2.20 is a pretty damn big valve for a 4.070 chamber. The flow numbers look very linear and better than I would have expected with that setup. What is the runner size?
If the chamber is only 4.070, why did you flow it on a 4.125? Wouldn't you want your chamber size to match the bore of the engine? I'm asking because I'm trying to learn. Thanks.
Different cylinder head shops flow their heads on a set range of fixtures. Its common to see a head flowed at 4.00", 4.100", 4.125", 4.150". They dont all have setups to flow everything in .01 increments.
DR J's, I would be interested to see if the 2.20 valve is hampered in a 4.100 or smaller fixture or what the chamber size would do if it was open it to a full 4.100. You know a head with that much runner volume and flow is likely to see 4.155+ bore sizing. Not trying to challenge anything you are doing there, just current to see the developmental aspects of what/how you are going about that port and chamber profile.
Anyone using such a casting as the Pro-Comp which is manufactured in China should be prepared for many who will take exception to that fact. Without speaking of the quality, I would say the final price should reflect the low initial cost of the castings themselves. If the cost of the castings is not low, perhaps such a business venture should be re-examined based on the risks at hand.
Looking at the comparison of the LS3 cylinder heads in the Hot Rod article, I am not sure how many folks feel about the price of $2395 (as quoted in the HR article). Generally speaking, anything produced in China can only remain competitive in the market because it is priced significantly below the American counterparts. For the sake of gaining some perspective, where are the GM castings made? Mexico? I for one would not care how thick the decks are or how big the spring pockets of Pro-Comp heads may be if the quality of the material is no better than the recylced Pepsi cans they use in Mexico to make the GM castings. Folks probably should not use that type of gear for an all out build or even a build that flow numbers at 380cfm could support (800hp+ N/A). Maybe that is an overly conservative view point, but, I would think that anyone who is really attempting to go about their build with scrutiny would say, "hey man these things are not up to par and will not last under my proposed conditions." If the build is on a budget, sportsman, bracket or what have you, why not option for the CNC ported GM castings at $1500-1700.
At the end of the day, there are a lot of folks who will see something for $50 cheaper and buy it no matter what. But these folks are not in it for excellence if all they are concerned about it economy. Take my comments for what they are worth; it is a brief analysis of what is happening here and in any manufacturing scenario- in general. Dr. J. you appear to have invested a lot of time and effort into your project here and it shows in your work. I sincerely hope the quality of materials will not compromise your dedication to good machine work.
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