Y2KZX12R
Needs a job
CompetitionCNC.com
Posts: 3762
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posted May 13, 2008 07:21 AM
Finally a CNC ported head for you ZRX1200 guys...
Competition CNC has a CNC ported head for the ZRX-1200. I'll post some dyno tests shortly.
Here is the flow figures. The velocity at the MCSA is 330fps @ 28" on a 1224cc engine. Thats about the same as a stock head on a stock engine. so there should be no low to mid range power losses, just gains everywhere.
We have a stage 2 aimed at more power above 7500 also.
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Y2KZX12R
CompetitionCNC.com
   
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SteddyTeddy
Pro
Posts: 1664
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posted May 14, 2008 07:34 AM
What's that oversize valve head flow that you just did?
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Y2KZX12R
Needs a job
CompetitionCNC.com
Posts: 3762
|
posted May 14, 2008 09:21 AM
Ted, the last head we just did oversize valves in we didnt CNC port. But I can tell you that with oversize valves the head does flow a little more air all the way up the lift range.
But after doing all the air flow calcs and velocity calcs on the o/s valve head the velocity at the valve seat is on the low side. This can actually reduce trapped volume and reduce over all VE on a running engine. There is a minimum velocity you want while the valve is about to close to trap in the last little bit of air that actuallygets into the cylinder.
IVC seat timing is very important on a ported head and most times you need to advance the intake cam a few degrees to trap more of the air in the cylinder.
This has been our findings.
Its one of those cases where more airflow on the flow bench may not translate into more HP. As the feed back comes in we are evaluating combos.
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Y2KZX12R
CompetitionCNC.com
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