanks everyone.... gives me a bit to think about, and answers a few questions I've had. I'm thinking I might try moving my current setup around to see how it sounds..... Technically the stack is a home made resonator, so I'll put that before the muffler and the muffler will be behind the axle mounted left to right.... exhaust exiting out back instead of next to my head..... I still want to buy a new muffler because of placement and piping, the current muffler has the in/out on the same end so I could make that stack. In the end the hope is to make 2 exhaust tips exiting the rear sides behind the rear wheels... one side muffler and the other side an electric exhaust cutout..... 1 Quote Link to comment
mainer311 Posted February 24, 2019 Report Share Posted February 24, 2019 That Walker might actually have packing in that center section where the perforations are. If it does, It’s a hybrid baffle/glasspack, and probably the best in terms of quietness. As far as diameters go, 2.25” would be a great size, and I think you should maintain that as much as you can all the way back. 1 Quote Link to comment
mainer311 Posted February 24, 2019 Report Share Posted February 24, 2019 17 hours ago, datzenmike said: Resistance to flow is the easiest, then there is resonance tuning but it works best at set RPMs and then there is sound absorption. Some makers use all three. Corvettes, Mustangs? and others use a vacuum operated gate in the mufflers to by-pass most of the sound deadening resistance if not all of it. I drove a Shelby Super Snake and when active you have to shout to be heard inside. It's friggin' loud Two banks of cylinders is way different though, especially when they cross the banks with X or H pipes. 1 Quote Link to comment
Crashtd420 Posted February 24, 2019 Author Report Share Posted February 24, 2019 1 hour ago, mainer311 said: As far as diameters go, 2.25” would be a great size, and I think you should maintain that as much as you can all the way back. You mean for all the piping from the header to the tail pipe? Or just after the muffler? 1 Quote Link to comment
datzenmike Posted February 24, 2019 Report Share Posted February 24, 2019 My thoughts are that if too large a diameter the exhaust will take the easiest way out and not be quietened much. The resonator and muffler should be like a press of people running through a corridor and into a large room. The exhaust has somewhere to expand and slow down into. When slowed down it has more time to find the exit and take turns getting out. The sudden high pressure short duration wave has been lowered and spread out over time. As the hot exhaust leaves the port it begins to cool as it travels down the cooler exhaust pipe and it will reduce slightly in volume so the pipe can actually reduce in size. I've never seen a tail pipe larger than the down pipe. Also the exhaust should move as fast as possible through the pipe as long as said pipe is not restricting. Stock pipe diameter is a function of restriction and cost to the maker. A smaller pipe will be a quieter/cheaper/and easier fit exhaust so you can increase the diameter by 1/4" or so. Keep in mind that a doubling of the pipe diameter will increase the flow by 4 times! Going from a 2" to a 2.25" is a 26.5% increase in flow or enough for increasing from a 2 lite engine to 2.5 liters. 1 Quote Link to comment
Crashtd420 Posted February 24, 2019 Author Report Share Posted February 24, 2019 (edited) I think I'll stick with the 2" pipes idea, and I found a resonator and muffler with 2 1/4 in/out..... What I'll probably do is see if i can make some simple changes ... install the resonator and new muffler and see how it sounds.... then secure it all properly where I really want it with some new tubes and proper bends... Thanks for everyone's input.... Edited February 24, 2019 by Crashtd420 1 Quote Link to comment
Stoffregen Motorsports Posted February 24, 2019 Report Share Posted February 24, 2019 (edited) 2" tubing comes in a variety of bend radius options, so fitting it overt the axle and around the shocks won't be too problematic. I like to exit in the rear corner with a turnout slightly to the side. Not only does this look nice, but it also helps with fumes. Anything exiting straight out the back has a tendency to curl back up into the bed (or back window of an SUV). Turbo mufflers are my go to muffler for quiet performance. That super turbo someone posted is a great design, but the offset/offset layout may or may not work for getting the exhaust out the back. Edited February 24, 2019 by Stoffregen Motorsports 4 Quote Link to comment
mainer311 Posted February 25, 2019 Report Share Posted February 25, 2019 Too large a diameter and you’ll get less torque in the lower RPM band. 1 Quote Link to comment
mainer311 Posted February 25, 2019 Report Share Posted February 25, 2019 12 hours ago, Crashtd420 said: You mean for all the piping from the header to the tail pipe? Or just after the muffler? I can’t remember what size your downpipe is (insert dirty joke here), but I’d try to maintain the same diameter for as far as you can. 1 Quote Link to comment
Crashtd420 Posted February 25, 2019 Author Report Share Posted February 25, 2019 10 hours ago, mainer311 said: I can’t remember what size your downpipe is (insert dirty joke here), but I’d try to maintain the same diameter for as far as you can. It's a header with a 2.5 diameter out, with a reducer to 2"..... 1 Quote Link to comment
Crashtd420 Posted March 12, 2019 Author Report Share Posted March 12, 2019 Well this is not the post I was hoping for today....... I got out of work a little early and it was almost 50 degrees out, I had about 30 minutes before i had to pick my son up so i figured why not get a test ride done around town and surprise him by picking him up in the datsun.... Well I got the surprise... it wont go into reverse or 5th..... wtf..... then the clutch pedal got stuck down, piston in the slave over extended and was leaking fluid.. I was able to pop it back in, guess it needs to be adjusted better.. seems like I have some more work to do ... back in the garage it goes.... Then i proceeded to step on a broom which poked me in the eye.... If that's not enough.... i got my work stuff out of my Chevy to go in the house and when I went to shut my door i slipped on ice and slammed my leg in thw truck door.... Fuck me ... and this all happened within 15 minutes.... As far as the transmission problem goes I'm really hoping it has something to do with my boot cover or tunnel plate..... I tested the gear shifting on the bench before I ever put it in the truck , all good.... Then I tested it while still on jack stands.... everthing worked..... Everthing buttoned up and back on the ground now no 5th or reverse.... I cant even get the shifter to move far enough over , it only goes to where 3rd and 4th are..... Hopefully this is something stupid and simple and the transmission doesnt have to come back out... Hope everyone enjoyed.... 1 Quote Link to comment
mrbigtanker Posted March 12, 2019 Report Share Posted March 12, 2019 Did the mount come off ? Meaning did your tranny shift to cause the shifter to get caught up on the floor board. Clutch slave blew out ? 1 Quote Link to comment
mainer311 Posted March 12, 2019 Report Share Posted March 12, 2019 Sounds like something to do with the striking rod. If the striking rod can’t line up with the slot in the 5th/reverse shift fork, you won’t even be able to move the shifter over. 1 Quote Link to comment
Crashtd420 Posted March 12, 2019 Author Report Share Posted March 12, 2019 39 minutes ago, mrbigtanker said: Did the mount come off ? Meaning did your tranny shift to cause the shifter to get caught up on the floor board. Clutch slave blew out ? No the mount is good... freshly made and installed.. transmission didnt move... truck hasn't left garage since the swap.... My cover for the trans and the boot aren't original, kind of a cobbled together mess of parts.... On the slave I am using the threaded adjustable one, it was just not adjusted properly, or should I say at all.... I kind of just eye balled it.... I knew I need to adjust it later but when I couldnt get it into reverse I tried pushing the clutch in harder like it was gonna actually do something to help.... well It did... it caused the slave piston to extend to far and get stuck out... got lucky and was able to get it back in with a light tap of my rubber mallet... atleast then I could drive the truck back in the garage.... I'll have to check and make sure i didnt rip the seal.... 2 Quote Link to comment
Crashtd420 Posted March 12, 2019 Author Report Share Posted March 12, 2019 36 minutes ago, mainer311 said: Sounds like something to do with the striking rod. If the striking rod can’t line up with the slot in the 5th/reverse shift fork, you won’t even be able to move the shifter over. This is what I'm afraid of.... I'll get things exposed and see what I find.... if I'm hitting something it should be pretty obvious.... if not I'll have no choice but to pull it back out and have a look..... just sucks..... really hopeing its something stupid at this point, but I doubt I'm that lucky ..... 1 Quote Link to comment
Crashtd420 Posted March 12, 2019 Author Report Share Posted March 12, 2019 Oh while I'm sharing stories this happened at work today...... After I got back to my machine I text my friend this.... I just got stuck in the bathroom with a bloody nose And some just blew up the toilet next to me.... Had to plug both sides for the smell.... Should have know the day wasnt gonna end well..... Goodnight to all I'll try again tomorrow.. 1 Quote Link to comment
datzenmike Posted March 13, 2019 Report Share Posted March 13, 2019 It'll be the hole or the carpet you wait and see. 2 Quote Link to comment
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