Air Filter

Test

Individual Throttle Body Conversion

This modification shows the seriousness of my project and definitly sets me apart by far from other SOHC KA24E turbo conversion done by others. After doing research on other KA24E-T project cars, I soon found out that cylinder #4 tends to run the hottest and was prone to detonation. Obviously this has to do with how much air is flowing into the cylinder and the amount of fuel that is mixed with it. I believe the lean mixture in cylinder #4 is a direct result of the log style of the stock intake manifold Nissan designed. I then decided to fabrication my own symmetrical intake manifold along with an individual throttle body conversion. This design is highly desirable as it facilitates equal distribution of air flow to each cylinder which is very important. All cylinders will have the same probability of seeing the same amount of air.

The first step is to buy the Nissan Motorsport Intake Manifold for the 44mm Mikuni Carb conversion. This is a true race style intake manifold.

This side of the manifold shows the carb flange. It is a universal DCOE bolt pattern that many carb bases share. To the right of cylinder 1 intake runner, is the water passage, just a round hole.

The manifold features direct, virtually straight runners into the head. The runners make a smooth transition from round to oval ports in a very short distance. The manifold is only 4 inches wide from flange to flange.

This is the carb side looking into the head intake side. Very smooth and direct runners allowing unlimited and unrestricted flow!!!!!!!!!!!!!

Here is the head intake side looking out to the carb side. Notice how there is no spot for fuel injection. I will still be using a fuel injection system, so I will have to find an alternative way install the fuel injectors. The compact design and all aluminum construction makes this manifold super light weight over the stock manifold. Bolts perfectly to the KA24E head, although one of the bolt holes had to be enlarged just a little bit.

When I took my head to Port Pros to have my head turbo ported and polished, I also had them match port and polish my Nissan Motorsports Intake Manifold to the head and the 45mm throttle bodies. This removed all the ugly casting marks inside the manifold and the polish machine finish is specificly for forced induction application, just like the head's polished finish. This should promote even better flow into the head.

The second step was to purchase a left and right set of TWM throttle bodies. Since the Nissan Motorsports intake manifold was intended for 44mm Mikuni carbs, I decided to go with the closest size throttle plate TWM has to offer. In this case, it was the 45mm size throttle plate. Its just one mm bigger than the Mikuni size, so it will do nicely. By using individual throttle bodies, this will equalize the airflow to all four cylinders...a sign of a serious motor. The TWM throttle bodies come with a DCOE bolt pattern, so it will bolt on to the manifold without any modifications. Sweet.

Left side part#:2910-4502
Right side part#:2900-4502 TWM

And the third and final step of making this conversion complete was fabbing the rest of the intake manifold. For this I found some Do-It-Yourself parts from Ross Machine. I purchased an ideal flow dome-shaped Plenum, 2 matching plenum vacuum end caps, a blank piece of aluminum flange, and 4 Velocity Stacks with an inner diameter of 1.88 inches which is 47.7mm. Now with all the parts in place, I can begin putting the whole thing together.

RMR-043 - Universal Intake Extrusion Half Round
RMR-048 - Universal Half Round Vacuum Endcap
RMR-044-200 - 2.00" OD Velocity Stacks Ross Maching Racing

Mocking up the quad throttle body setup

After doing a mock test set up, I realized a few things. The Ross velocity stacks were too wide to use. So I decided to make things easier by purchasing a set of TWM velocity air horns. These air horns bolt on perfectly to the throttle bodies and come in the same matching MM throttle body plate bore. I then cut out a hole on the back side of the plenum. Big enough to fit the flange of the air horn thru, yet small enough to keep the rim of the air horn to sit on the base floor of the plenum. This is the ideal inlet from the inside of the plenum into the throttle body. At this point, I also needed to decide where I wanted the point of entry of the intake charge to be on the plenum. To meet my goal of making this a symmetrical intake manifold, the point of entry had to be in the center of the plenum. A bottom entry soon became a logical choice due to space conditions in the engine bay. I also decided to install a blow off valve on the plenum. Since most blow off valves are small in design, I decided to mount it on top of the plenum. The blow off valve location ended up being directly across from the intake entry. This gives the compressor wheel maximum protection against compressor surge when the throttle plates do close to vent the incoming pressure at the most ideal and direct angle possible. I decided to use a 2.5 inch aluminum pipe with a nipple end for the intake connection. Once everything was measured out, cut, and mocked in place, all the air horns, end caps, flange and pipe were welded in place. When the manifold was finally finished, it just looked totally awesome. This is the ultimate KA24E intake manifold. The aluminum plenum was then polished to a super shine. This made a good looking manifold look even better.

HKS Super Sequential Blow Off Valve

After looking at several different models, I decided to go with the HKS blow off valve. I selected this brand because HKS offers 2 different models. The super sequential model, which is a base model, and the Type 2, which is an upgrade over the base model. Both models use the same flange, so this gives me the option to try either one by swaping out one or the other to see which one works best for my application. Lots of people have had great success with the base model, including high horsepower applications, so I decided to go with it as well. Since either BOV model can be used on the same flange, the flange can safely be welded on the intake manifold plenum without fear of wanting to remove it later. The only thing I didn't like about the design was the idea of the BOV venting straight without some kind of filter to prevent dirt or dust from possibly entering the intake track. So the stock insert was removed and replaced with the hose end adapter. This gives the perfect spot to bolt on a small air filter on the BOV, which allows the pressure to vent out yet filter any air that may return in.