i had three of my five cats taken out and i have a flowmaster 40 series dumped under the bed. my concern is that if i put headers on i might lose some torque. Any info from you guys that run the jba headers would be great. are they worth that 600 bucks?

 

I don't know about the torque, but unless you can get the headers at a great price then they may not be worth it unless you have alot more air coming in. Like with a blower.

 

you are worried about torque with headers yet you removed all your cats

btw headers add torque, it shows on the dyno sheet, and the people with them i think are happy with the power it gave.

im pretty sure removing the cats doesnt do you any favors.

 

Agree

You should gain torque. I think you are thinking shorty headers vs long tube headers. long tube headers make more/better torque over shorties, both make better/more torque over stock. Unfortantly no body makes long tube headers for our trucks(if they did they would be a PITA to put on.

I think cats are better now a days compared to before. Back in the day in the 70's up to the early 90's cats were very restrictive. Now they still restrict the flow some but not as bad.

 

Headers are a great mod. All the info you need including tech specs/performance is available on JBA's website www.jbaheaders.com I have one of their EVOL exhaust systems, they make a well engineered product.

 

By taking those cats out like you did.

Get some headers and it will prob bring you back to stock power. You destroyed your tq by taking out the cats.

Those little v6's need the backpressure.

 

I didn't notice any loss in low RPM torque on my 4.0L after installing the JBAs. However, the rest of my exhaust system is unmodified.

JBA's are built better than most headers and are worth what they charge. But on a bang for the buck basis, a $400 tuner/program from a company such as Bamachips is a much better buy and it installs in minutes instead of hours or days.

 

I realize this is an old topic but there is something I'd like to point out.

I believe his exhaust system was TOO restrictive and by removing three of the five cats he did himself a favor.

In states where vehicle emissions aren't of the greatest concern, two catalytic converters are standard. I have two cats. So you are saying with 5 cats, the extra back pressure gives him more torque than my two? I HIGHLY doubt that Ford did performance tests on an emissions controlled vehicle.

 

back pressure = bad.
exhaust gas volecity = good.

plain and simple.

 

yeah but they are high flow cats

 

wow.... you removed all those cats. i bet your truck is extremely loud.

 

nobody tell Griggs about this thread!

haha

Bob, you are first person I have ever heard say that the headers are worth the money, but your opinion is held in much higher regard so ....lol

 

Bob, you have since added the Thunderbolt/Magnaflow dual exhaust.....What do you think about this topic now??? Was there a change with the new exhaust added with the headers????

 

You need some back pressure. If you had none you would burn valves because nothing is helping all of the exhaust gases escape down into the manifold/header besides the positive pressure from the cylinder. Ever wonder why honda 4 bangers with no cats and an uncle bens can for a muffler have less torque than a .12 nitro motor?

 

ugh, its the exhaust gas volecity. the key is building an exhaust system is tuning it to the right size and lenght. u do not need backpressure, its a restriction and thats bad. u want a free flowing exhaust of the right diameter and lenght.

u loose torque by increase the size of the pipe diameter because it slows down the exhaust gas volecity at low RPMs. at higher rpms its flowing quick enough that a power increase can be noticed. this is true for any 4 stroke engine.

adding headers is a great way to gain power, why? because they help tune the exhaust gas pulses and increase flow. they are also tuned to help scavange exhaust gas out of the cylinder.

 

You have to have some backpressure to properly "scavenge" the exhaust gases from the cylinder to prevent burnt valves. When you force a gas into a restriction, the gas speeds up after the restriction, but the volume of flow decreases. With the overlap in exhaust flow from one exhaust stroke to another, the gases in the exhaust have sped up and create a low pressure area in the exhaust which helps the burnt gases from the cylinder more easily flow into the manifold/header.

Run an engine with open headers and see how good it runs. Then come tell me that backpressure, even some, is bad. Yes, too much is indeed too much and can affect the fresh air mixture in the intake manifold if there is any crank overlap. But you need some backpressure.

Hell even on my truck when I ran it straight piped and the last cat gutted, I put a 2 chamber flowmaster on and regained torque.

 

scavenging doesnt require "backpressure" scavenging requires the exhaust to be of proper diameter and length, when you have the proper diameter and length, it creates a siphon on the exhaust valve and pulls a vacuum in the cylinder, which helps air/fuel mixture get in the cylinder by sucking some in before the piston has to pull it in, rather than just the piston pulling it in, which gets more air/fuel mixture get in there, which creates more torque.....if you have too big of pipe, or not enough length, the exhaust will just dump through and you will have no siphon, which kills torque....

 

thank you.

034x4, notice how i said proper diameter and lenght...open headers wont do **** unless its on a forced induced vehicle.

 

Taken from www.flowmastermufflers.com/backpressure.html

Reducing backpressure too low, for the tuning of the engine...

By reducing the backpressure, some amounts of raw fuel (and fresh air) will be "scavenged" into the exhaust system. So by reducing the amount of air and fuel in the cylinder at the time of combustion.

* A degree of cylinder pressure will be lost (a decrease in available torque)
* Effective air/fuel mixtures will be leaner (possibly leading to parts damage).
* Ignition spark requirements will change.
* The exhaust system's temperature will rise (owing to the burning of air/fuel mixtures in the exhaust manifolding and pipes).
* Exhaust gas temperatures will increase (particularly notable during engine dynamometer tests).
* There will be a tendency of back-fire (or popping) during deceleration of the engine.

 

so i guess since flowmaster said u need some then its set in stone, right?

a properly tuned exhaust system should have at least a catalyist and a muffler, no doubt about that. but its more than just backpressure. i spoke w/ several engine builders (my teachers) from backgrounds in gas and diesel and they all agreed on what i said.

 

Man all i said is you need some backpressure. Backpressure is just restriction in the exhaust. If the properly tuned exhaust for so and so motor is 2.5" pipe etc etc. It would have more "backpressure" than a 3" exhaust on the same motor.

Why do you insist on being so aggressive in your posts. I merely copied the text to reiterate my point, yet you say by doing so I am declaring myself all mighty and there is no other correct answer?

 

because u insist to prove me wrong?

who gives a ****, STEELERS WON!