[cwebster]

Originally Posted by Rik

Did my picture of the dyno sheet not appear ? It's on my feed

Yeah, its fine. Thanks.

I'm not sure what those filter settings mean in terms of biasing the dyno graph. I was hoping to get something comparable to the "Correction Factor" (CF) that the DynoJet shows. That way we could get a more uniform comparison. At least they listed their estimate of what a DynoJet would show, given the same correction factors I assume.

[cwebster]

I went ahead and added a table to the end of the original post in this thread that contains a running tally of dyno results. I'm using it to get an idea of the range of power that new, stock ZL1s are making.

I'm seeing a substantial range of dyno numbers from stock 6th Gen ZL1s. I thought I'd investigate factors that can affect available power to account for some of these differences.

As has already been discussed, many factors affect Dynamometer results; Rear Wheel HP and Torque. Not the least of these is the type of dyno and parameters used by the operator to bias/ajust the resulting graph. However, even on the same dyno at the same shop with the same operator there can be a wide variation. This variation can be due to factors that the dyno hardware and software is unable to measure or compensate for. Some of these factors you can control and some you cannot.


Fuel:
- Octane rating: higher octane = higher HP/TQ
- Ethanol content - 0-15% in pump gas: less ethanol = higher HP/TQ (in stock eng).

Humidity: lower humidity = higher HP/TQ

Ambient Temperature / Intake Air Temp (IAT): lower temps = higher HP/TQ

Altitude: Higher elevation = lower air density (less O2 per volume) = lower HP/TQ

Friction & Lubricants: less friction = more available power
- Viscosity & friction modifiers
- Lubricant degradation at time of dyno

Mileage / Break-in (cylinder compression): seating the compression rings
- Low mileage may result in lower compression if rings have not yet fully seated.
- More aggressive break-in may seat rings faster, resulting in higher compression with lower mileage.
- Dyno runs and drag strip passes load the engine, increasing pressure in cylinders to more fully seat rings.

Besides the aforementioned "Correction Factor" (CF) and Smoothing, atmospheric conditions have a big effect on power. My dyno graph lists under "Run Conditions"; the temp, barometric pressure, and humidity but I don't know whether this was calculated to offset the results or just there for information purposes.

Ethanol has less BTU than Gas but higher octane. To take advantage of higher octane you must increase boost/compression and tune ECM, among other things. Blending ethanol with gasoline lowers overall BTU and so reduces available energy to a stock motor with stock tune. In other words, if you can get 93 octane, ethenol-free gas, you'll make more power than the E10 that's available at the pump in most places.

See Pure-Gas.org for locations in your area that sell non-ethanol gasoline: http://www.pure-gas.org/

Humidity describes the amount of moisture or water vapor suspended in the air. Water vapor displaces oxygen and other gasses and so it reduces the amount of oxygen available for combustion in a given volume of air.

Temperature affects the density of air. Gasses expand at higher temps and take up less space in a given volume of air. Less oxygen per volume of air means less available for combustion.

Altitude also affects the density if air. Gasses have weight - gravity pulling on the mass of these gasses. The higher you travel in elevation, the less air there is above you to push down and compress into a given volume. Also, the higher the elevation, the less effect gravity has on a given mass. This translates to less oxygen per volume of air available for combustion.

These atmospheric parameters are taken into account in the vaious "Density Altitude" (DA) calculators available. These are used by race tracks and drivers to more accurately estimate how a given pass compares to another track and/or another point in time. They're also used by airlines and pilots or any activity that relies on combustion of air/fuel mixtures.

Drive line loss in HP/TQ can be affected by lubricants used. The most important of these would of course be engine oil but transmission fluid, differential gear oil, and bearing grease could also affect performance. A more "slippery" lubricant may increase available power by reducing friction but result in more wear to drive train components. This is why petroleum companies use additives to adjust various properties of their lubricants. The efficiency of lubricants can degrade over time due to heat, absorbsion of moisture and chemicals, and suspended particles.


My thinking is that to get the most power from my car, whether at the dyno or the track, I should try to stack the deck in my favor.

Fuel: Use highest octane available, preferably ethanol-free if available
Weather (temp/humidity): Check forecast and select the date/time of the event that will offer the most favorable conditions
Altitude: Insofar as it is possible, select a location with the lowest altitude.
Friction: Use highest grade approved lubricants possible for the application and change them at an interval that prevents degradation.


I'd be interested to hear about any other factors I haven't mentioned too.


--Cal


A sampling of refs I found:

Z06Vette Forum: What factors affect HP/torque????

WhatWhenHow: Factors Affecting the Engine Performance
(very detailed scientific explanation)

SpeedHunters: Knowledge Boost: Ethanol Explained

Road & Track: How Does Ethanol Impact Fuel Efficiency?

OffShoreOnly: Dyno- Ethanol Fuel vs. Non-Ethanol Fuel

Bimmer Forums: How does humidity affect a car's performance?

Engine Tuner's Calculator


Ethanol-free Gasoline: http://www.pure-gas.org/

Density Altitude Calculators:

National Weather Service

Drag Times

Shelquist Engineering

Pilot Friend

[TheElementalCashew]

Mine was SAE. Sheet doesn't show smoothing.

[BoostedX2]

As always since 2012...GM is a day late and a dollar short when it comes to domination....I HAVE lived this the last 5 years..with gm resources they should be #1 in all categories!!!!

[Rik]

Mines an A10 not a M6 and the Mustang Dyno uses SAE (SAE JUN1349) then converts to Weather Correction Factor (WCF)

[mlee]

http://www.camaro6.com/forums/showthread.php?t=491947

[cwebster]

Originally Posted by Rik

Mines an A10 not a M6 and the Mustang Dyno uses SAE (SAE JUN1349) then converts to Weather Correction Factor (WCF)

OK, Thanks. I've updated the running tally.

Originally Posted by mlee

http://www.camaro6.com/forums/showthread.php?t=491947

Thanks. I've added it to the running tally. I couldn't see whether they published the mileage.

[HyperBlueX2]

Here was my run at the Rodgers Chevrolet show.... a bit disappointing...... everyone's numbers were low.....

A10.... sixth gear pull......

[Boilermaker128]

Wow those are low numbers...would be interested to see other vehicles on the same dyno same day to judge.

[kttxz06]

I can't vouch since I don't have a Zl1, but my Z06, same motor, dyno'd 568 at the wheels. A8. 100 degree heat. 100% humidity here in good ole Houston. Yea, these numbers are disgustingly low.

[Ryephile]

Originally Posted by HyperBlueX2

Here was my run at the Rodgers Chevrolet show.... a bit disappointing...... everyone's numbers were low.....

A10.... sixth gear pull......

Oh that was your car up there, cool. I don't think we got a chance to meet but your car sounded amazing.

FWIW, the other two stock 6th gen SS's made 370's, which percentage-wise vs. the SAE numbers makes sense with your A10 ZL1.

That's the thing about chassis dyno's, they're relative, rarely absolute.

[HyperBlueX2]

Originally Posted by Ryephile

Oh that was your car up there, cool. I don't think we got a chance to meet but your car sounded amazing.

FWIW, the other two stock 6th gen SS's made 370's, which percentage-wise vs. the SAE numbers makes sense with your A10 ZL1.

That's the thing about chassis dyno's, they're relative, rarely absolute.

I saw your car in the back, you were not present at the time.

The guy at the sign up said it was a Mustang dyno but the graph said Dynotech? Not sure...... I will have better dyno session in the next couple months.

Sorry I missed you.... I saw you in the crowd.

[Ryephile]

Yea I wasn't around my car much, having parked in the "back 40" and with all the action happening up front.

Hopefully we'll catch up at a future meet!

[Ryephile]

I took a short video of one of your dyno pulls.