Head Work Question
05-25-2012, 06:08 PM
#1
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Head Work Question
By shaving the head .030-.040 what does that put the Compression ratio at and what kind of increase in Power have ppl seen?
05-27-2012, 10:38 PM
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Placeholder. Give me a few minutes to run evereything.
The .1 difference is because of a difference in how I rounded the original answer.
This of course assumes that the head's chamber diameter is equal to the bore diameter, which may not be the case.
bore diameter: 84mm
bore radius: 42mm
total engine displacement: 1975cc
per-chamber engine displacement: 493.75cc
per-chamber head volume: 47cc
shave: .04"
.04"*25.4=1.016mm
bore radius^2*pi = area of bore
(42mm^2)*3.141592=5541.768288mm^2
area of bore * shave = volume lost
5541.768288mm^3 * 1.016mm = 5630.43658061mm^3
5630.43658061m^3 = 5.63043658061cc
per-chamber head volume - volume lost = new per-chamber head volume
47cc - 5.63cc = 41.37cc
per-chamber engine displacement - head volume = per-chamber swept volume
493.75cc - 47cc = 446.75cc
(per-chamber swept volume + per-chamber head volume) / per-chamber head volume = original compression ratio
(446.75cc + 47cc)/47cc = 10.5053191489
(per-chamber swept volume + new per-chamber head volume) / new per-chamber head volume = new compression ratio
(446.75cc + 41.37cc)/41.37cc = 11.7988880832
bore radius: 42mm
total engine displacement: 1975cc
per-chamber engine displacement: 493.75cc
per-chamber head volume: 47cc
shave: .04"
.04"*25.4=1.016mm
bore radius^2*pi = area of bore
(42mm^2)*3.141592=5541.768288mm^2
area of bore * shave = volume lost
5541.768288mm^3 * 1.016mm = 5630.43658061mm^3
5630.43658061m^3 = 5.63043658061cc
per-chamber head volume - volume lost = new per-chamber head volume
47cc - 5.63cc = 41.37cc
per-chamber engine displacement - head volume = per-chamber swept volume
493.75cc - 47cc = 446.75cc
(per-chamber swept volume + per-chamber head volume) / per-chamber head volume = original compression ratio
(446.75cc + 47cc)/47cc = 10.5053191489
(per-chamber swept volume + new per-chamber head volume) / new per-chamber head volume = new compression ratio
(446.75cc + 41.37cc)/41.37cc = 11.7988880832
The .1 difference is because of a difference in how I rounded the original answer.
This of course assumes that the head's chamber diameter is equal to the bore diameter, which may not be the case.
05-28-2012, 12:23 PM
#5
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Interesting. Veeeeery interesting. I have read reports of heads with Singh grooves running just fine on pump gas after shaving 1mm off the bottom of the head. Hm....
05-28-2012, 01:54 PM
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Likely because the actual comp ratio dropped down due to the removed material that makes the grooves?
At least that's the explanation I have.
EDIT: I hate touchscreen keyboards...
At least that's the explanation I have.
EDIT: I hate touchscreen keyboards...