I’ve recently noticed that when you hover your mouse over the sliders of the carburettor, intake manifold, exhaust header and pipe, one of the values that shows up is the gas flow. I don’t doubt that this value has a big effect on the characteristics of the engine, so I’d like some advice to know what values to target in-order to make the engine behave more like how I’d want it to
As an example:
- Does the flow value of the exhaust headers and pipe need to match for the engine to work most optimally?
- Should the flow value of the intake manifold be a percentage of the flow value of the carburettor, and if so, which percentage is most optimal for performance, or economy. Could it be that the values need to match as well?
- Slightly unrelated question, but one that’s been bugging me as well: Is it best to tune the intake side first, or the exhaust side of the engine?
I’ve also been experiencing some issues with torque dropping quite drastically when attempting to make low revving engines, so I’d be happy to get some advice about this as well 
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There is no single optimal solution for this; for every engine, and every application of that engine, there is an optimal solution. Sometimes that might be an engine optimised for maximum performance, sometimes it will be the same engine but tuned for economy, or smoothness, or whatever.
In the most general terms, an engine tuned for maximum performance will be at or near 100 percent flow values, or slightly restricted from those. An economy engine will be more restricted still. How much, again it depends on your application.
As for tuning, you have to adjust both induction and exhaust at once, since they interplay so heavily against one another.
Oddly enough, I find myself having to target a value that’s well below 100% in-order for the engine to produce a good amount of power, whilst also having a good torque and power curve. I frequently need to go as low as 60%, as an example, and this seems to be the case even when I attempt to make an economical engine
If I try to target 100% or more, often the outcome is either torque is produced very late in the rpm range, or drops off very suddenly
I did try to experiment with the bore/stroke ratio to mitigate this issue, but the same outcome kept occurring
Since I’ve enabled the Al Rilma update, the game’s charts have been very buggy for me, maybe this is what’s causing the problem? It could be that the power curve chart is providing incorrect readings for me, which is making me believe that the engine’s peak torque and power is earlier or later than it actually is. I know for a fact that the fuel map chart is definitely broken since the update, as it gives me a much more different reading of the air fuel ratio than the display in the test tab does