I am thinking about porting the stock throttle body and stock plenum when I install my K and N air filter. How much wheel horse power will it free up? Is it even worth it? Car is stock for now.
It will free up about .1HP if your lucky, honestly it's not worth your time. If you are going to do it then put most of your focus on the plenum, it is the most restrictive piece, not the throttle body.
If anything do it for the experience, just to say you did. I am going out on and limb to say you throttle respone will increase. I've notice the more air your engine can suck in, you widen the HP range in different weather e.g. rainy or hot muggy days your car is going to perform worst than stock, cold dense air days, your car is going to perform very well, seem very fast.
P.s. Don't be afraid to challenge the norm, most people you will encounter are sheeple.
Your sig says nothing about a 4.6 car so I am just going to assume that a 4.6 is what you have. Don't bother porting the plenum, you will get much better (although still meager) results going with an aftermarket plenum. As for porting your TB, you shouldn't do it for at least 4 reasons.
1. You need the air moving through the TB in very particular way. TB's are designed so that the change in throttle body position results in a smooth change in air allowed to pass the blade. Porting will change the way the air flows through the TB and you ruin this linearity. It won't be as extreme as zero to WOT with a fraction of an inch pedal movement, but it certainly won't be nice and consistent either.
2. If you port the area right at the blade, you will allow more air to pass the blade when it is closed. That will royally jack with your idle and probably cause you to burn a LOT more fuel when not moving. If you port everything except the blade, its still going to have the same airflow as before because the diameter at the blade's location didn't change. A royal waste of time.
3. At stock levels the TB is absolutely not a restriction. You will gain nothing even if you bought a new larger TB. Spend your time and money working on the components that will actually provide results. To give you some perspective, the stock TB for the 5.0 (302 CID) was 55mm, the stock TB for the 4.6 (281 CID) is either 65 or 70mm (can't remember which).
4. If more flow out of a TB is something you absolutely just have to get, I am sure there are a LOT of people around here that would gladly sell you theirs for a lot less than retail to recoup some of their loss.
Not trying to bash you, just trying to prevent you from wasting your time and money.
Your sig says nothing about a 4.6 car so I am just going to assume that a 4.6 is what you have. Don't bother porting the plenum, you will get much better (although still meager) results going with an aftermarket plenum. As for porting your TB, you shouldn't do it for at least 4 reasons.
1. You need the air moving through the TB in very particular way. TB's are designed so that the change in throttle body position results in a smooth change in air allowed to pass the blade. Porting will change the way the air flows through the TB and you ruin this linearity. It won't be as extreme as zero to WOT with a fraction of an inch pedal movement, but it certainly won't be nice and consistent either.
2. If you port the area right at the blade, you will allow more air to pass the blade when it is closed. That will royally jack with your idle and probably cause you to burn a LOT more fuel when not moving. If you port everything except the blade, its still going to have the same airflow as before because the diameter at the blade's location didn't change. A royal waste of time.
3. At stock levels the TB is absolutely not a restriction. You will gain nothing even if you bought a new larger TB. Spend your time and money working on the components that will actually provide results. To give you some perspective, the stock TB for the 5.0 (302 CID) was 55mm, the stock TB for the 4.6 (281 CID) is either 65 or 70mm (can't remember which).
4. If more flow out of a TB is something you absolutely just have to get, I am sure there are a LOT of people around here that would gladly sell you theirs for a lot less than retail to recoup some of their loss.
Not trying to bash you, just trying to prevent you from wasting your time and money.
Again, You will gain HP when the conditions are right, and lose when the conditions are not in your favor. The air is going to flow into the intake manifold no matter what you do, the science to the porting is not exactly rocket science, more volume of air in the top end the quicker the throttle respone but, hot air is a thief of horsepower, if you want continuity get forced induction or drive at night for the dense air. The "positioning" and Mass of air really matters before the MAF sensor. Stock Throttle body is 65 mm. I had my TB ported, the throttle response is amazing and at night when the oil is cooler and the air is dense it pulls like it had some type engine overhaul but, lacks power during the day. He ported my throttle body all the way up to the blade so the blade wasn't changed. 74 mm give or take, I never have regret the descision. No two upper plenums are shaped the same. So long as the air makes its way to the lower intake manifold the descision is not that big of a deal. End of Rant.