I have a 99 ranger 3.0. I have owned it for a couple of months. It is a great off road desert truck but does not have much getup and go. I know the 3.0 is not a power house and will never be but I was wondering if a exhaust up grade will help. If so I what are some proven recommendation? Thanks

 

Welcome to the forum

Factory Rangers have CAI(Cold air intakes) and tuned exhaust.

But they are tuned for mid-RPM power.

Tuned exhaust:
Years ago Racers discovered that exhaust manifold pipes of a smaller size would generate a Velocity in the smaller pipe that when dumped into the larger Collector pipe would create a LOWER pressure at the exhaust valves on that bank.
This lower pressure meant that the piston/crank didn't need to use as much power to push out the exhaust, some would be pulled out by the lower pressure.
This meant more power available for rear wheels.

The math for this is above my pay grade, lol.

The size and length of the exhaust manifold pipes and the size of the collector decide when the lowest pressure occurs in the RPM band.
Low, mid, or high, most stock exhausts are mid-range, the lowest pressure occurs at a specific RPM, so at or near that RPM is when extra power is felt.

Oh and just FYI, factory tuned exhausts is where the Myth of back pressure comes from.
People would put on larger exhaust manifold pipes, "free flowing" is the common term.
Then go for a test drive........."WTF!!! I LOST POWER!!!"
"this engine must NEED back pressure"
No 4-stroke engine runs better with back pressure, lol, the Myth.

What they did was LOSE the scavenged power from the tuned exhaust, so what happened was correct, the conclusion of why it happened wasn't.

You can't get extra power if you already have a tuned exhaust, BUT.....
You can change where that power(lowest pressure) occurs in the RPM band.
Most "headers" are tuned for lower RPM band.
"Racing headers" are tuned for higher RPM band.

And from the Collector back you can did what you like, as long as you don't use smaller pipe, lol.

On Dual exhausts there is another technique that has been added now, "H" or "X" pipes, because opposite banks will have opposite exhaust pulses traveling down the separate pipes, a cross pipe("H") or two("X") was added to help pull out exhaust better.

 

Thanks it definitely struggles at higher RPMs. I don't know if I want to deal with racing headers. I am not excited about pulling the exhaust manifolds and installing headers. It sounds like I should probably stick with stock.

 

If it stumbles at higher RPM then exhaust could be getting plugged up, Cats and Mufflers rust from the inside out, pieces break off and limit flow internally.
This is first noticed at higher RPMs

You can often use a vacuum gauge($25) to detect exhaust blockage.


Fuel flow.
There is fuel pressure and fuel flow, they are related but not exclusive.
A carb used 7psi fuel pressure and could run a 700+ HP engine at max power.
Your '99 has 70psi pressure for 140hp.

Gallons per minute(GPM) is the flow rate, the 700+HP would have more flow at 7psi than the 70psi does with 140hp.

They are related but not exclusive.

If your flow is getting low at maximum load then engine will struggle, regardless of pressure being "OK".
I would change fuel filter, it should be done every 5 years or so.

You can use fuel pressure to see if maybe the fuel pump is struggling with GPM, keep the engine at 2,500rpm(approx.) and watch the fuel pressure, if it starts to drop slowly then fuel pump could be the issue, assuming new fuel filter is in place.


There is also a REV limiter, if speedometer is showing under 5MPH or trans is in PARK or NEUTRAL, then computer will limit RPMs, 3,000rpm is approx. limit