Backpressure is it a mith or should i get one silencer in my exhaust?


King Sir

King Sir

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Basically im gettin a full custom exhaust made up for my civic and im wondering would a straight pipe be best surley backpressure is pointless and a more free flowing system would be better?

What are yer opinions?

Id appreciate if a mapper could give there opinion too Thanks

Il be going for a 2.5 system for a high comp b18cr

Thanks :meet::))
 
From what I have read on a N/A car they benefit from some back pressure. Akrapovic have some good technical data on their website about pulse tuning and the benifits that can have from back pressure.

Running no silencers will help with top end power however you tend to find that some tourque will be lost mid range as a result.

Also you will need to keep noise down for track too. I have a backbox and middle silence in mine.

Im sure someone with alot more knowledge will be along soon.
 
Sound man if i was puttin one in it would just be one small one hahaha
 
Maybe look at going for a 'dolphin' tip to help keep noise down too (If you plan on tracking it?)
 
A completely unsilenced exhaust is just daft imho, you won't be allowed on just about any track and it will turn your car into a police magnet. The "back pressure" myth is just a load of bollocks, the following article talks about how it all works in a reasonable detail:
http://www.mustangevolution.com/forum/f312/t296628/
In short - you optimize your exhaust diameter for a particular power band - the higher the RPM the larger exhaust you need.
I'd add some straight through silencers, won't hurt performance but will help with the noise a bit
 
oifovo said:
A completely unsilenced exhaust is just daft imho, you won't be allowed on just about any track and it will turn your car into a police magnet. The "back pressure" myth is just a load of bollocks, the following article talks about how it all works in a reasonable detail:
http://www.mustangevolution.com/forum/f312/t296628/
In short - you optimize your exhaust diameter for a particular power band - the higher the RPM the larger exhaust you need.
I'd add some straight through silencers, won't hurt performance but will help with the noise a bit
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I was under the impression that Pulse tuning is different to back pressure and the idea that you have a pulse back can help sucks out more gases.
 
Well noise wont bother me because i have something sorted to quieten it down ;) straight pipe it is so.

Will i really not be allowed on track cos its too loud?? Thought the whole point of a racecar was that one of the tradeoffs of being fast is its loud :run: :drive:haha
 
Maybe one small silencer so... i dono il see. I have a 2.25 straight pipe at the mo but havent hit vtec yet so i dono really how loud it is. But at 4000rpm id wake the dead :lol:

Il throw up a vid soon :ek9:
 
All tracks have noise limits as far as I'm aware, some fairly strict as well. People with the likes of Buddy Club Spec 2 often have to change their exhaust due to this, it is just too loud. I'm talking about track days btw, not sure what the regulations are for actual racing although I'm sure there will be some limits as well.
 
Ya i want to go to mondello an do a track day soon this year hopefully or i might just build a track car altogether
 
Think of it like a intake manifold some people preffer short runners because they give you more top end peak power..but some people preffer longer runners to gain more torque even if they have to sacrifice a little power...
 
King Sir said:
Well noise wont bother me because i have something sorted to quieten it down ;) straight pipe it is so.

Will i really not be allowed on track cos its too loud?? Thought the whole point of a racecar was that one of the tradeoffs of being fast is its loud :run: :drive:haha
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You being serious?? Every track has noise limits. Race series have noise limits. If they didn't have these limits tracks would be shut down due to noise complaints.
 
Murray said:
You being serious?? Every track has noise limits. Race series have noise limits. If they didn't have these limits tracks would be shut down due to noise complaints.
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Thats true ya still though #becauseracecar hahahaha People accross from the track should just get awesome soundproofing Lol
 
si8pny said:
I was under the impression that Pulse tuning is different to back pressure and the idea that you have a pulse back can help sucks out more gases.
Click to expand...

I think this is more important in the manifold than the "catback" section of exhaust.
My understanding is the same as Oifovo. Wider diameter moves torque upwards abit. Unless your engine makes too much power for the particular bore size you have and is being choked by it.
 
IMO the best exhaust is one where the velocity rate is high, you want the exhaust system to be pulling the exhaust gas out and not the engine pushing it out. I think these terms are aslo know as PUMPING LOSE, BACK PRESSURE and PULSE TUNNING (velocity). To get the optimum balance of the 3 is easier said than done but get them right and it would/should make a huge difference over stock.
 
JDM_DAVE said:
IMO the best exhaust is one where the velocity rate is high, you want the exhaust system to be pulling the exhaust gas out and not the engine pushing it out. I think these terms are aslo know as PUMPING LOSE, BACK PRESSURE and PULSE TUNNING (velocity). To get the optimum balance of the 3 is easier said than done but get them right and it would/should make a huge difference over stock.
Click to expand...

Ok thats interesting what would you recommend so?
 
jesse888 said:
Because racecar, yet no racecar is as loud....
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Theres that too ya :lol:ah once its loud and sounds unreal il be happy. No need for it to be unbearably loud but im on the hunt for performance for road use ultimately (private road use of course) :meet:
 
I should of said, how this is achieved is really down to trial and error.. a start is to make sure the internal diameter of the outlet pipe of your manifold is the same size as the internal diameter of your b-pipe and back box. BUT....I have seen custom exhausts made for some Honda race cars b18c/k20 units, using 2.5inch external from manifold outlet pipe, to 2.5inch b-pipe, to 3inch back box pipe all external measurements. It all depends on your set up of engine specs and mods.. its a process that takes time but will be worth it in the end.
 
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