Magnaflow versus Flowmaster ~ Showdown on the Dyno

Get 2.5" both ends and you'll be just fine.
I bought a 2.25" and Greg needed to swedge it to fit. The stock exhaust pipe you already have is also perfectly good. It's mandrel bent so there's no reason not to use it unless of course you want the exhaust to go somewhere else.

 

Force induction is a different beast when it comes to exhaust. I've seen guys put cut-offs on their pipes before the muffler and when they open them, they see gains anywhere between 20-30hp depending on engine/turbo they're running. FI guys prefer straight through mufflers for the most part.

 

Tooter, thanks for picking up the "backpressure" misunderstandings vs. the reality of exhaust flow. Keeps me from having to keep busting the myth (BS) of the backpressure term.

For everyone else, make sure you keep this data in context, we are talking about maybe 3 horsies or 3 torguies in this thread. While some seem to think they can butt-dyno and feel that change,,,, its a placebo effect for most. I suspect some could, but much fewer then are actually reporting changes.

BUY BY the sound! I use the term "chokemaster" just to get the flowmaster kids to tense up and go into the "dem's fightin' words son" mind set. Personally I prefer the sound of a packed muffler (fiberglass or steel wool) to the sound of a chambered muffler. That's why I have a Borla (had a Magnaflow initially) and not a Flowmaster,,, I bought by sound since the perf difference between any drop-in muffler change is going to be minimal and minor.

Also keep in mind that all performance tests done, dynos or 0-60 or 1/4 mile, etc. are done in open loop. Open loop goes to the AF maps in the ECU, so you are testing open loop performance.

Daily driving is done in closed loop, for the most part. Closed loop uses the AF sensor, mostly, for setting the actual fuel injected. So,,, what you measure in open loop does not always translate into daily driving affects.

 

+3 +3 is fairly significant when you realize that it was only from changing changing from one hi performance muffler to another high performance muffler.

Agreed.
Having solely run Magnaflows for years, I found that I really like the throaty sound of the Flowmaster much better. Plus the stainless steel muffler won't ever blow out because there's no packing to begin with.

Of course. I very rarely floor my truck. Most of all my driving is partial throttle between 1,000 and 2,000 rpms, which is why I'm only interested in bottom end off idle throttle response (torque).

Greg

 

I took a long trip to Sacramento and back and was able to finally log some reliable freeway mileage:

838 miles
27.354 gallons

30.6 MPG

This SMASHED my old record best of 28.9 mpg!


Greg

 

That's great! The only change here was the muffler? And the weather/temperature was about the same?

 

On the +3, let's just agree to disagree. A 2% increase on a dyno where the measurement error between runs can easily surpass 2% just doesn't fall into my significant category, noteworthy, yes, but can you feel 2%, ahhh...

For the open/closed loop, how do you know you have any closed loop gains at that rpm range? My point is that since it's maps vs. AF sensor and a AF ratio of around 12 for open loop, vs. 14-15 for closed loop, I question the direct correlation. But, this is not just for your assessment and data, or for just the 4 cyl, but for all. It's why I'm not a big fan of dyno data in general. It's an indicator, but is not directly correlated to daily driving (closed loop)

All this is IMHO though, so it's worth every cent you've paid for it!!

 

Yes.

Both results were recorded from the ideal conditions of hot weather, summer blend gas, unladen truck, and freeway driving. This is as good as the gas mileage can get.

My normal average is 23 mpg with no freeway driving, a fully loaded truck, frequent start/stop cycles, and lots of first gear crawling on steep rural roads. Considering those everyday work conditions, I'm still happy to get even that.

It's really satisfying to see the practical results of focusing only on low end torque. Each of the mods by themselves have only made tiny incremental improvements... but start adding up the cumulative effect of each of them working together and you get some real gains.

Greg

 

Ok. The comparative runs were the best run from each group, all done on the same dyno, and SAE corrected for temperature, barometric pressure and humidity. That's as close as anyone can get with a dyno.

And I do agree that the tiny differences cannot be felt. But I'm happy to make just a tiny incremental improvement from each mod, because when you take them all together you have real improvement that you can feel.

I totally agree... and that's why I am only interested in off idle/very low rpm/partial throttle performance. The dyno can only record WOT open loop. That's one reason we started the runs at 1,000 rpms, which no one ever does. Even at that, the results are still limited.

...but that's where gas mileage comes in.

Only gas mileage recording can objectively quantify subtle improvements that no one could ever feel. Averaging 30.4 mpg for 800 miles driving normally at 60-70 mph on the freeway is the impirical result of each of the mods' slight improvements all working together.

It is. I tell you, it's been so much fun doing these experiments to improve low end torque.
The end result is a truck that runs really good.


Greg

 

seriously, i don't understand why someone would spend their hard earned cash for a magnaflow for a yaris. i'm going to check and see if they make one for my lawn mower.

 

Because never being satisfied with good enough. Because of free choice.

 

I do...



(edit: deleted wrong dyno runs)


For the same reason anyone else installs an exhaust... the sound.

https://www.youtube.com/watch?v=FL4CcjF8Z18

Greg

 

Wow. That's a really impressive gain for exhaust esp on a yaris

 

Sorry... that was my mistake. I posted the wrong dyno runs. The difference was a lot less than that.

 

I called Flowmaster today, just had some random questions.

Summary is below, if you care. If not, please skip to the next post.


Does offset/center, in/out matter for sound or flow? No, the different options are provided to make installation easier.

Any reason to not get stainless (It doesn't cost much more). Nope, if it's available in stainless, that would be better.

There is a 50 Series Delta with a smaller case, why? To fit in tight applications. Stay with standard size if you have the room.

At least 12" of tailpipe? Yes.

How about pipe length before the muffler? Install in stock location. Ideally, you want the same length before and after muffler. Before includes cats, etc.

How about just a turn-down? Don't do that, the sound will be "trapped" under the bed causing lots of drone.

How about a turn-out, so it sticks out to the side? You could, but why? Just cut out and replace the stock muffler.

I did NOT ask how the number of doo dads affects anything.

 

Hey dan,

It's always interesting to hear any info from the manufacturers because they have an ongoing practical working relationship with their products.

Just some comments to the questions:

Entries and exits don't matter because the offsets are so slight in relation to the internals.

Get stainless. It'll last forever. So not only will there be no packing to blow out, there's also nothing to rust out.

Our trucks have plenty of room to install any muffler they make. I'm totally pleased with the standard model.

You definitely want a full length exhaust pipe. Anything less and you will get cab drone because plenty of sound comes out the end of the pipe. So you don't want that end anywhere under your truck. There is a huge difference in sound between when the windows are open and when they are closed.

I'm glad you didn't ask the "doo dad" question.

Greg

 

So, why can't a muffler be made this way, with a one-way valve? That way, there could always be a slight vacuum in the muffler; higher atmospheric pressure could never get in. Hmmm... One large valve probably wouldn't work. It wouldn't be able to respond fast enough to the exhaust pulses. So, a whole bunch of small valves? Could work, but there might be problems with the valves sticking after a while? Oh well, I guess just stay with Flowmaster for now.

 

It already is. Flowmaster is making them that way right now.



Trace the path of exhaust backwards and all you'll see are obstacles to reversion. The angled plates and the funneled opening create negative pressure areas behind them which scavenge the exhaust gases. And those negative pressure areas are only there because the features make it very difficult for the exhaust to reverse its flow.

Yes. They're the only muffler I've seen with anti-reversion technology already designed right into them.


Greg

 

I'm sure y'all know what the sizes are for the exhaust on a 4.0? I'm about to pull the trigger on a super 40 series and plan to do the instal myself so I wanna make sure I get the right muffler