Cylinder Head Development on Jan16 2010

by FSD | Print the article |

With more than 20 years of hands-on experience in designing cylinder heads and intake manifolds, we have the experience and the technology you can rely on to push your program up to the next level of performance. On a race engine, Cylinder heads are where all the power is made. Back in the “old days”, everyone used to work on cylinder heads following a “build-or-bust” methodology. You received the castings from the manufacturer, determined what the biggest valves you could fit in it were and then began hand-porting the head using the flowbench as a guide and believing that the more air it would flow, the more power it should make. After you were satisfied with your work, you’d grind the rest of the ports to match the first pair you spent so much time on. Then came the moment of truth – the Dyno. After a few pulls you might go from a Zero to a Hero… or vice-versa. Either way, it was an expensive exercise to find out that you gained a few horsepower from something you did and it was up to you to determine what exactly it was. The only way to find out was to take the heads off and try something else. After a few tests, involving the cylinder head shop, the engine builder and the guys in the dyno, you had hopefully learned something that you could apply to future cylinder head designs. Over time, you began to see trends and developed a feel for what worked and what did not. Now what happens when you change manufacturers? Now you are back at square one! You will probably be competing against other teams that have years of development time on an engine you know nothing about. The database you have compiled on your old engine might be useless, or even worse, it might lead you down the wrong path for a while. Back then, your only choice was to start the whole process all over on the new engine. Some things will work the same on the new engine as they did on the old and some things will not. Every engine is somewhat different.

Enter Technology. Today, the process is equally complex but can be far more productive and far more informative and enlightening. By properly applying the technology available to us in the form of simulation and modeling software, we can now achieve a result that is much closer to ideal from the very start. We digitize and reverse-engineer the stock cylinder head material and then draw a parametric model in CAD. Since the model is parametric, we can make small or large changes very quickly with extreme accuracy. We also know what the exact volume of the combustion chamber, intake and exhaust ports are before a single part is machined. When we make changes, we can accurately measure those changes and have complete control over them.

Now, using sophisticated tools such as CFD (Computational Fluid Dynamics), we can measure the efficiency of the ports long before they are ever cut in a CNC machine. More importantly, not only can we measure efficiency, we can also visualize what the flow is doing. We can make changes and observe what effect it has on the direction of flow through the ports and into/out of the combustion chamber. We can find the best combination of angles and radii used in the valve job to optimize flow and promote a faster burn rate during the closed cycle. We can determine, through analysis, what parts of the ports are being used effectively and which parts are not and make changes accordingly. Maybe there is a part of the port that needs to be filled in while another section should be enlarged. This iterative process  inevitably leads to a more efficient cylinder head design.

Topic: CFD, Cylinder Head Development, Featured | Tags: None

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