My 03 screw 5.4L is all stock. There have been no mods to this truck at all. How much more umph will I get if I just put a K&N air filter kit on it?

 

I rebuild 60's Mustang engines. Performance to me is head cc's, decking the block, cam, carb, ignition timing. So feel free to ignore anything I'm about to say.

Short answer. None, probably negative. First, on a good air day on a road with little traffic, pull you air filter and leave the top of the filter box off or the cylinder open. Now you have considerably less air restriction than with a K&N. Drive it up and down the road until you have a feel for it. Put the air filter back on and repeat. Or better yet have a buddy remove or replace the air filter each time and not tell you which it is and try to guess. The K&N air filter will make less than 1/2 that much difference.

As for negative. Using a manually oiled filter introduces the possibility of MAF contamination by the filter oil. At wide open throttle, the MAF is used for fueling calculations. Running rich due to a non-responsive or slow responding MAF could make significant power reductions. I'm sure that if a K&N professional oils the filter and dries it for several days in the air after oiling, this would be slight. But I'm equally sure, using oiled filters on my motocross bikes, that sometimes they will be overoiled or put on wet.

But it is cool to mod your truck. A chip might be my first mod if I was still young. With a chip tuner, you might even become more familiar with your truck. That was a key advantage for rodders back in my day.

 

I used to run a K&N filter. I have since ditched it for a regular fram. Oiling the filter was a pain and I was always afraid that oil would contaminate the MAF. I actually went through 2 K&N's because the stupid foam/rubber gasket kept coming apart because of the oil.

 

Well, I guess it just ain't worth it. I'll stick with stock filter. Thanks!

 

You said "kit"....do you mean drop-in filter or complete air intake kit? The drop-in adds a few horses, but is not enough to feel in the seat of your pants. The complete kits offer 10-12HP or so. I'm a fan of both. The MAF problems are a result of over oiling.

 

Agreed and don't take the stock exhaust system off.
There is little gain to doing these things on a heavey truck.

People forget that mods usually are effective at high engine speeds where you don't normaly run in regular driving.

On the filter, remember that at low throttle openings, the throttle body blade angle determines how much air is allowed into the engine, not the air filter.