Chevy HP/Torq

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by bryane, Feb 25, 2014.

  1. bryane

    bryane New Member

    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. Cowpie

    Cowpie Member

    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.
  3. j cat

    j cat Active Member

    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...
  4. Cowpie

    Cowpie Member

    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.

    View attachment LC9 Horsepower Curve.pdf
    Last edited: Feb 26, 2014
  5. j cat

    j cat Active Member

    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.
  6. Cowpie

    Cowpie Member

    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.
  7. j cat

    j cat Active Member

    if you need 340 ft lbs of continuous torque you are not going to use a 1500 5.3L GM chevy engine.
  8. Cowpie

    Cowpie Member

    That is a valid point, but it still remains, that the 5.3L does not have a relatively flat torque curve based on the numbers. It is a sad testament to GM engines that if one needs max torque of their existing engine, they should move up to the next one. I regularly use the max torque, daily, for a lot of my engines. Doesn't mean I need to move up in size. Wouldn't help anyway on my diesels. I get as much hp and torque from a 12.7L as I would get from a 15L. To utilize the max torque of an engine is not overdoing it and needing to move up in size. It is there, it was designed for it, so it should be able to be used on a regular basis. Just too bad that with GM's you have to put the RPM's on the roof to get what you need out of them.
  9. bryane

    bryane New Member

    I think this is the best point. "To utilize the max torque of an engine is not overdoing it. It is designed for it". So let it rev!!!!!
  10. phoebeisis

    phoebeisis New Member

    Need more torque-?? GEARING TQ multiplication etc
    It is why god invented gearing-different rear ends.
    GEARING-and HP are what actually make you accelerate faster. TQ X RPMs X CONSTANT=HP
    HP and gearing make you accelerate faster-
    For a given load-say moving one of our trucks-at 65mph with a 6000 lb trailer with 2x the drag and the same RR as the truck

    Low RPMS are good because they mean lower friction losses-BETTER FE-

    GMs KNOWS how to make V-8s-just look at the current 5.3 FE numbers(they beat Fords Twin turbo 3.6)
    We-you- us-know ZERO-by comparison to GMs engineers
    looking at a perfectly fine Dyno chart and somehow assuming a Ford is better based on a dyno chart-slightly more TQ at lower RPMS?? or tiny differences in the slope?
    Childish
    If an engine get better mpg-with the same load-who cares if it requires 150 more RPMS?
    A reasonable assumption is we don't know JACK by comparison to GMs engine engineers
    Look at what it does -FE and tow performance-
  11. Cowpie

    Cowpie Member

    The same engineers that gave us AFM? I feel much better now.:lol:
  12. phoebeisis

    phoebeisis New Member

    AFM-maybe 1,000,000 Gms sold with AFM??
    Just how many have failed?
    We only hear squeaky wheels? If 1000 failed 1,000/1,000,000 = 1/1000 one per thousand?

    Granted AFM not GMs finest hour
    But Ford with their 6.0 TD-had a very high percentage of problems
    Dodge-various ATs- huge PROBLEMS
    Honda 5 speed ATs with the V-6- lotta problems over 4-5 years

    All manufacturers have problems
  13. Cowpie

    Cowpie Member

    It isn't a matter of failing, but there is substantial evidence of oil consumption issues including several TSB's that have been put out on how to address the problem. I didn't want it, I was not given the option of not having it, and I wanted to avoid any potential problems, so I disabled the AFM feature on my 5.3L within 48 hrs of taking possession of it from the dealership.

    Might I have had a problem? Who knows for certain. Are the odds that I wouldn't have a problem? Probably. But it is of little comfort if I did nothing and I ended up with all kinds of problems like some others have. And it is really of little comfort that other OEM's have had more problems. That is a cool argument, the others have had more problems, so ours must be ok.

    Either way, it is something that has not proven to be a major technological advancement that benefits the buyer of their vehicles. And if I can't trust them that they will foist this stuff on us, I am not comforted in the overall design. Like Scotty once said in a Star Trek show or movie one time.... "the more complicated they make the plumbing, the easier it is to stop up the drain".

    It has been rather disheartening in some respects, how I have had to modify, disable, replace, or whatever several things about this 2013 to compensate for something the OEM has determined that would be best for me. After all, mother GM knows best! Shouldn't really be surprised, it seems that each new vehicle I have bought comes with a larger laundry list of idiocy compared to the previous vehicles. Sure, these new pickups come with a lot of very good features, but they seem to think the if a little is good, a lot is better. Problem is, what they think is something better does not quite play out that way in the real world outside of Detroit.

    As much as it sounds like I am really trashing my pickup, I am not. This is directed as some of the stuff the GM did in design and build. Sometimes, not always, but sometimes some things are better left alone instead of the Tim Allen methodology of "if it ain't broke, you can probably still fix it" that the OEM's seem to like.
  14. phoebeisis

    phoebeisis New Member

    Wait
    I'm not defending the AFM problem.
    No way would I buy a GM 2007 on until that problem is resolved.
    I -we-were nearly broke in 2007 when I paid $2950 for a 1998 Suburban with 195,000 miles on it
    Frankly I expected a piece of junk that would limp around town-but if we had another hurricane it would run well enough to get 3 adults 2 leggy dogs and 4 cats 100 miles North of New Orleans
    Yeah I expected junk
    but I got a real winner-we took it on 2 3000 mile road trips-and it has been really reliable for 7 years
    So I'm really happy
    If I had paid $40,000 for a truck-and it croaked or near croaked at just 100,000 miles-
    I would be pissed.
    But I didn't-so I'm really happy with my GM- it was a great piece of luck just when I needed some good luck!! Yeah 21mpg hy-starts every time gets me to work- easy to DIY work on-
    yeah I was lucky-some AFM owners-really unlucky-poor woman with a $15,000 lawn ornament!

    PS-One of the big selling points of GM trucks is their longevity- they are all in the top 10 of long lived vehicles-4% on the road with over 200,000 miles-so dying at 85,000 miles is BS of course

    But all Car Manufacturers have miscues-screwups
  15. bryane

    bryane New Member

    Umm. HP and torq. As far as AFM, I say its worthless but the the rest of this truck is bad ass. I don't know why but I'm a Chevy guy threw and threw and I'll always look for ways to make down falls positive when comparing it to Ford. It must be in our DNA for truck lovers. For me, I'll rarely use this truck to the limit. Yes I pull a popup but besides the full throttle acceleration while impressing my three kids or racing by a f150 just because. These trucks are impressive. It will take $6.00 gas for me to park it and drive the mini van.
  16. j cat

    j cat Active Member

    ford has picked up older gm truck owners because of these engine failures. Then you have these reports of GM/dealership saying the oil usage is normal with these...so instead of taking action GM delays the fix and hoping the engine warranty runs out...


    with these type forums hard for a manufacturer to hide these type defects...
  17. phoebeisis

    phoebeisis New Member

    Ford is making pretty good vehicles now
    Dodge is too
    so GM will certainly have to correct any chronic problems
    Guessing they are furiously working on it.
  18. Cowpie

    Cowpie Member

    Well there is some hope. A British based engine designer that has worked primarily with ethanol since the 1920's, has gotten with GM and put a 3.2L Extreme Boost Direct Injection (EBDI) engine in a Silverado 3500HD. This engine has the power output, including low end torque, of the 6.6 Duramax Diesel. And it beats the Duramax in fuel economy by a fair margin. And NO AFM! Just pure V6 power that does what a V8 diesel does!

    http://www.technologyreview.com/news/412095/a-more-efficient-ethanol-engine/

    http://www.automobilemag.com/featur...ethanol_boosted_direct_injection_ebdi_engine/

    this is a very good article with actual hp torque numbers....

    http://www.motor.com/newsletters/20100712/WebFiles/ID1_BestOfBothWorlds.html
    Last edited: Mar 2, 2014
  19. phoebeisis

    phoebeisis New Member

    Wow

    Ricardo Inc??
    Is this somehow related to The famous Ricardo-
    did all that famous combustion chamber research waaaaay back when??
  20. squatchy

    squatchy New Member

    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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