somebody educate me - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

nards444 · 07-17-2009, 08:06 AM

I would like to say Im a gear head, and probably know more than the average guy, but still am a novice.

When it comes to HP there is at the wheel and at the FLY. How the numbers we get are at the FLY correct? And and the wheel is always less. is this because everything behind the motor never really keep up with the Fly or what.

ItIsWhatItIs · 07-17-2009, 08:16 AM

Quote:

Originally Posted by nards444

I would like to say Im a gear head, and probably know more than the average guy, but still am a novice.

When it comes to HP there is at the wheel and at the FLY. How the numbers we get are at the FLY correct? And and the wheel is always less. is this because everything behind the motor never really keep up with the Fly or what.

The Hp at the fly is the actual Hp the engine is putting out. This number is obtained by an engine dyno (that's right...the engine is out of the car). The rear wheel Hp is obtained on a chasis dyno. The number is always less because of the HP you lose in the drivetrain between the fly and the wheels, old standard was 18-20% reduction but, with modern technology it might be less. Are their any dyno shop owners that can help us out here?

patriotpa · 07-17-2009, 08:18 AM

It's due to losses in the drive line. Some of this is due to friction. Flywheel numbers are read AT the flywheel. TO correct from RWHP to flywheel HP you need to know the driveline loss.

hollywoodGU · 07-17-2009, 08:19 AM

i just posted a responce but it didnt show up haha? basically the flywheelhorsepower is figured out exactly like "it is what it is" said it is. The loss comes because off stuff like friction and pressure when the power is being transfered from the fly to the wheels

nards444 · 07-17-2009, 08:22 AM

I know HP in all senses is kind of like theory, its true a lot of times but not always and can not always be relevant. So to get a true number can you average the two? my question is then why is HP advertised from the wheels, because that is what you are getting.

hollywoodGU · 07-17-2009, 08:24 AM

im assuming your asking why is horsepower NOT advertised from the wheels and that would be because at the fly there is more horse power= bigger number = more attraction

just like girls are attracted to guys with bigger...erm...well we wont go there

nards444 · 07-17-2009, 08:28 AM

yeah i understand that, but truth in advertising. But you might see that now with this govt

hollywoodGU · 07-17-2009, 08:33 AM

well techincally it is the truth, it is making 400+ HP (SS for example) is it putting all of it to the ground? no. But it is making that much.

patriotpa · 07-17-2009, 08:34 AM

Quote:

Originally Posted by nards444

yeah i understand that, but truth in advertising. But you might see that now with this govt

You're kidding...right?

hollywoodGU · 07-17-2009, 08:46 AM

Quote:

Originally Posted by patriotpa

You're kidding...right?

i know right...the government telling us the truth

The Riz · 07-17-2009, 09:31 AM

I would think the flywheel hp rating is more reliable and accurate. The problem with dynoing at the wheels brings to many variables into play. There's variation in how different dynos read the power being transferred to the wheels. With an engine dyno I thought it was more of what you see is what you get. I could be wrong I guess.

ElAntonius · 07-17-2009, 09:41 AM

Yep, dynos are actually fairly misleading...they can help in gauging the effects of something like a tune or an upgrade, or maybe comparing two cars at the same time, but as an indicator of performance they are not a very steady benchmark.

There's actually a good bit of truth in advertising the engine output...these engines are SAE certified which means that you should be receiving an engine with +-1% of the advertised rating...whereas your "wheel" hp rating varies based on weather, car, dyno, even the shop that performs the test.

Sack Rat 2SS · 07-17-2009, 10:15 AM

The drivetrain loss is different for various vehicles. For example, my automatic Trailblazer SS has a heavy duty tranny, very heavy driveshaft, heavy duty rearend, and the wheels and tires are large and very heavy as well. All this takes more flywheel HP to rotate on the dyno as compared to a strong but light weight drivetrain on a Vette. However, the flywheel HP is the same as the Vette's. My 2 cents.

Gentry78 · 07-17-2009, 02:35 PM

just one more thing that takes away hp to the wheels is vibration throughout the drivetrain

07-17-2009, 08:06 AM	#1
nards444 Drives: 1SS/RS Black Join Date: May 2009 Location: New york Posts: 2,123 View My Garage	somebody educate me I would like to say Im a gear head, and probably know more than the average guy, but still am a novice. When it comes to HP there is at the wheel and at the FLY. How the numbers we get are at the FLY correct? And and the wheel is always less. is this because everything behind the motor never really keep up with the Fly or what. __________________ 2010 1SS/RS Black, CGM stripes, polished Rims, Tinted windows, Hurst shifter

07-17-2009, 08:22 AM	#5
nards444 Drives: 1SS/RS Black Join Date: May 2009 Location: New york Posts: 2,123 View My Garage	I know HP in all senses is kind of like theory, its true a lot of times but not always and can not always be relevant. So to get a true number can you average the two? my question is then why is HP advertised from the wheels, because that is what you are getting. __________________ 2010 1SS/RS Black, CGM stripes, polished Rims, Tinted windows, Hurst shifter

07-17-2009, 08:28 AM	#7
nards444 Drives: 1SS/RS Black Join Date: May 2009 Location: New york Posts: 2,123 View My Garage	yeah i understand that, but truth in advertising. But you might see that now with this govt __________________ 2010 1SS/RS Black, CGM stripes, polished Rims, Tinted windows, Hurst shifter

07-17-2009, 09:41 AM	#12
ElAntonius Drives: 2010 Camaro 1SS A6 Join Date: Apr 2009 Location: Tampa, FL Posts: 140 View My Garage	Yep, dynos are actually fairly misleading...they can help in gauging the effects of something like a tune or an upgrade, or maybe comparing two cars at the same time, but as an indicator of performance they are not a very steady benchmark. There's actually a good bit of truth in advertising the engine output...these engines are SAE certified which means that you should be receiving an engine with +-1% of the advertised rating...whereas your "wheel" hp rating varies based on weather, car, dyno, even the shop that performs the test. __________________ A House Divided...

07-17-2009, 10:15 AM	#13
Sack Rat 2SS Drives: Silver SS/RS, Man 6 Join Date: Apr 2009 Location: DFW area, Texas Posts: 884	The drivetrain loss is different for various vehicles. For example, my automatic Trailblazer SS has a heavy duty tranny, very heavy driveshaft, heavy duty rearend, and the wheels and tires are large and very heavy as well. All this takes more flywheel HP to rotate on the dyno as compared to a strong but light weight drivetrain on a Vette. However, the flywheel HP is the same as the Vette's. My 2 cents. __________________ Silver 2SS/RS Man/6 CTS-V front 6-Piston Calipers, GM 3.91 Rear Gears

07-17-2009, 08:18 AM	#3
patriotpa Account Suspended Drives: 02 Silverado, 09 Vue, 10 1SS Join Date: Aug 2008 Location: Tired of apologizing when we should be kickin' butt! Posts: 1,962 View My Garage	It's due to losses in the drive line. Some of this is due to friction. Flywheel numbers are read AT the flywheel. TO correct from RWHP to flywheel HP you need to know the driveline loss.

07-17-2009, 08:19 AM	#4
hollywoodGU Drives: 1999 Firebird Formula Join Date: Jan 2009 Location: Monmouth, OR Posts: 656 View My Garage	i just posted a responce but it didnt show up haha? basically the flywheelhorsepower is figured out exactly like "it is what it is" said it is. The loss comes because off stuff like friction and pressure when the power is being transfered from the fly to the wheels

07-17-2009, 08:24 AM	#6
hollywoodGU Drives: 1999 Firebird Formula Join Date: Jan 2009 Location: Monmouth, OR Posts: 656 View My Garage	im assuming your asking why is horsepower NOT advertised from the wheels and that would be because at the fly there is more horse power= bigger number = more attraction just like girls are attracted to guys with bigger...erm...well we wont go there

07-17-2009, 08:33 AM	#8
hollywoodGU Drives: 1999 Firebird Formula Join Date: Jan 2009 Location: Monmouth, OR Posts: 656 View My Garage	well techincally it is the truth, it is making 400+ HP (SS for example) is it putting all of it to the ground? no. But it is making that much.

07-17-2009, 09:31 AM	#11
The Riz Drives: 2010 Camaro 2SS Join Date: Apr 2009 Location: Springfield, IL Posts: 48	I would think the flywheel hp rating is more reliable and accurate. The problem with dynoing at the wheels brings to many variables into play. There's variation in how different dynos read the power being transferred to the wheels. With an engine dyno I thought it was more of what you see is what you get. I could be wrong I guess.

07-17-2009, 02:35 PM	#14
Gentry78 HOOK'EM Drives: 97 c1500/92 olds Join Date: Oct 2008 Location: Texas Posts: 5,279	just one more thing that takes away hp to the wheels is vibration throughout the drivetrain

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