vega

BRAAP (a member here many people know), and my lonesome have been working on a set of mufflers that don't sound like fecal matter. I am having a difficult time finding just the mufflers (race mufflers). I DO NOT want an entire exhaust system. I do have the capability of fabing up mufflers, I have custom made equal length headers to an x pipe thus far. I DO NOT want the mufflers to have those two little connections keeping them together. I will be making this a side exit. I am looking for the highest frequency/note/tone/pitch I can get. I very much enjoy the higher, crisper, cleaner sound the european v8 makes. I hate with a passion the rumble of the harley/dumptruck American v8. I have heard flowmasters on these cars. I don't know if it was the particular flowmaster series or what. But that m3 was a dumptruck. I am trying to avoid that. Lower frequency sound for comparison (I am having a hard time finding the vid with the flowmasters) htt p://ww w .youtube.com/watch ?v=jAtPDWFM7jo&feature=plcp ------------------ http: // w ww.youtube.c om/watch?v=5B hxWH9Dg_M amazing high frequency sound htt p://ww w.you tube .com/watch?v= SbT0IqFIfnc ht tp://www.youtub e.com/watch?v=n_n8HiJ zA6A Here is a cutaway of a corsa muffler. htt p: //s805.beta.pho tobucket.com/use r/Phastek/media/March%202010%20Show/Corsa1.jpg.html?filters[term]=recent&filters[primary]=images I am rather sure that the chambers in the muffler can be designed as such to reflect frequencies to cancel out the unwanted frequencies. I just can't find the math anywhere to determine the dimensions of the chambers. I am working with 17.9 inch long primary tubes that are 1 and 5/8 in diameter, they go into a 2.5 inch collector, that then goes into a 3 inch x pipe, that will then go directly to the side exit mufflers. I am keeping it as short as possible to help retain the sound I am after. This is what I am avoiding. htt p://w ww.yout ube.co m/watch?v=klmAQFh1l-E Same motor different car different mufflers... ht tp://w ww. yo utube.c om/watch?v=IVWZMKMmjMQ So does anyone know how to design the muffler to achieve this? Or designing a resonator to do this? Or simply the chambers inside the muffler to do this? I am so stuck, and so is BRAAP. We are both at a loss here. For some reason the forum wouldn't let me post links? I put spaces in-between to allow them to come up.

Do you guys have a link?

Thanks for the info john.

I have a 280z. do they work with those?

That is a new way of calling them to me.

Thanks much fellas, big help. Btw, I don't want to sound stupid but, what the heck is a tc box? I haven't heard that reference before, I have been working on cars for over 10 years now. So you are kinda throwing me through a loop. That is the second reference I have read today.

I have been reading about subframe connectors. The most help I saw was some pics from Johnc. I am trying to find some decent pictures to how you fellas are welding the connectors to the subframe. Or more over where on the subframe you are actually welding them to. Also is there a bolt in kit that is being sold that I can bolt up and then weld? I would appreciate some pictures of this. I have seen a few but they are mostly at very bad angles or just show the floor rails. I get the floor rails, I don't get where you weld them to the rear subframe. Oh, correct me if I an wrong, but I don't think most of you weld to the front subframe just the rear?

I have been listening to many different muffler sounds in a myriad of configurations. I am making an attempt to contact both OBXr and this particular "youtuber" to find out which obx system this person used. This is the exact sound I am attempting to make. I like the growl to it vs the traditional dump truck open header/ header to glass pack sound that a great deal of people tend to enjoy.

Hmm well I feel sheepish, thank you for the correction. That makes WAAAY more sense.

Well I finally found the frequency I need to emulate that being 493.883hz tuned in 440hz which is N1 according to wiki. It looks like using your equation to find length also varies depending on the diameter. so i did some math and the diameter doesn't really seam to make that big of a difference. whether or not its as small as 1 inch or 4 inches. maybe i am figuring for L wrong 440hz(343.2mps)/2(493.883 the freq. goal) 1510083/987.7663=152.878266853 taking that and subtracting the .3(d) doesn't vary that much from 1 inch to 4 inches at 1 inch (.0254 meters) .3(.0254)=.00762 at 4 inches (.1016 meters) .3(.1016)=.03048 So there is only a range of 152.87064 meters to 152.847786853. that is 501.544 to 501.469 feet. first off that is very long and I know that there is no way that a car is ever 500+ feet. So there is something either I am missing or there is something else that is bringing the exhaust sound up in hz. I am going to go ahead and say that for the most part this theory must be wrong (or I did my math wrong) and the piping matters less than the muffler design. I am betting that the muffler systems on say a corsa vs a magnaflow are very different in where the baffles are placed. In the muffler one has baffles placed in a way to bring the lower grumble sound out of the tubing. The other has baffles placed so that the baffles are placed in a way to bring a crisp exotic sound. I know exhaust pulses and the like are a huge factor etc etc etc. Though I think this shows (correct me if I am wrong) how different mufflers can change the sound extremely differently. examples on a gt500 Corsa vs magnaflow and stock

And solving for d? Also what is the difference in the first second and third harmonic? I was always bad at algebra.

could you show me the math how you reverse engineered that? also i assume n2 would be the second harmonic? thanks for clearing this up guys.

I am working with a 336.6 CID sbc. At 7000rpm VE is at 83.8. Peak VE is at right around 5500rpm being at 92.1 RPM is a factor of cfm, it doesn't make sense to me that cfm is not a factor in the sound and the rpm is seeing that they are related. The higher the rpm the higher the cfm and vise versa. The formula should technically be able to find the frequency giving the cfm comming out of the engine. valve sizing as far as I can see and all other factors of the engine cause the ve to be where it is at, so ve is the only number that should matter there. which again is a factor of the cfm. Also one should be able to even out the pulses of the exhaust running first through an x pipe back into a single pipe. That single pipe is the one that matters in this formula. As for the formula given I understand that "N" is an integer being "1,2,3" what I don't get is what it is supposed to represent. It says the resonant node, are they trying to say the frequency that we are attempting to achieve, or something else that I am missing here? For example. if f=nv/2(L+.3d) and the req we are looking for is say again middle c (261.626 hz) at 20c, which would make speed at 343 mps (meters per second) the length is say about 1 meter and the diameter is .0254 meters (1 inch) then f would equal 44546.0087328hz which makes no sense to me that appears to be very high. A 3 foot open pipe with 1 inch diameter openings. Unless that happened to be the limit of the pipes ability to make x amount of HZ with max amount of allowable cfm to travel through the pipe. Which this does not tell us when it is too much cfm for the pipe and then the octave raises. Show me where I am wrong here, because I feel like I am missing something.

I have a theory in that based on what you just said about the pipe organ (there are two kinds of pipe organs open and closed tube. the closed tube has a varied opening). The theory is taking an air pump (engine) that produces a max amount of the given cfm (57132.3958333)when let into the tube. I want to know what size tube will give certain musical notes. That is what I am trying to figure out. I calculated cfm using this formula CFM = (CID * RPM * VE)/3456 As an example (not the note I am looking for in particular btw) Middle c on a piano plays at 261.626 hz. What dimensions of a tube would be needed to create a 261.626 hz frequency when forcing 57132.3958333 cfm through the tube? There must be some equation for what I am looking for.

So I am trying to make sense of the different varying formulas that I have found. Some of the formulas are not fully explained hence my questions. This is a "musical exhaust" related topic. I am attempting to figure out what the formula is to determine the frequency of a stainless steel pipe (the one constant) with air pushed through it with these following variables. ( A ) Length of pipe ( B ) Wall thickness of pipe ( C ) CFM going through the pipe ( D ) Inner Diameter of pipe Also I have read that overblowing a pipe will cause the frequency of the note to jump an octave. At what point is it considered to be overblowing a pipe? Is there a formula for the max cfm prior to the said overblowing? I am working with 57132.3958333 cfm btw this is the closest thing i could find. http://en.wikipedia.org/wiki/Acoustic_resonance it does not say what the value of the integer is supposed to be.

Dude... start a new thread.

The block and crank are getting crack tested as we speak. I dropped the block off at the builder last thursday. when i know you will know. also... mr 383. I am not here for an argument but you are wrong and I really don't have enough time to tell you why. I just check my email now after 5 days. I don't got online much, I don't have time. Bigger is not always better, this is personal experience.

Anyone in particular that you have in mind?

Anyone else aside grumpyvette have ideas?

Posted this in that forum. Looks like a great page! Thank you for the tip!

Neat, I hope to hear from him. I will check out the site.

Grumpy?

Called them. I've called 8 different cam companies. There are too many different opinions. one guys says 110 lsa, another says 114, another guy says 108 even. Then one guy said 236 intake, another says 242, another says 254. One guy says 247 exhaust, another says 254, another says 269. Seriously way too many opinions. I want an educated straight forward answer.

195cc intake runner, 64cc combustion chamber, aluminum, 2.02, and 1.60 valves Superflow sf 600 flow com air speed: 380-400FT, 375-410SC Intake; (.1)66 (.2)141 (.3)200 (.4)242 (.5)270 (.6)265 (.7)268 Exhaust; (.1)55 (.2)107 (.3)139 (.4)167 (.5)192 (.6)209 2500lb car 245/50r16 street tires rated at 320aa by firestone (I don't really need tq the car is very light and I am limited on tire) 1987 700r4 trans 3.545 rear gear ratio 10.25:1 compression chev 327 40 over now may end up 60 over soon 1.6:1 rocker ratio Looking for a solid flat tappet. I'm looking to have a very WIDE rpm range, as much as possible. Comp claims the old duntov 30-30 is between 2300-6900. I'm talking that kind of wide. The issue with that cam is that the one they sell it for a 350, in a 327 that would bump my rpm past what I want it to be. The 30-30 does suck (compared to modern cam profiles), I am just pointing out that a wide powerband in a solid flat tappet can be done. Also when I was saying the difference between a 350 and a 327. The small crank throw will up the rpm a bit. Instead of being at 2300 it would be like 2500-2600, and instead of being 6900 it would be like 7200-7300. That is too peaky for me. 2300 to 6900 would be perfect if it was rated for the 327. When comp rates those numbers they are all done with a 350 base. Not a 3.25 but a 3.48 crank. I'm looking for a 6700-7000 peak rpm, with it coming in as low as I can get it at. One thing I have heard and read a lot of debate about is the fact that the 327 doesn't sit at top dead center for very long so a wide lsa (about a 112-114) would be beneficial. Also it would kill the tq down low. The other end of this opinion is that one could do a 110 lsa and advance it quite a bit. I don't honestly know what would be best. Some help/thoughts/advice would be great. The car is intended for the road course at BIR in MN. Both the outer longer track and shorter center track. http://www.brainerdraceway.com/ It looks like 1st gear is just to get going and 2nd gear should be about 33 mph at 2500 rpm and will be 80mph at 6000rpm. 3rd will go from 55mph @ 2500rpm to 130 @ 6000rpm or 140 @ 6500 rpm so 3rd should be a great gear for most of the high speed sections. 2nd should be enough for any tight stuff. Overdrive is 200mph + so that's good for a bit of extra pull down a straight if I'm able to go faster than 140mph before braking for the turn. Looking at the Brainerd track it looks like a lot of high speed corners and long straightaways without too many tight corners. I have wide gearing so this should suit the track well but it means I need a wide powerband as well. Help and advise or a point in the right direction would be great.

My rims will be here on the 29th. I have a set of 245/50r16s already here I will post pics and fitment as soon as I can.