Muffler Tech

[tim13]

I have a 4 into 1 headers into 2.5" for about 10-12 inch then a hotdog type then 2.5 for another 2 feet to a turbo muffler then 2.5 over diff and out the side.

Its a 1600 xflow twin sideys.

I rather enjoy the rasp that i hear some of the other escorts on the net and also wish to drive around not setting of car alarms or attracting attention..

Sugestions please

I think the "go to" exhaust for a noiseyish but not ridiculous eskies used to be coby before diff coby after diff

[Crispen]

Well my bake bean can on my esky has shat itself.. Lasted a good 2 years from some old chap out in penrose that chucked it on there a few penny's. So I'm looking for something that's gonna gonna sound sweet coming out of the worked 1.6 banger.. Every other man and his dog goes for a coby on a esky but what are my other options? 4-1 extractors into 2inc pipe to bake bean can and out the end...

[Mr Vapour]

Well my bake bean can on my esky has shat itself.. Lasted a good 2 years from some old chap out in penrose that chucked it on there a few penny's. So I'm looking for something that's gonna gonna sound sweet coming out of the worked 1.6 banger.. Every other man and his dog goes for a coby on a esky but what are my other options? 4-1 extractors into 2inc pipe to bake bean can and out the end...

A coby is not a specific type of muffler, but a brand. What most people refer to as a coby is simply a resonator. but they sell extractors and mufflers.

almost every car needs at least one often two resonator. So don't be afraid to use a coby

And What do you consider sweet sounding as what so menu my neighbours obviously think sounds sweet, I want to throw a brick at their face aS they drive past.

[Crispen]

Went for a 3 core muffler. We did a test with a Coby but it was waaaaay to bwarrrrrrrrrrpy. It's a lot quieter which is kinda nice as I can now hear myself think now which is good? This also means I can't ignore the misses when she's having a yarn about something I've done.. /Insert unsure face here

[Roman]

Not mufflers as such, but check out this vid... very interesting!

 

[kpr]

This one popped up after watching that ^

 

[Yowzer]

How great would it be to have an engine dyno at your disposal

[Roman]

Been playing around in CAD again

Okay so it seems big pipe is best but where does it start to be diminishing gains for a real life HP amount.

Some TL;DR stuff in the spoiler below but it looks as though this would be a reasonable guide for exhaust size vs power output (green is good red is bad)




The actual pressure gain, given some real life pipe sizes and real life flow rates seems very low (the green areas are below 1psi pressure gain across 5m pipe)
If you found where the low pressure zones at the back of your car is, and had the pipe exit there. When you're going at speed this could end up making more difference than going up a pipe size or two, depending on power level.

If we consider that a 3" pipe flows at 100% (as it's the biggest sized pipe tested) and look at the % effectiveness of smaller pipes, it becomes clear that you take a big hit going to smaller pipes with big HP numbers but if you've got ~150hp or whatever then it makes bugger all difference what size you use. There's less than 2% loss going to 2.25" but you save a bit of weight and have more clearance etc.




Some gibberish and graphs below
 

So how can we tell how much air comes out of your engine, easy its the same amount as what comes in.
We can tell what comes in, as a rough guideline as (Grams/second of air)/0.8 = horsepower at engine.

 

The air coming into your engine is very dense on the way in due to low temperature, but it expands like fuck on the way out because its about 500 degrees. So 1 litre coming in might equal 30 litres on way out. (or whatever)

 

So I modelled some 5 meter long pipes of different internal diameters (1.75" 2" 2.25" 2.5" 2.75" 3") with given grams/second flow rates to represent power levels.
Not taking into account pressure pulses or anything just the flow rate.
so maybe similar to the exhaust conditions you could expect to see coming out the arse end of a turbo. Or sort of close to a nice equal length extractor setup.
Ignore the wonky starts of the graphs, its just the simulation coming to equilibrium

Exhaust "back pressure" with a 125hp engine:



~190hp engine:


 

225hp engine:




250hp engine:




~310hp engine:




375hp engine:



What's interesting is that the actual pressure amount seems really low, it's not like 30psi or something like that.

[Yowzer]

So what you're saying, is 3" errday

[Roman]

If you've got say 250+hp then sure but no point putting a 3" pipe on a Honda City or whatever.

I'm gonna run my 2nd map sensor into the exhaust somehow without melting all of the things and see if it comes close to matching the sim.

But pipe length itself seems to contribute bugger all to pressure increase.

 

Might chuck some bends in it and see what happens

[SOHC]

A coby is not a specific type of muffler, but a brand. What most people refer to as a coby is simply a resonator. but they sell extractors and mufflers.

almost every car needs at least one often two resonator. So don't be afraid to use a coby

And What do you consider sweet sounding as what so menu my neighbours obviously think sounds sweet, I want to throw a brick at their face aS they drive past.

 

I think Coby are the only guys making a chambered hotdog muffler?

[PedRac3r]

I think Coby are the only guys making a chambered hotdog muffler?

 

Dont know if you any of you guys have seen products from these guys www.adrenalinr.com  NZ company making some top notch mufflers and resonators etc. I fabbed a 3" zorst for my Hilux, from the turbo back and side exit dumping before the rear wheel, it was fucking loud, sounded like a open headered tractor with mad turbo whistle. Anyway, put a 450mm 3" reso from AdrenalinR in it and holy shit, what a difference. It took away all the raspy tractor sounds and ended up with a nice a deep tone throughout, and I would say its now mildly louder than a factory exhaust now. Would definitely recommend you guys try them. 

 

http://www.adrenalinr.com/products.php?pCategory=resonators Ive used Cobys before and they truely do not compare to the AdrenalinR products. Yes they are more expensive, but you get what you pay for.

[Testament]

quite a lol on that recent engine masters youtube video

but I did note they only squashed the individual tubes not post collector flow

 

you note that there is only 1% or 2% difference between 2.5" and 2.25" or whatever i some of the cases there, but if you are chasing all the HP's then even at only 200hp - that is 2-4hp,  which may be what is needed to hold off that pesky honda with its factory high flow head and 3" bee swarm.

 

also 0.3psi doesnt sound like much, but consider you only have 14.7psi putting air in at the front/that you have to overcome to get that stuff back out

 

funny that 0.3/14.7 = 2%

 

and given that bernoulli applies here too, and you have to accelerate the flow to a higher velocity with a smaller pipe entropy will be fighting you more there too (although entropy fights your everywhere and you can't win)

[Roman]

you note that there is only 1% or 2% difference between 2.5" and 2.25" or whatever i some of the cases there, but if you are chasing all the HP's then even at only 200hp - that is 2-4hp,  which may be what is needed to hold off that pesky honda with its factory high flow head and 3" bee swarm.

 

also 0.3psi doesnt sound like much, but consider you only have 14.7psi putting air in at the front/that you have to overcome to get that stuff back out

 

funny that 0.3/14.7 = 2%

 

and given that bernoulli applies here too, and you have to accelerate the flow to a higher velocity with a smaller pipe entropy will be fighting you more there too (although entropy fights your everywhere and you can't win)

A 1% or 2% difference in pressure in exhaust likely doesnt directly equate to 1% or 2% more power though, especially when the pressure differential is likely a lot higher at the time of exhaust gas being pushed out of the port. And as you say if your exhaust port is a bottleneck then extractors onwards might not be the point of restriction anyway.

I do understand what you're saying though, when you're scratching for any little benefit. This would seem to indicate that a bigger pipe for my car would have been better, but when I went to the shop the size of mandrel bends in 3" meant it would have been a mission to get around my diff. 

I wonder how much pressure drop you'd see from a perfectly timed pulse from a tuned length extractor pipe. 

It's enough to make a 2 stroke motor work so I'm guessing it's reasonable.

Will be interesting to see how this compares to a real exhaust though, as always results need to be considered in context

(in this case an overly simplistic look at a perfectly straight pipe with no pressure pulses)

I'll buy some long hose and plug my other map sensor back in tonight and get some readings though, will be interesting.

I wonder how much resolution you can get from a map sensor if you looked at it with an oscilliscope or similar, wonder if it could detect individual peaks and troughs.

[kpr]

less pressure in exhaust will benefit a big cam engine.  small factory cams no so much.   big cams with more overlap. means more time around tdc both cams are still open.  so get to a point where the exhaust gas goes, hey lets go back the other way because its easier.  can see this on a lot of dyno sheets, where people have thrown in big cams with bad extractors or an exhaust too small. usually a dip in power before it "comes on cam"  

 

with less pressure in the exhaust, earlier can start filling the cylinder.    everything needs to be matched up, adjusted and all working together to see good gains.  na sucks. 

 

 

would be interesting to see what the the header bash would do, if they used an engine with big cam overlap.  or as tom said a restriction after the extractors 

[Frosty]

Worked Eski engine.

4 to 1 Headers, 10" long 2" pipe, 2" Chambered Resonator, 2.25" intermediate pipe to behind the diff then 2.5" Back flow Muffler then 2.5" tail pipe if needed.

My preferred muffler is Magna Flow but there heaps of other hi performance ones out there.

Another trick I've seen is to cut the end of the chambered resonator and attach directly to the collector.

[DoBro Jesus]

Anyone know where to get headers/extractors for mazda klze/de engines, wanna get a touch more power and tone out of the telstar, can only find stuff in 'murica on ebay. Also has anyone had any experience in doing exhaust systems on these engines?

[Mr Vapour]

Where is good to buy mufflers. I'm proberbly going to get my bends and flanges, collectors resonators  from STA parts. But I dont like the mufflers they stock.  

 

Any one know of a good place to buy 2.5inch oval packed mufflers. 

[cletus]

Where is good to buy mufflers. I'm proberbly going to get my bends and flanges, collectors resonators  from STA parts. But I dont like the mufflers they stock.  

 

 

i recommend not doing that, their stuff is cheap but its crap.

[locost_bryan]

Anyone know where to get headers/extractors for mazda klze/de engines, wanna get a touch more power and tone out of the telstar, can only find stuff in 'murica on ebay. Also has anyone had any experience in doing exhaust systems on these engines?

Neil Allport built the Telstar Super Tourer that Radisich raced with the 2l V6 - probably a good place to start looking...