DIY 4" Intake with LS7 MAF (PCM of NC Kit)

DIY intake kit for TBSS

PCM of NC offers a DIY (Do It Yourself) kit for those wanting to install a through the fender intake on their trucks. Alvin at PCM of NC doesn't take credit for the concept as there are a couple other people selling them on a small scale basis not to mention ADM Performance was close to marketing them a couple years ago but scrapped the idea. Beyond that he did put together an economical solution for those not wanting to run down parts and build their own.

The kit comes with a rough set of install directions but the whole DIY concept is to allow the user to install and tweak it it to their personal preference. I personally did not like the extra silicone overlapping so I ended up trimming both silicone and aluminum tube. In the end I wished I had not trimmed quite so much on one silicone elbo and might end up ordering another one to get the horizontal part of intake up higher.

The advantages of the 4" intake are a two part. First it allows you to pull cooler air from outside the engine bay and the LS7 4" MAF flows better for trucks making more power (Heads, Cam, forced induction, etc).

This is my third 4" MAF style intake and I have never been a fan of the larger MAF on bolt-on trucks. In my experience they did not perform any better than the traditional tube style intakes sold by IEATSRT8 or Vector and for reasons I don't fully understand they effect how the truck drives/shifts. You would think that once you had the MAF/hz tables calibrated the ECM would never know the difference. But every 4" MAF tune I have ran (ADM, PCM of NC, Westers & Fast Motorsports) shifted differently.

The disadvantages are the truck requires special tuning, you need to cut a hole in your fenderwell to pass the 4" tube and you lose your OEM windshield washer fluid tank. You also have to repin your harness into a new MAF connector. See here

Special Tuning - You will need to update your low and high MAF airflow vs. frequency tables and your IAT sensor curve. Alvin sends tables to get you back running and in my case they were actually very close. Additional tweaking of VE is recommended as with any tune.

Fenderwell hole - Using a 4.25" holesaw you need to drill through the fenderwell (Figure 1). I drilled a 1/8 pilot to verify hole location on the bottom (Figure 2) to make sure I had proper clearance. Figure 3 shows the bottom 45 degree tube installed with the L bracket bolt (from the top) and the actual bracket (from bottom) I added in Figure 4.

Its recommended you install some type of edging on the new 4.25" hole. Something like small hose, door edge guard, etc. As mentioned above I also added a L bracket (Figure 4) to secure the lower portion in place.

The filter is pretty tight behind the passenger side brake vent on bumper (Figure 5 & 6). With a little patience and trimming on bottom aluminum tube I got it to fit very well and the filter was easy to remove.

Replacement washer tank - One of the reasons I have been reluctant to do the fenderwell intake is I did not want to give up my washer tank. Alvin has came up with a nice solution that tucks in the corner (see Washer 1 and Washer 2).

The new tank holds 1 quart of fluid and retains use of both front and rear washers. You will no longer get a low washer fluid indication as there is no provision for low sensor in the new tank.

I had to play with the pump mounting to get things to fit in the corner without hitting something but it really wasnt bad. Those of you that use a lot of washer fluid might not like this setup because of the 1 quart capacity and the small 1/2" NPT fill cap.

Overall - I think its a very nice setup and a good mod for bolt-on trucks and hightly modded ones. Even if you don't need the extra flow capabilities of the 4" MAF you will benefit from pulling cooler air.

My only complaint is the MAF sits really close to the upper radiator hose exposing the IAT to elevated temperatures. If I had it to do over again I would probably trim less as noted above and try to twist the intake to get it further away from the radiator hose. Actually I am thinking this might be a good place for a HSRK. I also have one minor complaint that I have not attempted to resolve. The kit comes with a small K&N filter to install on your PCV inlet and mine picks up a whistle under certain throttle conditions. Doesn't hurt anything but I find it annoying.


A few tips that apply to most intakes.

  • Wrap the upper radiator hose with thermo-tec wrap to keep the coolant heat away from the MAF housing. You can also squeeze the clamp and push the radiator hose down further on the water pump which is a truck I learned from Andy at ADM.
  • I always mark the tubing on my intakes about 3/4" in from the end. This way I know I have safe overlap with the silicone. Since this kit comes without finish, I had it powdercoated and taped both ends and left the ends natural (see Tip 1 image). I have seen several installations with various intakes where the installer did not get proper overlap and either had a leaking intake or the hose slide completly off. Having marks makes it much easier.
  • The silicone elbos often come with a rough or crooked edge. The best way I have found to make a perfect edge is to install the hose on a section of tubing and secure with a hose clamp. Use the hose clamp as a guide and trim with a sharp razor blade. (See Tip 2 image)

Final comments - Monitoring IATs it's obvious that having the filter behind the bumper does work. In the past it took intake flow and vehicle speed to drop your IAT levels after they were elevated. Now its mostly engine speed and vehicle speed hardly matters.

PCM of NC claims this intake will make 15hp over other aftermarket tube style intakes.

Highly recommended to those willing give up their large washer fluid tank and drill a large hole through the fender.

Kit (hold for larger image)