tummyboy

Ok guys I am new to imports but I am reading these threads on Dual exhaust making our civics loose power .... can anyone inlighten me on this becaue I can not think of a reason on why it would loose power considering how it helps big block engines or small block engines perform alot better ...

SatinSilver2k1

iTrader: (1)

dual exhuast are meant for V cylinder configurations not I-4's...haha...what's the point? civic's don't come with a V6 last time i checked...but that would be sweet...
as for loosing power maybe it's the back pressure or something...

tummyboy

You have a good point about them being designed for V engines but you would loose back pressure. (logically )

see I am concerned because I am doing all Ti exhaust with magnaflow mufflers and I dont want to drop the cost into it if it is going to cost horsepower cause I really dont care if it sounds better

Deejai35

iTrader: (5)

I haven't heard anything about the dual exhaust causing a loss of hp. I have been looking into getting a cat back dual exhaust. What did you find out about system production? I have been looking at the one by Ractive, its about $800.

pakman313

man dont listen to the negatives of what people say of it.... dual exhaust the is Shiet! i have that on my car right now and on the members ride and it feel like a i gain more hehe its all mental

WhiteRabbit

regardless of power gains/losses, titanium would make a fantastic material to make an exaust system out of! with stainless, you have to worry about sensitization near welds, heat trating is EVERYTHING to stainless! a very poor material choice for something that gets hot!

but Titanium? basically not heat treatable! need temperature of over 700 degrees C just to get a microstructure change.

definitely go titaium if you have the chance! (i bet they just market it for weight tho)

h2k1ex

Dual exhausts DO make you lose power, and it´s not because of the back pressure, its all about DELTA PRESSURE I know about the power loss from experience, it´s not a hypothesis or something.

Logan

Umm...dual exhaust = less backpressure. Less backpressure = gains in horsepower and loss in torque. Dual exhaust = less power? LOL. I wonder where people get off to sometimes. Why would they put dual exhaust on a Corvette, Ferrari, or other high performance car if it only had negative effects. This is what I (and apparently some folks at sports car manufacturers!) was taught.

h2k1ex

Because a Corvette, Ferrari or any other high performance vehicle have 6,8, or even more cylinders, arranged in a V shape, where a header comes out of each side, no Y pipe or any stuff like that. Not logical on a 4 cylinder, which only has one header. "This is what I (and apparently some folks at sports car manufacturers!) was taught". Damn, they lied to you and to other sports car manufacturers... what has the world come to!!

WhiteRabbit

i thnk the power concern becomse an issure when the fact is our engines run most efficiently with a pea shooter exaust, and wonder now why when they put a 3 inch tube running the distance, they feel bogged down in teh lower RPM's

if in crease teh sum size too much, you lose your backpressure. V config or not, it doesnt matter. they are moving a hell of alot more air than we are. that is the issue.

we just arent taking up enough air to REQUIRE dual exaust. but ill tell you what. what you CAN do to keep teh engine optimised is split it into 4 pea-shooter sized tubes. dual purpose, noone can stick a banana up your tailpipe! [IMG]i/expressions/laugh2.gif[/IMG]

WhiteRabbit

im curious, ive never heard of this, mayeb you could go into some detail here. is delta pressure just teh change in pressure as there are two pipes instead of one, and the sum pressure is just additive? i thought it worked that way, but i wanna know what delta pressure is.

WhiteCivic

This is a very simple answer guys. Civic motors can only take IN so much air....once you turn your exhaust into a VERY free-flowing system i.e. duals or a larger diameter exhaust pipe you will lose back pressure. Back pressure is essential to LOW END TORQUE!!! Not horsepower! A dual exhaust system will simply hinder your low end torque....but on the plus side.....once your engine is in the upper rpm's it will use the duals to its advantage in expelling the exhaust that is trying to get out.
I guess basically what i am trying to say is you will lose some low end grunt off the line but you will gain it back at the top end....so its all in what you want.
I have an extremely free flowing (illegal) exhaust on another one of my cars (ZX2..sorry) and the 1st thing I noticed was a pretty big loss leaving the line....but out at cruising speeds on the highway it really runs strong in the upper rpm's.

Logan

Thank you for better explaining it for me, Whitecivic. I still don't know where the heck some smart@$* gets off saying it's not worth it because it's a 4-cylinder. I think someone better call Honda and tell them they are stupid for putting dual exhaust on their S2000's. LoL. I will admit this, you could probably get a little better acceleration on the S2000 without dual exhaust, but then it wouldn't be the bad boy it is at pace. Anyways, bottom line is...if you are wanting high-end performance (like if you are on a race track and don't really plan to accelerate from 0 mph more than once [IMG]i/expressions/face-icon-small-smile.gif[/IMG]), a dual exhaust system is just for you! If you are wanting to have plenty of low-end torque for shredding your tires and accelerating hard from stop lights, don't worry about changing to dual exhaust. If you have any arguments with this, please have something to back yourself (references to articles in magazines or text books).

WhiteRabbit

what about just running a larger single pipe? does the same thing for you as a pair of smaller pipes......

Logan

*coughs* yah..uh..hehe...you could do that too. I'm not thinking outside the box right now. [IMG]i/expressions/face-icon-small-smile.gif[/IMG] You are right, you could do that too. [IMG]i/expressions/face-icon-small-smile.gif[/IMG]

avenger

<****> STOP SAYING BACKPRESSURE... BACKPRESSURE IS BAD PERIOD!!!! DELTA PRESSURE IS WHAT MATTERS</****>



click this link to learn

WhiteRabbit

this is the second time ive heard the term deltapressure, and the second time i will ask someone to define it. anybody feel free to go into specific detail what it is any why we should care about it, cause this is teh first time ive ever heard that term, so feel free to elaborate on this someone.

dragoon

iTrader: (2)

it's also not really a HP loss as it is a low-end torque loss. unless you have giant piping, however, there shouldn't be a huge loss, and if you just like how it looks, go for it.

Splicer

Hey guys. I posted a thread on the board a week ago asking about dual exhaust for my 2001 EX Coupe, and haven't stopped researching it yet. Here's the skinny everybody, and also, this should explain to you all a bit about this mysterious "delta pressure/back pressure" myths. Back Pressure is a term people on boards have seemed to pick up from other people, and got tossed around too much so people stopped realizing WHAT it was, just thought it was bad. Here's the deal. Engines need to breath. The more it can breath, the better it will perform, in a sense. That's why us riceboys all add cold air intakes, and such. That's what accepts the air into the engine. HOWEVER, it can only accept as much air as it can put out. This is where Exhaust comes in. The two work hand in hand. Your exhaust system whether it be dual or single, will increase horsepower just as much either way, IF DONE RIGHT. Let's face it, we all only have 1 Header, so whether we keep it as one pipe, or split it into 14, it's all coming from the same place. Now the best way to understand how a good exhaust system works is to compare it to a garden hose. When you turn on your hose outside, and hold up the end, the water slowly pours out. However, when you place your thumb over part of the exit, the water shoots out like mad! Same as an exhaust system. The more air coming out of the engine, the better it can breath. If the pipe off the header all the way down your exhaust is too thick, the air will stagnate inside the piping, and won't pull alot of air into the engine for performance increases. The thinner the pipe, the more pressure you'll feel coming out of the tip(s) when you put your hand in front of it. This is called exhaust velocity. The key is to find a happy medium, where the pipe is thin enough to keep the exhaust pumping out of the car quickly so it can breath, however thick enough to allow alot of air to pass through without making the engine work harder just to push all the air out. Dual exhaust over single exhaust won't help, NOR harm your horsepower gains, however the second muffler will add a little weight, but give you a great sound. The last thing to keep in mind is that your car needs more air at higher RPMs. This is why with a large aftermarket exhaust (2.5" or higher) You will notice a considerable loss in pickup off the line, but once the engine is pulling in more air at 4500+ RPMs, it will be pushing out enough exhaust to clear those pipes fine. If you're looking for more high end power (which realistically is more logical. Someone may get a quick jump off the line on you, but you'll slingshot right by them in second and third gear) than I suggest a 2 1/4" pipe from what I've collected for info so far for our cars. If you want a good balance of slight boost off the line, AND some decent gains at higher speeds, try a 2" or even a 1 3/4" pipe. This will pertain to either single OR dual exhaust. This is what I've gathered for info so far. I hope it helps you guys out. If you have any more info, or questions, mail me at: clintdogg@aol.com

Hope I could help guys!

-Mike

pakman313

damn i learned alot.. thanks dawg

Logan

Okay, this all sounds good...but what is delta pressure again? [IMG]i/expressions/face-icon-small-confused.gif[/IMG]

h2k1ex

It´s the pressure in the exhaust. Backpressure is just a hot-rodder term, check the link on the post explaining it. The delta pressure term probably means Total Pressure in the exhaust tubing, and for your car to work efficiently and without losing power you have to achieve a balance in the exhust gas speed. The reason I say that it makes you lose power is that I raced another 2k1 with a dual exhaust, my car is stock, and i won by about 2 seconds.

avenger

click the link in my previous posts

WhiteCivic

OK OK let me give you a real honest to goodness answer in a real world application. And please NOBODY take offense to this.....this is the truth. I have a 98ZX-2 that has 110,000 miles on it(highway). I took the exhaust resonator off and replaced it with a piece of stainless piping the same outer diameter( oh yeah and just for info purposes..ALMOST ALL CARS COME WITH STAINLESS PIPE NOW....INCLUDING NEW CIVICS )then I took my stock muffler off..made a adapter that went from 1 7/8" to 2.5" and installed a Dynomax Bullet Race Only muffler..and of course then welded a big hoochie chrome 5" tip on it.
Anyway I have ALL stock piping (1 7/8") stock exhaust manifold and the only performance mods are a K/N cold air kit (DIY) and the previous muffler stuff I spoke of. I lost a lot of low end-grunt on take off( car is a 5-speed) but in the upper rpm's it is a banshee...literally. And much to my dismay..I have yet to get beat by a 2k1 Civic or most anything that is of relative comparison. And this is an Escort people!
Duals look cool ..but they are more for show than anything...JUst IMO...later

tummyboy

Ok I appreciate all the info and I also appreciate the compliment for deceiding to go with Ti for my exhaust but if "Whitecivic" is right I dont thinkI am going duals because we dont have much low end to being with . Do you guys no anyone other than "Pakman" , not that I dont trust you "Pakman" but trying to get a couple of opinions

R3DF0G

Simple solution: use a "y" pipe. as long as the diameter of the pipe is not too big(2.25" should be good), you won't really lose anything. Those of you who said that dual exhaust should not be used on a 4cyl have obviously never heard of the S2000, MR2, Neon ACR, etc.....
Avenger's link explains it pretty clearly, pretty good reading if you're new to this sort of thing.

PS

our car's engine is too small for dual exhaust and yes it loses hp

WhiteRabbit

no car is too small for dual exaust, you see it on motorcycles and stuff all the time. if you want to do it for performance (haha) then your just gonna end up running a pair of pea shooters out either side of your car [IMG]i/expressions/laugh2.gif[/IMG]

LeroyBrown

there's really no point to puting a dual exhaust on a civic, unless merely for looks.. (simply put) dual exhausts are for engines w/ more than 4 cylinders that have two places wehre gasses leave the engine.. 4 cylinders have 1...

WhiteRabbit

4 cylinders have 4. V8 has 8. I-6 has six.

you have one outlet per cylinder! and you can tie up all those exaust ports up on a V8 just like you cna a V6, an I-4, a rotary engine, a 2 stroke engine, or even an I-8 engine! (made by jaguar in the 50's)

its just a matter of sizing the pipe right to get your desired airflow. you could put 4 pipes on our civics, skip the headers, and run a straight pipe for all 4 cylinders if you wanted to! but if you want to keep stock performance, well, you figure out how big each pipe has to be [IMG]i/expressions/face-icon-small-wink.gif[/IMG]