[SuziBlu]

Has anyone run just a resonator only, if so, are they too loud. ?

My system is pretty loud now, an I want to go a bit bigger, and thinking resonator only.

[sideways]

Yes and yes.

Very loud.

[SuziBlu]

So out of the question hey, cool, plan B

Was just wanting the least restriction, what did you go for after trying resonator only ?

[JrZook]

What size you running atm and what is the collector size of your extractors? I'd look for some sort of straight through glass packed muff. Moto muff would work!

[SuziBlu]

Its 2", gunna change the whole thing, and was gunna go 2.5 for when its all together.

It comes out in front of the passenger wheel, going out back.

Got me cam made finally, Tighe are gunna send it when they get the new springs.

So twix that n the big carbs, she should boogie.

[jono165]

As a rough indication I have extractors, cat into a muffler the same dimensions as factory but with a 2"in/out and that is 87db at 3000rpm, 1m away at 45 degrees to the outlet, we are allowed 90db at 3000rpm down here last time I checked.

[atari4x4]

http://www.exhaustvideos.com/faq/how-to ... -diameter/

[droverdave]

I had 2 resonators in a 2" pipe.

It was soooo loud, but not so bad driving around town, but as soon as you got on the highway, the noise was out of control.

Got a muffler fitted in stead of one resonator, and that shut it up good. still a bit of a note, but quite alright at constant speed.

[SuziBlu]

atari4x4 wrote:

http://www.exhaustvideos.com/faq/how-to-calculate-muffler-size-pipe-diameter/

I read his writings a while back mate, cannot agree with all he says, have read other much more in depth stuff that go into mathematics of it all, temp, gas expansion and contraction, speed of pulse and gas, a lot sort of negates his stuff.
He is saying that a motor is a motor, all engines use the same amount of fuel to generate a given HP, thats where he lost me, my big block gave me around 30 liters per hundred kilometers on its best day, my Statesman, under ten, very similar horse power, yet he says both needed the same some exhaust.

[atari4x4]

Let me guess one was carby & the other was EFI

[SuziBlu]

oh yes, but his was, any engine will produce a given horsepower for a given fuel.

I did not say that, its a very common thought. No thought of fuel octane either.

In marine engineering, you have to know (for the exam) the formulas to work out how much fuel an engine will burn at a given horsepower, this be regardless if its a beautiful old Blackstone or Gardner that runs on the smell of an oily rag, or an inefficient 2 stroke GM, or a latest model computer controlled "todays" engine.

Engines do not burn an exact amount of fuel per horsepower, this is bullshit.

So to say that a 400hp engine, or any horsepower, require a X size exhaust is over simplifying things to the point of being worthless.

[droverdave]

SuziBlu wrote:

Engines do not burn an exact amount of fuel per horsepower, this is bullshit.

So to say that a 400hp engine, or any horsepower, require a X size exhaust is over simplifying things to the point of being worthless.

i think you are illuding to this

http://en.wikipedia.org/wiki/Brake_spec ... onsumption

I dont put alot of faith in the linked calculations.

the big assumption is : "A good section of straight pipe will flow about 115 CFM per square inch of area"

This basically defines his results, and ive got no idea where he got it from.

[JrZook]

SuziBlu wrote:

Have read other much more in depth stuff that go into mathematics of it all, temp, gas expansion and contraction, speed of pulse and gas, a lot sort of negates his stuff.

Do you have the equations as to how you derived the 2.5inch as the required size for your system? What's your projected HP at the crank?
I'm curious....

[atari4x4]

JrZook wrote:

SuziBlu wrote:

Have read other much more in depth stuff that go into mathematics of it all, temp, gas expansion and contraction, speed of pulse and gas, a lot sort of negates his stuff.

Do you have the equations as to how you derived the 2.5inch as the required size for your system? What's your projected HP at the crank?
I'm curious....

+1

a 2" mandrel bend system will be plenty

[MacDaddy]

+ 2
Have to agree, 2in is all you will need...

[SuziBlu]

I did start trying to do calcs, but the amount of info out there that somewhat contradicts itself is amazing.

The main thing is the manifold pipes as I understand it, after that, on a small system it seems to me, go with the size of the collector, so, (my over simplification) go straight out with no down sizing as I have now.

Not all that scientific, but got dizzy and fell off my chair trying to decifer all the info out there.

My exhaust man say 2.5 is most common as so cheaper for him to install for me.

[SuziBlu]

atari4x4 wrote:

JrZook wrote:

SuziBlu wrote:

Have read other much more in depth stuff that go into mathematics of it all, temp, gas expansion and contraction, speed of pulse and gas, a lot sort of negates his stuff.

Do you have the equations as to how you derived the 2.5inch as the required size for your system? What's your projected HP at the crank?
I'm curious....

+1

a 2" mandrel bend system will be plenty

According to some, on the size of my engine, and expected horsepower, a 1 an 5/8 will give best low down torque figures, seems awful small to me.

[atari4x4]

i'd use the collector size & run with that, no need to over complicate things.

a larger pipe might be cheaper but it's going to be harder to fit within the constraints of the sierra.

if he's an actual "exhaust man" surely he doesn't just make everything out of 2.5" and call it good due to it being the most common, can't see it working too well on nanna's hyundai & farmer fred's turbo landcruiser.

EDIT:

^^^ you know, they're probably right... it's only a pissy little 1.3/1.6 not a BBC or 2JZ with a massive single turbo

[SuziBlu]

Yea the collector it is.

Matey has been my exhaust man for ever, good bloke, goes from shit hot stuff to just to cover for license.

He was the one who said, (because no expensive tuned systems available) just run straight out from the collector.

Who wants a turbo anyway, spesh when you can get this.

http://www.pulleyboys.com/store/product ... ductid=207

Wish I had have seen this before going down the road I am.

[atari4x4]

that looks like a nice kit, would be even better if it was EFI.

wouldn't say no to a boosted 2jz, but there is now way it would fit in a zook.
http://youtu.be/-qPWH4VUdCs

[SuziBlu]

dunno, where there is a will there is a way.

Geez wish my engine bay looked as sweet as that.

[Gwagensteve]

I'd agree with 1 5/8 for maximum torque, 2" for maximum HP at high revs and for ease of construction.
2.5" is a waste. it's heavy, noisy, and there's absolutely no way it will be cheaper than 2"

I have built exhasuts for a bunch of cars including a few G16B engined sierras. I did one with a 2.5 exhaust and even with lots of pipe, lots of 90˚ bends and a triple flow muffler, it was stupid loud. Just pointlessly, obnoxiously, embarrassingly loud.

2.0" is plenty and much easier to keep quiet.

Steve.

[SuziBlu]

Steve, can you explain how 1 an 5/8 is best for torque please, free flowing as I understand it is best, that would be chocking things.

I can only go by my exhaust shop on prices, he says 2.5 is cheaper than 2.

More common.

[tassie jeeper]

from my experiences i too am confused iv found smaller headers give more torque and from the headers back go as big as u can without getting that raspy noise that no-one wants to hear i put a 2" exhaust on my H20A with a virtually straight though oval exhaust its nice and deep and doesnt get that horrible raspy crackle u get when the tail pipe is too big i wouldnt go over 2" on the 1.3-2.0's

i agree with steve on the 2" being a good size but cant understand how a 1 and a half in exhaust gives more torque...? not being cocky i just want to learn something new.

iv learnt from experience that usually going up .5" from stock size and a slightly more open muffler (not hotdog) gives far more throttle response and grunt.

[atari4x4]

since when does 1" 5/8th's equal 1" 1/2

1 /12 =38.1mm
1" 5/8th = 41.2mm
2" = 50.8mm

pretty sure it's all about exhaust gas velocity & making most out of the scavenging effects from each pulse.

http://lmgtfy.com/?q=exhaust+gas+velocity

[tassie jeeper]

atari4x4 wrote:

since when does 1" 5/8th's equal 1" 1/2

1 /12 =38.1mm
1" 5/8th = 41.2mm

pretty sure it's all about exhaust gas velocity & making most out of the scavenging effects from each pulse.

fair enough i was rounding up as half of 8 is 4 so 5/8ths is just over half and when u talk of 5/8ths of an inch over 1/2 u showed it to be only "3.1mm" which i believe is negligible in an exhaust IMO

[MacDaddy]

This link is about Back Pressure, but it has some very good exhaust info, bigger is not better -
http://www.gomog.com/allmorgan/exhaustbackpressure.html

[JrZook]

tassie jeeper wrote:

i agree with steve on the 2" being a good size but cant understand how a 1 and a half in exhaust gives more torque...? not being cocky i just want to learn something new.

A strong reflected wave comes from the exhaust pulses entering a different atmospheric environments ie pipe diameter step/merge collector/end of the tail pipe into open atmosphere etc. When this reflected wave of negative pressure (vacuum) reaches the exhaust valve at the correct time it can effectively draw out the exhaust gasses and pull in fresh intake charge. Commonly referred to as exhaust scavenging. The scavenging effect actually exists over a broad RPM range.

The timing is based on a function of the pipe length whereas the intensity of the reflected wave is based on exhaust gas velocity with is therefore a function of pipe flow and thus pipe CSA. With the smaller pipe the exhaust gas velocity is high and therefore the reflected pulses are stronger, increasing the scavenging effect. This obviously starts to occur at lower gas flows hence lower RPMs, thereby increasing torque earlier in the rev range. The compromise is that the exhaust may start to become a restriction at higher RPMs resulting in a reduction of Hp.

Opposite end of the spectrum is a large CSA pipe. Here the scavenging effect only starts to become significant at higher gas flows, when exhaust gas velocity is up, hence higher RPMs. IF the pipe is too large, the velocity will become quite low and you may loose out on any benefits of this scavenging effect as you just won't have the flow for it.

Moral of the story is that it would be more beneficial to have a pipe slightly smaller than a pipe that is far to large on anything that doesn't live at high RPM 100% of the time. You would end up with more area under the torque curve which would be wayyy more advantageous than an extra kw or so right up the top of the rev range.

Suziblu you have an 8 valve 1600? If so I say you could probably make around 100-110ish HP at the flywheel with those mods?? I doubt may factory cars that make that much power have exhausts bigger than 2". Something to think about...

[JrZook]

MacDaddy wrote:

This link is about Back Pressure, but it has some very good exhaust info, bigger is not better -
http://www.gomog.com/allmorgan/exhaustbackpressure.html

If you want some proper reading material, rather than internet stuff, get into books by A. Graham Bell and David Vizard. Actual data in them backed up by real theories, calculations and proven dyno results. Still require critical analysis to make sure you correctly apply the information to your situation.

[atari4x4]

damn you write some pretty words JrZook