My Gotts Experience

Well... three years ago I promised that you might see some posts about our Ford Expedition.  It's finally here!!   Sorry, life gets in the way sometimes...


  One of the most basic mods in the car modification world today is to the air intake. Many times this takes the form trying to increase the amount of air getting into the engine.  You can accomplish this by several different methods.  Some are as simple as stock air box modifications or replacement of the stock airbox, or more complicated, expensive and fun methods like turbos, or superchargers. We have to understand that for a modern fuel injected vehicle if adding lots of horsepower, torque or fuel mileage was as simple as some work and hardware store parts, the manufacturers would have done it as a way to increase their CAFE numbers. Go into this project expecting a small gain for the money spent and you won't be disappointed.

  The project vehicle used here is a 2001 Ford Expedition 4wd with the 5.4l engine. These large SUVs represent a good value if you need a big vehicle for cargo or people and a good tow rating. Their low average fuel MPG keeps the prices artificially low. They got excellent crash ratings, the drive trains were also used in the full sized trucks meaning that parts are reasonably priced and plentiful.

  The Gotts mod is simple and cheap modification that uses the stock air filter housing It is meant to imitate the performance increase of a CAI without the cost and hassle of the CAI instillation.It is named the Gotts mod because it was first posted on F150 forum by a user named Gotts.  I used only a few tools and hardware store parts to complete this mod.  Unfortunately, I don't have access to a 4 wheel drive dyno to be able to test if there was if any increase of horse power or torque from the Gotts mod.  So with that spiel out of the way lets get down to the good stuff.

Complexity:  This is a solid one wrench job.  If you can do your own maintenance you can do this on your own.

Tools used: 8mm socket
                   Flat head screwdriver
                   Small prybar
                   Miter Saw (this could be easily substituted for any cutting device able to cut the pipe)
                   Bench grinder (this can be substituted for any sanding device)

Supplies: 3" PVC pipe (I bought schedule 40 as it was what Home Depot had)
                3" to 3" rubber pipe connector

Price: $20.38
              $8.39 for 2 foot of 3" PVC, Home Depot
              $11.99 for the pipe connector, ACE Hardware

Disassembly of the stock intake is quite easy. Pop open the retaining that holds the assembly closed and remove the air filter. The filter housing is held in place by two pins that push through rubber grommets in the mounting plate and the stock air tube is just press fit into the fender with the rubber grommet. Pop that grommet out as we are not going to need it anymore. Here is what you should have removed at this point.

Now remove just the tube portion from the air filter housing. This is accomplished by sliding a flat bladed screwdriver in between the housing and tube when the plastic catch is at. Then simply pull the air tube out.  This part is pictured on the left here:

Now cut your pipe approximately 4-5 inches long.  I originally cut mine 6" with the intentions of measuring and cutting it to fit for the blog pictures, but 4'5" inches is where I ended up with at the end.  Additionally, I painted mine piping black as I did not want any white to show in the engine bay. This was completely unnecessary as once I cut and fit everything the way I wanted it, none of the PVC pipe is actually visible.

As you can see in the photo, the pipe is quite a bit larger inside diameter than the air tube.

This is good, but its also quite a bit larger outside diameter than the air tube. This creates the next bit of work.  You have to sand down the outside edge of the pipe to get it to fit the hole in the fender. Now I bought schedule 40 PVC pipe so the wall is quite a bit thicker than some other piping, schedule 80 pipe would be even thicker. There is 3" PVC electrical conduit available that is thin walled and would require less work. I did not want a full stick of conduit sitting around not getting used, so I bought the 2' section that Home Depot had.

I sanded down the end of my pipe, about 1 1/2 inches seen here.

The sanding looks rough and bit dirty.  It doesn't effect its operation at all. My gloves were much filthier than I thought and I was rubbing the sanded part to get any loose dust or particles off as I didn't want them inside in the pipe. You can see the paint didn't stick terribly well either.. that's what I get for painting when the humidity level was well into the 90% range.  As you can see I ended up cutting my pipe until its almost the length of the couple to get every thing to fit well.  The pipe itself goes into the fender 1-1/2 inches and the black portion inserts into the coupler right up to the end of the black portion. It assembles like this:

Tighten up the pipe clamp at this time. Then you slide the other end of the coupler over the the end of the air filter housing and tighten down the pipe clamp. The slide the works back into place and press it down into the rubber grommets. This is what you get:

Put your air filter back in the house and clamp the air tube back into place.


RESULTS!!

The $64,000 question.  What did you get from it? Is it worth the money?  

I have seen this mod in a few places, but noone could ever come up with any provable, repeatable information on what this mod provides, why should I do it, and why its better than stock, or any of the other CAI type mods that intake air outside the engine bay.  I don't have access to a 4wd dyno, so I'm not going to talk about HP or torque numbers. If someone had a verifiable dyno pull showing this specific mod, I would love to post it here and credit the heck out of you.

I hooked up the Harbor Freight scanner as its the easiest to read and take pictures of. Note: I did this while driving.  That was a stupid idea, I wanted a repeatable environmental condition and it worked out that morning drive was the best time to do it. 

First.. with the stock readings at no throttle cruising

We can see .02 lbs/s of air moving past the MAF at 75.3 degrees F. Here is a picture of the dash thermometer at the time. 

We can see 71 degrees at the sensor.  I was a bit surprised to see 4 degrees different, I expected it to be cooler.  But it was a sunny morning and I had been driving about 15 minutes at this point.

Now with the GOTTS installed.

73.4 degrees F!  I was surprised to see any difference. This was actually measured at the same point in my daily drive.  Once again right at 15 minutes of driving.  The outside temp sensor once again read 71 degrees F. As we can see however the MAF is seeing .02 lbs/s of air. So there doesn't seem to be an increase of measurable air flowing through the MAF. The cruise control may not have had the throttle open the same amount, I did not take the time to configure the screen to show throttle position on the same screen as intake temp and MAF. 

Seat of the pants feelings towards this....  I did feel like there was a slight increase of throttle response, more down low than in the higher RPM range.  BUT... That could be attributed to my driving style. I bought my 5.4 for the torque of it and that is most prevalent down lower in the RPM range.Peak torque is measured at 3000 RPM and I very rarely ever exceed 3k RPM while driving.

One other thing of note.  I used an Amsoil EA dry-flow air filter for these tests.  This is a performance style air filter that uses a dry media rather than an oiled one. This were great filters, too bad they are discontinued now.

Comments, questions, insults??  Post 'em below!!