Temperature and HP

synolimit · 09-23-2013, 02:40 PM

Quote:

Originally Posted by SouthArk370Z

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.)

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.

Z eliminator · 09-23-2013, 05:07 PM

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

Redglare · 09-23-2013, 05:39 PM

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.

DEpointfive0 · 09-23-2013, 05:44 PM

Quote:

Originally Posted by Redglare

Engines in north america are rated under ,SATP - Standard Ambient Temperature and Pressure is a reference with temperature of 25 degC (298.15 K) and pressure of 101 kPa.
or in normal units; 77 degF @ 1 atm = 1.01 bar.

so the Z produced 332hp at those conditions, you start raising temperature and or pressure and your horsepower suffers.

so to the people who bought the Z in colorado the actual horsepower is closer to 300 crank, those in Arizona during summer 100+ F weather are also not getting the 332hp.

so ideally, if you drive your car in Florida during the winter you will be right at sea level 29.96mm Hg ~ 1atm, and the temperature will be right around 77 depending on exact location, now drive the same car in Florida during the summer and you will also be less then advertised.

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

Redglare · 09-23-2013, 06:01 PM

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.

DEpointfive0 · 09-23-2013, 06:04 PM

Quote:

Originally Posted by Redglare

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)

Redglare · 09-23-2013, 06:09 PM

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.

09-23-2013, 05:07 PM	#17 (permalink)
Z eliminator A True Z Fanatic Join Date: Jul 2009 Location: Ontario Canada Posts: 1,659 Drives: 370 Z 7AT Sports Rep Power: 19	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 __________________ 12.343 @114.14 . 4.5 stroker motor is now being built. Dec 1 2015.

09-23-2013, 05:39 PM	#18 (permalink)
Redglare Enthusiast Member Join Date: May 2012 Location: FL Posts: 387 Drives: C172 Skyhawk GIII Rep Power: 175	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. Last edited by Redglare; 09-23-2013 at 05:54 PM.

09-23-2013, 06:09 PM	#22 (permalink)
Redglare Enthusiast Member Join Date: May 2012 Location: FL Posts: 387 Drives: C172 Skyhawk GIII Rep Power: 175	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. DEpointfive0 likes this.

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09-23-2013, 06:01 PM	#20 (permalink)
Redglare Enthusiast Member Join Date: May 2012 Location: FL Posts: 387 Drives: C172 Skyhawk GIII Rep Power: 175	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.