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I think in hotter weather, the 10 to 1 compression and gasoline even at 93 octane causes the engine to spark knock and the computer is retarding the timing to eliminate it, just cutting power and throttle response in hotter weather. In cooler ambient temperature the engine doesn't spark knock as much so timing can run more advanced which would enhance throttle response.DCO
This is the most probably explanation. Gasoline engines tend towards pre-ignition during high throttle opening, low-RPM operation and exacerbated by higher temps. Most modern engine management systems will start retard timing once the intake air temps reach in the 90-100 degree F. range, which will be practically all the time once outside air temps getting up around 80 degrees F.

The other thing is actual pre-ignition during operation. Our Rav4 is specified to run on 87 octane gas, but that same engine with probably very close to identical programming, is specified to make more power on 91 octane gasoline when used in Lexus models. We have a very heavily speed-patrolled section of slightly uphill freeway that we drive very often. When running on 87 octane gas and with the cruise control set at 65 MPH/1800 RPMs, the engine always comes out of torque converter lockup mode climbing this grade. With 91 octane gas, it almost never comes out of lockup mode. And that's mostly temperature dependent. On the warmest days, even on 91 octane, it will sometimes unlock climbing that grade, probably because we're also running the A/C but also because the higher intake temps are causing timing to be retarded.
 

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Air intakes are compromised in many ways. Having a direct route for outside air to get to the filter raises the risk of water, leaves, bugs, and dirt getting in.

Pre-ignition is most likely to occur at low RPMs and high throttle openings. To minimize heating of the intake airstream, you want the flow to be fast so there's minimal conduction from the walls of the intake tract. However, fast flow at low RPMs means restriction at high RPMs.

In the first generation Miata, the best performing air intake actually utilized the high pressure region at the base of the windshield, rather than trying to duct through the bumper grill or an opening in either the corner parking light or flip up headlight cover. Any intake along the side of the vehicle like I think it is in the 451 is operating in a low pressure region unless the body in front of the intake is shaped to create a pressure wave there, or the intake juts out into the airflow.
 
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