Whats back pressure??????

I've been reading some forums and somebody was talking about back pressure. They also said that its good for NA cars. Could anybody explain what it is.

Back Pressure is the pressure in the exhaust.

Back Pressure is bad. Velocity(speed through pipes) is good... but to get Velocity you need back pressure. all people are saying when they talk about back pressure is to Tune the Pipe diameter to your Engine (Displacement, Powerband, ect) KAs like 60mm for midrange 75mm for Top End.

When your going under power to exhaust stroke just before the valve closes there is a vaccum (valve overlap) which is needed for the next intake to compression stroke. Back pressure can be adjusted by the exhaust pipe diameter that you use. Just as R.W.240 stated

Back Pressure is the pressure in the exhaust.

Back Pressure is bad. Velocity(speed through pipes) is good... but to get Velocity you need back pressure. all people are saying when they talk about back pressure is to Tune the Pipe diameter to your Engine (Displacement, Powerband, ect) KAs like 60mm for midrange 75mm for Top End.
its odd that a guy who has never had an import knows all this stuff about imports........and he drives a chevy truck :iceslolan

Back pressure happens in all cars, not just imports.

Backpressure Is Found In All Exhaust Systems.

Some Backpressure Is Good On Na Cars.
Backpressure Helps Build Low-end Torque, But Too Much Is Bad For Total Power. If You Reduce Back-pressure You Increase Top-end Hp Because It Frees/speeds Up Exhaust Flow And Some Minor Backpressure Is Good For Low-end Torque. The Key Is To Find A Happy Medium Or The Ideal Setup For Your System.

Backpressure Is Not Wanted On A Turbo System Because The Turbo Needs A Free Flowing Exhaust To Spool Quickly. Also The Turbine Itself Creates Alot Of Back Pressure Between The Turbo And The Head.

its odd that a guy who has never had an import knows all this stuff about imports........and he drives a chevy truck :iceslolan

Some people believe that the best tuners have a lot of domestic expirience. The skills transfer very well. I know because I used to be all about domestics.

I don't agree, when you are used to domestics, you get used to doing things like a good head job and getting an extra 10-30% increase in power, sometimes 30-45%, do that to an import and usually max will be around 25%, domestics have so many gray areas to boost up power, imports are better built and usuall maxxed out, so the increase is usually less. eg, a 3.5L VQ put out 287Hp, a 3.8 T-bird 200Hp, leaving a big margin for improvement.
The new M3 3.0 or is it 3.3L I-6, 333HP, even dinan could not upgrade the engine much more, they got like an extra I think 10-30HP, any more and it would be like building a race engine, so they resorted to swapping an M5 engine cuz thats the best major power gain they could think of. Vette 5.7L 400Hp, I've heard of guys with 550Hp-600hp out of the same block after a complete rebuild of the engine.
To sum it all up, I think it will be very frustrating to switch from domestic to import cuz the things you are used to doing to get power are already done, and now you have to find new ways, but I think it will be more liberating to move from import to domestic, where anything small can get you tons of power. But I would ratheer go with Quality than Quantity.

The new M3 3.0 or is it 3.3L I-6, 333HP, .

Actually it's 3.2 liter, but you're right about the rest of the stuff tho.