[Xantho99]

Honestly, will running 3 inch exhaust on my 02 GT really hurt anything? I am more concerned about the sound of the car than the power right now.

I'm planning on:
-Long tube headers w 3 inch collector
-3 inch H pipe
-3 inch 40 series flowmasters, dumped

[HMUSN]

you don't really need 3 inch unless you plan on making LOTS of power.

[Xantho99]

Originally Posted by HMUSN you don't really need 3 inch unless you plan on making LOTS of power.

Define lots of power

[HMUSN]

600 +

[Xantho99]

so my question is: will it hurt my engine by running 3 inch exhaust?

[HMUSN]

you might loose a bit of TQ but other than that it won't hurt you

[00SlvrStang]

you will definately lose some power on the low end but it wont hurt the car

[WilltheThrill]

Originally Posted by HMUSN you might loose a bit of TQ but other than that it won't hurt my feelings.

[Xantho99]

someone said that it would burn my valves...

[ModMustang97GT]

They are concerned that it will run lean from that. More flow means more air, and a potential miss reading of the engine computer and leaning out the fuel. It shouldn't be an issue. If anything I would think it might go rich. Either way, a tune would take care of any issues. Get it tuned and enjoy the MUCH LOUDER sound.

[cliffyk]

It won't increase "flow", the engine can only pump so much air/exhaust gas; and that's the root of the problem; the flow volume will stay the same and the flow velocity will decrease.

A 3" exhaust (44% larger area than a 2-1/2" pipe) will do is significantly reduce the velocity of the exhaust gasses--and then, aside from reducing the low pressure "wake" behind each exhaust pulse, it will allow the gasses to expand faster (and cool), The larger diameter pipe will also radiate heat better and further cool the gasses.

So, "Who cares of my exhaust gasses are cooler?"

You should, because exhaust gas is a fluid and like any fluid it thickens as it cools. Thicker means more power is required to push it out the tailpipe, and more power required to push it out the tailpipe = less power to make the car GO...

------------------------
BTW--2-1/2" (what I and most others are running) is arguably too big for an n/a 4.6 L dual exhaust, however no one makes 2-1/4" or 2-3/8" stuff and it's not really that much too big to matter. 3" on an n/a engine would be "too big enough" to matter.

[acmillr]

Originally Posted by cliffyk ------------------------ BTW--2-1/2" (what I and most others are running) is arguably too big for an n/a 4.6 L dual exhaust, however no one makes 2-1/4" or 2-3/8" stuff and it's not really that much too big to matter. 3" on an n/a engine would be "too big enough" to matter.

That's why you get less power with open headers------LOL

I see the misinformation is still bountiful on this board.

[mattstang]

i have 2 and a half on my truck to 3'' single chamber flows.. didnt make any difference

[cliffyk]

Originally Posted by acmillr That's why you get less power with open headers------LOL I see the misinformation is still bountiful on this board.

Open headers are NOT an exhaust system, study up on fluid dynamics first then come back and hurl insults...

Edit: Hook those same headers up to a set of pipes that's too large or too long and power will suffer...

[acmillr]

Originally Posted by cliffyk Open headers are NOT an exhaust system, study up on fluid dynamics first then come back and hurl insults...

You mean like for two or three years at a university?? However, I was not trying to insult you personally. The guy asked a question- "will 3" exhaust hurt me?" The answer is NO on his set up. There's way too much rationalization going on here.

[cliffyk]

I apologise if I come off as an engineer/engineering professor--problem is I am (MSME MIT '71 and never stopped learning since then).

Too large a diameter exhaust pipe will hurt power output for the reasons stated; it may not do it to an extent that anyone (but me) would care, but it will do it nonetheless...

[acmillr]

Let's be friends anyway........... LOL.

BTW> No engineer here. Just pullin your chain.

[mattstang]

so engineers what do you need to have to take advantage of a 3" setup

[HMUSN]

^ something other than a 2v


so yea.. all this adds up to is.. you will lose a little TQ.

[mattstang]

hey i said engineers not docs so GTFO




















sorry doc