Hey guys am running a blown small block chevy, 1"3/4' headers into 3" collectors out to 8x5" magnaflow mufflers (yes, I know O/T) then baffles in the end of the tail pipes. All stainless mandrel. Can anyone suggest ideas on how to reduce db/noise level? Thanks in advance. Yes already searched and no results.
Are you talking about inside noise, or outside "spectator" noise? Full-length tailpipes will do quite a bit. If that's not doable, at least put turndowns on the mufflers. A lot depends on how much space you have for mufflers. As a general rule, the bigger the muffler, the quieter it is, although there are exceptions. It might be possible to use resonators at the end of the system, too. 1 5/8" headers for a blower engine?
Sorry 1 3/4 headers. Outside noise. I'm thinking I have to make cones or plates inside the baffles. Definately some experimenting!
One of the reasons full pipes are quieter are more bends. I had my pipes running straight shot from the headers, through flowmaster 40s and the end cut off when I did my new rearend, took it to goodguys before having a chance to get to a mufler shop. Sound bad*** cruising and idling, made my brain itch on the highway home. 1 90 and a 45 bend later, the noise was cut almost half. the more turns the soundwaves have to negotiate, the more they cancel themselves.
I am afraid that when you read this you are going to dismiss my post and regard it is as unhelpful sarcasm. However the single best thing you can do is simply uncork the exhaust and run it open header. Bro, how quiet do you want it??? I read your post and it sounds to me like you have built a solid exhaust system. You want the thing to rumble at least a little bit so that blower does not look like an ornament placed on top of the motor. I would say you have already done what needs to be done.
I'm more than happy with how it sounds believe me. But when i have to knock 14db off it at 3500rpm to get rego i'm prepared do experiment. Exhaust is also wrapped with tape from collector to muffler. I think i'm running out of options...
An "X" pipe is suppose to change the harmonics enough to change the sound out put. I'd also try different mufflers. or maybe actually install a set of resonators instead of baffles in the tailpipes. Gene
Maybe you could use a factory type muffler after your magnaflows to get your paperwork? then take them off? Don't know your laws, can they test the DB's on the side of the road?
I put an X pipe in my system and I was shocked as to how much of a change it made and still has a nice exhaust report. I also have Porter's.
a crossover pipe behind the headders a second set of muffler behind the others, maybee look in speedway for something stock car or some walker headder mufflers I am sure this is kinda like a detroit diesel, a lot of noise comes off the pipes, insulate some off engine and drive about a hour in my shop and you could find something how about some chev pickup stock mufflers 3 in in and 3 out???
the above is true...kind of. if you place a 1" tube 'balancer' between the pipes near the trans. mount, it will make a notable difference, there is a specific science to it, but in laymans terms, depending on how you have your joins arranged, you want to look in the tubes in that area mentioned, to which you should see a varience in colour from the gray, that is the 'ideal' spot....allegedly. Similarly, as mentioned earlier, adding 2x45's will ***ist, as it wont detract notably from the exhaust flow, but will influence the sound. A discussion of late based around flow/volume, and the effects of heat/temperature suggest that rather than increase the tube dia. at the rear of the pipes, it is better to actually reduce the diameter at the rear section, on the basis that you want to maintain exhaust flow, and since there is a significant temerature reduction, your g***es will effectively slow down due the volume reduction based at the lower temperature, hence it's common practice to actually downsize at the rear of the car. Bottom line, if you add the 'link pipe', as well as 'experiment' with resonators & a reduced dia at the rear, there should be a notable dB reduction, without comprimising performance. Cheers, Drewfus
Back years ago ,,when the cops weren't so forgiving ,,i used Honda Motorcycle inserts in each pipe ,,held by one bolt ,,they were easy to remove when you wanted ,,but very quiet around the cops n in town ,, Now tho ,,i don't run Any Mufflers with the Speedway Hedders on my 6;71 Blown Small Block Chevy in my '27 "T",,the cops around here all have Harleys or Hot Rods ,,so ,they give me a big thumbs up when i cruze by ,, times have changed fer sure ,,
I remember a pinkish coloured, full fendered '34 three window with a cammer, is that the car? Stuck in my mind because I remember watching him try to park it on more than one occasion, it obviously had a spool in the rear end, didn't like to turn and the inside tire always chirped when it did. Sure did sound good, though the Supertrapps kinda whistled a bit.
Yeah i was going to put a 1" pipe behind the trans. Should've gone with my gut feeling when i made the system up and before i wrapped it. I agree and think supertrapps are the way to go, hopefully will make a noticeable difference. I'll update in a week or so once i have something fitted and take a reading. Cheers.
Took the baffles i made, out of the tail pipes and put on the Supertrapps and they worked a treat. Took the measurement on the meter and we're in business! As a note i took a reading with no baffle or supertrapp in the tailpipe, just the mufflers on and at idle it was louder, but at WOT the measurement was lower than with the baffle. Anyway, it was interesting. Thanks for the ideas.
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