bazhart
Barcelona
- Joined
- 20 May 2009
- Messages
- 1,343
Yes Luddite, broken studs were common due to corrosion between the head and cylinders.
Of course power in an engine is all down to the compression pressure at ignition, which is a function of cylinder filling and static or geometric compression ratio.
That's why turbos and superchargers work and why high compression pistons do as well (within detonation limits).
It is also why the Porsche engines with variable cam timing (and later ones with lift as well) produce good power in the mid range because they can increase the air flow at high revs (bigger inlets and wilder cam timing) without losing the cylinder filling at lower revs (when the cam timing is softer and/or the lift reduced).
It is also why oversized engines produce better power at both mid-range and top end. Better mid-range because of increased flow while there is more time and better top end because although the breathing limit of the engine has been reached the combustion pressure is pushing down on a bigger piston.
As the revs increase there is less time for the compressed air to leak past the rings - and this is why at low revs the Carerra's with worn rings would be gutless and why - as soon as they came on the cam and the piston speed increased - they took off like a 2 stroke.
With new rings they got back a lot of bottom end but the jerk wasn't so noticeable.
Baz
Of course power in an engine is all down to the compression pressure at ignition, which is a function of cylinder filling and static or geometric compression ratio.
That's why turbos and superchargers work and why high compression pistons do as well (within detonation limits).
It is also why the Porsche engines with variable cam timing (and later ones with lift as well) produce good power in the mid range because they can increase the air flow at high revs (bigger inlets and wilder cam timing) without losing the cylinder filling at lower revs (when the cam timing is softer and/or the lift reduced).
It is also why oversized engines produce better power at both mid-range and top end. Better mid-range because of increased flow while there is more time and better top end because although the breathing limit of the engine has been reached the combustion pressure is pushing down on a bigger piston.
As the revs increase there is less time for the compressed air to leak past the rings - and this is why at low revs the Carerra's with worn rings would be gutless and why - as soon as they came on the cam and the piston speed increased - they took off like a 2 stroke.
With new rings they got back a lot of bottom end but the jerk wasn't so noticeable.
Baz
