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What does 4.10 Gears mean on a Dyno

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Old 7/13/06, 05:13 PM   #1
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What does 4.10 Gears mean on a Dyno

I have seen some responses from people on here regarding lossses in HP and TQ on the dyno when done with 4.10 gears.

Exactly why would you lose HP or TQ when on a dyno because of 4.10 gears...Id like to know, As you can see I have a few mods myself including a custom dyno tune and 4.10 gears...


Thanks
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Old 7/13/06, 05:26 PM   #2
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Good question.....I've been wondering too.

I last dyno'ed at 296/316 and since have added 4.10 gears. What should I expect to see now, all things being equal?
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Old 7/13/06, 06:26 PM   #3
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Quote:
Originally Posted by dcranford
I have seen some responses from people on here regarding lossses in HP and TQ on the dyno when done with 4.10 gears.

Exactly why would you lose HP or TQ when on a dyno because of 4.10 gears...Id like to know, As you can see I have a few mods myself including a custom dyno tune and 4.10 gears...


Thanks
Its a basic fact that reduction gears are not 100% efficient. In other words, if you put in 300 hp, you get less than 300 hp out. The more the reduction, the less effcient they are and the higher the loss. 3.55 gears loose a little hp, 4.10 loose a little more. Lots of other factors effect exactly how much you loose, but don't be surprised to see 5 to 10 hp difference between 3.55's and 4.10's.

Hope that helps

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Old 7/13/06, 07:38 PM   #4
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So do you benefit more from having the 4.10's or the 5 to 10 hp's.
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Old 7/13/06, 08:17 PM   #5
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good question

so is there more benefit from having the pull of 4.10's or the 5 to 10 HP of a higher gear ratio (3.55)
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Old 7/13/06, 08:23 PM   #6
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Quit bench racing and let your butt decide what you like
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Old 7/13/06, 08:37 PM   #7
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You're not making any less horsepower. It all has to do with how the dyno calculates horsepower vs. torque.
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Old 7/13/06, 11:53 PM   #8
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yes, the engine is producing the same amount of power, but the gear ratio kills the number the dyno calculates. I think it is the same sort of error as if you dynoed in 3rd gear for example. car producing the same power, but dyno numbers are off.
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Old 7/14/06, 04:54 AM   #9
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From the Mustang Dyno web page (www.mustangdyne.com) FAQ:

Q:
Why does the dyno show a power loss after a differential gear change (say a 3.42 to 4.10 gear)?
A:
The Chassis Dynamometer measures power that reaches the tires, not Engine Power. Therefore, any changes you make to your drivetrain may result in a change in your chassis Dynamometer results. A steeper gear ratio will provide the following,

1. Higher peak force to the ground
2. Higher average force to the ground
3. Lower top speed (MPH)
4. Higher peak acceleration rate in all gears
5. Lower peak horsepower

The reason you lose your peak hp is based on higher acceleration rates, increased gear mesh/losses, higher tire losses. These will affect your peak horsepower number in a negative fashion. Losing approx. 5% is expected when changing to a significantly steeper rear gear. Engine power was not reduced, power to the ground was. In exchange, you have more force available which is what allows you to accelerate faster off the line. If you enjoy the feeling of Gs forces as you accelerate, you made a wise choice. Do not be discouraged by the peak power numbers—they are just a reference.
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Old 7/14/06, 05:04 AM   #10
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One of the magazines ran an article on the Drag pack. They did a before and after with 4.10 gears and lost 5-7 HP at the wheels. No other changes.
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Old 7/14/06, 11:10 AM   #11
 
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Quote:
Originally Posted by SixtySix
Quit bench racing and let your butt decide what you like
Amen brotha... I've never won a race on a dyno yet.



Quote:
Do not be discouraged by the peak power numbers—they are just a reference.
Exactly... peak power numbers only mean something on the dyno. They have virtually no significance on the street or at the track. There are literally dozens of other variables that have as much (or more) importance on how quickly the car accelerates. Personally, I would rather have low dyno numbers and a quick car, than big dyno numbers and a pig car.
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