AIR INTAKE

 

 

 

 

 

 

Like the exhaust work, I had to go through a few designs before I came up with the current air modifications. This is a good history of the progression of the design.

The initial steps not shown were basically wrapping duct tape around the middle of the OEM air box with no air filter inside (though I did use a K&N filter at one time). Later on, I added the Weapon-R Dragon Intake. The modifications you see below came after the Weapon-R Dragon Intake.

TunedRX300 at Club Lexus came up with the idea of the lower air intake (known as the bullhorn on this page) a little bit before mine. He has an excellent design that works with the existing air box.

The top parts consist of a heat shield cut up from a cooking pot I got at WalMart ($5), a Weapon-R pipe (the filter went to Carlos for his VR6...pretty and it is just to help him win car shows) ($152 for the complete Dragon Intake System), a Blitz Performance SUS Air filter ($110) (though you can find clones). The original Weapon-R filter just plugged the air unlike the Blitz Performance SUS filter. My cousin will not even race with the Weapon-R filter on in his VR6. This leads into a lot of other plumbing I will get to.

 

A Blitz Performance SUS Air Filter. The center circle on the top is cut out in my modifications. More on that later.

 

 

Weapon-R pipe

 

 

Weapon-R Dragon Intake Air Filter now used for show in my cousin's Golf VR6.

 

 

What I did was velcro and glue together the top of the air filter to the back of the pot (after I cut out a hole). We also made holes for the clamp that hooks up to the brake fluid bracket. Note the plastic piece you see inside with the duct tape on it. I will get to that in a bit.

 

 

How does this fit together? I had to make a hole at the center part of the SUS air filter and add a PVC piece (the black piece you see above) to lock into the middle of the air filter. The black piece can be found at Home Depot and is basically a small cone with a little cone on top of it and off center. It fits easily into the top of the plastic OEM piece that once connected to the air box. All of the PVC used cost under $50.

 

 

 

Two pictures of the black adapter piece.

 

 

Black OEM piece with modification on the end.

 

This gives much better flow rate. The theory for me with the air filter here and the heat shield is for better response at low RPM (especially off the light at the track). The OEM configuration...even with the air box...took too long to allow air to reach.

 

This is a picture of the black adapter piece before being converted. You have to chop off that ring you see at the top if you want to do my mod so as to allow it to enter the center hole of the air filter. Another idea that works, especially if you are not going to open up the hole in the middle of the SUS filter, is to leave the ring on so that the ring can sit flush against the middle circle on the SUS filter. Either way, you need to carefully crumple this piece to get it into an oval shape. Do not worry as it will fit in the OEM piece. You will need to use some caulk as even though it will fit, there is a small area where air can still escape (and thus you lose some boost if you do not caulk it).

 

However, this part of the mod only makes this area more efficient than the air box. One needs more air to get more power and that needs to come from somewhere.

 

Enter the bullhorn mod you see above. Underneath the driver's side headlight is a bullhorn mated to a half U PVC piece that goes where the air resonator used to be. Using the OEM plastic tube below the fusebox this rams the air in. I secured the bullhorn with plastic ties and a lot of duct tape. Again, not pretty but no one can see it. I got the bullhorn for $20 on sale at Radio Shack. The diameter of the white area is 1.75 inches.

 

 

I had to relocate the horn to the left of the hole in the center as previously it was on the right side. This is easy to do and there are existing holes for the screws on the left side.

 

 

In the picture above look straight down the hole in front of the white piece attached to the blue pipe. I made a little space in this picture so you can see the duct tape and plastic ties on the L-joint into the bullhorn.

 

 

Here is a rear shot of the bullhorn from inside.

 

 

One of the brackets used to help secure the bullhorn along with the duct tape and plastic ties. The bracket came with the bullhorn and is screwed into place where the screw holes were for the OEM air resonator that was tossed.

 

 

The L joint behind the bullhorn.

 

 

The L joint with bullhorn shown against the ground. This was during the redux that I will talk about at the bottom of the page.

 

 

This is how the original bullhorn design looked just before the redux. My cousins and I were just about to remove this piece for the upgrade.

 

 

 

 

An interesting piece you can see in the pictures above is a small half-U-shaped plastic piece that sits at the intersection of the vertical plastic tube to the OEM plastic air tube underneath the fusebox. The last thing you want is the air being rammed in through the bullhorn only to get partially dispersed into the engine bay back through the OEM air entrance behind the headlight. You can use this piece to force the air toward the engine. Just push it down enough so it does not block the OEM entrance. You will not have a problem.

 

 

A recent mod idea occurred to me after removing the plastic radiator cover. What about a top side air inlet? Thus, we used a piece of PVC pipe secured with plastic ties as you see above parked on the right side of the engine. The air runs through the grill when the hood is closed. It lets out air at the OEM entrance seen in the picture below. NOTE: After recent analysis, this mod works very well in cold weather, but actually seems to hurt the times in warm weather. So for now, this pipe is off.

 

 

Note battery on right and OEM air hole on left. Headlight would be on top of picture. White plastic piece is an L-shaped piece that runs to the front of the OEM air hole. Do not block it totally as you need some space there for some extra air to enter when the RX starts up. I tried it by blocking it totally with the blue PVC piece and the RX hated it, so make sure you follow my instructions on this one. You can also see what this looks like when the OEM plastic piece is removed in the picture below. Now you see where the air comes up from the bullhorn mod.

 

This air setup brings up two good questions.

1) How do you filtrate the air? I have two means...race mode and driving mode. There is a small plastic tube (about 4 inches long) that goes inside the air filter and sits flush on the black PVC piece that goes inside the air filter. This helps ram the air to the MAF sensor for better power. After finishing racing for the evening, I put an equal piece back on with some very fine screening (OK, sometimes I forget) that is secured by duct tape. The picture below shows the race mode configuration for a better view without screening and to get more power.

 

 

 

A picture of the plastic piece that is inside the air filter and how it locks in with the black adapter piece.

 

 

 

Looking through rear of air filter. The piece you see sticking through is the black adapter piece without the white piece attached. Note how the top ring is chopped off as opposed to the earlier picture of this piece. It will not fit unless that top ring is removed.

 

 

A picture of how far the white plastic piece goes in once the air filter and heat shield are put on in normal position.

 

 

A picture on the other side of how that piece on the other side connects inside the air filter.

 

Thus, I get ram air from the outside along with quick (but largely heat-protected) air from the engine with this configuration.

2) Do you get the infamous P0171 lean OBDII code with all the air getting in there? Rarely and not when you think it might happen such as high speed. Usually when starting off and if I floor it and then let off there is a delay between the fuel and the air and about 3 times a month I get this, but under normal or racing conditions never. I keep an Actron OBDII scanner with me just in case.

KEY: I learned this on the night of my record run. Do not shove the Weapon-R pipe in so much into the air filter or the 60 foot times will be miserable and you will lose boost. This avoids taking air through the air filter (that you need for more power). Position it so that that the front part of the Weapon-R pipe just goes no further than the black rubber piece above without any excess of the tube visible inside the air filter area.

AIR MODIFICATION REDUX

After running the current air modification for roughly a year, I felt it was time to increase the air volume. One very important thing I learned with the old bullhorn design is not to trap air, but rather to let it breathe in a few places. My Blitz Performance SUS Air filter seated before the MAF sensor is an example of this.

Why? When one rams air in there are some choke points...primarily where there are bends. If too much air flies in (as in my first design), it dams up and creates pressure. This pressure in turn blocks the ram air flow that I need for power.

In the Redux, we made a few changes, but for all intensive purposes the Redux is just a slightly larger tube and some aesthetics.

There is a noticeable amount of torque greater than before, and the RX is smoother during gear shifts. I do not feel any damming of air (like a loud roar when I hit the gas). In addition, the exhaust sound seems surprisingly quieter than before, yet the idle is slightly higher than with the previous air design.

 

Yes, there is a bulge when one does this type of modification. This is after the Redux, but I had one on the original, too. This could be avoided by not using a curved joint after the bullhorn entry, but instead a slashing design shooting straight at an angle from the bullhorn to the bottom of the OEM black adapter piece shown earlier. We chose to go with the original type of design, just because we knew it had worked. The tires will not even come close to rubbing.

 

 

This is the new bullhorn design (same bullhorn used originally though), with a larger tube than before. This is before we used duct tape and plastic ties.

 

 

This is the entry to the black OEM adapter piece shown earlier. One change from the old design was the removal of that white curved piece that throws the air toward the throttle body. This was part of the idea to remove pressure buildup for easier and faster airflow to the engine.

 

 

This is where that piece in the prior pictures joins with the black OEM adapter piece. Notice that the bottom part engulfs the top part, unlike in the original design. There is actually some room between the two pieces (that white semicircle ring) at the area where they join where air can seep through while ramming its way in. We chose not to caulk this area as it would result in pressure buildup and thus block airflow.

 

 

This is after the duct tape and plastic tie treatment to secure the unit.

 

 

This is a zoomed out shot of the same area. Take note of the white area not taped. We left this uncovered for a reason I will talk about in the next picture.

 

 

This is looking from the front of the bullhorn. The three holes release pressure buildup and allow the airflow to be smoother, and that is the reason for the untaped white area behind the bullhorn.

 

 

The front of the bullhorn as seen from in front of the front bumper. The diameter here is 3 inches.

 

 

This was the blue top air entry unit seen in earlier pictures. My cousin painted it black for aesthetic reasons, but we also made a performance change. The white piece on the end is different from the original. We actually ended up chopping off a little bit of the end of it, while still having more of it than the original, so it went into the front of the OEM adapter piece a lot more. This was due to the removal of the curved pieced that redirected airflow. Thus, this helps force the rammed air from below to keep its course in check toward throttle body somewhat and also adds additional airflow.

 

 

This is how that piece looks on top when installed.

 

REDUX THREE

 

 

 

Three nights after I did Redux two and noticed a .2 second lower time in mid 60 degrees weather at my track (not records but outstanding for the weather), I did another change and made a 4.5 inch diameter entry. Take note of the three vertical holes at the back as I will discuss them later.

This gives my RX a horde of torque. The accelerator pedal literally pushes back at my right foot when I floor it. This version of the air inlet does not have the smooth shifts that the last design has, but they are by no means rough. Having this large inlet serves dual purpose as a quasi air box.

Even with the pedal mashed to the floor, there appears to be no drop off in terms of peak power as the air always seems to be there. In the last two designs, I have observed some loss of peak power after the 1st gear. This does not mean that the car is not accelerating, just that the airflow seems to have died down slightly after wide open throttle. Keep in mind that the 4.5 inch entry is larger than the tubing the rest of the way toward the engine. The Weapon-R pipe has a 3 inch diameter.

 

A rear image of the bullhorn.

 

 

There is a bulge but not as deep as the last design.

 

 

This is a comparison of the last design (right) with the new design.

 

 

An example of the almost finished and installed piece by my cousin Rodrigo.

 

 

These are the 3 vertical holes seen earlier. They are to relieve pressure just like in the last design and prevent air damming and less effective airflow to the engine.

 

 

A rear view of those 3 holes.

 

 

This is the end of that that blue and later white tube that has an entry on the top of the radiator. The white piece does not sit in as far as seen and actually sits a little bit further back as it is slightly chopped off. As mentioned earlier this is partially to improve airflow and keep the rammed air from below partially in check in moving toward the engine rather than out the front where that white piece is.

 

 

Notice the white tube coming around the black OEM adapter piece. This is not totally covered and the air actually escape slightly between the two pieces in order to avoid pressure build up.

 

 

The modification to the black adapter piece came about a week after the 4.5 inch opening modification above. Here, I decided to go back to the half-U piece modification I had used in the first design to force the air toward the engine. This was the finished piece.

 

 

My cousin and I started out by cutting the bottom of the OEM black adapter piece and widening out the space left behind. We also cut up an L-joint with a 3 inch diameter.

 

 

When we put these two pieces together you get the following. Notice, there is still a little space at the top for air to enter. As with the first design, one cannot completely cover the air entrance or the RX will choke when the engine starts (even if you have that air filter upstream).

 

 

Image looking from the bottom up.

 

 

My cousin and I sanded down that interior to widen it out and smooth it for better air flow. We also painted it black. Unlike the previous design, the top piece goes over the bottom white piece you see in the picture below, so that no rammed air will escape until the filter at a bare minimum or unless it decides to make u turn around the white piece we just put inside the black adapter piece. One can now get in more airflow than before since this bottom area of the black piece was widened out.

 

 

 

Unlike the last design that did not include this piece inside the black adapter piece, there is a substantial difference in the pedal. With the last design, it felt like one was pushing on to an overstuffed pillow. With the new design, it feels like one is pushing on to a highly wound up spring.

 

A week after the piece above, I did another modification to the black adapter piece. I removed the white piece mentioned above and did a piece that turns the air horizontally, like the similar piece in the original bullhorn design. Notice the white piece sticking. That piece is a small slightly curved rectangular piece that covers the gap left over from the bottom of the piece that enters the black piece. This looks similar to the front of the last white piece that I used and allows for a lot more air to enter than previous designs.

 

 

This is looking straight up the white piece. Notice how inside it arches way more than the last piece that went in there. I had to use a very thick water tubing PVC piece and then sand it out and that is the reason that it looks rough inside. This piece is smaller than the piece comes up from the bullhorn (and thus fits inside it), but there is no air loss since the black tape around the bottom of it seals the gaps. Also notice the back of the black piece is cut slightly and this allows for more air to enter into the gap space that I will talk about in a few pictures.

 

 

 

I had to seal the inside as the front white rectangular piece would otherwise be only sealed by the black tape.

 

 

This is the gap space I was talking about looking from the entrance of the black piece. As mentioned earlier in other designs, if you seal this entirely up, the engine will choke when starting, even though you have the air filter downstream. I have tried variations and always the same issue, so there is this gap space.

This particular design has helped me get some of the lowest, as a group, 60 foot times (all under 2.750 the first night I tried it in competition) and the torque is more noticeable off the light than anything I have ever had before.

Now, if the piece of above was the cream of the low-end power air mods, this next piece was no doubt the cream of the high-end power air mods.

 

 

Using PVC again, I replaced the black OEM piece with the white piece show below. The real difference is the piece on the far right side, which does not allow air intake from behind the head light as on the OEM piece. Previously, I had mentioned that this was a no-no and the engine would choke, but having it wide enough (3 inch diameter) seems to have done the trick. However, there is a drawback.

 

 

It is still important to get more air from inside the engine bay, including from behind the headlight. After testing at the track, I was off .1 in my 60 foot times, which is significant (2.8s in competition versus 2.7s normally) and everything else such as weather and fuel level were well within normal for my testing purposes.

 

 

I later painted the piece black.

So what is the good thing about this piece?

The shifts are the smoothest yet with my air modifications and even in solo runs where my times are normally .3 seconds slower than in competition, I was running at least 122 km/h, something I normally only do in competition (and then again with 18.1s or lower) and several of the times in competition (only 18.3s) were extremely close to 123 km/h. It is very noticeable on the highway when you ram the gas pedal to the floor and the RX just hauls (since some air is already coming in and it is not from a dead stop where the low end torque problem appears with this mod).

However, I did some retuning the night after this modification and I managed to get an 18.094 and a fastest speed of 123.55 km/h, which was not too far off from the then existing record of 123.69 km/h. In addition, I had the second fastest solo run at that time with an 18.144 (with a 3.022 60 foot, if you do the math, this might have been a record run with a 2.7, though I did have a 123.17 on that run, the fastest trap speed ever recorded running solo).

The main trick with the air mod was to push the white piece that sits inside the air filter a little bit farther back and away from the direction of the throttle body. It sits entirely inside the filter and is within 1/2 an inch of the rubber seal where the Weapon-R pipe goes into, thus better taking the air on the low end side through the filter inside the engine bay.

 

This piece was an attempt at gaining greater low end and also high end power. It is about twice the diameter of the old piece entering the air filter and a significantly large exit as seen in the next photo. Notice how the filter above has been expanded in size to accommodate the 3 inch diameter.

 

 

Notice the larger entry and also how it sits back. The air from the filter area can swoop around this piece to provide extra air for low-end power.

 

 

Back of the piece fitting through the enlarged entry into the air filter.

 

 

This is a little more for aesthetic reasons with the rubber piece. That hole you see on the heat shield actually serves a purpose in preventing too much hot air from gathering behind the shield.

 

 

This design was something I had thought about for some time. The top part channels the air from the bullhorn, while the bottom one from the engine air.

 

 

The back view

 

 

Notice the wire mesh. This is where the engine air goes.

 

 

Later, I reattached the heat shield. With this design I clocked in October an 18.021, so I am pretty sure with a little bit cooler weather, I will break my record.

 

 

This is an example of a failed piece. It was an attempt to pull in cooler air from an area where the engine used to take in its air on the OEM setup. The RX choked and sputtered. Only with a lot of gas could one get it going. Issue here was the tube was too long to take in the air quickly enough.

 

 

We removed the heat shield (it is like not coming back) and ran tape around certain areas where the metal met the PVC. We realized that air was leaking through these now taped areas. The area where it takes in the engine air does not seem to have an issue. I ran similar times when I tested it given the weather conditions and I feel that the lack of heat shield may improve dispersion of the hot air. In the future I will clean this area up aesthetically and maybe put a tiny shield near the area where the engine air enters at the lower portion of the PVC piece.

 

 

Here I turn the piece slightly so it aims for the air between the battery and the fusebox. I plan to put a shield around this area to keep some of the hot air away similar to the past heat shield but specifically more for this area. Part of the wrap for the battery wraps around the left side to help seal the area better for the time being.

 

 

The piece to the right of the blue gasket is a steel piece that Hangar-1 made for me based on the design of the similar PVC piece above. After cutting the steel (3 inch diameter and 7 inches long), they welded it and then painted it (when still hot) and then washed it down with water to give quasi-aluminum look to it. It is a cool piece even when the engine is super hot and part of the wrap around the battery covers the air entrance. There is no wire mesh unlike the last one. This piece stays very cool. First night with it, clocked 18.077. The piece cost about $42 USD.

 

Some more shots of this piece below.

 

 

 

 

 

 

One drawback with this ram air system is that it does have a lag if you start from a dead stop, such as at a track, even if you powerbrake (which I do not recommend doing, I have a method I will reveal later on page 8), but it is still better over the stock air intake system.

REMOVAL OF BULLHORN AND DOUBLE TUBE

 

 

 

 

 

 

This version is an attempt to improve the efficiency of the lower part of the intake. The last intake design incorporated a 4.5 inch opening that entered into a 3 inch opening as it approached the engine bay by the fusebox. In this version, we eliminate the 4.5 opening and go to two 3 inch wide tubes (6 inches combined over the 4.5 inch opening). These two tubes meet slightly above. The reason for this is as the vacuum of the engine pulls air in, with the last version from a dead start there would be some hesitation as the air already pulled through would need a moment to catch up. Granted, some air was available in the 4.5 inch wide section after the bullhorn, but this was not sufficient.

By incorporating the hookup of the two tubes, there is a better efficiency for the engine vacuum to be able to pull up air and then have an immediate recharge in the other tube when it needs it. In preliminary testing on the highway, I noticed that the engine was noticeably louder (bigger roar) and sometimes would shake due to the amount of air it was taking in, but no check engine light of any kind. From a dead start, it is more responsive and acceleration is smoother than the last version.

 

After it was painted black. The two long tubes at the end are about 9 inches on the left and 8.5 inches on the right.

 

 

At installation, and this is before the lateral tube was installed.

 

 

A wider perspective.

 

 

Installation of lateral piece.

 

 

A wider perspective.

 

 

Another perspective and showing front air entrance.

 

 

Underneath shot showing duct tape and plastic ties.

 

 

Another shot underneath toward air entrance.

 

 

Less of a bulge.

 

This particular piece was recently tested in conjunction with the last steel piece in the upper part of the intake, but only achieved similar results in terms of time as with the bullhorn intake. The one difference is that it had a higher km/h velocity traps than normal, above 124.50, meaning that although slower than the bullhorn most of the way down, it radically picked up speed near the end to enable the higher km/h.

MODIFICATION TO UPPER INTAKE MODULE

 

 

This particular piece is based on a combination of all that I had done previously and replaced the previous steel piece that was here. It includes a heat shield made out of a small cooking pot and uses a rubber piece from a previous air filter to attach the pot to the PVC piping.

 

The key design element is this 7 inch long PVC piece that has a .75 inch length insertion in terms of width and covers a little more than half of the circumference.

 

 

Rammed inside the 7 inch long piece is the lower of the two pieces shown. A 3 inch to 2 inch reductor. Note in the previous photo that the piece is also pushed in.

 

 

The idea works as follows. Engine air is necessary otherwise the engine will choke at low idle. This is the reason for the incision on the top of the 7 inch long PVC piece. However, we want the air from the lower intake near the front bumper to be able to shoot in its cold air. That cold air enters the dark area with the 2 original inch opening while the engine air enters from the top and is covered by the heat shield to keep that air temperature lower. The lower 2 inch opening piece is sufficiently stretched forward so as to permit the lesser likelihood that the cold air from the lower ram intake will sneak out the incision at the top of the 7 inch piece. This visible in the previous photo of the 7 inch piece above. In addition, the vacuum of the engine will also help pull the air forward.

 

 

With heat shield attached. Not the incision point on top where the engine air enters.

 

 

View with MAF sensor in background. This would be seen as it would from the perspective of airflow advancing toward the engine.

 

 

Reverse view of the previous photo.

 

This piece was recently tested and success was infrequent. The vehicle jerked back on occasions after a dead start due to having too much air volume and nowhere to put it. On the track, it could manage no better than 18.5. I have gone back to putting back the previous piece and will continue with another, newer design concept after that.

MODIFICATION TO LOWER AIR INTAKE MODULE

 

 

This modification is a second version of the previous one shown above and includes a 45 degree angle (instead of 90 at the mid-section) and the addition of two small bullhorns (4 inch to 3 inch reductor pieces). The idea is to smooth out and improve air flow along with gathering more air at the bumper hole than the previous piece.

 

A view front the front.

 

 

Another view from the front.

 

 

A view inside of the 45 degree angle.

 

 

An upward view toward the engine bay.

 

 

Mini bullhorns attached. As might have been seen on the shot from the front of the vehicle, some air does pass by the two mini-bullhorns and this is necessary to avoid building up a pressure dam of air that impedes air flow into this intake.

 

 

As with the original bullhorn intake (see the last photo shown on this page), two mini bullhorns are set back slightly to also prevent a pressure dam of air.

 

REMODIFICATION OF UPPER AIR INTAKE

 

 

A reworking of a piece mentioned above.

 

 

Top part of piece was cut off to allow smoother flow of backpressure of excess air. The vacuum of combustion and the effect of the heat shield as a funnel help keep cool air going in the right direction toward the engine.

 

 

 

Piece was the glued into the heat shield itself at the top tip.

 

 

Actual configuration of piece is actually inverted of what is shown, with long piece actually facing downward.

Success was also infrequent with this piece.

MODIFICATION TO LOWER AIR INTAKE

 

 

 

 

 

 

 

 

As seen in the last photo, an attempt to smoothen out the air flow from the previous design. The small mini-bullhorns on the front were chopped off slightly and the entire piece was modified to curve toward the front bumper hole. First trials in 60F weather clocked an 18.211 with an 18.5 during the day, but with an excessive number of P0171 lean errors.

Note: Do to an excessive amount of air allowed in at sea level in Florida, I have since removed this lower air intake.

ADDITION OF AIR FILTER

 

 

 

 

 

This is a Weapon-R V2 air filter that was added in preparation for a return to sea level in the near future. It cost under $60 USD. What was done here was to place a 4 inch to 3 inch reduction PVC piece on to the piping below the fusebox so that it could direct the flow of air to the air filter. In addition, a bucket was cut so that it had a 4 inch length (so as not to hit the fusebox) in order to serve as a heat shield. This particular set up has good low-end torque, but on the higher end it appears to lack the power that was had without the air filter.

Unfortunately, this was a dismal failure having caused a great drop off in performance on the track by more than .5 seconds.

 

 

The current topside setup used when I arrived back in Florida with a different (larger and black) coupler. What has also been done here is to seal off the y-section open behind the battery and removing the black plastic adapter that allows the air from the bullhorn intake to enter into the engine bay area. Thus, the vehicle only takes the air from just in front of the fusebox for the most part.

 

This modification was an attempt to reincorporate the bullhorn intake for sea level. Here, the silver y-pipe is turned around. This design basically helps allow too much air from the bullhorn intake to exit via the pipe and air filter shown here. At the same time, the air filter, a Spectre available at Autozone for about $24 USD, allows the engine to have some air available for starting up the vehicle. Testing with this setup has also helped eliminate a noted jerking when the throttle body is closed such as coming to a stop or even upon initial acceleration say from a traffic light.

 

CRANKCASE VENT FILTER

 

 

 

 

 

 

The purpose of this modification was to remove from the intake manifold the injection of hot air/gases/vapor caused by the action of the crankcases. The OEM setup has two hoses along with a PCV (positive crankcase valve) to reinject such gases/vapor (basically oil residue/vapors) back into the combustion. However, this has the effect of increasing air intake temperature (reducing power) and reducing octane (which at sea level, also reduces power). These APC crankcase filters (about $9 USD each) were attached to stock hosing in the case of the front crankcase and to black vinyl tubing the case of the rear crankcase. Finally the entrances on the air intake and the intake manifold were blocked off with rubber caps (with the last photo showing the rubber cap for the intake manifold (which connected to the rear crankcase). The other rubber cap is visible on the intake tract by the filter for the front crankcase. I had considered at one time to add a catch tank like that on my other friend Michael's, my college roommate, Z06 Corvette , but after experimentation seeing no mist or sediment sprayed on the engine areas by these filters, I considered a catch tank unnecessary.

After a few months of experimentation and due to the effects of humidity, I removed these breather filters. One recent modification is that the PCV valve has been hollowed out to allow greater flow.

 

This is the hole in the bumper where the air enters into the bullhorn (the top of which is seen in the photo), but for those of you with an OEM airbox or stock set up, most of the air that goes to your engine goes through this area and up to that black u-turn piece, which in the stock setup is that OEM black adapter piece shown and modified earlier. Thus, all the bugs, leaves, etc. that you find stuck on your air filter or in the bottom of your airbox most of the time get in through this area.