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We are currently disscussing on the MR2OC why the 3.4 5VZ has such a low redline. What are the limiting components and how can we improve the upper RPM power with the lack of cams for this engine. How far can we push the bottom end?

Here is what we have come up with so far:

The valves are likely to float (due to weak springs) when the rev limits are raised, especially if forced induction is used. Where can we get stronger valve springs of the appropriate size. What other toyota motors have the same size valve springs?

The rods and pistons look as though they should handle RPM's in excess of 7000.

The berrings may fail due to inadiquate oil flow, both volume and pressure. Would shimming the oil pump regulator solve this or, are there high volume oil pumps available for this motor?

Please give us your expert input and ideas.