There are different approaches to intake port geometry, depends what type of conditions you're trying to achieve. For example if you are trying to induce tumble to the intake air, you would use more of a "ramp" style intake port, where you increase the surface area of the port floor vs the roof.ringo wrote: ↑Mon Feb 12, 2018 5:09 amif i were to hazard a few guesses:
i don't think the valve seat is perpendicular to the valve stem due to the need to have a very vertical and straight intake run into the cylinder.
the intake valves in the cylinder are also different sized
the exhaust valves are also different sized.
interesting nugget about the jet combustion going to the walls first before ignition of the lean mixture.
Do you suppose the high exhaust temperatures that produce NOx also contribute to valve seat recession?Mudflap wrote: ↑Tue Feb 13, 2018 12:51 amFrom an inertia perspective the best setup would be a very low speed machine turning slower than the crank.
I was not debating the motor performance.
Regarding the previous valvetrain discussions - Honda's 990 cc motogp engine revved to 16000 rpm with single springs and buckets (which are known to have the highest friction compared to roller followers and fingers and up to 30% higher inertia compared to fingers).
I wonder if valve rotation can be achieved with PVRS. Given the durability requirements and the extreme exhaust valve temperatures valve wear must be quite hard to tackle. Maybe there is an advantage to springs after all ?
Absolutely, other than material tribological characteristics valve recession is mainly driven by temperature, seating velocity (it should be kinetic energy at closing really but for reasons unknown seating velocity is still used in the automotive industry) and to a lesser extent seat angle.
If only the rules didn't prohibit Copper Beryllium seats nowTommy Cookers wrote: ↑Tue Feb 13, 2018 1:20 pmtraditionally SI engines have little or no oxygen in the exhaust gas
these engines have lots and so the oxidation potential might seem to be greater than otherwise
but the exhaust gas will be rather cool
high-strength copper beryllium can be quite hard and it could be mechanically hardened in situ
intentionally by use of dedicated rolling equipment and incidentally by valve impact
it would be rather elastically compliant under impact
it can go to 10000 microstrain elastically (at room temperature)
it will run cooler than the usual valve seat insert materials
in typical use it's pretty corrosion resistant
Are these sodium filled valves for the exhaust?Mudflap wrote: ↑Tue Feb 13, 2018 11:01 pmToyota used Aisan manufactured valves. Other companies that have supplied F1 valves include Del West and Xceldyne.
G&S are also quite popular with british high end racing engine makers.
Honda have made their own valves for the LMP1 V8 but if I had to guess I'd say they are now getting them from Aisan.