jump to navigation

Why Don’t Cars Display Engine Performance Data? July 27, 2009

Posted by federalist in Energy, Open Questions, Transportation.
trackback

Most modern cars have engine control computers and sensors that can tell not only whether your current tank of fuel is contaminated but also whether you would benefit from higher-octane gasoline. Yet few (if any) cars readily communicate those data to the driver. Why not?

Many car engines are designed with higher compression ratios that require “premium” gasoline for optimal performance. These cars can still run on lower-grade fuel: They rely on knock sensors to detect the failure of low-octane fuel to resist detonation and can adjust valve timing to counteract it. However this adjustment reduces engine efficiency and power, so typically drivers want to avoid it. (Conversely, higher-octane gasolines are sometimes sold at such a premium to regular that their higher cost might outweigh the efficiency benefit to engines tuned for them.)

But gasoline octane rating is not the only factor that determines safe engine timing. Air density, which decreases with altitude and temperature, also affects detonation. Fuel that works great in summer or mountains may bog your car down in cold or sea-level conditions. Only your engine knows for sure whether it’s running optimally, or whether it would benefit from a bump in your fuel tank’s octane.

Apparently some aftermarket engine computer interface devices (e.g., the ScanGauge or the DashHawk) can allow a driver to monitor engine timing retardation in realtime. Ideally manufacturers should convert these data into useful dashboard information. Perhaps something like, “Your current fuel is handicapping the engine. Increase tank octane by 2 for optimal performance in current conditions.”

Advertisements

Comments»

1. Cheap HVAC Sensors Could Save Tons of Energy | Federalist - June 10, 2017

[…] Years ago I noted that modern gasoline-powered cars operate inefficiently on gasoline with suboptimal octane, and their engine control units even detect when that is occurring. If they simply communicated this fact to their operators, they could be fueled with the right gasoline, saving money, energy, carbon. But there are still no cars that do this! (I hate to invoke government, but if it took a government mandate to get automakers to put tire-pressure monitors on their cars, at a substantial cost, I wouldn’t chafe at government mandating an essentially free “low-octane” notification on the dash.) […]


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: