Arrvaxx's quest for the 10s.

Arrvaxx · 09-23-2014, 10:05 PM

Found this:

Wallace Racing - Braking HP Loss at Altitude Calculator

500hp at sea level = 482 at 1200' = 464 at 2400' = 446 at 3600'... linear (18hp/1200')? Really? That doesn't seem right.

I'm pretty sure my numbers are largely due to -me-. I'll get better.

Crazy number of calculators at the site: Wallace Racing - Automotive Calculators

Hotrodz · 09-23-2014, 10:15 PM

Remember to that there is about a 18 to 20% difference between bhp and whp...whp being the lesser of the two.

Arrvaxx · 09-23-2014, 10:18 PM

Right but I was just investigating the affect of altitude on HP; was it linear or not. It appears to be linear which doesn't feel right but hey...who am I.

Hotrodz · 09-23-2014, 10:20 PM

10-4, I'm not an engineer nor did I sleep at a Holiday Inn Express!!!

N8GTOL · 09-23-2014, 11:19 PM

That peak hp calculator is a gross over simplification of reality as it is based only on standard atmosphere with elevation. Also, that calculator does not really apply to your car since you have turbos which will just work harder (up to a point) to make up the pressure loss from increased altitude and temperature (aka density altitude). It may take your turbos a little longer to get peak boost and peak torque and therefore it will feel less responsive in the low and mid range rpms, but generally speaking your peak HP numbers will be much less affected by changes in altitude when compared to us lesser NA folks (and even supercharged vehicles to lesser degree). Superchargers are mechanically driven so they will only increase manifold pressure by a fixed amount relative to the outside air pressure. Your turbos will keep working until they hit the wastegate spring pressure (regardless of the outside air pressure).

As I alluded to, density altitude is the more relevant factor in assessing power loss of an engine as it accounts for changes in air density from both altitude and temperature. Density altitude is not linear but its kinda close. At 1000ft elevation and a temp of 70F, the density altitude is more like 2000ft. Humidity will also rob power as the air mass is replaced with water vapor at the same pressure.

Hotrodz · 09-23-2014, 11:51 PM

Outstanding explanation and according to my butt dyno is spot on. It's weird how on some days my car's responsiveness is like a dog until it gets wound up and then other days she just move out like being at a lower elevation. I assumed that is was mostly a factor of atmospheric conditions. Humidity and high temps are killer period!

Thanks and repped...

FPenvy · 09-24-2014, 08:44 AM

Quote:

Originally Posted by Arrvaxx

Found this:

Wallace Racing - Braking HP Loss at Altitude Calculator

500hp at sea level = 482 at 1200' = 464 at 2400' = 446 at 3600'... linear (18hp/1200')? Really? That doesn't seem right.

I'm pretty sure my numbers are largely due to -me-. I'll get better.

Crazy number of calculators at the site: Wallace Racing - Automotive Calculators

seeing that makes me feel accomplished since i still have a better time than most of the guys at lower almost sea level areas lol

Super Werty · 09-24-2014, 09:23 AM

By the way you should try the da calc on dragtimes

Arrvaxx · 09-24-2014, 10:08 AM

Quote:

Originally Posted by Super Werty

By the way you should try the da calc on dragtimes

Cool! This has density.

DA Calculator - Density Altitude Calculator - DragTimes.com

09-23-2014, 10:05 PM	#31 (permalink)
Arrvaxx A True Z Fanatic Join Date: Jul 2013 Location: Whore Island, MN Posts: 1,243 Drives: 40th F.I. Twin Turbo Rep Power: 18	Found this: Wallace Racing - Braking HP Loss at Altitude Calculator 500hp at sea level = 482 at 1200' = 464 at 2400' = 446 at 3600'... linear (18hp/1200')? Really? That doesn't seem right. I'm pretty sure my numbers are largely due to -me-. I'll get better. Crazy number of calculators at the site: Wallace Racing - Automotive Calculators __________________ 2010 370Z 40th Anniversary (#480 born 1/19/2010) Fast Intentions Twin Turbo \| Varis Arising II \| Limited Edition Recaro Sportster \| Tuned by Specialty Z \| 604hp 525 torque @14lbs boost on 100 octane

09-23-2014, 10:15 PM	#32 (permalink)
Hotrodz A True Z Fanatic Join Date: Aug 2012 Location: NW, AZ Posts: 9,330 Drives: 10 Nissan 370z Nismo Rep Power: 2684385	Remember to that there is about a 18 to 20% difference between bhp and whp...whp being the lesser of the two. __________________ *Fast Intentions TT Installed and Tuned by Seb at SpecialtyZ 610whp 560tq:\|Fast Intentions 3" TT-TDX*\|SpecialtyZ/Fast Intentions 72 Row Oil Cooler\|SZ 6 Puck Clutch & Flywheel\|3GsCustoms\|Z1\|Wavetrac\|Hotchkis\|Whiteline \|Blitz\|Fortune Auto 500\|Fujimura\|SPL\|H&R\|TK\|TWM\|RPM Rollbar\|Sparco\|Next Level Performance\|TrackSpec\|AeroFlow Dynamics\|Pioneer\|

09-23-2014, 10:18 PM	#33 (permalink)
Arrvaxx A True Z Fanatic Join Date: Jul 2013 Location: Whore Island, MN Posts: 1,243 Drives: 40th F.I. Twin Turbo Rep Power: 18	Right but I was just investigating the affect of altitude on HP; was it linear or not. It appears to be linear which doesn't feel right but hey...who am I. __________________ 2010 370Z 40th Anniversary (#480 born 1/19/2010) Fast Intentions Twin Turbo \| Varis Arising II \| Limited Edition Recaro Sportster \| Tuned by Specialty Z \| 604hp 525 torque @14lbs boost on 100 octane

09-23-2014, 10:20 PM	#34 (permalink)
Hotrodz A True Z Fanatic Join Date: Aug 2012 Location: NW, AZ Posts: 9,330 Drives: 10 Nissan 370z Nismo Rep Power: 2684385	10-4, I'm not an engineer nor did I sleep at a Holiday Inn Express!!! FPenvy likes this. __________________ *Fast Intentions TT Installed and Tuned by Seb at SpecialtyZ 610whp 560tq:\|Fast Intentions 3" TT-TDX*\|SpecialtyZ/Fast Intentions 72 Row Oil Cooler\|SZ 6 Puck Clutch & Flywheel\|3GsCustoms\|Z1\|Wavetrac\|Hotchkis\|Whiteline \|Blitz\|Fortune Auto 500\|Fujimura\|SPL\|H&R\|TK\|TWM\|RPM Rollbar\|Sparco\|Next Level Performance\|TrackSpec\|AeroFlow Dynamics\|Pioneer\|

09-23-2014, 11:19 PM	#35 (permalink)
N8GTOL Base Member Join Date: May 2010 Location: San Diego Posts: 228 Drives: and flies Rep Power: 22	That peak hp calculator is a gross over simplification of reality as it is based only on standard atmosphere with elevation. Also, that calculator does not really apply to your car since you have turbos which will just work harder (up to a point) to make up the pressure loss from increased altitude and temperature (aka density altitude). It may take your turbos a little longer to get peak boost and peak torque and therefore it will feel less responsive in the low and mid range rpms, but generally speaking your peak HP numbers will be much less affected by changes in altitude when compared to us lesser NA folks (and even supercharged vehicles to lesser degree). Superchargers are mechanically driven so they will only increase manifold pressure by a fixed amount relative to the outside air pressure. Your turbos will keep working until they hit the wastegate spring pressure (regardless of the outside air pressure). As I alluded to, density altitude is the more relevant factor in assessing power loss of an engine as it accounts for changes in air density from both altitude and temperature. Density altitude is not linear but its kinda close. At 1000ft elevation and a temp of 70F, the density altitude is more like 2000ft. Humidity will also rob power as the air mass is replaced with water vapor at the same pressure. Hotrodz likes this.

09-23-2014, 11:51 PM	#36 (permalink)
Hotrodz A True Z Fanatic Join Date: Aug 2012 Location: NW, AZ Posts: 9,330 Drives: 10 Nissan 370z Nismo Rep Power: 2684385	Outstanding explanation and according to my butt dyno is spot on. It's weird how on some days my car's responsiveness is like a dog until it gets wound up and then other days she just move out like being at a lower elevation. I assumed that is was mostly a factor of atmospheric conditions. Humidity and high temps are killer period! Thanks and repped... __________________ *Fast Intentions TT Installed and Tuned by Seb at SpecialtyZ 610whp 560tq:\|Fast Intentions 3" TT-TDX*\|SpecialtyZ/Fast Intentions 72 Row Oil Cooler\|SZ 6 Puck Clutch & Flywheel\|3GsCustoms\|Z1\|Wavetrac\|Hotchkis\|Whiteline \|Blitz\|Fortune Auto 500\|Fujimura\|SPL\|H&R\|TK\|TWM\|RPM Rollbar\|Sparco\|Next Level Performance\|TrackSpec\|AeroFlow Dynamics\|Pioneer\|

09-24-2014, 09:23 AM	#38 (permalink)
Super Werty Track Member Join Date: Jul 2013 Location: AZ Posts: 668 Drives: '13 Sport Rep Power: 13	By the way you should try the da calc on dragtimes __________________ The Build

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