Well, I guess patience is a virtue. I spoke with my design engineer today and was very please with what he had to say. It took me a couple years to find the right person to design the head, and several more months for him to actually get started once the cash retainer was paid. At that time, I gave him a set of parameters to work within and the goals we wanted to achieve. I've stated them in the past, but will do so once more for the new members. I don't understand this stuff to much, but will explain it the best I can, based on what he told me.
My main concerns (or parameters): First, the new head needed to utilize existing exhaust port patterns (no need for new header designs). Next, was to eliminate the need for a port divider. And lastly, I wanted to maintain the stock OZ250-2V intake pattern, so the head would accept the existing OZ intakes, including the 2V, the triple SU, and triple Webber manifolds. I also asked for him to design a new 4V intake to suit.
The goals: Simply put, increase midrange performance as much as possible. Mid range because we want this head to perform best as a street head for daily street/strip usage. We also wanted to see improvements in the lower and upper ranges, and maximum efficiency in the chamber design. Not knowing the wet distribution pattern of the OZ head, we were not sure if any gains would be possible. Only wet testing the OZ head would yield the answer.
We started by flow testing the OZ-2V head, both wet and dry to find it's strengths and weaknesses. While the dry flow (CFM) far exceeds the US log heads on the intake side, the exhaust flow is similar, or only marginally better. The chamber efficiency is about the same for both, as the wet distribution pattern (WDP) is about fifty percent. Basically, when the fuel/air mixture enters the chamber, it flows off to one side and only fills half (or less) of the chamber, resulting in loss of power. It too, like the US log heads, requires a large amount of total ignition advance to efficiently burn the fuel/air mixture completely, during the power stoke. The more total advance required, the more power it robs. The overall goal is to reduce total advance as much as possible and gain as much CFM as possible.
The next step was to redesign the chamber and intake ports to obtain the best possible wet distribution pattern. This is the most crucial step when designing a new head, CFM is secondary. It doesn't do much good to increase flow, if the fuel/air mixture isn't distributed efficiently across the piston surface, and total ignition timing remains unchanged. Our goal was to increase WDP to at least 80% if possible. This is made possible by modifying and reshaping the port and chamber, increasing intake velocity, eliminating dead spots, manipulating swirl patterns, and playing with various valve combinations. While there are other means of doing so, like chamber styles, additional valves, valve placement, etc, these parameters were not possible to apply in our given design limitations. .
I'm not quite sure what he did, but after speaking with him today, I am confident I hired the right person as he is extremely good at what he does. The new designs were wet flowed last night and to my surprise exceeded our goal, as the new chambers achieved 100% distribution. This means the entire chamber is receiving the fuel/air mixture across the entire piston surface, which is of course, outstanding. This alone translates into huge power gains over the OZ head in all three ranges (low, mid, and upper). While we are not sure yet, he thinks total ignition timing will be reduced by as much as 10 degrees, or more.
Next he flow tested the new intake ports. I'm not ready to release the info yet (CFM rates), but will say the new ports out flowed the old designs across the board, with the largest gains at 300 and 400, and ample gains at 500 to 600. In other words, the new head is going to be a beast, when compared to the OZ250-2V, and incomparable to the US log head.
Our next step, which begins next week, is to see what gains can be made to the exhaust ports. I can't wait to see what he comes up with. If it's anything close to what he did with the intakes and the chambers, we may not need a second design (Crossflow).
My main concerns (or parameters): First, the new head needed to utilize existing exhaust port patterns (no need for new header designs). Next, was to eliminate the need for a port divider. And lastly, I wanted to maintain the stock OZ250-2V intake pattern, so the head would accept the existing OZ intakes, including the 2V, the triple SU, and triple Webber manifolds. I also asked for him to design a new 4V intake to suit.
The goals: Simply put, increase midrange performance as much as possible. Mid range because we want this head to perform best as a street head for daily street/strip usage. We also wanted to see improvements in the lower and upper ranges, and maximum efficiency in the chamber design. Not knowing the wet distribution pattern of the OZ head, we were not sure if any gains would be possible. Only wet testing the OZ head would yield the answer.
We started by flow testing the OZ-2V head, both wet and dry to find it's strengths and weaknesses. While the dry flow (CFM) far exceeds the US log heads on the intake side, the exhaust flow is similar, or only marginally better. The chamber efficiency is about the same for both, as the wet distribution pattern (WDP) is about fifty percent. Basically, when the fuel/air mixture enters the chamber, it flows off to one side and only fills half (or less) of the chamber, resulting in loss of power. It too, like the US log heads, requires a large amount of total ignition advance to efficiently burn the fuel/air mixture completely, during the power stoke. The more total advance required, the more power it robs. The overall goal is to reduce total advance as much as possible and gain as much CFM as possible.
The next step was to redesign the chamber and intake ports to obtain the best possible wet distribution pattern. This is the most crucial step when designing a new head, CFM is secondary. It doesn't do much good to increase flow, if the fuel/air mixture isn't distributed efficiently across the piston surface, and total ignition timing remains unchanged. Our goal was to increase WDP to at least 80% if possible. This is made possible by modifying and reshaping the port and chamber, increasing intake velocity, eliminating dead spots, manipulating swirl patterns, and playing with various valve combinations. While there are other means of doing so, like chamber styles, additional valves, valve placement, etc, these parameters were not possible to apply in our given design limitations. .
I'm not quite sure what he did, but after speaking with him today, I am confident I hired the right person as he is extremely good at what he does. The new designs were wet flowed last night and to my surprise exceeded our goal, as the new chambers achieved 100% distribution. This means the entire chamber is receiving the fuel/air mixture across the entire piston surface, which is of course, outstanding. This alone translates into huge power gains over the OZ head in all three ranges (low, mid, and upper). While we are not sure yet, he thinks total ignition timing will be reduced by as much as 10 degrees, or more.
Next he flow tested the new intake ports. I'm not ready to release the info yet (CFM rates), but will say the new ports out flowed the old designs across the board, with the largest gains at 300 and 400, and ample gains at 500 to 600. In other words, the new head is going to be a beast, when compared to the OZ250-2V, and incomparable to the US log head.
Our next step, which begins next week, is to see what gains can be made to the exhaust ports. I can't wait to see what he comes up with. If it's anything close to what he did with the intakes and the chambers, we may not need a second design (Crossflow).
This is also the reason for designing an intake from scratch. It must match the requirements of the new ports, for the best gains. 
You guys have done your homework!!!!!!
