I have been thinking about installing a Magnaflow Offroad Pro series exhaust, High flow cat, and headers. Does anyone have a setup like that? Does it sounds good? Does it provide torque / performance increases? I know there are other systems out there, but I really like the short pipe design, that dumps down before the axle. Magnaflow is the only brand ive seen that has that design. Any suggestions on headers? My goal is to make the engine breath better, and hopfully get more power

 

Scavenging exhausts have been used by car makers since the '50's

What it does is to use the exhaust pulse from one cylinder to lower the air pressure at the other cylinders on that bank.
It is a science, but the basics are:
Small diameter pipe at the head, but large enough not to restrict flow, the small diameter creates a high Velocity Pulse in this pipe.

The Collector is the larger pipe connecting the other small exhaust pipes on this bank

When this high velocity pulse gets to the Collector it creates a pressure drop, like a siphon, in the other pipes.

The size and length of the smaller pipes and the size of the collector must be tuned to a specific RPM for that engine size, thats the science part.

The way it works to get extra power, is when an exhaust valve opens the piston pushes out the exhaust gases, this requires little effort but not 0 effort.
With Tuned exhaust when you get near the tuned RPM the low pressure pulls the exhaust out, so less power is lost at the crank, so more power at the wheels.

It's called scavenging exhaust system because it doesn't use any power, it scavenges extra power by creating the lower pressure.


Basically you have low-band headers, mid-band(car makers use these) and high-band, for racing.

Most people use low-band headers for more low end power.
Rangers all have mid-band headers now.

If you get low-band headers you lose the mid-band.

Newer dual exhaust vehicles are also now using "H" or "X" pipe scavenging systems.
Basically a crossover pipe setup that uses opposing bank exhaust pulses to help pull out exhaust, aiding the header scavenging system.


The MYTH of back pressure comes from scavenging stock exhaust systems
People would install "free flow" exhaust, basically larger pipes at the heads and back to tail pipe
When they went out for the test drive they found they had LOST POWER!!
"WTF!!.........this engine must NEED Back Pressure!!"

The losing power part is what would happen if you removed a scavenging exhaust system, and replaced it with regular exhaust system, but their conclusion was wrong.

No 4-stroke engine needs back pressure, try putting a potato in the tail pipe, lol, certainly won't increase performance.

You can replace your mid-band for low-band headers for better low end performance
And larger pipes after the collector can give you a better lower tone sound.

The 4.0l SOHC engine runs 9.7:1 compression ratio, so it will ping/knock on 87 octane fuel
Ford had to install a Knock sensor, this retards the spark when running regular gas, so you lose a bit of power because of this.
Running higher octane in this case will get more power from this engine.


Air flow is the key to adding power, this is why a 5 liter engine has more power than a 2 liter engine, it can use 3 liters more air so more fuel in the same time frame.
And why turbo or super charging works, you are adding more air, so can add more fuel in the same time frame.

Car makers are not in the habit of restricting air flow into an engine, they WANT good performance numbers, but some engines do have throttle bodies that can be swapped out for larger ones, not sure what's available for the 4.0l SOHC engines

 

RonD

Your knowledge made my exhaust system easy. I'm happy with the cherry Bomb then a straight pipe and an exit right by the back wheel. Thank you again.

A bigger throttle body. That would mean a bigger plastic pipe after that right? So it can drink more air all the way. Plus bigger air intake by the air filter right? Would the MAS. Air sensor. Need to be adjusted or replaced. To make it work for the new stuff? Or does it just do its job without a problem? Basing that the sensor just responds to what it gets.

I can't thank you enough for busting the back pressure myth.

After cleaning the MAS with the spray. Instantly made engine better. Everybody needs a bottle of that MAS cleaner. Even in the cold it dried fast. I was burning rich. Big gas smell. All gone instantly. In my area it was $8.99. I say well worth it.

Happy New Year All.
Jim

 

I think I will keep factory heads, install magnaflow exhaust, high flow cats, and a K&N air intake. Will doing this throw off any sensors?

 

Fuel injected Rangers all came with Cold Air Intakes(CAI)
And they are 200% over needed air flow, so air filter can get 50% clogged up before you would notice effect on engine performance.

Some like the sound of new air filter system, and that's OK, but.......if you can hear it then you are restricting air flow


As long as MAF sensor and O2 sensors are reused then you will be fine

Changes from the Collector back change the sound of the vehicle and shouldn't effect performance unless you use smaller pipes, which would be bad
Larger pipes give a lower tone to exhaust, just like on a pipe organ, larger pipe lower note


Happy New Year Jim

 

Thank you Ron

Hope the New Year is starting great for you.

Jim

 

How about High Flow Cats? Would it be better to leave the Factory cats on, or get high flow ones from flowmaster or magnaflow?

 

As long as they work they are fine to use, "works" means cleans exhaust to your years specs
As said they can only change the sound of the exhaust, there is no power gain over working factory equipment.

Nothing in a factory exhaust system restricts the flow, "High Flow" is a sales pitch

 

I was looking at some of those CATs at autozone.com yesterday. The price is under 100 for a few. To me thats a great deal. They are listed as being the main CAT in the system. So they would go at the spot you see. The other bennifit I saw was they come smaller than the big one. Rated for every state but Cali.

Then the problem I ran into was install. To remove the current on you need to cut pipe. After you cut it. It will be on an angle. From what I could see. So that would be left to the installer to figure out.

Ron brought up. Meeting the standards of your year Ranger. What would be the harm of a universal CAT that meets standards of today? Or would that be like putting in a DOG were you need a CAT? Talking of what it might do to the engine.

I agree totally with the high flow term. Your forcing through 3 substraight materials. It takes power and lots of heat. If it doesn't get hot enough it won't do diddly.

Example. When emission test were done with a sensor inserted into the tail pipe. Requirements was a hot engine. True was before CATs. But that is what makes it get rid of lots of toxins that the CAT of today does.

Stay happy guys
Jim