Mechanix185E

36lb is huge.

howi

Howi

iTrader: (2)

yo this forum is messed.
i just submitted a reply and noticed that i replied under the user "Mechanix185E" for some reason.
i guess i was automatically signed in as Mechanix185E some how.

Howi

neofreak

knightsports fc605 dual, no y-pipe, dual from the downpipe and back.

Ni5mo180SX

I prefer single.

3RotorRocket

Im going single thanks for tha info people

NZConvertible

Mo matter how you argue it, you will not be able to notice the weight difference between a single or dual system, and that's what this discussion's about.
You've just said there aren't too many removeable things that weigh 20lb, so you're admitting you have to remove a lot of other stuff to drop 200lb. Most people aren't in the slightest bit intersted in removing that much useful stuff from the car.

I've explained this countless times before, so I'm not going to go into detail. Like I said above, it's all about using the right pipe size. Two 2.5" pipes have less flow resistance than a single 3", but two 2.25" pipes have more flow resistance than a single 3".

That's compared to the heavy stock exhaust, which is a pointless comparison. The difference between aftermarket performance single and dual systems is ~20lb.

Howi

iTrader: (2)

i never argued whether you'll feel the difference between a dual or single. I was just sharing my opnion about dropping weight in a car, and that's simply weight adds up.

yes, you would have to sacrifice many options (whether they are useful or not is totally up to you) in your car to drop 200lbs, it's very obvious. and i really don't understand why you're telling me that most people aren't interested in dropping all that "useful" stuff; i was simply stating that you can easily drop 200lbs off of your fc.

do you mind explaining to me how you came about these results? i'm very interested in the process you went about calculating these numbers.

i agree.

howi

neptuneRX

aside from AC, and power steering, what are some easy ways to drop weight? I would like to skim off 200lbs, maybe a little more depending on what I have to loose.... would removing the carpet help? I hate the color anyways?

NZConvertible

My point was that unless the weight difference is noticeable, there's no point in making a big deal about it. People quote numbers all the time without thinking about what they really mean. 20lb may feel like a lot in your hands, but have you tried picking up your car lately?
Your comments were slightly contradictory. If "there aren't too many things you can pull out of a car that weighs over 20lbs by itself" (your words) then how can 200lb be as easy as you say?

It is not easy to remove 200lb from an FC without sacrificing a lot of stuff that most people don't want to lose.
They're not calculated. They're taken from measured data of fluid flows through pipes, so take into account both cross-sectional area and internal surface area.

Howi

iTrader: (2)

ok nz... let's just forget it, let's not use this thread to argue about what each other said. maybe you can pm me you icq or msn # and we can talk about it then.

ic.. where did you get this from? who conducted the experiment? i really wanna read it myself. thanks!

howi

NZConvertible

I'm in the HVAC industry, so we have technical manuals and other resources with flow data in them.

Howi

iTrader: (2)

damn... i would like to read it if i could....

it's funny cuz initially i thought you actually calculated it.
and i thought, "how the heck did you do that?" "you obviously assumed turbulent flow, and not laminar, right?" "how did you find out flow velocity?" "what epsolon did you use for surface roughness?" "what was the density of gas?" "what mu did you use?" "did you look up the moody chart to find this?" ..... etc etc...
but it was an experiment, not a calculation.. hehehe...
well, i trust experiments more than theories anyways (provided that they were conducted fairly accurately, and simulated the real environment).

the only other thing i'd like to know is, did the experiment use steel pipes and hot gas for flow? because, and i'm sure you know, that they affect turbulent flow in a pipe quite a bit.

howi

NZConvertible

I don't have data for hot gases, but since the pipe diameter is the only variable it's still a valid comparison.

Rx7Boi

3" Single down/mid pipe to Apexi duals

88IntegraLS

All I want to know is, is there such a thing as a quiet single that will fit in the stock muffler cavity? Quiet as in not setting off alarms with a header and stock main cat . . .

1987RX7guy

iTrader: (3)

You didn't search well enough. Me and Mazdaspeed7 had enough threads to go through about this on N/a's and TII's are also talked about a lot. Practically every week this comes up man.

Say what?






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Aaron(3rotorrocket) Simple as this man. If you are looking for power go with a single as large as you can find. I have seen people on here talk about 4" exhausts all the way back. But I am sure that wasn't cheap. I personaly Like to retain the Stock look so that people/cops do not get drawn to my car. I don't really need nor care about a lot of attention from driving around. Dual exit to me means I get to retain a Stock looking Exhaust and it will do the following: Maintain lower noise than a single because there are two mufflers to handle the exhaust pulses(noise from the engine) rather than one, which becomes more important as you open up the exhaust since with mroe flow you get more noise. It will also last longer because your mufflers are seeing ~50% of the heat compared to one muffler. What this means is that your mufflers will hold up better for longer than a single, which is good if you don't have a lot of money to keep buying shitty fart cans to replace your muffler. Over time mufflers tend to change tone as they age and will keep getting louder and louder throughout their life on your car. With two mufflers this will be reduced like many of the other things. Simply put I don't want to ruin the asthetics of my Car nor do I want to get ticketed for noise violations while driving around town. I appreciate my hearing and do not want to loose my ability to listen to the beautiful "purr" from my car. Copared to other cat backs my system sounds very nice IMO(you have to hear it to know what I mean as others say they don't like it). I personally don't like any of the singles out there nor do I like the fact that they all look like RICE cans. By these I mean APEXi, HKS, CS and every universal can out there. The APEXi was originally going to be my choice of exhaust. UNTILL I heard it. Not to mention it has 4.5" tips!!!! fokin A that is One HUGE tip. Then they are angeled up and out which again looks like a friggin ricer exhaust to me. And the clearance looks horrid from the pics I have seen so far. ugh

Anyways you will probably end up choosing something you personally like. Whatever man its your car just try to keep everything in good taste and I won't give you flak for it.

Santiago

NZConvertible

Your arguments with MS7 are totally irrelevant in this thread. We're talking about a turbo exhaust, so the comparison between collected and uncollected exhausts is of no use.
Please stop perpetuating this myth.

1987RX7guy

iTrader: (3)

Perhaps it should have been: Me and MS7 had arguements about this many times. TII exhausts and which one is better are also highly debated?

Howi

iTrader: (2)

huh? of course it ISN'T a valid comparison if you did not use hot gas, not to mention (correct me if i'm wrong) the experiment probably used condensed air, right? i assusmed that cuz you said you're in the HVAC industry.

there is a HUGE difference in density between condensed air and hot burning exhaust gas (remember, our exhaust gas is hot enough to retain ignite fuel, that's why our cars backfire as soon as the unburned fuel meets oxygen at the end of the exhaust system).

i'm afraid that the density difference could be a large enough of a factor to throw off your statement about how 2X2.25" is worse than 1X3", but 2X2.5" is better than 1X3".

there's more than 1 variable here:
1) diamter (obviously)
2) density of gas (i still don't know what kindda pipe was used in that experiment)
3) type of pipe (even regular steel pipe has a different friction factor than stainless steel pipe)

- desity is a variable becuase velocity is dependent on it
- type of pipe is another variable becuase different types have different friction value (epsolon), which translates to a different Reynold's #, which will define a different friction factor (f) in the end. velocity is also dependent on this friction factor (f).

3RotorRocket

Who makes the best set of duals?

1987RX7guy

iTrader: (3)

I would Say Racing Beat Without a doubt.

NZConvertible

You're completely correct that different temperatures result in very different airflows, but you've missed my point entirely. The data I used to compare pressure drops through various sizes of pipe was for the same gas flowing though the pipe of the same material at the same temperature. Thus the only variable in my comparison was pipe diameter. This gives percentage changes in flow that give you a clear indication of the effect changing pipe diameter has.

If you're not happy with my comparison you're welcome to find your own data. Good luck finding anyone who's done scientific testing of exhaust gases through small-diameter steel pipe and then made the results easily available. If you prove me wrong I'll happily stand corrected.
Condensed air? You mean compressed air? No we don't used compressed air. Most of the air and gas systems we use are low-pressure, apart from refrigeration systems.

3RotorRocket

Im thinking about getting the RS-R Exhaust that Jarred has.

Howi

iTrader: (2)

thanks for clearing things up!
i could not interpret this from your brief explanation in previous threads.
you're correct about your numbers, but they still only apply to the gas and pipe used in the experiment.
this is why:

Q (flow rate) = v (velocity) X A (cross sectional area)
which, in a case of a circular pipe, becomes:

Q = v (pi/4)d^2 (d=diameter of pipe)
which, becomes a non-linear equation. it's in fact an equation for a parabola.

now, in this parabola equation, v (velocity) determines the shape of this parabola (whether it's skinny or fat). because v is dependent on so many variables (material of pipe, density of gas, pressure loss... etc.), the shape of the parabola would change dramatically. if you change the experiment to a COMPLETLY different system from the real scenario (steel pipe & hot burning exhaust gas), the new velocity is gonna throw the Q (flow rate) way off. when you have different shape of curves, the threshold for dual/single exhaust diameter would change.
however, you're right, the diameter is still the most influential factor, because it has a power of 2 in the flow equation.

what's w/ the attitude man?
if someone tells you that an 1" pipe has more flow than a 2" pipe, and that it was "proven" by his experiment. what would you do? actually, it's more like what SHOULD you do? you should question his staement and ask him where this so called experiment came about. how was it conducted? what environment was the experiment trying to simulate? and HOW CLOSELY SIMULATED WAS THE EXPERIMENT TO THE REAL THING? and finally, how was the experiment data interpreted?
and if his reply did not make sense to you, you should try to challenge it and explain to him why you think it doesn't work.

i know that you're a respected forum member. and for once someone questions the source of the data you provided, you gave me attitude. instead of using the chance to have a nice technical discussion w/ me, you told me that if i'm not happy w/ your ****, i should go find my own. what the **** is that man? i was just trying to understand the experiment and potentially inform everyone that it may not be accurate. i'm leaving this thread. lates guys.

howi

3RotorRocket

Im going with the racing beat dual and thats final.