Exhaust questions

Mark_in_Tulsa · December 12, 2004

When you guys are redoing your exhaust, with a cat back system. Where are you getting most of your power. I would assume its the muffler not the new pipes. The reason I ask this is because I also own a Hemi Ram. And from what I have read from their forums, is that changing the pipes at all has only shown to keep the power the same, or decrease it. The Dodge guys have found that just changeing the muffler out, and leaveing the pipes alone, has increased the power.

My question is, if I just add a new muffler, (magnaflow) will the rest of the system be to restrictive and counter act any performance I would of gottin from the Muffler.

Down the road, also plan on headers. Will I see any gains with headers mufflers, and the stock pipe. I am just trying to see how much I can save, if possible.

potz1999 · December 23, 2004

A Dodge??!!

Everything is part of a system. Just like adding a performance intake will give you so much extra power, that extra power is increase with the addition of a less restrictive exhaust.

Since many OEM exhausts are now mandrel bent, the muffler is the most restrictive element. The replacement of that with a less restrictive one will net you a fair gain. As far as pipes go, the trick that the aftermarket uses in approaching new-models is playing with the routing. They go for less bends and try to keep the gas moving at higher velocities, which makes more power.

I am the type of person who says go all out: get the headers, the cats, y-pipe, and cat-bat system. This will get you the most power (downside - most expensive).

Assuming that your pipes are mandrel bent, the headers, muffler, and stock pipes will give you some decent gains.

The real question with the pipes is diameter. There is a trade-off between high flow and high velocity. A bigger pipe will give you higher flow, but slower velocity. A smaller pipe gives more speed, but flows less. The engineering involved in exhaust design is quite complex and it is difficult (at least for me) to say what would work best for a general situation. I would put my faith in an engineered system before I would play the odds on welding in just a muffler that ended up robbing me power.

budhayes3 · December 24, 2004

If you go too big on the pipes, you may lose some bottom end, it all depends on your setup and what you plan to do. If you're going to stick with the stock cam and torque converter, you probably could get away with just doing the muffler and you'd still feel a power increase. Myself, I'd do a whole system and a cold air intake at the same time if the funds allow for it, but if you're in a pinch you should be OK with just the muffler.

As far as headers go, I'd save up for a good set of long tubes, more bang for the buck. From what I've read, they seem to increase power throughout the powerband without sacrificing low end. I have shorties for a couple of reasons...when I first purchased them, nobody was making long tubes with CARB approval, this is my daily driver and I have to pass NJ state emissions, and I was still under warranty and didn't want to go too nuts at the time. (didn't want a set of unapproved LT's screaming "look at me...now charge me for that bank1 sensor1 O2!)

capnfrantic · December 24, 2004

Sportruck magazine did a Hemi 5.7 in Feb/05 issue. Thorley headers and catback produced 35.6 more HP and 32 more lb-ft torque! Seems to me that is a heck of an upgrade! Evidently these Hemi's are "choked" from the factory. Just chiming in....

budhayes3 · December 24, 2004

Sportruck magazine did a Hemi 5.7 in Feb/05 issue. Thorley headers and catback produced 35.6 more HP and 32 more lb-ft torque! Seems to me that is a heck of an upgrade! Evidently these Hemi's are "choked" from the factory. Just chiming in....

<{POST_SNAPBACK}>

Those are some impressive numbers!

Mark_in_Tulsa · December 24, 2004

Sportruck magazine did a Hemi 5.7 in Feb/05 issue. Thorley headers and catback produced 35.6 more HP and 32 more lb-ft torque! Seems to me that is a heck of an upgrade! Evidently these Hemi's are "choked" from the factory. Just chiming in....

<{POST_SNAPBACK}>

I read that also. And from what I understand all of that was from the headers. Something about headers work REALLY REALLY well with hemi designed motors.

What I was saying that the pipes are good enough unless you want to push 400 hp in it. So just replaceing the muffler has been good enough for the Hemi guys.

Thanks for the replys guys, I had given up on it.

Oh and all the mods I plan on are; cold air, pcmforless, and exhaust stuff.

At least thats all the mods the wife will allow..............for now.

LikeaRock14 · December 27, 2004

Potz is dead on. As much as most people assume a larger pipe diameter is better, it isn't in some applications, i/e mainly bolt on mod situations. If you plan on heavy mods or forced induction or No2, then by all means you will benifit from a larger system.

Finding the right diameter tubing without hurting performance is critical, although it varies on every engine. Even if the tolerences are .3 different on cylinder bore/vlave machining and everything on the heads, that slight difference might affect performance with a new exhaust system. Use the right pipe diameter, you'll have good velocity and produe the most power!

And remember, the best thing you can do to gain power is allow your engine to breath. Allow air out, allow more in.

As far as headers go, they of course help "make" power, but at the same time they are unleashing the extra horsepower vy allowing the engine to force the spent exhaust gasses/air out with less effort. A properly designed header will give you awesome results with the rest of the exhaust behind it changed.

Good luck!