I had always heard that engines take about seven miles to warm up. Someone told me that modern cars like the Fit only take two miles. Is this true? The Fit's engine light goes off after a minute or two. Anyone know when the Fit's engine at peak efficiency?

 

for an ENGINE to be FULLY WARM, it takes roughly 20 min. of driving. The most accurate way to check if the engien is warm, is to check teh temp on the engien oil.

 

Depending on how cold it is winter/summer my rsx takes 5-15 mins before the engine it warm enough to engage Vtec. On the FIT we have the cold light so I figure it is warm enough when it goes off. I don't know what temp the car is at when the light goes off but it takes a few mins.

 

I'd agree with the ~20 minute assessment, maybe a bit less. The outside temp can make a big difference, at least in Minnesota during the winter!.

I wouldn't consider the engine fully warmed when the light goes out, it's just 'cold' anymore. I'd think getting the engine up to full normal operating temp would take more than 2 minutes or so of running time.

Is this something someone with a ScanGauge could answer?
a) What's the engine temp when the cold light go out?
b) What's the engine temp after 15-20 minutes or so of steady driving?

 

The temp cold light goes out at around 54-56 degree C.

Normal driving hovers around 80-83 degree C.

I've seen it go over 90 degree... but then the fan kickes in until around 85 degree.

BTW, they're all coolant temperature.

 

On my ScanGuage the cold light goes out at about 125 degrees F. The normal operating temp is around 180. On a warm day in stop and go traffic the fan will kick-in around 213 degrees F.

 

So is my friend correct when he says it less time for contemporary cars to fully "warm up" than cars built in 80s and 90s?

 

Yes, you are correct. Auto manufactures what the car to warm up as fast as possible to reduce the emissions and improve engine efficiency:

-Closer to operating temps = closer catalyst approaches operating temp
-Gasoline burns more readily at 200 F; less fuel is needed to keep car running smoothly when engine is warm.

 

Thanks everybody for the good info on when the lights go out - I always wondered at what temp that was (damm I miss a real gauge!)

As far as warming up sooner than they used to - I'm no expert, but here's my thoughts.....

The coolent temp isn't the temp of the overall engine. It takes a while for all the oil and the engine block to heat up to the normal operating temperature. The coolent flow is controled by a thermostat, so I can see why that heats up much more quickly than the rest of the engine. I don't think you'll see 'peak' efficiency until the rest of the engine gets fully warmed up, which will be more than the time it takes the light (measuring coolent temp) to go out.

Is it warmup time less time than it used to be? I'm guessing it is, for 2 reasons:

1) Engines (overall) are broadly speaking, smaller than they used to be - I'm guessing that the time to warm up is less - no data here - maybe a thermodynamics guy can chime in.....

2) The oil in cars today is MUCH thinner than it used to be - when the engine is cold, the oil in todays cars still flows pretty easily, so the engine runs smoother with less internal friction sooner. In the old days, cars would just groan after being started in a Minnesota winter. Now it's still not super happy for the first few miles, but there's not much complaining to be had. There's a big difference between 10w-40 and 5w-20 oil!