Quote:
Originally Posted by efnfast
Better air flow without the plates and rods in the way? I would assume yes, but a measurable difference?
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Good question.
I asked Marc Haibeck about this some years ago, and if I recall, I believe he said it might be only 5-6 hp range (on an non-ported head)**.
Difficulties in controlling the variables in actual testing (using a actual LT5/dyno) are significant.
And, theoretically the harsh** taper immediately following the SPTs may perhaps significantly obscure the effect on performance that removal of the SPTs (alone) might have had.
**Acoustics: Those that know seem to suggest that to
practically eliminate reversion in the runner air column, the rate of change in diameter should be 4% or less. The change immediately below the SPTs on my (then stock) 90 heads was approximately 3 times that! However, if the head is ported, then that second restriction would be removed, and the effect of then removing the SPTs would be much more significant.
Either way...Performance wise (on so many levels) removing the plates and rods can't hoit!!