Does weather does affect performance?

[b4gel]

Cold air intakes wouldn't sell very well if they didn't improve performance. Along with decreasing airflow resistance it's all about the cooler air for more power. I've noticed optimal performance for all vehicles I've owned is ~5C/40F as the cold air really wakes up the engine and traction is still decent. My 10th gen Si is no different.

Disagree with that. Cold air intakes sell well because they make noise. Rarely do they improve performance.

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[gtman]

Disagree with that. Cold air intakes sell well because they make noise. Rarely do they improve performance.

I was going to chime in with the same basic thought with a twist. Cold air intakes marginally do improve performance but like you said, adding sound is a big draw to them. The real loser is short ram intakes. They heat soak like crazy. Anyone buying an SRI for a noticeable performance gain will be disappointed especially in hot weather. Sound good though.

 

[Marjammer]

Fuel economy does take a hit in the winter though for a lot of people...longer warm up periods, under-inflated tires, winter grade gasoline, denser air causing higher drag, etc.

You gotta swap out that summer tire air for winter tire air.

 

[b4gel]

You gotta swap out that summer tire air for winter tire air.

The summer air gets chilly in there

 

[PhilF]

I've owned my 2018 Civic Si Since June (8 months), and I notice that temperature does affect performance. I have found that if the temperature is 50 F and above, my car performs much better, everything from acceleration to better gas mileage. For example, yesterday was a nice 55 degrees F, and everything was so much smoother, from shifting to basic acceleration. Also I was averaging 31 mpg doing some spirited driving. This morning the temp was 38F (cold for the Bay Area), and even after everything was warmed up, I felt as though I had to push down harder on the pedal. Accelerating seems a bit more restrained, shifting not as smooth, and average gas mileage this morning dropped to 26 mpg. Also I feel boost takes a bit longer and is much less.

What I feel is that this car drives much better between 50 degrees and 90 degrees F. I don't know if it's the ECU maybe tuning things down or possibly the transmission doesn't work as well in the cold. I don't have this issue at all with my two Toyotas, they drive the same cold or hot weather. Does anyone else feel the same, that your Si drives better in warmer weather? I would like to know if I'm the only one who notices this.....

EDIT

I want to make it clear, it does not drive bad in colder temps, performance just seems a bit down compared to driving in warmer temps

I don't have an SI, however, in my 2016 EX-L during one of my regular trips to Northern NY from Central Pennsylvania in 2018, the temperature did not go over 15f for the entire trip (exclusively highway, including I87) I usually average 45+ mpg, using cruise set at 67-8, when temperatures are above 40f for most of the trip, sometimes over 50mpg when temperatures are in the 70's or higher. This is calculated mpg, not the dash indicator. On the trip with the sub 15f temps, I barely got 35 mpg, and the car seemed sluggish. It will be interesting to compare my next trip performance on the same route with my 2019 Touring, same drivetrain with larger, wider tires. It will be warmer and hope to at least come close to 45 straight highway. Not a scientific comparison, however, my "Butt Dynamometer" is telling me my 1.5t doesn't like super-cold temps. BTY, I ran Mobil1 0W-20 & all maintenance was up to date. Shell 87 fuel used for these trips.

 

[fenix-silver]

I don't have an SI, however, in my 2016 EX-L during one of my regular trips to Northern NY from Central Pennsylvania in 2018, the temperature did not go over 15f for the entire trip (exclusively highway, including I87) I usually average 45+ mpg, using cruise set at 67-8, when temperatures are above 40f for most of the trip, sometimes over 50mpg when temperatures are in the 70's or higher. This is calculated mpg, not the dash indicator. On the trip with the sub 15f temps, I barely got 35 mpg, and the car seemed sluggish. It will be interesting to compare my next trip performance on the same route with my 2019 Touring, same drivetrain with larger, wider tires. It will be warmer and hope to at least come close to 45 straight highway. Not a scientific comparison, however, my "Butt Dynamometer" is telling me my 1.5t doesn't like super-cold temps. BTY, I ran Mobil1 0W-20 & all maintenance was up to date. Shell 87 fuel used for these trips.

Winter blend gas will reduce your fuel mileage, although I wouldn't expect by that much.

 

[newskate9]

Once upon a time I was friends with a few crotch rockets. I never could prove anything of course, but I did and do believe, cold evening rides were amazing. It was like getting a different machine at times. Once I actually thought I heard the engine of one of my bikes thanking me for the night ride........... Those engines were nothing like the tech under our hoods theses days, but it felt like it made a huge difference then.

 

[saz468]

No question. In my experience, the turbo seems to prefer milder, low humidity weather like what you'd see in Spring or Fall. Hot, humid summer temps sometimes has the car falling flat on it's face.

That’s true where I live in Florida the summer is hot and humid and the winter is the same when and if we have a cold spell my car performs a lot better especially if it down to 50 degrees

 

[tinyman392]

Winter blend gas will reduce your fuel mileage, although I wouldn't expect by that much.

On top of that, the cold will reduce it further by like 10% if I'm not mistaken.

 

[fenix-silver]

Great resource I just found: https://www.fueleconomy.gov/feg/coldweather.shtml

 

[FLOPPER]

I just mix ~2 gallons of E85 with a tank of 91 to get 93ish, though. Ends up being cheaper than even just filling with 91, since E85 is generally cheap.

I've been doing this ever since I saw your first thread/post that recommended this--thank you!

To the OP--I'm pretty sure 93 only makes a difference if you're tuned, so since you say you're keeping your car all stock (YAWN), yeah, I guess you probably won't see a difference between that and 91.

 

[amirza786]

I've been doing this ever since I saw your first thread/post that recommended this--thank you!

To the OP--I'm pretty sure 93 only makes a difference if you're tuned, so since you say you're keeping your car all stock (YAWN), yeah, I guess you probably won't see a difference between that and 91.

I like (YAWN) stock. Now it's nappy time

 

[Captaindicki]

I like (YAWN) stock. Now it's nappy time

Right. What’s wrong with keeping these Sis stock, or mostly stock? This gen in particular is amazing as is from factory. Iv added some bracing and grip enhancements. But beyond that, not gonna mess more with the already great recipe. It’s never gonna challenge a Type R no matter what enhancement is thrown at it. If I wanted that level of increased performance, I’d have bought instead the R

 

[gtman]

I agree. The Si is an amazingly polished, balanced machine right from the factory. Nothing wrong with that. On the other hand, modding it to be even better isn't a bad thing either.

 

[04sthemi]

i live in Central FL, have an 04 ram i modded an used to take to the 1/4 mi. Like mentioned above on a 50* winter night at the track my truck would run about .3-.5 tenths faster than middle of the summer, it was very consistent with that part.

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