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I drive a 4-speed automatic with a 1.1L 70 HP engine. Naturally, I very frequently find myself in situations where pressing the gas pedal deeper doesn't increase acceleration (i.e. maximum engine load).

Some of these situations include

  • going uphill (speed decreases with time),
  • upshifting at ~2,800 RPM for efficiency when pulling away and
  • going the speed limit on the highway in the highest gear (~4,000 RPM).

How do these situations affect engine wear and efficiency?

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  • 3
    "I very frequently find myself in situations where pressing the gas pedal deeper doesn't increase acceleration" - Yes, a 70 HP engine will feel and behave like that.
    – MonkeyZeus
    Jun 13, 2023 at 18:56
  • 2
    Hence why that statement is prefaced with "naturally"
    – James T
    Jun 14, 2023 at 8:04

2 Answers 2

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All these situations affect wear only in an academic sense.

The most important factors aren't included:

  • Proper maintenance: Oil and filters are regularly changed. No faults with the cooling.
  • RPM not over redline, not too low with high load (shouldn't be an issue with an automatic).
  • No high load on an cold engine. Warm up gently.

Generally speaking:

An warm engine is quite tolerant against high load. In fact, it requires regular high load to keep it healthy.

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  • 1
    Yes, oil is key. If you're worried about protecting your engine, buy a more expensive oil with a high HTHS specification that resists breakdown (like Red Line).
    – Carguy
    Jun 13, 2023 at 11:05
  • Why does an engine require regular high load to remain healthy?
    – findwindow
    Jun 14, 2023 at 15:57
  • @findwindow primarly because oil needs to be warm to have an cleaning effect, and to vaporize water and fuel contaminations
    – Martin
    Jun 14, 2023 at 20:02
  • Egr valves contaminate the intake tract with soot unless the engine is under high load
    – Martin
    Jun 14, 2023 at 20:21
  • Particle filters, if equiped, need prolonged high load to activate the cleaning cycle
    – Martin
    Jun 14, 2023 at 20:22
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Historically, a dead spot in the middle of the pedal meant a lean condition under load. I have a Hyundai 2.0 manual, and it has a large dead spot. The proof is, as you back off to the point where the car would be only maintaining, does it seem to regain power? It's a lean condition, set by the factory for emissions, not fixable unless you have access to the source code. (Oh,for the dullards, and lugging an engine lean does not lower emissions just because you're fuel-starving it. The emissions, especially NOx, go up. So more fuel is NOT worse.) Regarding load, gas engines are most efficient at about 80% load. If you are concerned, search UltraGauge on Amazon. They cost $50-$150 and plug into the OBD-II port, and many give you live stats while driving. Also, search WOT in the diagnostics. All modern engines re-set their fuel curve during Wide-Open-Throttle. If you NEVER floor it, your fuel curve will go off over time.

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