Race muffler... Dynomax Bullet?

Anybody run a Dynomax bullet race muffler?

I'm looking to build a simple 2.5" exhaust for a 1.8 16V Rabbit track car. The Dynomax bullets seem to get decent reviews and are cheap.

12" http://www.summitracing.com/parts/WLK-24215/ or... 18" http://www.summitracing.com/parts/WLK-24236/

Basically I just want to run the header to the bullet to a turn down or turn out before the axle to minimize weight. I know it will be loud, but will it knock the noise down enough to not be ear bleeding and piss everyone off at the track? Is the 12" enough or are there downsides going to the 18"?

The car currently has a 2" cobbled together straight pipe all the way to the rear bumper with no muffler/resonator, but a simple multi-plate SuperTrapp stuck on the end. While reasonably effective it's still stupid loud, and most've what I've read leads me to believe that by the time I remove enough plates to get even somewhat quiet, it starts to rob power. Swapping in the 16V engine from the current 8V this winter so I'd like to go to 2.5" and put a permanent resonator under the car.

Just use a cheap Thrush/Cherrybomb instead? Worth more $$ for something else? Thanks!

moroso spiral would be my vote.

I ran 2- 2.5" 12" bullets on my Mustang back in the day. Even with the MAC EL shorties, Bassani off-road X-pipe, it was loud but not unlivable. Cops never hassled me about the noise either.

Ran a 3" bullet on my diesel for a long time, but it is a diesel truck. It is loud no matter what.

If you are super concerned on noise, run the 18" ones.

Ranger50 wrote: Cops never hassled me about the noise either. ... If you are super concerned on noise, run the 18" ones.

Well to clarify this is a track / auto-x car. I generally tow it to the track, though I may drive it to/from a local track or auto-x from time to time next year.

I don't mind loud, I just know some tracks have noise limits (97~100db? at trackside) and it would be nice if I could do the bare minimum to meet that without having to change/deflect/rig something up mid event.

I'm just getting started here, but I've heard the 16V's are a good bit louder than the 8V's, and this is a slightly hotter motor with moderate cams and 11.5:1 compression.

These make great mufflers

Probably the same thing as as a Thrush glasspack minus the red paint, most Walker/Dynomax/Thrush is. They take the edge off but they are loud. I have one on the Yugo with a side exit, hearing protection is mandatory when flogging or cruising above 60mph.

Kenny_McCormic wrote: Probably the same thing as as a Thrush glasspack minus the red paint, most Walker/Dynomax/Thrush is. They take the edge off but they are loud. I have one on the Yugo with a side exit, hearing protection is mandatory when flogging or cruising above 60mph.

Yeah I was thinking that it might be wise to make the turn down removable and then fab up a simple side exit 90 degree pipe with my existing Supertrapp plates as a slip-on that I could put on the end in addition to the inline muffler if I wanted to run it on the street to/from a track event (where the power loss wouldn't matter). I guess I'll just run the bullet with a downturn first and see how loud it is.

Nobody out there has raced a 16V VW? I know they're uncompetitive in ITA vs. the 8V's in ITB but there has to be some people out there who like doing things the hard way.

Those work great paired with turbochargers. Otherwise they are loud and the fiberglass burns out of them overtime.

I would look at the Moroso Spiral or a SuperTurbo style muffler (get one with the inlet and outlet on opposite sides for best flow)

OPINION:

On a V8 with headers, a glasspack sounds like E36 M3 at WOT but awesome at idle. I have no idea how this relates to your engine.

"These make great mufflers"

"cept they require a pressurized oil source and return drain . . .

turboswede wrote: Those work great paired with turbochargers. Otherwise they are loud and the fiberglass burns out of them overtime. I would look at the Moroso Spiral or a SuperTurbo style muffler (get one with the inlet and outlet on opposite sides for best flow)

It seems that on dyno runs (from what I've read on the internets) the hot rod guys have seen HP losses with Moroso Spiralflows vs. the Dynomax bullets, though they are quieter.

Some reading on the improved touring forums shows most 4 bangers getting away with a single Dynomax bullet into a turndown and being under the 100db limit track side. I'll likely run the bigger 18" muffler with a turn down and go from there.

Interesting information. Good to know, thanks!

I run a 12" (I think) Summit Racing glass pack under my civic with the obigatory fart cannon coming out the back and it is quite tolerable on the street and has yet to blow the sound meter at any track I have run it on. Barber, Road ATL, Roebling. al of which have noise constraints.

I'm not a fan of the spirals. They not only do a relatively poor job of noise cancellation, but they require the flow to go from linear to circular. Turbulence ensues, flow drops, HP drops.

Bullets. FTW.

In reply to curtis73:

I tend to agree. I don't have any experience with those mufflers, but I have a ton of air flow experience. Any time you change the direction of airflow it creates a loss in flow and an increase in pressure before the direction change, which is even worse if turbulence is introduced.