Anyone experiment with high flow mufflers?

[Three6Eight]

I really dont want to add one to my metro because I dont want it to sound like a ricer car but if it helps with mileage Im all for it. I just wont get and oversized tip.

[Danronian]

If you're adding a muffler since yours is rusted out, I would go with the oval shaped muffler instead of the cylinder shaped import car type. The oval one will sound much deeper, and still be high flow enough for a metro.

[Sludgy]

IMHO, big mufflers don't help FE. They reduce pumping losses somewhat at high RPM and WOT. But if you want good mileage, you never stomp on the gas like that.

I've often thought that a smaller muffler would be better for FE on my truck, because the OE muffler is such a big aero obstacle.

[trebuchet03]

If you're trying to increase FE by increasing exhaust or intake capabilities -- that means you're not driving for FE. You should NEVER outflow your stock exhaust or your intake (of course, I'm sure there's a couple very rare exceptions)

[Daox]

Exception:

Turbocharged cars can see mileage gains from enlarging exhaust pipe diameter and using high flow components.

[8307c4]

First off, most people never see an increase in mpg when the car has more power, resisting that urge is one tough challenge, perhaps more so if you haven't driven 10-20 years with an impeccable driving record.

Most people, once the power is there, git it.
Hence they end up getting less mpg and they wonder what it was all about?

Theoretically speaking, increasing SPARK or AIR would yield better mpg IF you can keep your foot off the throttle, but a self-admited ricer? It takes a lot of self-discipline, kind of like those old grey-haired guys you always see driving the super fast cars doing the speed limit, about like that. Oh yes, age helps.


Now to install a muffler...
With a high flow exhaust system you need more than a muffler, you need pipes and a high performance manifold, in addition to a second cat, what you really need is called 'dual exhaust with headers,' and this is impractical because the cost of this runs 4-6-700 DIY and you're easily looking at a few thousand with a mechanic doing things, and of course muffler work usually requires welding.
And no, a muffler alone won't do squat.

For all that and the purpose of experimenting you're as well off installing Double platinum spark plugs, some decent high performance spark plug wires (such as Accel's 8mm or better yet Taylor 10.2mm), and a high performance cap and rotor.
DIY will set you back 1-200 and now that you're getting serious SPARK you can see for yourself if the +power = +mpg line of thinking is right for you.

But no, in most cases it will not increase mpg, but as much if not more so because once folks feel the power there's not much doing.

The trick is to resist the urge and actually use less fuel than before the upgrade, give it less throttle to accomplish the same acceleration means the increase in SPARK (and/or AIR) does the work while less fuel is used in the end.

Originally Posted by srt-4

A car requires back pressure to make torque. The smaller the engine, the more back pressure is required. For the OP I would leave the stock exhaust alone, unless it needs to be replaced. You will burn more gas trying to get the mass of the car going if you lose torque on the bottom end because of a 'bigger' or more free flowing exhaust.

The decrease in torque has less effect than the increase in HP, in the battle of horsepower vs. torque it is the horses that always win. Yes, you can manipulate torque and horses to a point and even to the extreme, but no matter how well manipulated a torqued setup gets, it's the vehicle with the most horsepower that wins.

Although impossible in a real life application (because horses and torque can't have one without the other), in the following case example:
A car with 100 horsepower and 0 pounds of torque
vs.
A car with 100 pounds of torque and 0 horses.

The car with 100 horses would win, every single time.
Yes, if it were possible, and we agree, leave the muffler alone

[csrmel]

go for a light weight muffler that is quiet. like the one off a late 90's honda civic. its big, but thin and light. and covics are quiet cars. plus a muffler designed for a 1.6 engine has got to be basically no backpressure on a small metro engine.

[91CavGT]

If you could decrease exhaust backpressure while increasing exhaust velocity at low rpms where your cruise rpm is then that should help to increase FE.

To do this though you'd probably have to go with a slightly smaller than stock manderal bent exhaust system with a very free flowing muffler. It would increase low end torque at the expense of high rpm horse power.

[Danronian]

Originally Posted by csrmel

go for a light weight muffler that is quiet. like the one off a late 90's honda civic. its big, but thin and light. and covics are quiet cars. plus a muffler designed for a 1.6 engine has got to be basically no backpressure on a small metro engine.

That is true, but from my experience, the parts store universal mufflers are always about half the weight of the OEM Honda muffler. Just for that reason, I would probably go with a cheaper/new universal "Oval" muffler instead.

[SL8Brick]

I fitted my Volvo 240 wagon(non-turbo) with an OE cat-back exhaust from a 240 turbo. Basically, its only a ~.5" difference in pipe diameter...but the turbo system uses only 1 muffler while the n/a system uses 2. The exhaust note isn't obnoxious and it still retains the OE look...so no hastles from local law enforcement.