trickster

The only concern I have is that an engine needs a certian amount of back pressure and i would think straight pipes you would cut that back, Because an internal combustion engine runs on a vaccumized system.......too little back pressure = not enough intake pressure = not firing right = no motor. And that should sum it up. Hope this helps.

kalealmighty

unless you plan on taking the cats off you will be fine

AZFX4

I'm running straight pipe. You might lose a little low end but nothing crazy.

navierstrokes

Everyone considers it but only gets the answer it depends.

Heres the truth:
Putting straight pipes on your truck, or decreasing your "back pressure" will not hurt your engine or performance. Below the answer is fully explained.

The claims:
"If you put straight pipes on it will kill your MPG"
-Actually, lets consider what could be going on: did you do this in the middle of winter or in the summer as a project when the air is hotter and less dense? Chances are you did it once it got nice out, the air contained less oxygen per volumetric unit, and cheated your engine out of a fair test.

Why does anybody put straight pipes on anyway? To improve MPG? Probably not... now that your cheating the engine of oxygen, your excited that your car finally sounds like that dragster you saw at the strip or Vin Diesel's latest car in 5 Fast 5 Furious and your revving people at stop lights and pulling out a little harder or holding that gear a little longer to let everybody know you have a hot rod now.

Previously, before your straight pipes you probably drove to maximize your MPG and brag to your buddies that your truck gets +2 miles per gallon more than their, well this is a ford forum so... their chevy or rusting out dodge. Now your just driving it like a normal person and probably revving up when you go show your buds and theyre asking you about your MPG because they like your sound but dont want to burn the same hole in their pocket you are driving around in hot rod mode.

When do you do this anyway? A month after you buy your new truck? Naah probably once the engine is getting old, your out of the manufacturer's warranty and the engine's performance is decreasing. That's a good one to think about.

Claim:
"I'm going to hurt my engines back pressure and blow a part or head gasket or one of those other critical parts!"
No your just throwing around words because you don't really know the answer and dont want your engine to go to crap faster than it already is. People who do experience engine breakdown after straight pipes were probably running their engine too hard or were going to experience the same breakdown anyway.
-physics: your engine is running at 5000 rpm its 4 stroke so your looking at 2500 exhaust cycles per cylinder per minute. Think of your catalyst and muffler like restrictions in the flow of a pipe. Now put 2500 impulse pressures on this pipe system per minute. bang, bang, bang... your exhaust is building up "back pressure" to trying to get through the exhaust. Its not all making it because it doesn't have time to make it to the lower pressure in the milliseconds before the next bang.

So where's all the pressure going? "back" up to your engine. Your engine is trying to get rid of the exhaust to make room for the next intake of air and fuel. Preventing the exhaust from escaping is decreasing your efficiency, end of story. Its also pressurizing your engine and header cavities, which puts more stress on your components. (This stuff happens really really quickly, youtube transparent engine, you can hardly see the ignition flash without a high speed camera because it happens so quickly)

Magnaflow:
Great company, great products. Get an x-pipe system, and gain +6-9 HP on your car!!! Increase performance, get better sound and increase flow!!!! Yeah... increase flow.

X-pipe argument:
It really makes your exhaust perform better! Sure it does, consider the cross section of the x and cross section of your pipe, it works like an expansion chamber and evens out your pressures. P.S. turbulence sucks and it has no solution, for a few cycles your exhaust is going to swirl clockwise then a butterfly lands on your antenna and it swirls the otherway... dont believe the B.S. more flow is where its at. Talk to an exhaust engineer who no longer works in the industry and isn't trying to promote a product, they dont have the solution for turbulence either. They try a bunch of engineered and educated solutions, iterate small changes, and sell you the best dyno sheet. Don't be fooled.

The dirty truth:
Put it on, try it, record seasonal performance (even if your not straight piping). Keep a mini notebook in your glove box and write down the numbers when your filling up. (remember to touch a metal grounded object before returning to the pump handle if your doing this while in the process filling up).

Have fun with it, drive like a goof for a bit, rev like hell, but report your honest numbers back here and lets see what we get. Check your fluids too!

Greg_G

I cut the muffleR off my 99 and is ran fine...

yotehunter422

You'll lose power that's about it. My friend swears that if you cut off all restriction, including headers, it'll mess up your engine.

CheezeIty

This is coming from a guy who has done this twice. Your truck or car wont die as a result. Now the environment you live in could affect the style of straight piping your exhaust. Most will tend to want the full length over the rear axle for the best sound and to keep the water from entering the exit. If you want the sharp harsh bark I'd suggest short pipe under the cabin.

white89gt

10 year old thread... sorry if you joined just to answer that.... but I don't think he'll see it.

RVT1KR

Dragaxx

Probably not. =)