Hey Larry,
Just to claify the point I was making with my comment about Lump porting. I was making the point that if you took a Chevy 250 I-6 with 1 barrel carb, stock intake, stock cam, stock exhaust and stock ignition and did a Lump port head modification
only . The gains would be barely perceptable due to the OVERALL ineffiecency of the Total engine package.
Increasing port flow, improving flow path and runner volume with Lump porting would likely be fruitless if the exhaust and especially the intake (1 barrel carb)were so highly restrictive.
Conversely,the addition of the Lump port modification to an engine that had already been modified with After market intake, larger or mutiple carbs, Headers, increased compression and an Ignition system would see a dramatic difference once the blatantly ineffiecient stock intake runners were modified with lumps to allow these OTHER modifications to realize their full potential.
I was using this example to illustrate that the benefit of a single modification cannot always be fairly judged on it's own individual "Play" but rather it's ability to contribute to the "Team effort" )
I realize that I'm likely just repeating myself but I wasn't sure you got my point about the fairness of judging any single modification on it's own without exploring it's ability to "enhance" other modifications.
Again . . . . it's all about "The Combination"
Automotive Breath said:
The groove alone provides benefits not found with increased compression. I have done this before, groove an engine with out increasing the compression and the performance improves.
This is key bit of infomation in regard to the current discussion surrounding the issue of compression because as I see it grooving alone would decrease compression due to increased (minimal albiet) chamber volume.
Presuming the info Automotive Breath has provided is correct your question about the result of "groove only" resulting in increased performance has been answered Larry.
I find it interesting that although we are all in agreement that INCREASING compression improves performance, that it appears that the benefit the groove provides seems to out weigh the negative effect on performance that the DECREASE in compression resulting from the grooving operation (increased chamber volume) would usually net.
'Crockett
