[RonnieSan]

After driving my car around for the past few days, I've notice as lot of loss of low end power. My exhaust setup is as such: stock resonator to Aero turbine muffler. 2.25" pipe from the muffler back where it splits into two 2.25" pipes at the rear axle.

Would switching out the split pipes with 1.5" or 1.75" pipes help me regain some loss low end power? I understand more backpressure helps with low end power. And just when does low end become high end. I sadly have an auto and so I'm looking to increase power between 0-4000 rpms. I want most of my power between 2000-4000.

Thanks in advance.

 

[AUTOBOT]

Well, I hate to say this but if power was a concern, you should not have gone with duals. A single exhaust would have been much better.

Now, that being said, yes dropping the pipe diameter after the split will help.
The way you have it now, your piping has an area of about 15.9" and when it flows into duals of the same size, that doubles.

A little geometry (rounding numbers to the nearest 100th)
2.25" pipe has an area of 15.9"
Two 1.75" pipes have a combined area of 19.23"
Two 1.5" pipes have a combined area of 14.13"

Since there realy isn't anything inbetween, it is kind of a tough call on weather to go a little over or a little under but I would tend to believe a little under would be better. Not 100% sure on that and maybe somebody could shed some more light on it but I do know keeping 2.25" pipes after the split is way too much.

 

[04 elantra cvvt]

You may also be causing turbulence where the pipe splits causing too much back pressure at that spot. In other words, that split might be choking the car. One of the best things to give you some more low end grunt, would be to upgrade your ignition system. Let the fire through.

 

[RonnieSan]

Yeah I know a single pipe would have been much better, but I wanted the dual tips in the back because I lean more towards style. I'm just very irritated by the lack of low end that came as a result of the new exhaust... I have to rev up to at least 4000 in order to get anywhere and it's ridiculous on the freeway when my car won't go past 4000 rpms on a slight incline. The acceleration is stupendously slow. Not very safe to have such slow acceleration either. This setup is getting to be more expensive than I thought. My gf warned me about it already. Stupid Elantra. I want to sell it and buy a Scion tC.

 

[04 elantra cvvt]

Why spend money on a Toyota? Take the car to an exhaust shop and get them to chek the y-pipe. I know that sometimes, where they join the two together, there is a little bit of the new pipe extending inside of the old one. Imagine putting a soda straw into the side of another. When you do, part of the one you inserted is sticking into the other. This would block part of the flow. But if you cut the one you are inserting so that it is a flush fit, you have no more restriction. This may be what's happening with your set up. I had the same problem once. They can usually clean this up, and it'll make a world of difference.

 

[AUTOBOT]

Yeah but I think his problem is the larger pipes after the split. Since at that point, the air is no longer being pushed especially at lower RPMs, it feeds back into itself creating more back preasure. It isn't as noticeable at higher RPMs because more air is being pushed out and therefore less air has a chance to feed back.

 

[RonnieSan]

So I don't get it. Do I have too much back pressure or too little? The thing with my "Aero Turbine" muffler is that it creates a suction so it's actually pulling air out of the exhaust.

 

[Bnystrom]

So I don't get it. Do I have too much back pressure or too little? The thing with my "Aero Turbine" muffler is that it creates a suction so it's actually pulling air out of the exhaust.

That's if you believe the marketing hype. It sounds like a crock to me.

A little geometry (rounding numbers to the nearest 100th)
2.25" pipe has an area of 15.9"
Two 1.75" pipes have a combined area of 19.23"
Two 1.5" pipes have a combined area of 14.13"

The formula for area of a circle is pi x the RADIUS squared, not the DIAMETER. Ergo:

A 2.25" pipe has an area of 3.97 sq/in.
Two 1.75" pipes have a combined area of 4.81 sq/in.
Two 1.5" pipes have a combined area of 3.53 sq/in.
Two 1.625" (1 5/8") pipes have a combined area of 4.15 sq/in, which is the closest match to the single 2.25" pipe.

 

[AUTOBOT]

The formula for area of a circle is pi x the RADIUS squared, not the DIAMETER.

Grrr, you're right.

It has been so long since I have used geometry. LOL
I actually did quite well in it (A's) but after almost 15 years of not using it, the formulas tend to escape me. LOL

Well, if the choices are 1.5" or 1.75", I would still go with 1.5"

 

[tharptroy]

I'd lean towards 1.5" first.