4.0 Performance

[brando3279]

I just posted a question of which 4.0 I have, but now I am wondering what kind of bolt on power I can get for it. Kind of looking for more noticeable power, if any. I am looking at headers, throttle body spacer, and cold air intake. If anyone knows more parts/ how well these perform, i'd appreciate the help.

 

[Lariat]

You'd get better preformance out of the headers and the airbox mod. Throttle body spacers do nothing for EFI motors. Remember, you don't want to loose torque by freeing up the exhaust too much. The loss of back pressure is also the loss of torque.

 

[RonD]

The right headers can move the power band to lower RPMs so better start off power.
Headers don't add power they shift the power band to higher or lower RPMs.
Stock exhaust system is tuned for mid-range power

Just FYI, the back pressure thing is a bit of a misunderstanding of cause and effect.
You want 0 back pressure at the exhaust ports, negative pressure is even better.
What you want is velocity in an exhaust system.

When someone put larger exhaust pipes on a manifold and they lost some power they then surmised that the larger pipes must have lowered the "back pressure" so "an engine must need back pressure" to run better.

But what actually happened is that they increased "back pressure" with the larger pipes, so lost power.

This is where "tuned" exhaust comes in.
A smaller pipe increases the velocity but lowers flow, larger pipe decreases velocity but increases flow.
When using a manifold with a collector what you want to do is to get a good velocity from one exhaust port so when its "pulse" reaches the collector(much larger pipe) the velocity from that 1 pipe will cause a pressure drop in the collector as it expands to fill the larger pipe.
This causes a pressure drop in the other exhaust pipes on that collector, so 0 or negative pressure at the other exhaust ports.

If you make the exhaust pipe bigger then velocity goes down, which means pressure at the other exhaust ports will go up not down.
This is where the back pressure myth came from

So the tuning of the exhaust system is not just bigger is better, lol.
The volume of the cylinder and pressure at the exhaust port need to be considered along with changes in RPM to calculate a large enough and small enough pipe size.
You want to create enough velocity without limiting flow.
There are also pulse counts to consider as well, lol, so not a simple thing and way above my pay grade


Best bolt on would be to remove fan and fan clutch and install an electric cooling fan.
Frees up horse power and has better low speed cooling.

After that, headers sound better and as said can shift power band lower to give better start off power.

CAI is a waste of money for power, but for looks and sound they are nice.

If you look here
http://www.therangerstation.com/tech_library/index-engine-fuel.shtml

Click on the 4.0 V6 link and at the bottom of that page are bolt on upgrades also other upgrades

 

[PlumCrazy]

The best thing you can do for these motors is have the exhaust ports opened up. The money spent trying to get a noticeable power increase out of the motors would be better spent on a 5.0 swap...and this is coming from someone dumping money into a built, boosted 4.0..

 

[RonD]

Also as a thought..........

You have a 2000 Ranger so have the 4.0l OHV engine, it is rated at 160hp

The 4.0l SOHC was put in Rangers in 2001 and up, they are rated at 207hp

And I have read it is a straight swap, trans and motor mounts are the same.
Even computer will work.

Your stock 4.0l OHV in good running condition is worth money to someone with a bad 4.0l OHV or who is doing an upgrade swap
This would off set the cost of a 4.0l SOHC, and you can often find these cheap if timing chain issue has raised it ugly head.
That's a 30% HP increase and you are still "stock" for the most part so not a resale issue

 

[PlumCrazy]

SOHC isnt worth it IMO. I would rock an OHV over the SOHC any day

Sent from my XT907 using Tapatalk

 

[adsm08]

SOHC isnt worth it IMO. I would rock an OHV over the SOHC any day

Sent from my XT907 using Tapatalk

Agreed. The SOHC's numbers are better on paper, but the extra trouble they cause and the effort into fixing them is NOT worth it. This is coming from the guy who takes his engine and trans out because he is bored.

Also, TB spacers are worthless on ported EFI engines.

They worked with carbs, and to a lesser extent with TBI/CFI. The idea behind the spacer was to lengthen the runner and give the air and fuel more time and space to mix up. Since the fuel is well atomized by the injectors and not even introduced until right at the intake valve a TB spacer is pointless on an EFI system.

 

[brando3279]

Okay, all this sounds good. Sounds like just keeping it stock is the best way to go, again, that's why i'm asking, I don't want to sink in $1000 worth of parts that will increase gas by 1 mile and give me 5 more hp over stock.

 

[truckerdawg]

Only bolt-on you would notice is nitrous. But not a good idea in your scenario.

 

[aspevacek]

Rather then look at the motor for power do a simple gear swap that will give you more of a seat of the pants feel then any amount of cash dropped into the 4.0l OHV motor.