Holm86 wrote:Dragonfly wrote:Current V8 regulation also define the spacing between cylinder bore centers.
Holm86 wrote:Is it legal on the new engines to offset the cylinder bore from the center of the crankshaft?? Some engines has this to reduce friction and gain a bit more torque.
Its just offset by a few mills so when peakpressure occurs the piston rod is parallel to the cylinderwall so the peakpressure forces i directet straight down to the crank.
Isn't this leading to the same effect like having the piston pins slightly off-center.
Yes its the same. But if you offset the pins the piston will still tip slightly. Offsetting the bore should prevent the piston from tipping. Reducing friction.
I have read that Mitsubishi did this on their new 1.8 diesel in the lancer etc.
this would be disadvantageous in a high speed engine eg current F1
largely because maximum side thrust depends on all/any load in the rod, not just combustion load
at high rpm higher rod loads occur eg with piston deceleration near TDC than with peak combustion load
asymmetry (offset) as suggested would increase the peak (inertial/eg deceleration) loads
inertial loads are the fundamental limit to rpm and power under capacity-limited rules (or they were!)
the offset was widely used in race engines 100 years ago (rpm was then very low, combustion loads were dominant)
today it makes sense only in an engine that has very high combustion loads relative to the inertial loads
as you say, a diesel, or a dragster ?
BTW used eg in the VW V5 etc to get 2 rows of cylinders in 1 block and head, the (big) offset can only be right for 1 row ??
it might be worth considering in 2014 (never thought I'd say that)
(the rpm/inertial loads won't be critical to design, combustion heat release near TDC for best expansion and efficiency will be)
(this is also enhanced by (eg short) rod length relative to stroke, although that increases side thrust and peak inertial load)
near-ideal heat release will be made possible by complex injection strategies, in effect controlling combustion, hence efficiency