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I was reading some threads about some guy losing tq and hp and at first they thought it was because he had 3inch pipes and they told him to get reducers...like i've said before i dont knwo much about exhaust so y is a thicker pipe worse...wouldn't it let more exhaust out...some one please explain:help:
 

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raliesportslayr said:
I was reading some threads about some guy losing tq and hp and at first they thought it was because he had 3inch pipes and they told him to get reducers...like i've said before i dont knwo much about exhaust so y is a thicker pipe worse...wouldn't it let more exhaust out...some one please explain:help:

All engines work differently.

A bigger pipes will decrease backpressure in an engine, reducing the pressure I would think leave less for torque and more for HP, 4 cyl engines work better with hp rather than torque because they are generally light cars and dont need the torque to move. So a bigger pipe may increase hp but lose torque that's why a lot of ricers upgrade to a bigger pipe.

V8s generally output a lot of torque- hell thye have 8 cylinders at work. they don't need back pressur so much because of the excess power they output, but they also weigh a lot. so they still need torque but the engine supplies it thouroughly.

the v6 engine needs it's back pressure, it weighs a bit, and could use the torque the more you open the pipe the more the engine lets out pressure. so the engine runs looser. but the v6 doesnt produce enough torque to keep moving.

So what do we do, we add power, we add superchargers or turbos, we port the engine. putting out more pressure allows us to release more pressure, but if an engine is not putting out a lot of pressure, releasing more pressure would not do it any good, so a smaller pipe doesnt let out all the engines pressure for torque. now if you had a Superchrager and running a ported v6, going up to 3 inch piping... is still a bit much, but 2.5-2.75 piping will help compliment the power increase.

It's something along those lines, could be wrong in parts but it'sbasically the v6 requres back pressure to run good torque numbers and opening the ehxaust would lessen back pressure thus reducing torque numbers = slower.
 

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If the pipe is too big, you will lose bottom end torque and horsepower due to a lack of backpressure. Bigger isn't always better. If the guy with the 3 inch pipes had an all out 400+ hp motor, then he would be fine because he has a motor that makes peak power and torque higher up in the rpm range than a mostly stock, bolt-on car like most of us have. On a bolt on 3.8, 2.25 inch pipes are ideal.
 

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Diameter

I think the diameter problem has to do with keeping the exhaust gas velocity optimal. The length and diameter of header tubes, collector size and exhaust size all affect the shape of the HP curve. Generally speaking long, small header tubes make better low end torque. So do smaller pipes and cross overs. Nobody needs 3 inch duals unless they have a supercharged Cadillac 500 c.i.d. engine or a big diesel.
 
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