Temperature and HP
 

I drive a stock 370z. I noticed a measurable change in HP when temperatures recently dropped from 85ºF - 100ºF to 65ºF - 80ºF.

I know the stock Power is (SAE) 332 hp @ 7,000 rpm; 270 ft lb of torque @ 5,200 rpm in a perfect world.

What would be your guess for HP at 65ºF and 100ºF for a stock 370z?

650hp

333, 315

I'm saying the engine will produce, not WHP, OP said the car makes 332HP, which is at the flywheel

And I'd like to edit my answer

In all seriousness, I'd expect the manufacturer's numbers for the car to be accurate at lower temps, and the car most likely makes much less power than stock at 100 degrees.

Yeah, and 65 degrees isn't that cold, especially if "room temp" is 68 degrees

Texas
 

100ºF+ Its very noticeable drop in power. Oil temperature gauge gets about 220ºF max but the radiator stays perfectly in the middle.

...

http://www.the370z.com/nissan-370z-g...loomy-day.html

:tup:

Of course. Hot air makes far less power than cooler, denser air. I would expect that the numbers claimed by Nissan are best case scenario numbers, and you give up a lot of power in the heat. How much exactly? No one can tell you.

DE- ok deleted reply so you can edit your power rating...

Lol, you didn't need to, I already edited it :)

oh, i thought you wanted no history of the edits. :icon17:

The ECU starts limiting power when the Intake Air Temperature gets to ~85-95 F. You are not gaining power at lower ambient temps, the ECU is restoring normal operation. The question should be: How much power am I losing at 100 F? (My answer is: I dunno.)

How much power am I loosing at 100ºF?
 

It feels like 25 hp.

How are you estimating that? The only real way to figure it out would be to dyno the car at 100 degrees, and add back in the drivetrain loss. Even then, it wouldn't be 100% exact.

Its not the ecu per say, its the tuner. You can pull whatever timing you want based on intake temp. The way its setup though is based on possible experience with knock at higher temps. Instead of pulling timing individually the main timing map can just pull with temps which is real easy. But you could set the timing in stone in the timing/knock maps and set intake temps to all zero. You won't lose power then based off of temps but you'll be driving around in cooler temps with a crappy tune because the timings so low so it works when its cold or hot out. Here's a pic of my WRX. At 85 degrees it pulls zero timing. At 86 degrees it pulls 0.35 and so on.

FYI in the turbo world 1 degree of timing can be about 10hp. So 85 vs 100 we're looking at only 0.35. The power loss is minimal with-in the tune but denser/cooler air can get you a few ponies. At 104 though and -2.11 you're looking at a good 20hp loss.

At the drag strip there is a big difference in the summer months vs runing in late Oct or early Nov.
my best times have been when is 38 to 43 degress temp.
the moter even sounds differnt.

Z

Science, I could go on and on, write a whole paper on how and why it's affected,

but basically; hot & humid air contains less molecules of Oxygen, when a hydrocarbon (gas) combusts, oxygen is the limiting reagent, the more O2 you have per square inch in air the more O2, the more fuel you dump, bigger explosion.

Vq37 was rated at sea level, almost all N/A engines are rated at sea level ~14.7 psi.

As far as temperatures... for every 10-11-degree Fahrenheit rise in intake air temperature past 77F, SAE Standard condition temperature (25C), you can expect engine horsepower to decrease by about 1% at the same barometric pressure.
(noticed I underlined intake air temperature), it's actually higher then outside ambient temperature, especially with the VQ running as hot as it does.

How are engines rated in Europe? Because they are advertised at 326HP if my memory serves me well

there is a small difference between the SAE and EEC test protocol in how they calculate output/drive train loss, basically a EU 370z will make same horsepower dyno as a north American Z on the same dyno/ same conditons.

I know that, I doubt Nissan makes 2 different ones (maybe different tune, but I doubt it)

But thanks for the name "EEC" I'll look into it (just food for thought)

yea I like sticking to the SAe :)

also fun fact; SAE was changed around ~2007,

so a 2003 nissan 350z making 287hp would actually be calculated as less horsepower in 2013. If I remember correctly like 15hp less. so a 2007 350z actually makes over 30hp vs the 03.