Resonators - Are they a restriction?

[ygoslo]

As the topic says - do resonators provide a noticeable restriction to exhaust gas flow? My car, with stock front pipes, compliance cat and 3 inch Fujitsubo cat back with 2 resonators and a muffler, is extremely quiet and feels like it is being choked when I accelerate. 5 minutes ago I dropped the rear section of the exhaust off, (just adjacent to the diff) so from the cat back it was just a straight(ish) pipe with 2 resonators and no rear muffler. I expected it to sound ridiculously loud, but it just sounds mild - like you'd expect a 3 inch exhaust to sound when the muffler is fitted.

So anyway - it seems that the resonators are what has made it so quiet (either that or the cat, I guess) but will they be restricting the flow of gas significantly? If so, I'll get one of them binned...

I checked to see if there were any restrictors bolted in any of the joins and there weren't, and there doesn't appear to be any packing (steel wool etc) in the exhaust.

I don't mind it being quiet (I could go for a little more noise though) but if the quietness is killing the performance I want to do something about it.

 

[godzilla]

I think if you had a few of them it would have some sort of an effect on power as the exhaust gases have to expand in the resonator and the contract again to pass through so maybe it would make a bit of a difference.
http://auto.howstuffworks.com/muffler5.htm

Thats my theory anywho.....

 

[steveP]

yeah i never run resonators, too restrictive. if anything just chuck a mid muffler in to make it a bit quieter.

 

[ygoslo]

So mid mufflers are less restrictive than resonators?

I must admit I don't know a whole lot about the relative merits of various exhaust components - my Silvia's exhaust is just a straight pipe with an RSR "muffler' I can fit my entire arm through. It is about 17 million decibels.

 

[x3emotorsports]

There are different designs of resonator or mid-mufflers or 'hot-dogs' as many call them. What you want is a straight-thru' hot-dog that reduces the exhaust noise and low the pitch.

Each system uses different ways of lowering exhaust noise.

Hope this helps, ivan

 

[Dr_Josh001]

Hot dog resonators would make next to no difference in power; they are just a pipe the same width as the exhaust with holes. Their only purpose to take away the garble garble from the turkey in the engine.

 

[jungle]

You say compliance cat- there's your probelm. The compliance workshop unless you ask and provide them with something you want, will put the cheapest and generally i'ts around 2.5 inch ceramic cat which will choke the car like mad. Forget your resonators, they reduce the cackle and that's about it if it's a straight thru design.

The CAT is where its AT! Get yourself a good 3inch 'metal cat' item , there are a number on the market. If you'd like my opinion, get a Catco metal cat. These are the highest flowing on the market and from experience stand up very well to track use in high hp engine. The other one tends to fold itself over a little at the entrance which will begin to cause a restriction.
Both are roughly the same price so it's your choice bro!

 

[Guest]

CATCO 3 Inch Hi Flow Cat 706.2 CFM wow they really are very high flowing.

http://www.catco.com.au/products.htm

 

[ygoslo]

Yeah the cat has been high on the list for a while... It is a nasty looking thing. I need 2 (need one for the Silvia as well because I've just found out the previous owner made mine "gutless"), so I'll probably grab a couple this week.

As the budget doesn't stretch to $400-odd for the metal cats, would an X-Force or Catco 3 inch high flow be decent? I note that the X-Force is rated at about 570 CFM - will this be good enough? They are both available for $175 through Just Jap.