Danny 171

Hey guys, I’m wondering what it is with 12a’s sounding like the have a thin coffee can for the muffler. My newer racecar has this sound and I despise it, but some other 12a’s I’ve heard sound near-identical to 13b’s. Is it all down to the muffler or perhaps a lack of something else?

GSLSEforme

Sounds good to me,it's a rotary. You'd hate it a lot more without that muffler,it's doing a good job of muffling the exhaust. You would not believe how loud it would be without the muffler.
A system for a streetcar would be quieter. System on that car only has to get exhaust below a specific decibel to be allowed to run at track. Any more muffling will restrict exhaust and drop power level.
Nice looking car! Can you tell us anymore about it?

t_g_farrell

iTrader: (1)

Sounds good to me too!

Jeff20B

iTrader: (13)

That actually sounds pretty good. What I'd recommend to improve the way it runs is go direct fire on leading ignition. There are several ways to do it.

Danny 171

I’m speaking more about the metallic-like sound, I’ve only heard it on 12a’s for some reason. It’s almost like it’s running through a hollow can or something. My old 13b never had the sound I’m talking about.

GSLSEforme

Your old 13B likely didn’t have an exhaust system like what’s on the car in question. Probably had an exhaust manifold,more stock exhaust system. What kind of exhaust system was on the other 12A cars/engines you mention. Without a system specifically made to quiet the rotary noise,the exhaust note is very tinny,doesn’t sound good.
The system on car in video is very low restriction and a very slight tinny sound can be heard. If there was a 13B in the engine bay,it would be tinny,maybe a tad more so.

chuyler1

iTrader: (1)

I can't see from the video, but cheaper, thin walled headers tend to have a more tinny sound. Thicker headers deepen the tone and last longer, but also add weight.

Danny 171

My old 13b was a carb’d 6 port with a small beidge. No muffler, Racingbeat header, 2 resonators I’m pretty sure did nothing, it was insanely loud and had no tinny noise. My other 12a is a racingbeat header and muffler and has much less tinny noise.

The headers are a very good point, that’s something I’ll have to look into

LongDuck

The stainless packing in the resonator does increase backpressure a bit, but it also slows and cools the exhaust pulses, which helps with the tone of the exhaust when it hits your muffler. The RB header is an efficient design, and their presilencer is made to work with it for stock applications. As the others have mentioned, this is a form following function issue, because how the car sounds is secondary to how fast it can get around the track - or your priorities are a little off!