Muffler Tech

[mjrstar]

ED:

 

My KP ran 245 wheel kw on a 2.5inch mandrel bent exhaust and was almost silent (the fuel pumps were louder than the exhaust at idle), and on boost induction noise exceed exhaust noise by about 4:1 

 

It had one long reso up front and an offset pressed steel muffler after the diff. (not some shiny rubbish straight through job, horrid noise is about muffler quality rather than size and quantity)

 

Starlet now it runs a 3'' side pipe which is the opposite of the old system..

As far as drone goes, i reckon that tip diameter plays a big part in this massive 5" tip =drone

 

 

Remind me how much horsepowers were you looking for?

[0R10N]

Cool. Yeah Spence/Simon, all the Mazda wombles reckon 2.5" is fine (they apparently do b-outs at 200kW in 5th gear because they're dorks) but spoke to Paul earlier and he reckons 3" - so I would probably go with your recommendation.

Matt I'm hoping for around 170kW at all four so not heaps of power (my gearbox is made of cobwebs and false hope).

Car currently has a 2.5" tip coming off the muffler, I dunno why it's so shitty. Was a generic Pitstop one that AJ whacked on last time to try and tame the noise a bit. Original system was an Al's Mufflers one that was made ages ago.

[Spencer]

3" is big and can be a pain, but its free power. Apart from keeping it quiet and space there is no real downside.

[KKtrips]

I run a 2.5" the full length of the Commy and as you know that is 5 litre and I suppose it's about 175-200Kw.

I was told by who a good exhaust builder (Shaz's old man) that 3" would be ~ zero gain and also droney. He has built some pretty reasonable spec race cars over his time so would take his word without hesitation.

Not to mention the bottom of a 3" would hang 1/2" lower which can be all the difference in a low car.

[Spencer]

Man don't start this KK.

[KKtrips]

Man don't start this KK.

wat?

[Spencer]

Not being a dick, but we have thrashed this subject. Your motor is somewhat choked with a 2.5" pipe KK its how it is, there is dyno results all over the show of engines making substantial gains with bigger pipes. Im talking 2L engines going to 3" and picking up power. Like I said if you have space issues and its not going to work no big deal, but if you can, go for it. Ed will make his power easier, probably have a better/quicker spool.

The 5.3 in my truck has a factory 3" exhaust, there is easy power to be made going bigger proven all over the interwebs. Shit I'd run two 3" pipes on the 455 if I was chasing power in that thing.

[dr.wylde]

ok i've read this whole thread! So... lets see if i got this right  Hypothetically if I was to fit a bigger pipe to my 1275GT minge. would it make much of a difference? Its currently runs a 1 3/4" pipe if I made  a 2" system with a reso after the collector and a free flow muffler at the back  i would see a power gain? aw heck could I use a 2.5" pipe system?

[mjrstar]

^^ in that case put a 12 inch system on it if you are considering making more that 100 flywheel Hp in your mini, best of luck fitting a reso anywhere other than right near the rear subframe in a mini.

 

I have a 2.5'' system on my mazda and it looks like I will have to buy an edible hat if the thing can't make 250 wheel KW due to restrictive exhaust.

 

as far as air pumps go a 455ci is a long way off 1275cc - google tells me that's about 5.8 times the capacity?

 

 

 

 

 

 

I think what spenno is saying is that if 3'' is viable due to space / packaging it's a good option but don't lose sleep over a nice mandrel bent 2.5 system robbing all of your hosepowers..

[Spencer]

Its the zero gain thing KK said, its not the case. I mean shit open headers with maybe a megaphone will be best for outright HP, but yes fit what is practical for your scenario and if you can fit a 3"zaust on your turbo Mazda do it.

If I had a 1275 and I was chasing ponies and didn't give a fuck if it was noisy as shit the hell yes I'd fit a 2.5" exhaust, you have nothing to loose accept clearance and your hearing.

[Spencer]

Also MJ did you dyno your car pre and post 3"?

[mjrstar]

I had planned on taking it back to the dyno but never did

There was probably a subtle change in power (not enough to notice it by seat of the pants) by going to the 3'', keeping in mind that the engine is very factory, no headwork, only running Na cams etc.. it certainly didn't feel like it was making an extra 20kw or any noticeable improvement in spool, but does now make a cool noise.

[sr1600]

Edwardo , id stay with 2.5" for the extra ponies you may find will make your gearbox into a lunchbox anyway.

 

At least the parts will all stay inside the gearbox if the casing stays in one piece.

[Testament]

engine size is mostly irrelevant power means burning more fuel and burning more fuel means flowing more air. more flow, bigger pipe = less pressure drop, less pressure drop = less pumping losses or more delta_P and delta_h across the turbo  either of these things = more power or or more efficiency.

 

if its a worthwhile amount more, thats a whole different kettle of fish and gets rather subjective.

 

in eds case it probably depends mostly can he fit all those big 3" muffler/resonators under the car? if he can then definitely consider giving 3" a go if it fits in the price plan

[Spencer]

Yea there's a point of diminishing returns obviously. Fit the biggest shit that works with your space/ears

[Rookie]

3" or bust. It is the mufflers that effect the noise not the pipe diameter.

[kpr]

3"  doesn't mean it has to be loud. Easy to make quiet on a turbo car, turbo does half the work for you.

[Truenotch]

Silly turbos. They don't even need mufflers. 

[0R10N]

Come to think of it there may not actually be enough room for a 3" without scraping on shit/trying to fit it around the rear diff being 4WD.

 

Might have a chat to evil_si about it, I do like the setup he made for Ryan's Grande.

[mjrstar]

Ed you will probably get 80% of the benifits of going to a 3 inch front pipe then tapering it back to 2.5 for the rest of it. there would be some gain in a full 3 inch system but i would be VERY surprised if it was double digit power increase at the same boost level. save your monies and put a proper rear muffler on your current exhast system (it's already 2 1/2 with a couple of reso's up front isn't it?)

 

I know a bunch of peple with cars making well in excess of 400 wheel Kw's on 3 inch exhausts so I would be surprised if you even notice a decernable difference at your ~170 kw target (this is factory output for an evo 4) which runs a less than ideal crush bent 2 1/4 system.

 

I'm not anti 3'' exhausts - two of my cars run them, but they are not that easy to package and sometime the percieved gains are a lot greater than real world results.