Chevy HP/Torq

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

  1. j cat

    j cat Epic Member 5+ Years 1000 Posts

    that 1983 B body V8 I had max torque was @2750 RPM. towed my 20 ft 4,000 lb boat. when you live where there are pretty good grades you know where the max torque band is...
  2. paracutin

    paracutin Rockstar 100 Posts

    I call BS. The following numbers are from dyno runs conducted by SuperChevy magazine. As you can very clearly see, the 302, 327 and 350 from 1971 made their max torque at 4,000 rpm - 4,500 rpm.

    RPM 302 327 350 350 ('71)
    3000 167 196 208 199
    3300 184 210 232 223
    3500 206 232 254 246
    3800 233 261 283 275
    4000 248 275 298 291
    4300 272 297 318 311
    4500 283 308 329 324
    4800 301 324 341 340
    5000 311 333 347 347
    5300 326 344 352 355
    5500 333 349 353 361
    5800 347 347 350 362
    6000 350 348 348 361
    6300 353 352 348 353
    6500 356 347 342 345
    6800 356 339 329 332
    7000 352 331 312 319

    RPM 302 327 350 350 ('71)
    3000 292 332 364 349
    3300 293 334 369 354
    3500 309 348 381 369
    3800 322 360 391 379
    4000 325 362 391 382
    4300 332 363 389 380
    4500 331 360 383 378
    4800 329 355 373 372
    5000 327 350 364 364
    5300 323 341 349 352
    5500 318 333 337 345
    5800 314 314 317 328
    6000 307 305 305 316
    6300 295 293 290 295
    6500 287 281 277 279
    6800 275 262 254 257
    7000 264 248 234 239
  3. grampy

    grampy Rockstar 100 Posts

    This tread is getting rough ! I may as well throw in my $.02 and run for cover !!
    I own two 3/4 ton chevys. 4X4's, a '97 w/the 350 and an '07 6 liter. The '97 was my go anywhere, do anything truck for many years. Last year I bought a low mileage 2500 HD classic that's now my daily driver. I've kept the '97 and it's now the ranch 'beater'.
    If you'll just put your charts, graph's and spec sheets away for 60 seconds - here's my take. My '07 will out pull the '97 anywhere, with any load at any RPM. I've towed and hauled enough with both of them to know that. I rarely wind either of them above 3500. Am I comparing apples to apples - pretty close I believe, there's only 16 cubic inches difference in engine displacement. Both trucks have 5 speed manual trans, same rear end, same gears' , load ratings - close to the same. Being a farm/ranch family, we've got several older trucks around too, two that are somewhat comparable - One 'brand X' with a 360 w/auto and a '79 GMC w/a 350, manual. Even when those old trucks were doing the work around here, they couldn't pull with either of my "newer trucks ! So what I'm saying - yes the mfr's have improved power and torque. The ratings ARE a numbers GAME !!
  4. Cowpie

    Cowpie Rockstar 4 Years 500 Posts

    Ok. I'll bite. Which incarnation of the 327 was the data pulled from? From what I read recently, to bone up on the info, the stock 327 with the Rochester 4bbl reached max torque at 2800 rpm. Since this is the one I had at one time, I used that number. I believe I also referenced the 283 and that seems to be missing from the list. It is true that other incarnations of the 327 got their max torque nearer the 4000 rpm you show.

    As for one vehicle out pulling another, we all know that transmission gear ratios and rear end ratios play an equal part. Unless the identical transmission and rears are used, it is not an apples to apples comparison. I have a 12.7L diesel in my semi that I can walk past 14L and 15L engine equipped trucks on hard hill pulls all the time with equivalent loads, and I get better fuel economy than most of them do. It's all in the specs.
  5. grampy

    grampy Rockstar 100 Posts

    I don't think you read my post close enough. Both pickups have the same trans. ( NP 4500 ) , both have the same 14 bolt GM rear end, both have 4:10 gears. Even the tires are very close to the same diameter. They are almost the same empty weight too. My 6.0 WILL out pull the 350 & at the same speed & RPM, in fact a full gear difference with the same trailer and load on the same grade. And if you think I don't like the older truck - or I'm biased, you are dead wrong, that 'old' '97 chev. is one of my all time favorite vehicles.
    To add to this, I once owned a Chevy pickup with the 327, it was a racehorse ! It was a 'runner' !! But put a heavy load behind it and you had to run the hell out of it to keep up with traffic. Won a couple bets with that 327, runner - yes - tugger - no.
  6. paracutin

    paracutin Rockstar 100 Posts

    Read the article. I provided the link.

    This thread is about HP & Torque for small block Chevy motors. Why must you always throw in info on diesel semi engines? That was a rhetorical question. No need to explain.
  7. Cowpie

    Cowpie Rockstar 4 Years 500 Posts

    I did read the link you posted. They did not even try to replicate the engine varieties that are about to be mentioned in this post. They stuck only with the 11:1 compression HO varieties that were designed as Vette or muscle car engines. There were compression ratios across the spectrum in the 327's and that tied to various cams and other tweaks netted a broad range of performance characteristics depending on the application. This also explains why they did not even consider the 283 in their engine lineup. They obviously were only concerned with the high performance varieties.

    To the diesel mention, it was meant as perspective to show that power to the ground is not always related to power of the engine itself. There are parasitic losses that occur in the drivetrain and can have a deleterious effect on the work that one can get done with a vehicle. This is why I can net as much to the ground from my 12.7L as others get using 14L and 15L engines. The very same principle applies to gas engines, small or large block. Thought I would explain anyway in an non confrontational way just is case others have not taken that into consideration.

    Now back to the 327 I mentioned earlier and low rpm torque. There were several incarnations of this engine. when introduced in 1962, there were four distinct varieties of the 327. One of the engines developed 350 lb of torque at 2800, another developed 360 lb at 3200, another developed 344 lb at 4000 and another developed 352 at 4,000. Sure there were engines then that developed their torque at the same higher rpm as we are getting today, but these were primarily targeted at either the performance autos or general automotive. The pickups, throughout the entire run of 1962 thru 1969 got 327's that developed their torque in the ballpark 2800 rpm level, including the last and only two varieties of 327's in 1969, both 2 bbl varieties that hit max torque of 320 lb at 2400 rpm and 325 lb at 2800 rpm respectively.

    Every year the 327 was produced, there was a "working" engine or two in the group that was designed to reach peak torque below 3000 rpm. And you can read about every incarnation of the 327 from 1962 thru 1969 here:
    Last edited: Apr 1, 2014
  8. paracutin

    paracutin Rockstar 100 Posts

    Thanks for the article. It is good information. Let's do a little comparison.
    One of the 327s made in '62-'63 put out 360 lb/ft of torque at 3200 rpm. I chose this one because it made the most torque in those years.
    The 2010 L96 makes 342 lb/ft of torque at 2000 rpm. 800 and 1200 rpm lower than the engines mentioned in your article.
    Now lets take into account GMs testing procedures. This is from the Super Chevy article I linked above.

    Speaking of ratings, it is also important to note that these differed wildly from those used today by the OEMs. Where the new LS3 small-blocks are tested to the latest SAE net (flywheel) standards and are rated with full accessories, exhaust and the factory induction system (basically the way it comes in the car), pre-1972 engines were rated in optimized condition sans accessories (open dyno headers, no accessories, no air inlet restrictions, etc.). What this means is that a 370hp LT-1 from 1970 is actually much closer in actual power output to the 300hp LT1 circa 1995.

    One can deduce that the 360 lb/ft of the 327 is actually more like 300 lb/ft once it is dressed for production. Once again, the modern engine makes more power at a lower rpm than the old iron does.
  9. Cowpie

    Cowpie Rockstar 4 Years 500 Posts

    While the testing procedures and the total power output may be different, the point at which it reaches it's full torque remains the same though. The amount of power is not the issue, it is the point a which the total torque becomes available. You are paying for it, you should be able to realistically have it available within normal operating rpm ranges. And most people are not pulling their RV around the countryside at 4000+ rpm all day long. It is very realistic that they would, under a load like that, be operating in the 2000-3000 rpm band a lot of the time.

    The OP was making the point in a nutshell... why the total torque is not available where the engine is normally operated, or sooner in the RPM band? My point is that it was in earlier engines. I never used the argument that one engine did or did not have more total power, just the argument that one engine (like the 5.3L today) does not give the peak torque at the normal operating band that the vehicle is used in compared to the 327 that did give it's total peak torque in the normal operating band.

    I suppose whether one needs that total torque at any point in what they are doing is another issue altogether. Most don't. But it just proves that marketing will pick up on anything to try and make the sale. Even if it has no bearing on real world use. And that causes many to get their panties in a wad. They are paying for something that will not realistically give them what they are paying for in real world applications. No matter the vehicle, if you tell me it delivers xxxx torque or xxxx hp, then it should deliver that in a range that is most applicable to what folks normally do with that vehicle. Else it is all a marketing lie. And that is basically where we started in this thread.

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