Does weather does affect performance?

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amirza786

amirza786

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Winter and Summer gas blends also have an effect on the performance too.

Summer blend has close to 2% more energy than winter blend.

On winter MPGs should be normally worse due to the combination of different factors like the gas blend and weather.
Colder Air requires more fuel to keep the air fuel ratio on check. Remember that cold air has generally more oxygen so if the ecu don't add more fuel the car will run leaner than normal. To overcome this the ECU adds more fuel to the mix.
We are currently on winter blend here in California. Our state mandates the different blends....
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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.
 

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Actually I was wrong, you can get up to 100 octane, but there are only a few gas stations around California that offer it, and it's like $8 a gallon. Premium used to be 92 octane standard, but California banned the additive MTBE (which is a carcinogen that was showing up in groundwater) which was primarily used as an additive to oxygenate gasoline, so refiners switched to 91. Really, I don't think there is to much difference using 91 or 93, you probably have a very minor performance bump
Yeah we have a few stations that have racing fuel that is typically available close to a track and like you said expensive as hell...
 
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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.
CAI are banned in California unless they are certified (CARB Exempt). There is a lot of illegal street racing in San Jose, and a very popular road where they race at night is right where my companies business park is located. There have been some weekends where I had to go into the office and the police have stopped people and are checking their engines for modifications such as CAI.

Anyway there could be a number of factors, like you might have dryer air where you are (we have had a lot of rain, so the air is pretty saturated), and as others have mentioned, we are on winter blend which may not give us the same performance when it's colder and there is more moisture in the air
 

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almost every car ive owned had better response/acceleration in varying degrees in cooler temps.

super hot weather is the worst for performance. like 80 degrees and warmer.
I think the direct injection in this car is the reason very cold temps are not enjoyed. The car needs the cylinder walls to retain some heat to atomize fuel unlike previous cars with port injection in which more heat could be retained in the head and there was more space and time for atomization.
 


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Are you setting your tire pressures when the temp changes? I think that's more liable to change the feel of your car than ambient temp/how much power your engine is making.
 
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Are you setting your tire pressures when the temp changes? I think that's more liable to change the feel of your car than ambient temp/how much power your engine is making.
I check them once a month and keep them inflated to 34 psi
 

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I check them once a month and keep them inflated to 34 psi
10 degrees = 1 psi. If you're driving one day when it's 30 degrees and another when it's 70 degrees without adjusting your pressure inbetween, your car is going to feel different for sure.
 
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10 degrees = 1 psi. If you're driving one day when it's 30 degrees and another when it's 70 degrees without adjusting your pressure inbetween, your car is going to feel different for sure.
Yeah, I don't really have time to adjust the pressure as temps change. If the pressure goes below 32 psi i add air otherwise I leave the tires like they are
 

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thank god only 4 short weeks left till i take it out of its winter hibernation. The cool air (5 C) does wonders for mine, along with the PS4s summers providing outstanding cold grip and 94 in the tank. itll be Christmas in march!
 


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thank god only 4 short weeks left till i take it out of its winter hibernation. The cool air (5 C) does wonders for mine, along with the PS4s summers providing outstanding cold grip and 94 in the tank. itll be Christmas in march!
i bet those ps4 summer tires handle amazing! thatll be my next set of tires for sure
 
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i bet those ps4 summer tires handle amazing! thatll be my next set of tires for sure
I'm just going to stick with the Goodyears until they wear out. Not the best tires, but they have so far served me well. Of course I'm not super duper boosted ;-)
 

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Try the Firehawk Indy 500. Their price is amazing and they are a rebranded Bridgestone tire. This particular one sits in between the RE760 and Potenza S04-PP.
Right now Im using the S04 on my car but the price of the firehawk is hard to ignore. The difference is riddiculous. Plus I don't need that much grip anyway (AWD :p).
Many people are happy with them according to the reviews.
 

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I'm just going to stick with the Goodyears until they wear out. Not the best tires, but they have so far served me well. Of course I'm not super duper boosted ;-)
I sold mine to my work colleague 30 min after they came off the car...LOL. He was more than happy to come pick them up from my Honda dealer. selling them is also an option
 

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Here's a website that had some equations to back things and also had some pressure and temperature corrections to back things up.

I saw it on an old Corvette thread years ago. When I was frequenting Z stuff more and while I don't know if it was current for the change they did around... what... 2005 (I remember the RSXs went from the A2s to I think the Z3 from '04 to '05. They was supposed to be an actual 10 HP gain .. but the change in claimed power went from 200 to 201 because the standard changed the same year the refresh went into effect. It shows the revision was back in August '04 when all this was going on.).

Someone had derived that the correction factor worked out to 1.11% horsepower per 10F. Never checked his work but it sounds right.

https://www.corvetteforum.com/forums/c5-tech/661637-how-much-does-temperature-affect-h-p.html

That'd work out on an Si to be about a 10 HP bump with temperature going from 90F to 40F. I think it'd be an even greater effect on an intercooled car as the larger the delta between IATs and ambient, the better the intercooler could do. Math doesn't really care though.

Again... old stuff, but it was an interesting read at the time and easy to find because I recalled it was on a Vette forum that reference another site with some math... and math is fun.
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