As a rule of thumb, it is ideal for your intake manifold to flow "at least" as much airflow as the maximum amount that the intake port on your cylinder head is capable of flowing. To determine this amount of airflow, the factory cylinder head must be evaluated at all valve lift intervals up to the maximum lift that the valve is being opened. Although there is no "penalty" for making the intake manifold flow better than the intake port on the cylinder head, it will not necessarily perform any better than an intake which is a closer match to the flow of the stock cylinder head intake port.

Oversimplification of the intake manifold design, although a "quick and easy" way to get "big" flow numbers, will typically result in a loss of power below 5,000 RPM. This is what happens when the intake runner is shortened considerably and maximum airflow is the ONLY consideration. When compared to the stock intake manifold, such designs will usually lose a minimum of around 20 HP at the wheels up until about 5,000 RPM. Around that point, power production will typically become equal. Above 5,000 RPM, gains will be minimal in most applications, and will only favor "max effort" setups that utilize some form of supercharging and/or very high revving engines. For street applications and even most highly modified setups, the use of such a manifold will be detrimental to overall performance.

When testing the factory intake manifold, we were quite surprised to find that it flows VERY well. The TYPICAL flow rate per runner, EVEN WITH the IMRC blades in place ranged between 250 to 263 CFM. One particular port, the front driver's side port, flowed considerably better than the others. We suppose that this is due to the fact that it is the only port which syphons airflow from directly behind the left throttle body manifold opening. Since this particular runner is shrouding airflow "directly behind" the throttle body opening, this might explain why the other (rearward) runners are flowing less.

Typically, there is a 4% variation "from intake runner to intake runner" on the stock manifold with a MAXIMUM deviation of 11.8% between the "best flowing" (driver's side front runner) and the lowest flowing runners. This shows that although the original manifold flows quite well, it is not "balanced" from runner to runner.

Flow Rating of the Stock Cylinder Heads

Testing of the factory intake port on the stock 3 valve cylinder head indicates a MAXIMUM flow capacity of 236 CFM. To put this in perspective, the "original" Edelbrock Performer 5.0 cylinder head designed for the 1986-1995 Mustang applications flowed a maximum of 212 CFM with the 1.9" intake valve and 220 CFM when supplied with the optional 2.02" intake valve. The popular "Twisted Wedge" cylinder heads flow about 245 CFM on the intake port "out of the box" with their standard 2.02" intake valves. It is actually quite impressive that the stock cylinder head flows 236 CFM "completely stock".

During our many years of dyno testing, we have found that a typically modified engine which has a head and intake combo that flows a "combined" 220-235 CFM per runner (where both the head AND the intake support that level of flow with a "normal" compression ratio) it will typically make around 1.1 HP per cubic inch. Keep in mind that this is usually in an application that has a "free flowing" exhaust and an upgraded camshaft profile. Interestingly enough, if you take the cubic inch displacement of the 2005+ Mustang 3 valve engine (281) and multiply it by 1.1 (given the flow rate of the cylinder head and intake manifold), this equals 309.1 HP. This not only confirms why the engine is generating it's factory rating of 300 crankshaft horsepower, but also why your typical "good running" 2005+ 3 valve Mustang will put down around 265 SAE corrected horsepower to the rear wheels.

Given the flow rate of the stock intake manifold, it does not appear to be a restriction on your typical stock or mildly modified application where the cylinder heads have not been modified. This is not to say that a higher flowing intake manifold "CAN NOT" improve performance over stock, but rather to confirm that the factory intake does not represent a measurable restriction on the stock factory cylinder heads. Because of this, we are not willing to "go out on a limb" and make ANY potential power gain predictions based solely on airflow. This testing shows that the primary user for an upgraded intake manifold on this engine will be using either ported cylinder heads, a form of supercharging, or both. These are the people who will benefit most from an aftermarket intake upgrade. People with completely stock engines MIGHT find some improvement, and we will be happy to provide exact details when they are available, but our initial testing has indicated that any aftermarket intake for this engine will only be ideal for more heavily modified applications.

Flow testing the maximum capacity of the stock intake port.

Testing The Possibilities...

Before developing and finishing a new intake manifold, you must first determine how much airflow is POSSIBLE, given the size and shape of the original factory intake port at the cylinder head opening. To do this, we hand fabricated a custom test fixture for our computerized flow stand. This allows us to determine the actual MAXIMUM possible flow that the opening will support, given a 100% efficient port design. Of course, we all know that NOTHING is 100% efficient.

By drawing the airflow through the port opening, without the aid of a "flow guide", the maximum amount of airflow that could pass through the stock opening was 258 CFM. This is because the airflow was turbulent, due to the fact that there was not a smooth transition into the opening of the port. To properly evaluate the most flow that the opening will support, it is necessary to create a radius to allow the airflow to enter the port and bench smoothly. This was done with clay, and this is a common practice among most cylinder head porters who do not have a pre-fabricated acrylic flow guide for a particular application. With the clay radius in place, maximum airflow increased to an impressive 344 CFM. This means that given a 100% effective/efficient intake runner design, the MOST airflow that you could possibly pass through to the cylinder head would be 344 CFM. This is not a "realistic" target, but at least it gives us a general idea of what might be possible.

After speaking with some very well respected cylinder head experts, we found out what the CURRENT limits of cylinder head flow for these 3 valve heads are. When using the stock sized intake valve with a fully ported head, up to 296 CFM has been achieved. With a larger intake valve, maximum flow has been measured at 311 CFM. Given this information, and knowing what the maximum POSSIBLE flow capacity for the port is, we set our goal at 315-320 CFM per runner. Unless someone does a "substantial" re-design of these cylinder heads, this amount of flow SHOULD support just about anyone's needs at this time OR in the foreseeable future.

Flow testing the negatives pulled from our runner cores to measure maximum airflow for each set of runners.

When designing the runners for our new intake, we decided to eliminate the "cross over" that is present in the factory manifold. The "crossover" design has been used in many other high performance automobile applications, even by manufacturers such as GM and Chrysler. The benefit of this setup is longer potential runner length, but the downside is the fact that there simply isn't enough room "from front to back" on the manifold to support the "elongated" shape of the intake port at the cylinder head. This does not allow the port to maintain it's shape when "crossing over" with the runners from the other side of the engine.

After doing a lot of measuring, we determined that there was enough hood clearance to maintain as much runner length as the stock manifold, but without the need to "cross over" the runners. There are many benefits to this. The most obvious is the fact that we were able to maintain the same basic runner shape throughout the entire manifold. We were also able to streamline the path where the air enters each port runner. In addition to this, we came up with an arrangement that eliminates the previously mentioned "shrouding effect" that the front runners have over the rear ones. This ensures that the rear runners flow just as well as the front ones. For consistency, we were able to make the runner cores in "pairs". This means that the port shape and flow down each respective side of the manifold will be completely "identical". All of the "driver's side" ports flow the same, and all of the "passenger's side" ports flow the same as each other. This allows us to ensure that the runner-to-runner flow rates are "balanced" and that they all flow basically the same amount of air to each cylinder head intake port.

Actual flow test data showing the stock intake manifold capacity, the maximum possible flow supported by the original intake port and the flow capacity of our new intake manifold runner designs.

When measuring the actual airflow capacity for our new runners, we were very pleased with the results. The driver's side port flows 327.3 CFM, and the passenger's side flows 330.2 CFM. This means that the maximum deviation between ANY of the runners is .8% or 8/10ths of one percent. Compared to the factory manifold, this indicates a flow increase of as much as 30.3%, and a port efficiency that is 96% of the maximum possible flow that the port will allow. Even when testing the runner cores mounted inside of a model that simulates our plenum configuration, flow does not go below 320 CFM. So, we were able to meet our flow requirements to support "the best" head flow capacity that is currently available. Using this intake manifold on ANY existing 3 valve cylinder head will not pose a restriction on performance.

Answers To Anticipated Questions

Q: Will this manifold be plastic?
A: This manifold will be a two-piece design aluminum casting that is CNC machined with a powder coated black finish. It will also feature at least one set of bosses for a direct port nitrous system to be fitted.

Q: Will this intake sacrifice low RPM and midrange power?
A: The length of the runners have not been compromised or reduced, so the use of this manifold is not expected to have a substantial effect midrange power/torque. The IMRC plates WILL NOT be supported by this manifold, which will (just as removing these plates on the stock manifold) result in a small loss of low RPM responsiveness. Since this intake is not intended for people with "stock" setups, the overall gain in useable power will more than offset any losses in the lower RPM's.

Q: How much will it cost?
A: At this time, we are unable to quote an "exact" price, as we will not know the final production cost per unit until we have made our first run of pre-production samples. This product will be priced reasonably.

Q: Can I be one of the first to try (a pre-production unit) it on my vehicle?
A: We have received MANY requests for this, and we already have a wide selection of various test vehicles which will be getting the first units for evaluation. The results from most of this testing will be made available for all to see here on our website.

Q: When will it be available for sale?
A: As mentioned earlier, this product has been in development for quite some time. Final tooling is underway, and although unlikely, there is ALWAYS a possibility of some unforeseen issue that could delay the release of the product. Fit testing has been performed on our in-house Mustang on several different occasions, so we are fairly confident that there will be no physical fit issues. With the production of something totally new (such as this) there is always a chance for delays. If no major issues arise, the product should be ready for sale "soon".

As always, keep an eye on our website for future updates!