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Old 04-13-2018, 02:13 PM   #25
Riftur
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Join Date: Jan 2016
Drives: 2013 Scion FR-S
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Quote:
Originally Posted by mazeroni View Post
I'm in the camp of having noticed and been surprised by the difference of "pep" between temperatures and humidity. But I'm not sure I'd say there was ever much of a measurable difference in terms of acceleration.

Someone over on the MK6 GTi forums (when I had that car) posted dyno results from the same dynometer between a hot and humid day vs a cool day with almost no humidity. They found that the WHP changed nearly 30 hp. (the motor was said to actually produce up to 230 at the crank compared to the listed 200.) I can attest to how shit the car felt on 90+ degree days. So on cooler days you got the full 230-ish.

So that sort of goes to show, at least in the case of a FI motor that requires lots of air volume, how weather can affect things. But density of air wouldn't be as important on an NA motor, and thus heat wouldn't play as big of a role, right? You put a new intake and filter on the GTI and you get 10 hp. On the FA-20 you get what, like 1 hp?
First, I mostly only noticed a big difference when I was already at speed and needed to pass someone. Second is it is definitely from the weather. This morning was 70 when I left for work and the car was feeling normal again. Just now when I drove home I tested it and as even though its not very humid today I did feel a slight drop. I checked my filter and its still fine. Thanks all!
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