Gears & Axles - changing gears changes ET but not trap speed

Overheard this conversation, the guy seemed smart and was explaining how gears do not add or take away horsepower (I knew that) and they only slightly change where your engine is revving at the drag strip.

I have seen guys go to the trouble and expense of changing out the gears in their car and running virtually the same ET and in some cases actually run SLOWER.

Can someone explain?

Taller gears, ie 4.11's vs 2.73's get the car into the powerband faster and accelerate the car faster, leading to a faster ET. But it doesn't add any hp which is what you need for a faster mph, so it won't make the mph improve. This is provided your tires hook up and you aren't spinning because of the extra gearing. Changing from 3.23's and a stock stall to 4.11's and a 2800 stall netted me about .5 quicker et. Even though I added weight and lost some hp due to the 12 bolt. I also dynoed about 30 ft/lbs less with the stall. But it more than made up for it at the track.

Overheard this conversation, the guy seemed smart and was explaining how gears do not add or take away horsepower (I knew that) and they only slightly change where your engine is revving at the drag strip.

I have seen guys go to the trouble and expense of changing out the gears in their car and running virtually the same ET and in some cases actually run SLOWER.

Can someone explain?

This depends on the engine and transmission. I've seen cars pick up MPH after going to higher gears and lower gears. We just changed from 4.11 to 4.56 gears in a car and the MPH went from 165 to 168. This is a 2300 pound car with a 600 inch engine. Not what you would expect. My old 71 Maverick picked up MPH going from 4.56 to 3.80's. With 4.56 gears it was way over the motor at the big end. And sometimes that's not a bad thing. Years ago I had a 283" Nova, it held the IHRA national record and hit the rev limiter a little past the 1,000 foot mark. But with no torque and a Glide it was much faster that way than with a lazy launch. It always ran 113 MPH because that where the rev limiter hit and it just stayed there.

Al 05 Z82

in my case i always knew the power was there with 3.73s and a 26 inch et street was maxing my mph at 6500 rpm with a 10.2@134.4 changed to 28x9 full slicks which actually are 27.3 inch tall went 9.73 @140.8 so thats 1/2 second et and 6mph gain with just 1.3 inch taller tyre and yes 60ft was within fractions!!!! since have changed to 3.45s only ran once before issues little worse 1.587 60ft went 9.76 @142.8mph so picked up another 2mph!!!!should be having another go soon!!!! cheers