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Thread: Chevy HP/Torq

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  1. #1

    Default Chevy HP/Torq

    This is just a curiosity question more than anything; but why is Chevy engines HP and Torq always at the upper end of the RPM range when ford HP/Torq at the lower end. Is this a philosophy that chevy has?

  2. #2
    Jr. Engineer Cowpie's Avatar
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    I have always wondered that myself. Considering torque is the "work" part of what is going on, and pulling heavy or hard requires some decent low end "grunt", it has boggled my mind why someone would need to put the RPM's on the ceiling to reach max torque. That is why I have generally liked inline motors. I would kill for a decent sized inline 6 instead of the V8 in my Silverado. An inline 6.0 would be a killer engine. Not something for beating everyone on the freeway, but would be one serious motor for working. Oh well, not going to happen anytime soon.
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    with the 5.3 and 6.2 L engines the torque band is rather flat when compared to other manufactures engines . with the 4.3L gm engine you have little low end torque .. at the higher rpms you get the max torque but only at the max rpm.. the torque chart is a gradual slope ..

    with the GM truck V8 engines you will find the max torque is just below the max rpm horsepower mark. the amount of power/torque is not much different at the peak when compared to the middle of the operating rpm range. this then makes these v8 engines a good choice when towing or hauling.
    the torque chart is a very flat line from 1500-5000rpm...

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    Jr. Engineer Cowpie's Avatar
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    Well, flat line is a somewhat misleading description. From the range you mentioned, we are talking about 20% or more (at least 70 ft lb) difference in torque on the 5.3 LC9. And inline engines will usually meet their max torque rating substantially lower than the GM V8's we are talking about here. Many inline gas engines meet their peak torque 1500 rpm or more LOWER than the GM V8's.

    LC9 Horsepower Curve.pdf
    Last edited by Cowpie; 02-26-2014 at 04:59 PM.

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    Quote Originally Posted by Cowpie View Post
    Well, flat line is a somewhat misleading description. From the range you mentioned, we are talking about 20% or more (at least 70 ft lb) difference in torque on the 5.3 LC9. And inline engines will usually meet their max torque rating substantially lower than the GM V8's we are talking about here. Many inline gas engines meet their peak torque 1500 rpm or more LOWER than the GM V8's.

    LC9 Horsepower Curve.pdf
    your chart shows from 1500-5800 rpm a torque of 300ft lbs and is pretty flat.

    other years the V8 5.3L has basically the same torque range. V6 is not very flat. it is a gradual increase as the RPM/hp increases. max is not a factor since , max to the ave value of torque with the v8 is not all that different.

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    Jr. Engineer Cowpie's Avatar
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    Actually I would take exception to the relatively flat. At 1500 RPM, torque is barely at 270lb. At 4200 it peaks at 340lb, and does a nose dive after that. 270lb is a full 21% lower than max torque. Now, that 70 lb of difference wouldn't make that much difference in my semi truck which hits a peak of 1850 lb at 1200 RPM and holds it solid thru 1550 RPM, but 340 lb max torque minus 70 lb is really substantial. One has to get to 2100 before crossing the 300lb threshold. But then it just rides along that until about 3200 RPM before it rises to the max at 4200 RPM.

    While the graph looks relatively flat, the numbers speak another story. Very few people are going to run at 4200 RPM around the country side to get the power they need. Many are not going to constantly run above 3200 RPM. So the 2000-3000 average than most would be operating at, the torque is 40 lb off its max, which is roughly a 12% loss of available torque. Pretty sad.

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    Quote Originally Posted by Cowpie View Post
    Actually I would take exception to the relatively flat. At 1500 RPM, torque is barely at 270lb. At 4200 it peaks at 340lb, and does a nose dive after that. 270lb is a full 21% lower than max torque. Now, that 70 lb of difference wouldn't make that much difference in my semi truck which hits a peak of 1850 lb at 1200 RPM and holds it solid thru 1550 RPM, but 340 lb max torque minus 70 lb is really substantial. One has to get to 2100 before crossing the 300lb threshold. But then it just rides along that until about 3200 RPM before it rises to the max at 4200 RPM.

    While the graph looks relatively flat, the numbers speak another story. Very few people are going to run at 4200 RPM around the country side to get the power they need. Many are not going to constantly run above 3200 RPM. So the 2000-3000 average than most would be operating at, the torque is 40 lb off its max, which is roughly a 12% loss of available torque. Pretty sad.
    if you need 340 ft lbs of continuous torque you are not going to use a 1500 5.3L GM chevy engine.

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    Quote Originally Posted by Cowpie View Post
    Well, flat line is a somewhat misleading description. From the range you mentioned, we are talking about 20% or more (at least 70 ft lb) difference in torque on the 5.3 LC9. And inline engines will usually meet their max torque rating substantially lower than the GM V8's we are talking about here. Many inline gas engines meet their peak torque 1500 rpm or more LOWER than the GM V8's.

    LC9 Horsepower Curve.pdf
    But look at how good those arcs look. These engines are very well designed. Have you ever looked at a ford or ram power curve? the 5.0 hits its max torque at the same general rpm range, right around 4200. And guess what, actual dyno numbers it maxes at 284 ft lbs, so why worry about a chevy being at 270 on the low end and climbing to 340? It starts out at damn near the ford max! I havent ever actually seen a ram 5.7 curve but ram says max torque is also reached at 4200 rpm.

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    So you are going to compare different displacement engines and try to make a point? It didn't get made here. It still is not something to brag about that taking the engine to such a high RPM to reach max torque is admirable. Especially since the vast majority of people never operate their engines at those RPMS, even when working them. So, the typical vehicle owner has to deal with roughly 20-25% of unavailable torque compared to the numbers that the OEM's brag about and print in their glossy brochures. And the numbers are thrown out like marketing tools anyway and mean nothing. "our pickups beat the others in hp". Well they might, but it really is only a marketing tool and nothing for the consumer, because very few consumers operate their vehicles in the 4000-5000 rpm range it takes to get those hp numbers, while going to work. And GM really had no intention of people operating at those high of RPM's. After all, they stick stuff like 3.08 rear ratios in pickups along with double overdrive transmission gears. So it is all disingenuous clap trap about what these engines are.

    Now you take the heavy commercial trucks, they are designed and spec'd so that during normal daily operation, they are at their MAX torque band consistently. So when the OEM says that their engines have a max torque of whatever, they mean you actually are going to be in that max torque band day in and day out and be able to take advantage of it, and it was designed to be that way. Not like a typical auto or pickup engine that the only real time anyone is going to operate it at max torque is if they put it on a dyno. That is the general beauty of inline engines. The meet their max torque usually at rpms that are more in line with what people will operate the engines on a daily basis. This is the primary reason, though not the only one, I have never cared for V engines. But since inlines are not offered as an option in pickups nowadays, then we are stuck with the V's.

  11. #10

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    Point was mainly that all you guys are bickering about max power being reached in the 4200 rpm range, which is where all the truck companies land for max power. A secondary point being that Ford claims much higher numbers with the 5.0 than chevy does with the 5.3, but the 5.3 actually puts out nearly the same numbers on the low end than Ford actually gets in the max range.

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