What type of mufflers are you running?

dave harris · 05-13-05, 04:37 PM

Starting to look into mufflers - what brand, length, diameter etc are you using.

How do you rate the sound levels? and would you do it differently?

thanks everyone

Neal · 05-13-05, 05:34 PM

A pair of Borla XR-1s. Not real effective!

Bob Childress · 05-13-05, 07:32 PM

Hi Dave

I have a mono CAV with a 342 4-barrel and 1 5/8 inch crossover headers into a stock CAV muffler. The stock muffler is a perforation and packing design and is quieter than the two baffle mufflers I tried (FlowMaster and SpinTech). I also tried a pair of SuperTrapps added to the stock CAV muffler.

All this was initial testing so don’t be too critical about the technical details, that will come in the future after I get some idea of the ballpark numbers. Basically I did not find a baffle design that was quieter AND potentially less restrictive.

All measurements were made with the db meter 3 feet high and 10 feet directly behind the muffler. I used a medium quality Radio Shack brand meter set to the A-Scale. I also borrowed two brands of baffle mufflers to test but I cannot find the actual numbers I recorded (how convenient). Nevertheless, both brands of baffle mufflers were VERY noticeably louder than the stock CAV muffler so I returned them to the owner. The mufflers tested are listed below. I concluded that the stock CAV muffler is actually pretty good. A 3 db reduction was easy to get just by adding the SuperTrapps but I do not know how horsepower was affected. I do know Frank Catt has done a lot of work on this with a design of his own and maybe he would have something to say here. Here is my data, meager as it is, and with some missing records and a few pictures:

A 1 CAV (PowerFlow SS P/N# GE-265X350C60-20886 dual 2 ½ in and dual 2 ½ out)
B 1 CAV + 2 SuperTrapp (P/N# 444-2503 4 in diameter with 12 plates)
C 1 CAV + 2 SuperTrapp (P/N# 444-2503 4 in diameter with 6 plates)
D 1 CAV + 2 home-made baffles (1 ½ in equilateral triangle x 24 in long)
E 1 SpinTech (P/N # 33310 dual 2 ½ in and dual 2 ½ out)
F 2 FlowMaster (P/N # FLO842553 SS Delta 80 Series each muffler single 2 ½ in and single 2 ½ out)

RPM 1,000 2,000 3,000 4,000
A-----84----84----91----92
B-----81----82----88----91
C-----77----81----85----88
D-----83----81----88----89
E---->86 (cannot find data sheets)
F---->86 (cannot find data sheets)

I hope this helps you get a handle on what is out there and if you find something good, be sure to let us all know.

Bob

Bob Childress · 05-13-05, 07:34 PM

picture 2

Bob Childress · 05-13-05, 07:35 PM

picture 3

Bob Childress · 05-13-05, 07:36 PM

picture 4

Bob Childress · 05-13-05, 07:37 PM

picture 5

dave harris · 05-13-05, 09:13 PM

Hi Bob,

thanks for the great input! I have the same basic Radio Shack sound meter and was going to do the same types of measurements.

I've seen some nice mufflers that I think would work, but they are all 24" long for the muffler only and that just won't fit without sticking out the back of the car!!

If I come up with something better, I'll let you know!

thanks again

Andy Besic · 05-13-05, 09:26 PM

Dave,

Next week I will be assembling as set of Heddman hedders 1 5/8" to 3" slip-on collectors (part # 14043)to 2 Magnaflow 3" in/out 6" round perforated and stuffed type mufflers (part number 12619). The collectors are 5" long, the muffler is 14" with 3" long ins and outs. I figured I will be able to shorten them to about 23" overall when welded together. I'm sure they are quieter than what I'm running now, Flowmaster scavenger collectors (very loud) with some baffles welded in the end (still loud). I have driven it this way on the street for about 2k miles with no trouble from officer square nuts! I'll let you know how they work in a week or two.

Andy

Bob K. · 05-13-05, 11:53 PM

Any idead what kind of dB level pure headers into a collector runs?

Bob K. · 05-13-05, 11:54 PM

By the way Bob, beautiful GT40.

dave harris · 05-14-05, 03:38 AM

Thanks Andy,

by the way, did you get the faxed information on the G50 transaxle I sent you?

cheers

Andy Besic · 05-14-05, 08:21 AM

Dave, Yes I did thank you.

Bob K. My current set-up of headers, collectors, baffle and a turn down is actually quieter IN THE CAR than most combos I have tried. 3000-6500rpm sounds like music. The problem with most muffler set-ups is an annoying resonance within the car. The standard GTD muffler is much quieter when standing behind the car but inside the car is a joke.
My .02

Andy

Bob K. · 05-14-05, 04:08 PM

[ QUOTE ]
Dave, Yes I did thank you.

Bob K. My current set-up of headers, collectors, baffle and a turn down is actually quieter IN THE CAR than most combos I have tried. 3000-6500rpm sounds like music. The problem with most muffler set-ups is an annoying resonance within the car. The standard GTD muffler is much quieter when standing behind the car but inside the car is a joke.
My .02

Andy

[/ QUOTE ]

Thank you. I am currently investigating which GT40 is best suited for me. But I really do not want to put a muffler on it. [img]/ubbthreads/images/graemlins/cool.gif[/img] But since I do not know how loud this will be, I am not sure how Plolice friendly this will end up being. I just want it to have a really throaty sound and be nice and loud, inside and outside of the car.

dave harris · 05-14-05, 04:53 PM

Bob K.

Ping Farhad Faili - he just put some new mufflers on his after the 347 stroker installation - they sound great - I think that they will be loud enough for you on the outside!

Graham ("Wine cave man" - cuz he digs caves for wineries here in the Napa/Sonoma counties in Calif.) has an original GTD with straight thru pipes. If he keeps it around 3000 - maybe 3500 rpm it's not TOO loud - - but after that it's basically wide open so you get full song - sounds great, but the local constabulary knows exactly which streets he's on anywhere in the county!!

cheers

Iron Sheik · 05-14-05, 07:33 PM

Here is the link. http://www.carchemistry.com/tubemufflers.html
If you call them they will make any sizes/length you like. You can have up to 3 inserts inside for the sound. Mine are 3" in/out about 15" long (I think). They come ceramic coated

Bob K. · 05-14-05, 08:51 PM

Dave Harris- Thank you for the information. I really appreciate it a lot.

Faili F.-That engine is incredible looking! Looks very nice.

Simon · 05-14-05, 10:39 PM

Just installed a Magnaflow 4x9 oval #14378 and sounds pretty good, not to loud till you crack the throttle. [img]/ubbthreads/images/graemlins/shocked.gif[/img] I think it will do well at cruise rpm then roars good at 3000 and up. Nice thing is I only had to buy one. Now back to welding and some polishing.

Howard Jones · 05-16-05, 12:12 PM

Dave, How loud do you like it? If you like it loud then drop by and check mine out.

Does anybody have a stock GTD muffler they don't want anymore ? I would be in the market for one if its cheap. I have a project in mind. If so drop me a email.