i have a question about backpressure when adding a Y-pipe while keeping everything else stock...

will i have abnormal backpressure which might affect exhaust flow out of the engine.......and also do aftermarket Y-pipes use larger diameter piping than the stock Y?

 

Dont worry, you still get plenty of power using the stock cat back.

The Y-pipe outlet is 2.5". This is the same size as the inlet on the OEM cat.

 

yea, dont worry about ur back pressure. Just keep your cat on, unlike me...who was to take it off and fry everything due to no back pressure BUT ANYWAYS!! yeah, the Y-pipe would be a great investment for u right now.

 

Lies.

 

so there is no difference in the diameters between the stock and aftermarket y-pipes?

i didn't know the inlet for the cat was 2.5", if that's so then basically Y-pipe diameter doesn't change when going aftermarket.....just the pre-cats are removed

or am i still missing something

 

The aftermarket pipe diameter is larger than OEM. But it's not larger than the cat openings.

 

There is also no such thing as back pressure

 

ok, that makes sense, just trying to grasp how i'm going to put on a Y pipe while keeping everything stock

i take it the most an aftermarket Y differs in diameter is +.25"

 

Sure there is. It can be measured.

 

Go ahead and get that for me

 

If you insert a static pressure probe at the upstream end of the exhaust system, you can measure the pressure. In automotive parlance, this is called "backpressure."

To normal people, it's just called "pressure."

It's just terminology.

 

well i just used back pressue because i've heard that term somewhere......i'm just worried i may improperly alter my exhaust flow due to having stock header diameter, increased Y-pipe diameter, and stock catback diameter(mainly concerned about restrictive B-pipe)

but maybe getting exhaust out of my engine is not as complex as i make it out to be

 

It's not. Less back pressure is always better.

 

also mzmtg, i read on another forum that you have a leaking front caliper........if you have ABS i can help you out since i've got two good looking calipers i took off my max, just tell me left or right and its yours, just pay shipping

 

You might have a case for "resistance to flow pressure" but there is no "back pressure". Only exhaust gas velocities. Becuase I didn't see any flowing backwards from the tail pipe to create any "backpressure". hehe

 

That is incorrect.

 

It's still the pressure that the engine must overcome to move the gas through the pipe. Call it whatever you want.

 

When is backpressure a good thing?

Notice I only mentioned pressure, not velocity...

 

I'll call it by it's correct term. Exhaust gas velocity

 

Because there is not backpressure. No such thing.

 

Pressure is always a factor when dealing with fluids flowing through pipes.

 

gotta run to class, i'll be coming back to this later

mzmtg, above i put up about a caliper....lemme know if you want it

 

Let's all read the basics about pumps and piping systems...

http://www.roymech.co.uk/Related/Pumps.html

 

You can look at from a pressure standpoint if you wish. I'll look at it from a velocity standpoint.

 

They are related. One affects the other.

 

I can ignore the pressure aspect if the velocities are high. But can if the "backpressure is low" will the velocities be high?

 

In a properly designed system, one can minimize pressure while maximizing velocity.

 

But you just said "the less backpressure, the better". Nothing about velocities at all. By just saying that, the person should install a 3.5" exhaust system to lower the "backpressure" as much as possible.

 

Oh yeah? Well you said:
Pressure acts in all directions, regardless of flow direction.

So there.

 

How much pressure is exerted directly backwards in the flow of the exhaust pipe? More than the 1 bar that is already exerted at the other end?

 

Yes. The pressure inside the pipe must be higher than atmospheric, or the exhaust wouldnt flow out of it. Fluids always flow from areas of high pressure to low pressure.

 

Didn't you just say the less pressure the better?

 

Now you're just being silly.