kito Posted February 1, 2012 Share Posted February 1, 2012 So I've finally got my LT1 in the Z and it's together enough that I can take it for a drive, but I have one little problem. It's loud. Insanely loud. Shakes the whole house loud. I'm running JTR headers to a Y-pipe, through an 18" resonator, and then out to a single magnaflow in the stock location. I used to be running the same magnaflow on my turbo L6, and right now I'm really missing that sound. I know that 2 extra cylinders and no turbo means it's gonna be louder, but I was hoping the resonator might do a little to dampen that noise. The motor is pretty much bone stock, except the intake and what was necessary to fit it into the Z. The interior is covered in 100 sq. ft. of fatmat with a layer of fiber insulation on top of that, but even so sitting in there is kind of like sitting on the inside of a jet engine. Any suggestions on things I can try to tame this beast? Is it possible that poor engine tune is to blame for some of this noise? It's my daily driver, and I'm willing to sacrifice a bit of power if I can get it as quiet as possible (close to stock-quiet at idle would make my day). I'm really not trying to attract attention to this monstrosity. Quote Link to comment Share on other sites More sharing options...
Wedge Posted February 1, 2012 Share Posted February 1, 2012 For one thing you could put a catalyser and maybe fit a glasspak instead of the resonator other then that I really don't know. Quote Link to comment Share on other sites More sharing options...
kito Posted February 1, 2012 Author Share Posted February 1, 2012 Yea, putting dual cats in is definitely an option. The question is whether I'd be able to fit them in there. Has anyone done this successfully? Getting cats here in CA is also really expensive (Unintended side effect: I want cats, but the law is making it harder for me). Quote Link to comment Share on other sites More sharing options...
Leon Posted February 1, 2012 Share Posted February 1, 2012 Check for exhaust leaks first, then get quieter mufflers if no leaks are found. I'm sure there are plenty of V8 guys here that have a more detailed solution, search the Exhaust and V8 sections. Quote Link to comment Share on other sites More sharing options...
rsicard Posted February 1, 2012 Share Posted February 1, 2012 Kito: Which resonator and magnaflow muffler are installed? I am installing nearly the same engine and exhaust and would like it to have a good sound and not LOUD. I plan to have two resonators before the crossover and then to a Y pipe and on to a Flowmaster super 44 muffler which has few traps within. Quote Link to comment Share on other sites More sharing options...
kito Posted February 2, 2012 Author Share Posted February 2, 2012 The muffler is the regular 3" oval body offset/offset magnaflow. I'll have to take a look to see what the resonator is, but I won't be back to my car until the 21st. I'm starting to think there must be some sort of problem, because there's no way this setup should be as loud as it is. I'll let you know what I find out. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted March 9, 2012 Share Posted March 9, 2012 My rx7 has a 5.3, I'm running a true dual exhaust with x pipe, no resonators, and 2 magnaflow 2.5" out back, it's plenty quiet. I don't think I've heard much for complaints about magnaflows being loud. Are you running it in a garage or enclosed area? Positive there aren't any leaks? Quote Link to comment Share on other sites More sharing options...
kito Posted April 8, 2012 Author Share Posted April 8, 2012 I did a summary check of the gasket surfaces and didn't find any signs of leaks. I am using a gasket in addition to the sanderson headers, contrary to their recommendations. I think one thing that's contributing to this impression is that the cabin vibrates quite a bit (from the stiff motor mounts maybe?), which makes it sound much louder inside than outside. Quote Link to comment Share on other sites More sharing options...
randy 77zt Posted April 8, 2012 Share Posted April 8, 2012 A cat convertor makes alot of heat.my 77 280 had a cat just below the drive shaft with a long heat shield above it.If the original car didnt have a cat you will have to install heat shielding .Do you have any sound deadening under your carpet?Most newer cars have a big sound mat on the firewall inside the car.I used to run a big magnaflow 3" pipe X 21" oval offset outlet muffler in the space where the cat used to be but i bottemed the car out and now have a shorter dynomax .my car is a 3.0 l series turbo engine.I liked the longer magnaflow better.A friend of mine is putting a 5.3 gen3 chevy in his z and we talked about using 1 of those magnaflow oval mufflers that have 2 pipes in and 2 pipes out and mounting it under the drive shaft. Quote Link to comment Share on other sites More sharing options...
GOTHALOSISM Posted April 8, 2012 Share Posted April 8, 2012 Mine is not that loud, running 2.5 from the headers to a y-pipe then to a glasspack right after the Y (right past the tranny mount). Then I have 2.5 out the stock location. I do have a spare rampage muffler that I will be tossing on to make is more of a sleeper car. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted April 12, 2012 Share Posted April 12, 2012 This is the rx7 I mentioned above. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted April 18, 2012 Share Posted April 18, 2012 Nobody specifying whether single chamber or dual chamber mufflers? One is more than twice as loud than the other. Quote Link to comment Share on other sites More sharing options...
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