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<blockquote data-quote="Saltydawg" data-source="post: 156210" data-attributes="member: 2944"><p>If your rear wheels were connected directly to your engine crankshaft at a 1:1 ratio you would be correct.</p><p></p><p> However, using the gearing in a transmission and your rear end you effectively multiply torque available at the rear wheels.</p><p></p><p> Picture a common diesel engine running down the road in top gear...lets say a 1:1 ratio (for ease of math). This truck also comes equipped with a 3.0:1 rear end.</p><p> Now your 7.3L diesel engine makes 500 lb/ft of torque at its peak.</p><p> Running that through the tranny and rearend will multiply the torque at the rear axle by 3.0:1...for a grand total of 1500lb/ft of torque at rear axle.</p><p></p><p> Ok now lets assume a 7.3L gas job. This motor could easily produce 400lb/ft of peak torque.</p><p> Running it through the same drivetrain as the diesel you end up with 1200lb/ft of torque at the rear axle.</p><p></p><p> Now lets change the ratios a bit. </p><p></p><p> Lets bump the rearend gearing up in the gas job to 3.73:1. Plugging this new ratio into the torque figures we jump to 1492lb/ft of torque at the rear axle for the gas job.</p><p> Only 8 lb ft less than the diesel.</p><p></p><p> What this does however is cause the motor to run at a higher rpm to maintain the same speed down the road. Good thing its a gas motor that is happy turning higher rpm's.</p><p> You could do the same for a diesel motor and multiply the torque at the rear axle, unfortunately diesel engines don't like high rpm's.</p><p></p><p> You can run much higher gearing with a gas motor than you can with a diesel which allows the gas job to play on a level field with the diesel.</p><p></p><p> The drawback is the gas engine is less fuel efficient and has greater internal parts wear because of the higher rpm's.</p><p></p><p></p><p> A gas job rated 450hp and 350lb/ft WILL out pull a diesel rated at 350hp and 450lb/ft if you use the proper gearing to take advantage of the gas engines higher rpm range.</p><p></p><p> The gas job will also visit the graveyard sooner if you do this regularly <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" />.</p><p></p><p></p><p> edit: Picture 2 farmers out in a field looking at a big rock they need moved.</p><p> One farmer weighs 300lbs and the other weighs 150lbs.</p><p></p><p> Both of them need a lever to move the rock.</p><p></p><p> The big guy only needs a level 4 ft long to move it cause he weighs a lot more.</p><p> The little guy needs a lever 6ft long to move it cause he weighs a lot less.</p><p></p><p> Lucky for the little guy he is much quicker on his feet and moves his level twice as fast as the big guy and gets his rock moved first.</p><p></p><p> Leverage/gearing can give you all the torque you need. You just need to be fast enough (high rpm's) to make up for the longer disntance you have to travel.</p></blockquote><p></p>
[QUOTE="Saltydawg, post: 156210, member: 2944"] If your rear wheels were connected directly to your engine crankshaft at a 1:1 ratio you would be correct. However, using the gearing in a transmission and your rear end you effectively multiply torque available at the rear wheels. Picture a common diesel engine running down the road in top gear...lets say a 1:1 ratio (for ease of math). This truck also comes equipped with a 3.0:1 rear end. Now your 7.3L diesel engine makes 500 lb/ft of torque at its peak. Running that through the tranny and rearend will multiply the torque at the rear axle by 3.0:1...for a grand total of 1500lb/ft of torque at rear axle. Ok now lets assume a 7.3L gas job. This motor could easily produce 400lb/ft of peak torque. Running it through the same drivetrain as the diesel you end up with 1200lb/ft of torque at the rear axle. Now lets change the ratios a bit. Lets bump the rearend gearing up in the gas job to 3.73:1. Plugging this new ratio into the torque figures we jump to 1492lb/ft of torque at the rear axle for the gas job. Only 8 lb ft less than the diesel. What this does however is cause the motor to run at a higher rpm to maintain the same speed down the road. Good thing its a gas motor that is happy turning higher rpm's. You could do the same for a diesel motor and multiply the torque at the rear axle, unfortunately diesel engines don't like high rpm's. You can run much higher gearing with a gas motor than you can with a diesel which allows the gas job to play on a level field with the diesel. The drawback is the gas engine is less fuel efficient and has greater internal parts wear because of the higher rpm's. A gas job rated 450hp and 350lb/ft WILL out pull a diesel rated at 350hp and 450lb/ft if you use the proper gearing to take advantage of the gas engines higher rpm range. The gas job will also visit the graveyard sooner if you do this regularly :). edit: Picture 2 farmers out in a field looking at a big rock they need moved. One farmer weighs 300lbs and the other weighs 150lbs. Both of them need a lever to move the rock. The big guy only needs a level 4 ft long to move it cause he weighs a lot more. The little guy needs a lever 6ft long to move it cause he weighs a lot less. Lucky for the little guy he is much quicker on his feet and moves his level twice as fast as the big guy and gets his rock moved first. Leverage/gearing can give you all the torque you need. You just need to be fast enough (high rpm's) to make up for the longer disntance you have to travel. [/QUOTE]
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