Freeing up or adding hp?
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Post Fiend
Joined: Jun 2004
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From: Joppa, Maryland
Freeing up or adding hp?
Do CAI/exhaust systems free up potential power or are they 'making more' power?
This is a bit of battle going on at a mazda site i've been going to. It seems to me that bolt ons are just freeing up existing power, and not actually 'making' power. Is the train of thought correct, or do you think otherwise?
Obvisouly with things like lighter wheels, underdrive pulleys and that type of thing you are just freeing up power thats there, but does the same principle apply to CAI/exhaust systems?
If cai/exhaust are 'freeing up' then at what point does it become 'adding'.. supercharger, turbo, nitrous? cams, intake, etc? What does everything fall under?
Discuss
- Paul
This is a bit of battle going on at a mazda site i've been going to. It seems to me that bolt ons are just freeing up existing power, and not actually 'making' power. Is the train of thought correct, or do you think otherwise?
Obvisouly with things like lighter wheels, underdrive pulleys and that type of thing you are just freeing up power thats there, but does the same principle apply to CAI/exhaust systems?
If cai/exhaust are 'freeing up' then at what point does it become 'adding'.. supercharger, turbo, nitrous? cams, intake, etc? What does everything fall under?
Discuss
- Paul
Postmaster
Joined: Jul 2003
Posts: 2,628
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From: Calgary, Canada
Lighter wheels and underdrive pulleys translate to less parasitic drag; meaning they take away less from the vehicles capabilities. Technically, the same could be said for CAI and exhaust; factory intake and exhaust are usually restrictive. With those you're really just letting the engine do it's thing more efficiently, without any real modifications. Adding major modifications like forced induction (blower, turbo, nitrous, etc), cams, shaving heads, etc are what I would consider major addons or modifications.
To specifically answer your first question, a CAI allows more air flow, more air flow means more fuel can be burned, more fuel burned = more power, more fuel burned needs somewhere to go, hence the requirement for bigger, more free flowing exhaust.
To specifically answer your first question, a CAI allows more air flow, more air flow means more fuel can be burned, more fuel burned = more power, more fuel burned needs somewhere to go, hence the requirement for bigger, more free flowing exhaust.
Last edited by furball69; May 15, 2006 at 08:46 PM.
Post Fiend
Joined: Jan 2005
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furball69 gave a great explination, but I found that the secret to making hp with bolton's on a modern engine is proper tunning, if that computer ani't happy, nobodies happy. Alot of people will buy cai's, or headers, and are disapointed because the computer is compensating for the mods, and they get no increase, or seem to lose power. A good programer can make all the difference in the world.
Posting Guru
Joined: Dec 2002
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From: Racine county, WI
Freeing up power is like taking weight out of the car and making power is like changing the characteristics of the engine via an exhaust system change or bolting on a different intake. Even a high flow air filter is making more power.
Gone but not forgotten.
Joined: Jul 2001
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A common misconception re horsepower is that the more air available to an engine and the least restriction to exhaust will increase horsepower (I have seen it argued here over and over), but that is true only to a certain point. An engine will use a certain volume of air depending on several factors and no more. Increasing air available beyond that point makes no difference to output. Exhaust back pressure can be relieved with bigger pipes, but bigger is not necessarily better since a big pipe can reduce exhaust gas velocity. The best situation is when the pipe is wide enough so that there is the lowest level of positive back pressure possible while achieving the highest exhaust gas velocity (scavaging). Many who add on huge exhausts and air systems are only shooting themselves in the foot.
Dono
Dono
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Post Fiend
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This is so true, too large of an exhaust will rob you of hp, or at least at any usable rpm range, also more air without more fuel can be piontless, and too much air is a waste, cause the engine can only use somuch. When adding mods, it's good to do your homework, and benifit from others experience. It's also hard to beat a good dyno tune, it will let you know whats too much, and not enough.
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Joined: Apr 2006
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From: New Springfield Ohio
I'm going to have to agree with dono and furball. In the sense that more flow means more power. But only up to the point where the design of the engine can use that flow.
Dono brings up a good point about exhaust size.
Dono brings up a good point about exhaust size.
