Dyno Differences Between 4.10, 3.73, and 3.27?

myponyrocks · Jan 8, 2009

bhuff30 said:
As others said, you will likely make LESS power on the dyno with higher gear ratios (3.73, 4.10, ect). There are 2 effects happening on the dyno.

The first, is that higher gear ratios absorb slightly more power. The teeth are angled slightly more to get the same contact patch on the gears and they just absorb a bit more power.

The other effect is the load on the engine. Higher gear ratios put slightly less load on the engine than lower gears. Similar effect to dynoing in 3rd instead of 4th.

^^^ Winnnnah!

Jbauer · Jan 9, 2009

heres what you need to know... 4:10s feel like a 50 shot of nitrous and your quarter mile times will improve by frikin 3 tenths.. now thats a huge gain. If you couldnt feel the diffrence in your friends 4:10, then your either frikin ignorant or your friend has an automatic..because 4:10s in a manual is a HUGE gain for whats being done and the price on these cars.
You wont lose Any HP on the dyno..because you'll be using a tuner with a 93 octane tune to compensate for the gear ratios...or atleast, thats what i'd do.

myponyrocks · Jan 9, 2009

Jbauer said:
You wont lose Any HP on the dyno..because you'll be using a tuner with a 93 octane tune to compensate for the gear ratios...or atleast, thats what i'd do.

You lose a percentage on the dyno with 3.73s, and you lose a slight percentage more with 4.10s. It also depends on the HP level of the car getting the gears since it's a percentage loss. So a simple 93 tune might not even be the answer to cover the gap.

The two ideas behind a dyno are seing how mods affect your gains and to see if your tune is safe. Obviously numbers fluctuate on dynos because of so many different outside effects such as barometric pressure, humidity, temp whatever... but it still the basic idea of the thing.

So yes a car that had a 93 tune and then installs 4.10s, on a perfectly exact day will see a small loss of hp on the rollers after the 4.10 install.

Also obviously, on the street the rear gears put you more into the power band on these cars and feels like more rwhp (which we also know gears don't physically add or take away hp, they just modify where your shifts place you in the powerband).

Remember, some folks use a speed cal as well and not a handheld.

Jbauer · Jan 9, 2009

sorry, double post.

Jbauer · Jan 9, 2009

right, but i said 'which is what i would do'..personally not a big fan of speed cals. I would have a 93 octane tune.

what i'm saying is if you dyno the car.. THEN install the gear, along with the tuner you will make more power on the dyno than you did before the gear. Your not going to really make that much less power on the dyno after gears, its a very very slight loss of HP even with more than stock power level and you'll more than compensate for it with the tuner. I cant imagine a 15 HP loss with 4:10s at anywhere near stock power level

I mean, its about 3 or maybe even 4 tenths off the quarter mile with 4:10s especially with drag radials.. its pretty much almost a 50 shot of nitrous. imho, this is a rediculous fear..who cares how much HP you lose (which you wont if you use a tuner) if you have a faster car

Think of it this way, OP.. your going to have a consistant 13 second car

Jbauer · Jan 9, 2009

right, but i said 'which is what i would do'..personally not a big fan of speed cals. I would have a 93 octane tune. diablo tuners are like 150 on craigslist
what i'm saying is if you dyno the car.. THEN install the gear, along with the tuner you will make more power on the dyno than you did before the gear. Your not going to really make that much less power on the dyno after gears, its a very very slight loss of HP even with more than stock power level and you'll more than compensate for it with the tuner. I cant imagine a 15 HP loss with 4:10s at anywhere near stock power level

I mean, its about 3 or maybe even 4 tenths off the quarter mile with 4:10s especially with drag radials.. its pretty much almost a 50 shot of nitrous. imho, this is a rediculous fear..who cares how much HP you lose (which you wont if you use a tuner) if you have a faster car

Think of it this way, OP.. your going to have a consistant 13 second car

erzats · Jan 9, 2009

Horsepower is how fast you are going when you hit the wall torque is how far you go through the wall

02nightmaregt · Jan 10, 2009

When i did my gears i noticed no loss in HP. If you really do lose any i'll bet its only like 1-2 hp, if that

fromadig91 · Jan 10, 2009

erzats said:
Horsepower is how fast you are going when you hit the wall torque is how far you go through the wall

I thought it was how far you take the wall with you

Regardless I'd like to follow that quote up with "Horsepower sells cars, Torque wins races" Carroll Shelby

erzats · Jan 10, 2009

believe you are right froma on both points. I stand corrected

fasthippo · Jan 11, 2009

there should hardly be any difference in the dyno at all because it doesnt make the engine make more power, and it doesnt make the drivetrain any more efficient. it just changes the gear ratio.

if you change gears on your bike do you get stronger? no. the different gear ratio is just making it easier to do the work. so while you may pedal faster to go the same speed, you'll get to that speed faster.

Green&GoldGT · Jan 12, 2009

Some factors that could result in different dyno numbers from a gear swap are that each set of gears have a different mass, heat, differences in the weather between the dynos, or maybe someone took their car to a different dyno.

Stang|ess · Jan 13, 2009

http://forums.nasioc.com/forums/showthread.php?t=1478091

interesting read.

Dyno Differences Between 4.10, 3.73, and 3.27?

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