Agree with you, except for the last sentence. Why did Toto Wolff resist the call for revised testing of compression ratio, when the other 4 PU manufacturers & FIA want the same ?
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Agree with you, except for the last sentence. Why did Toto Wolff resist the call for revised testing of compression ratio, when the other 4 PU manufacturers & FIA want the same ?
Mod post - when quoting very long strings please edit according to the points that you are raising; it really spams the thread. People will have read the post multiple times before they get to the talking point.catent wrote: ↑03 Mar 2026, 20:27…
In fact, the bodywork dimensions you reference were changed four times between 11 December 2024 and 10 December 2025 (a calendar year). Surely, if the FIA felt this solution was beyond what they intended, they could have told Ferrari as much and modified these bodywork dimensions yet again, to effectively prohibit such a solution. The FIA did not do so.
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Could have purely been done out of principle.
Again, peak cylinder pressure =/= compression ratio.
It is when cylinder cutting moments
No it doesn’t; you have varying IVC points, you have piston ring leakage, you have varying strategies with the throttle body to control engine braking / airflow through the engine.FW17 wrote: ↑04 Mar 2026, 18:49It is when cylinder cutting moments
I don't even know what that means, but compression ratio is only one factor in peak cylinder pressure.FW17 wrote: ↑04 Mar 2026, 18:49It is when cylinder cutting moments
try calculate the CR when the engine is off throttleMartin Keene wrote: ↑05 Mar 2026, 12:11I don't even know what that means, but compression ratio is only one factor in peak cylinder pressure.
Compression ratio is a mathematical value calculated by dividing the cylinder volume, calculated from the bore & stroke, by the combustion chamber volume at TDC. It is a mathematical value defined by the geometry of the engine.
Peak cylinder pressure is based on the operating condition of the engine while it is running.
Lets assume we have an engine with a compression ratio of 16:1, hot or cold, doesn't matter, we are running 20 degrees of ignition advance, 3 bar absolute boost pressure and at sea level, and the PCP is 200 bar, all random scenarios and numbers picked off the top of my head.
Increasing the ignition timing to 22 degrees, changing nothing else will increase PCP, because the combustion process will start earlier in the cycle, thus gas expansion will star earlier, so the engine is being asked to compress an expanding mixture in the cylinder.
Increasing the boost pressure will increase PCP because the mixture is already at a higher pressure before it starts to be compressed.
Increasing altitude will reduce the PCP because the mixture is at a lower pressure before is starts to be compressed, assuming we have not corrected that by increasing boost pressure.
A compression is nothing to do with the engine is on or off throttle, it is a geometric ratio of the design of the engine.FW17 wrote: ↑05 Mar 2026, 16:08try calculate the CR when the engine is off throttleMartin Keene wrote: ↑05 Mar 2026, 12:11I don't even know what that means, but compression ratio is only one factor in peak cylinder pressure.
Compression ratio is a mathematical value calculated by dividing the cylinder volume, calculated from the bore & stroke, by the combustion chamber volume at TDC. It is a mathematical value defined by the geometry of the engine.
Peak cylinder pressure is based on the operating condition of the engine while it is running.
Lets assume we have an engine with a compression ratio of 16:1, hot or cold, doesn't matter, we are running 20 degrees of ignition advance, 3 bar absolute boost pressure and at sea level, and the PCP is 200 bar, all random scenarios and numbers picked off the top of my head.
Increasing the ignition timing to 22 degrees, changing nothing else will increase PCP, because the combustion process will start earlier in the cycle, thus gas expansion will star earlier, so the engine is being asked to compress an expanding mixture in the cylinder.
Increasing the boost pressure will increase PCP because the mixture is already at a higher pressure before it starts to be compressed.
Increasing altitude will reduce the PCP because the mixture is at a lower pressure before is starts to be compressed, assuming we have not corrected that by increasing boost pressure.
3 bar at BDC of compression 48 bar at TDC, injector not adding fuel
That would look like 16:1, except that it summarily dismisses thermodynamics and dozens of real world effects.
A lot of stuff…Martin Keene wrote: ↑05 Mar 2026, 17:01I think so, makes me wonder how much other stuff on here people type with such authority is based on similar 'fact' as well...