Mechanical question about axel ratios and straight line runs
08-30-2006, 05:43 PM
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Mechanical question about axel ratios and straight line runs
Ok, somewhat of a noobish question but I am not great at the mechanics of cars, so here goes.
Someone was telling me the other day that you could take a Dodge Charger 5.7 HEMI or similar muscle car (Mustang GT?) and by simply modifying the axel ratio gear in the back, the car can be made to outrun even the most expensive sports cars (from an RS4 all the way up to the 911 Turbo).
He said that basically such a modded car would be a dog getting up to 80mph or so but that eventually it would overtake it. He explained that is how state police cars are modified to work and are able to catch any car.
How exactly does that work out and is there even partial truth in this scenario?
Someone was telling me the other day that you could take a Dodge Charger 5.7 HEMI or similar muscle car (Mustang GT?) and by simply modifying the axel ratio gear in the back, the car can be made to outrun even the most expensive sports cars (from an RS4 all the way up to the 911 Turbo).
He said that basically such a modded car would be a dog getting up to 80mph or so but that eventually it would overtake it. He explained that is how state police cars are modified to work and are able to catch any car.
How exactly does that work out and is there even partial truth in this scenario?
08-30-2006, 05:47 PM
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I might add...
The converse of this scenario that he laid out was that the same HEMI Charger could have its axel ratio modified so it would outrun the RS4 and other cars in very short distances, including 1/4 mile.
08-30-2006, 05:50 PM
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the higher numerical final drive ratio (trans high gear x axle ratio) = lower top speed.. but!...
the higher numerical ratio gives the car a more seat of the pants rocket like launch and acceleration feel up to it's shortened top speed.
Having a numerically high final drive ratio does take ~2-3 tenths off of the e.t. in a quarter mile drag race.
Your friend's b.s. about cop cars is just b.s. period. Most any competent driver in a car with 300+ hp can outrun Crown Vic's and Hemi wanna be Chargers (most out there have the V-6 btw)
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A lower numerical final drive ratio is a "gas mileage" setup. Lower rpm's in high gear = less gas.
Having a numerically high final drive ratio does take ~2-3 tenths off of the e.t. in a quarter mile drag race.
Your friend's b.s. about cop cars is just b.s. period. Most any competent driver in a car with 300+ hp can outrun Crown Vic's and Hemi wanna be Chargers (most out there have the V-6 btw)
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A lower numerical final drive ratio is a "gas mileage" setup. Lower rpm's in high gear = less gas.
08-30-2006, 05:53 PM
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if changing a rear axle ratio was that effective... ricers wouldn't be placing....
200hp worth of stickers on their cars.
In the real world, a higher numerical rear gear ratio gives a slight advantage... it's a torque multiplier... not a high hp mod as your friend would have you think.
In the real world, a higher numerical rear gear ratio gives a slight advantage... it's a torque multiplier... not a high hp mod as your friend would have you think.
08-30-2006, 05:56 PM
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He said such cars could do 1/4 mile in 7 seconds?!?!
Sounds like he was far off based on what you're saying.
He also said the axel mod would shave 5-6 seconds off of a 1/4 mile time.
He mentioned something called hams, a box that gets put in the rear of these cars as part of the mod, and said they were called hams because they were the size of one. I couldn't figure out what it did, and didn't ask him to explain it.
He also said the axel mod would shave 5-6 seconds off of a 1/4 mile time.
He mentioned something called hams, a box that gets put in the rear of these cars as part of the mod, and said they were called hams because they were the size of one. I couldn't figure out what it did, and didn't ask him to explain it.
08-30-2006, 08:43 PM
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Yeah..
That's why I posted. Unfortunately I am still learning about cars and physics but I know enough to have seriously doubted what I heard. I just was not able to put a rebuttal into a properly quantitative format.
Thanks for clearing it up.
Thanks for clearing it up.
