NEED HELP W/BACKPRESSURE

[Mach428]

Your just not used to how the Power curve has shifted thats all, my V6 felt the same way when I put Flows on it.

 

[xneox]

I get anything but comments about rice. In fact I have to tell people that it is a 6, which surprises many. I think it sounds ricey after 3000rpms and no matter what mufflers you get like it was said before, the motor gives itself away. Oh and an x pipe (in my opinion)will make it sound more ricey and more so if you get rid of your Cats. If you go straight thru keep your cats you will get a nice idle, I have yet to hear a sound clip that sounds like it does when your standing next to the car.

I'm glad you like the way your car sounds....that's what it's all about, right? You make a good point about the difference between a clip and the real thing. I can't say I've heard any modified sixxers up close & personal.

But from what I've read I believe the general consensus is that an H or an X will lessen the top-end ricey popping.

You can try and get any mufflers you want, the only difference I hear in sound is whether it is a chambered muffler or a straight thru design, chambered is louder and not as efficent performance wise(in theory), straight thru will be less loud(or more ricey as you put it) but breaths better, thats it in a nut shell.

I couldn't agree more, but the more our engines breathe without major mods the more low-end we lose. Period.

I felt loss of low end power when I got duals, but highway driving was a bit more fun to do. Now that I have gears that insignificant loss of low end is so negligable that it really is not worth losing sleep over wether it is a pre or post 99 car.

Now, the rolleyes just makes you look cocky.....completely unnecessary....

You just admitted that you felt a loss. You changed your gear ratio and couldn't feel it anymore, but that doesn't mean it went away. Imagine what kind of jump off the line you'd have with gears AND no low-end loss.

Quote:
If ever I decide to throw supercharger money into it....well.....I think I'll be able to afford an exhaust upgrade too.....

Why Waste your money, Do it right the first time. Obviously your speaking from lack of experience here. How is letting your engine breath a bit better hurting performance again?? Your talking about exhaust temps going down and stagnant fumes in the exhaust system. Your not changing your headers or increasing the diameter of the pipes all the way thru the system, unless you want too for SC, turbo, or Nitrous. So how is a true dual system hurting performance, I don't understand your logic here??

Obviously I'm speaking from lack of experience? Dude, you have no clue, and you make it extremely difficult to have an intelligent conversation when you attempt to flex your internet penis. Give it up.

The most restrictive part of the Mustang 3.8 stock exhaust is everything behind the cats. That's a fact. Flow-thru duals move peak torque higher in the RPM range...so much that people notice without having to run the car on a dyno. That's significant, and it's also a fact.

If it's your preference to have all your power higher in the RPM's then fine. Some people, like me, would rather jump from light to light faster. After all, the real world is very unlike the dragstrip.

 

[Mach428]

The most restrictive part of the Mustang 3.8 stock exhaust is everything behind the cats. That's a fact. Flow-thru duals move peak torque higher in the RPM range...so much that people notice without having to run the car on a dyno. That's significant, and it's also a fact.

.

Thats what I noticed when I put my dual flows on, feels weaker right off the line

 

[ITFEEDS]

Yeah I,ll have to deal with it until I get sum gears.

 

[ITFEEDS]

Yeah I,ll have to deal with it until I get sum gears.

 

[peyotesands]

I felt loss of low end power when I got duals, but highway driving was a bit more fun to do. Now that I have gears that insignificant loss of low end is so negligable that it really is not worth losing sleep over wether it is a pre or post 99 car.

I don't highway drive. The problem comes from a dead stop. the car is a slug until the RPMs get around 2700 - 3000 then you can feel the car start to pull hard as though it suddenly found it's power. That's how my mustang behaves, i'm not saying the original poster has that same problem. But anyways, i was considering remedying the situation in one of two ways until I had the cash and time to get a supercharger, either install a higher stall coverter OR get a low geared rearend (4.10s or 4.30s) If having a low geared rear will practically make the sluggish feeling negligible then that pretty much makes up my mind. I won't ever bother with a converter since I intend to have the auto swapped out eventually anyways.

Anyways, after getting true duals installed I suspected the power band had shifted into the higher RPMs and after reading post after post and article after article on this topic I'm convinced that's exactly what the "problem" is.
it can be remedied, just need some patience.

 

[CANTONRACER]

I have seen numerous cars lose rwhp on a dyno when the relieved the so called "restrictive" back pressure. I saw an LS1 car jump almost 30 rwhp when he capped his cut out. That was an extreme...but rarely do I see something can from lotsa exhaust.

A larger exhaust is needed when...

You have lotsa cubes...
You have lotsa rpm...
You have lotsa motor...

The 3.8L has none of the above. It is all low end and mid range. So you lose your bottom end and you throw gear at it...woo hoo...your absolutely going no where, sorta like one step back, one step forward...yet your wallet is lighter.

You do not want a short diameter tire, low rpm and geared vehicle. Sure, you thinking your going faster, but your not.

My old Z28 combo ran 1 single 3" dia pipe, no cats. Motor was 389", 3600 lbs, shifted @ 6300 rpm, ran 11.7's@116 mph. Break that down, that is 2-1/8" dia pipe duals.

So technically, your basically running more exhaust than my motor that was over 157" larger, spins 1000 rpm higher and made 2.5 the rwhp.

My new combo, big honking heads, 7000 rpm shifts, lotsa stall, looking for upwards of near 500 @ the wheels on motor and then spray a 200 shot on top of that...I am going with a single 3.5" exhaust..which breaks down to roughly a dual 2-1/2" system.

You would be surprised how many bad cars have smaller than you think exhaust systems...

 

[xneox]

I have seen numerous cars lose rwhp on a dyno when the relieved the so called "restrictive" back pressure. I saw an LS1 car jump almost 30 rwhp when he capped his cut out. That was an extreme...but rarely do I see something can from lotsa exhaust.

A larger exhaust is needed when...

You have lotsa cubes...
You have lotsa rpm...
You have lotsa motor...

The 3.8L has none of the above. It is all low end and mid range. So you lose your bottom end and you throw gear at it...woo hoo...your absolutely going no where, sorta like one step back, one step forward...yet your wallet is lighter.

You do not want a short diameter tire, low rpm and geared vehicle. Sure, you thinking your going faster, but your not.

My old Z28 combo ran 1 single 3" dia pipe, no cats. Motor was 389", 3600 lbs, shifted @ 6300 rpm, ran 11.7's@116 mph. Break that down, that is 2-1/8" dia pipe duals.

So technically, your basically running more exhaust than my motor that was over 157" larger, spins 1000 rpm higher and made 2.5 the rwhp.

My new combo, big honking heads, 7000 rpm shifts, lotsa stall, looking for upwards of near 500 @ the wheels on motor and then spray a 200 shot on top of that...I am going with a single 3.5" exhaust..which breaks down to roughly a dual 2-1/2" system.

You would be surprised how many bad cars have smaller than you think exhaust systems...

Thank you.

 

[ITFEEDS]

I think that was the most info. I have ever got about dual exhaust this forum stuff is pretty cool.Thanks to all of you that put your sense in for someone like me it helps out a lot because, this is my 1ST mustang and my 1ST dual exhaust. You all helped.

 

[GREENBIOCH]

I understand what you guys are saying, but if your gonna do any further modding like I am, in the process of BV heads and camming it. Then you might as well do it right the first time and get a bit larger exhaust whether it be dual or single. If exhaust is all your gonna do and then stop modding then it probably isn't worth the cash like you said, unless you like it to be louder and that is it.

 

[Pro-Hawk]

I PUT MAGNAFLOWS WITH 2 1/4 PIPING WITH 3" TIPS. (CAT BACK)

Ok I agree with Buff, but I think what happened is your tips screw the speed of the gasses up. The 3"+ tips look cool and may sound cool to you, but as a rule of thumb you only go lower ID no more than a 1/2" after the muffler. I mean if your running a 2.5" pipe you either use a 2 1/4 - 2.5" ID tail pipe. The bigger ID pipes than the rest of the system cause it to make a vortech and moves back up the exhaust system and slows it down even more. This also from what I've heard causes problems with gas mileage since back pressure helps scavanges the chambers, the bigger tips cause the BP to suck more fuel when the vavles are opened. Now keep in mind this is all hear say and opinion. I guess if your MPG goes down I'm right