muffler for ITA 240sx

so i was kicked out during the last session with just few more minutes to go while running in HPDE because they finally caught me at about 104dBA :o and the sound limit at Infineon is 103dBA. they said that i had been running 102 - 103 all day until now when they recorded 104.

i am running a straight 3'' pipe with S&S headers and seems like its time to get a muffler, which bring me to the question... anyone has any idea on how loud are these glasspack mufflers - something like summit glasspack muffler pretty sure they are not that loud since these are street legal - and also if anyone has any suggestion on which muffler i should go with and if using supertrapp will be ideal on 240sx. whatever i use needs to meet the 92dBA sound limit for Laguna Seca.


any ideas/suggestions are welcome and much appreciated

thanks a lot

I switched from a glasspack to a Borla XR-1 Sportsman when I increased my exhaust size from 2.25" to 2.5"on my G-Prod car and I barely registered 90db at Road America.

Strong recommendation from King Motorsports. On the GT site, multi-national champ David Finch recommended Borla as well. Not exactly cheap, but they work very well with little power loss. They're pretty light too, but stainless steel construction.

http://www.borla.com/products/product_mult...Racing+Mufflers

Put a two chamber Flowmaster on the car, hang it off the rear in the stock position and have the tip point down. That will get you in compliance with the sound folks.

More discussion here:
http://www.gt-racecar.com/forums/topic.asp...archTerms=Borla

Ditto the flowmaster in the stock location. I never have a problem, it's one of the quieter cars. I added a turndown with a band clamp to redirect depending on the location of sound control. Usually direct to the inside of the track.

Jason.

thanks for the info guys.

Tristan / Jason, is it the Flowmaster 40 Series Delta Force® Race - Two Chamber? also, if i go with Flowmaster 30 Series Delta Force® Race - Three Chamber any idea if that will result is more power loss? Do you think the 2 chamber flowmaster will comply with the 92 limit?



Borla XR-1 Sportsman seems good too and from price standpoint its not a whole lot more then the flowmaster.



Greg, how much louder was the glasspack then the Borla? I can use the glasspack but the only thing i am worried about is that it might still be too loud for 92 limit for which i think if i use supertrapp on top it might do the job.

I was usually right at 88-90db with the glass pack and 2.25" exhaust with my old race header at almost every track I've ever run at, but for some strange reason, I was at 99-100db at Grattan at the last national and I don't know why... I can only think it was a combination of the weather, near sound which me making an upshift right in front of sound, and the terrain is kind of a natural bowl which might have been a weird accoustical effect causing me to read high. Also, my glasspack was 4 years old and might have started to blow the guts out.

Anybody in Cen-Div who has ever heard my car with the old exhaust knows how quiet it was/is. I'm pretty good friends with the region's sound worker, and she usually kids me that the only time I'm loud enough to register on the meter is when I'm near another car. That's why I was suprised I was reading so high at Grattan.

Keep in mind this is a limited prep prod motor which makes quite a bit more power than an IT motor. At the June Sprints with the new header and Borla exhaust, I was making even more power than before, and also twisting the motor another 500rpm higher, yet was still at 88-90db.

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i am running a straight 3'' pipe with S&S headers [/b]

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We have great success with walker dynomax race bullets. They are compact, cheap ($50) and work. That said get rid of the 3" pipe it's WAY too much and killing your midrange torque. 2.5" is plenty big enough and will be quieter too! I just got rid of a 3" system on a 91 240sx last week and the "seat of pants" dyno (test runs up and down the street) say it pulls quite a bit harder. Just my 2cents.

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We have great success with walker dynomax race bullets. They are compact, cheap ($50) and work.[/b]

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The Dynomax bullet is not going to help at all in the sound department though. I got busted at my driver's school at Roebling for being just over 103, and a warning at Summit for being right at 103 with 2-1/2" exhaust into a bullet muffler (stock location). Here's a short in-car from VIR with that muffler: http://video.google.com/videoplay?docid=60...0334934058713&q - sounds great, but it's plenty loud. I ended up switching to one of their round (6") race mufflers; still a straight-through design but much quieter. I'm still in the mid-90s at Summit, but that's plenty quiet for most tracks. You are probably going to have to go with the Flowmaster if you want to stay under 92.

yes, it's been a while, but I am pretty sure it's the Flowmaster 40 Series Delta Force® Race - Two Chamber.

These mufflers aren't all that restrictive. And keep the three inch pipe. these motors like to breath, especially if you are using a long exhaust pipe. You shouyldn't need anything else with this set up. be sure to have a tip that you can either turn down, or adjust away from the track sound set up.

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i am running a straight 3'' pipe with S&S headers
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sorry guys thats a typo... i am actually running a 2.5'' with S&S



from the replies it looks like flowmaster 2 chamber might be the best option though borla seems good too but i am also thinking that i should stay away from the glasspack.

while digging through some old posts from 2004 i came across a post that mentioned that Moroso Spiral Flow muffler might also be a good way to go. it looks like a pretty straight through design. any of you have any experience with this and know if this will limit the sound to around 90dBA? and would you recommend this over the flowmaster or borla? the reason being that if i go with flowmaster i will have to bend the pipe a bit more for the muffler to fit in the stock position because of the fuel cell (right now its a fairly straight pipe with some minor bends and passes below a part of the fuel cell) whereas if i go with borla or moroso or any other muffler that is not as wide as the flowmaster 40 series i will not need to bend the pipe. i am also not sure if the extra bend will have any negative affect on the power but if not then i dont mind going with the flowmaster. i will put up couple pictures of the exhaust in the evening as it is now on the car.

I run a stainless magnaflow race(a lot like the borla) with the exit pointed down in front of the sub-frame. It sounds loud inside, but outside and video I've not had a problem even at Laguna-Seca. This brings up another point that you'll want to point your exhaust away from the sound station. Sound disapates as it travels and the farther it travels to get to the microphone the quieter it'll be. I believe that the microphone is on the up-hill between 5 and 6 on the outside(drivers right) at least that's where it was last time I was there.

James

Dynomax race oval 3" in 3" out in stock location. 90db and NO power loss on the dyno.. I also use a race bullett just behind the drivers seat when 101db is ok.

Joe

If they are still available, Nissan Motorsports carries a Borla competition system for the 240SX/S13 (99996-14851). Identical to the street system, but w/out the pre-muffler. And it may be the only 240SX system available that ever saw a dyno. Back to back testing vs. an open pipe provided a 12 ft/lb gain in torque w/zero HP loss. If NLA from Nissan, the Borla P/N is 14851. A cheaper/lighter alternate (as indicated above) would be to merely dump the exhaust in front of the rear axle. Utilize a rotating end piece that will allow you to set the exhaust away from the sound meter at any track you are running at. The only downside to this type of system is that, on longer races, it can sometimes be fatiguing to the driver as the sound can resonate thru the floor pan.