can I get firmer shifts
Captain
Joined: Jun 2007
Posts: 730
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From: Columbus, GA USA
6500 is not low for a truck engine (yes there IS a difference btwn car and truck engines, these days it is mostly in the computer tune, but still) but compared to car engine (granted, mostly 4 cylinders) it is low.
now are you so naive that you think horsepower is what matters in moving the truck? the torque is what you need in order to move the vehicle, and the more you are making the faster you will accelerate,
someone once put it to me (ok not me, but i overheard it) this way, Horsepower is how fast you hit the wall, and torque is how far you push the wall. simply put, the Torque is what actually matters when talking about moving a vehicle, the more you have down low the better.
now are you so naive that you think horsepower is what matters in moving the truck? the torque is what you need in order to move the vehicle, and the more you are making the faster you will accelerate,
someone once put it to me (ok not me, but i overheard it) this way, Horsepower is how fast you hit the wall, and torque is how far you push the wall. simply put, the Torque is what actually matters when talking about moving a vehicle, the more you have down low the better.
Veteran
Joined: Aug 2009
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From: Missouri
Horsepower is always going to be in the higher rpm range versus torque. Here is some numbers for a Cat 3406E which is in the big rigs. HP 500@1800 TQ 1850@1200. Even though these engines can go up to 2100rpm's, they have more pulling power in the lower RPM range which means 1200-1800 and get their better fuel economy in that range. Even in car engines, they can go up to 6000rpms but their max torque is way below that level. Higher horsepower equals higher torque but the highest torque value is way below the max horsepower in any engine. Revving an engine to its max rpm will not make it pull any harder past it's max hp or max torque rating which is quite a ways below that max rpm. Just a waste of wear, tear, and fuel when ever someone pushes their engines to it's max rpm level.
Veteran
Joined: Jul 2007
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Horsepower is always going to be in the higher rpm range versus torque. Here is some numbers for a Cat 3406E which is in the big rigs. HP 500@1800 TQ 1850@1200. Even though these engines can go up to 2100rpm's, they have more pulling power in the lower RPM range which means 1200-1800 and get their better fuel economy in that range. Even in car engines, they can go up to 6000rpms but their max torque is way below that level. Higher horsepower equals higher torque but the highest torque value is way below the max horsepower in any engine. Revving an engine to its max rpm will not make it pull any harder past it's max hp or max torque rating which is quite a ways below that max rpm. Just a waste of wear, tear, and fuel when ever someone pushes their engines to it's max rpm level.
Veteran
Joined: Aug 2009
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From: Missouri
Gearing has nothing to do with optimum shift points. If you do a graph on torque and horsepower and notice the drop off points, going to the highest rpm's will not assist in making anymore power to the rear wheels. Once they both drop off to a certain extent, that is all you will get. To go redline is futile in getting anymore power to the ground, even the Pro Stockers, Rails, Funny Cars, Crotch Rockets, etc. all have rev limiters to limit top rpm's because they can all go further past that and they have that infamous red light to tell them when to shift which is their optimum shift point. Optimum shift point is right around 500-800 rpm's past max HP depending upon gearing, not redline! Cars usually drop that much through their shifts and that will still bring it at the max HP rating. I had a strip car and I had my light come on at 5500rpm's to tell me to shift and it had a rev limiter built in to kick in at 6500rpm's and that was with 4.56 gears in the back. That car made close to 500hp at 5000rpm's and torque was 450ftlbs at 4500rpm's. That was on a dyno before being put into the vehicle. If I went further towards the rev limiter after the 5500rpm's, I could feel the car fall off and not make anymore power. Power is just as useful and relevant in determining vehicle performance as is torque. In some situations it's more useful, because you may not have to play with gear ratios and a calculator to understand what's going on.
A car accelerates hardest with gearing selected to stay as close as possible to the engine *power* peak, subject to the traction capability of the tires.
Not all cars should be shifted at the redline for maximum performance. You can determine optimal shift points by graphing horsepower vs. velocity or transmission torque vs. RPM. Engine torque alone will not determine shift points.
V8 powered cars do not need to be redlined as much as the 4 cylinder cars do. They both make their power in different areas of the rpm range. Gearing only helps with acceleration and getting from point A to point B fast but a person does not need to be redlining their engines to do so.
A car accelerates hardest with gearing selected to stay as close as possible to the engine *power* peak, subject to the traction capability of the tires.
Not all cars should be shifted at the redline for maximum performance. You can determine optimal shift points by graphing horsepower vs. velocity or transmission torque vs. RPM. Engine torque alone will not determine shift points.
V8 powered cars do not need to be redlined as much as the 4 cylinder cars do. They both make their power in different areas of the rpm range. Gearing only helps with acceleration and getting from point A to point B fast but a person does not need to be redlining their engines to do so.
Last edited by 45AutoPete; Jul 11, 2010 at 08:40 PM.
Veteran
Joined: Jul 2007
Posts: 478
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Gearing has nothing to do with optimum shift points. If you do a graph on torque and horsepower and notice the drop off points, going to the highest rpm's will not assist in making anymore power to the rear wheels. Once they both drop off to a certain extent, that is all you will get. To go redline is futile in getting anymore power to the ground, even the Pro Stockers, Rails, Funny Cars, Crotch Rockets, etc. all have rev limiters to limit top rpm's because they can all go further past that and they have that infamous red light to tell them when to shift which is their optimum shift point. Optimum shift point is right around 500-800 rpm's past max HP depending upon gearing, not redline! Cars usually drop that much through their shifts and that will still bring it at the max HP rating. I had a strip car and I had my light come on at 5500rpm's to tell me to shift and it had a rev limiter built in to kick in at 6500rpm's and that was with 4.56 gears in the back. That car made close to 500hp at 5000rpm's and torque was 450ftlbs at 4500rpm's. That was on a dyno before being put into the vehicle. If I went further towards the rev limiter after the 5500rpm's, I could feel the car fall off and not make anymore power. Power is just as useful and relevant in determining vehicle performance as is torque. In some situations it's more useful, because you may not have to play with gear ratios and a calculator to understand what's going on.
A car accelerates hardest with gearing selected to stay as close as possible to the engine *power* peak, subject to the traction capability of the tires.
Not all cars should be shifted at the redline for maximum performance. You can determine optimal shift points by graphing horsepower vs. velocity or transmission torque vs. RPM. Engine torque alone will not determine shift points.
V8 powered cars do not need to be redlined as much as the 4 cylinder cars do. They both make their power in different areas of the rpm range. Gearing only helps with acceleration and getting from point A to point B fast but a person does not need to be redlining their engines to do so.
A car accelerates hardest with gearing selected to stay as close as possible to the engine *power* peak, subject to the traction capability of the tires.
Not all cars should be shifted at the redline for maximum performance. You can determine optimal shift points by graphing horsepower vs. velocity or transmission torque vs. RPM. Engine torque alone will not determine shift points.
V8 powered cars do not need to be redlined as much as the 4 cylinder cars do. They both make their power in different areas of the rpm range. Gearing only helps with acceleration and getting from point A to point B fast but a person does not need to be redlining their engines to do so.
Even tho you are not making as much power going past peak, you are still accelerating FASTER in the lower gear than you would be in the next gear at that same point. (Unless, if you graph it out like I said, the plots meet. Then that is the optimum shift point.)
You must consider gear ratios in each gear to determine optimum shift points for maximum acceleration. It's not JUST a function of maximum power.
Veteran
Joined: Aug 2009
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From: Missouri
Exactly! Thank you Sharps.
Veteran
Joined: Jul 2007
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Which is not what I was talking about. What gear you have in the rear has no effect on what rpm you need to shift at. I'm not saying what he said is wrong, I'm just saying that's not the point I was trying to get across.
Hall Of Fame
Joined: Jun 2005
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From: Riverton, UT
http://en.wikipedia.org/wiki/Chrysle...#8.0_Viper_V10 V10 Output was 310 hp (230 kW) and 450 lb·ft (610 N·m).
Last edited by hydrashocker; Jul 12, 2010 at 12:39 AM.