1. PeugFra

    PeugFra New Member

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    Looking at the yearly power and torque ratings of stock 360-2 engines (E57) I was surprised to see that they peaked in 1974-1975:

    year power torque
    1971 175@4000 285@2400
    1972 175@4000 285@2400
    1973 170@4000 285@2400
    1974 180@4000 290@2400
    1975 180@4000 290@2400
    1976 170@4000 280@2400
    1977 155@3600 275@2000
    1978 155@3600 270@2400


    How did they do this, with all the emission-oriented modifications going on?
     
    Last edited: Aug 9, 2018
  2. traintech55

    traintech55 Senior Member FCBO Gold Member

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    One thing most people forget is that the factory certifies an engine combination for a couple of years. It is just to costly to do on a yearly basis. 1974 was the last year for leaded gas, but could run safely on unleaded. 1975 was the first year for unleaded fuel, but had already had the E.P.A. certification. That is why the ratings are the same.
     
  3. Snotty

    Snotty Senior Member FCBO Gold Member

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    Since the "new" "SAE net" ratings started in '72, I doubt that '71 rating is correct.
     
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  4. polara71

    polara71 Old Man with a Hat FCBO Gold Member

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    Agreed....good eye
     
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  5. PeugFra

    PeugFra New Member

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    I got the 1971 figures from LA - Chrysler small block V8 engines, where it says:

    "The initial power ratings [for the 360] were 255 hp and 360 lb-ft, gross, or 175 hp and 285 lb-ft of torque net ..."

    I wrote the net figures in the table for easier comparison.

    @traintech55:
    If the 1974 certification was valid for 1975 as well, does that imply that there were no modifications to the engine between 1974 and 1975?
     
  6. traintech55

    traintech55 Senior Member FCBO Gold Member

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    Yep. They are identical. I have switched between the two years many times.
     
  7. traintech55

    traintech55 Senior Member FCBO Gold Member

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    Yes. The engines were identical. I have switched between the two many times.
     
  8. traintech55

    traintech55 Senior Member FCBO Gold Member

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    I hate when my phone does not show I posted a previous reply.
     
  9. commando1

    commando1 Sergeant at Arms FCBO Gold Member

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    I always was told that the 340 was better than a 360.
    I see the peak hp is @ 2400 pm and now I understand.

    What killed it, the bore/stroke ratio?
     
  10. Snotty

    Snotty Senior Member FCBO Gold Member

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    What killed what? Are you asking why they stopped making the 340?
     
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  11. commando1

    commando1 Sergeant at Arms FCBO Gold Member

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    No. I'm asking why the 340 is the choice for a hipo SB over the 360.
     
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  12. CBODY67

    CBODY67 Senior Member

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    The last year's 340 had 1.88 intake valves rather than the prior 2.02s. The 360HO was pretty much the same motor, but I'll have to look at the specs to make sure. 360 had a longer stroke for a little better torque in lower rpms, which is what was needed in the cars that were getting heavier. I'll have to research the bore/stroke AND the more important stroke/rod length ratios again . . . it's been decades since I first did that.

    Sometimes, you need to look at ALL of the engine's specs and compare them, including cyl head castings, intake manifolds, exhaust manifolds, and distributor advance curves/timing settings to really see what might have been tweaked a bit. Looking at the ratings and nothing else is just the TIP of the iceberg.

    Remember, too, that the "net" figures were with vehicle exhaust and basic accessories installed. Unlike "gross" where it was just the engine on the dyno stand, with a "house" exhaust past the exhaust manifolds. Seems like the "net" figures also have a carb inlet temp spec, too?

    1975 was the first year for catalytic converters. 318 2bbl, 360HO, 400HO were available as full dual exhaust cars w/o catalytic converters. "Fleet engines", which also includes "law enforcement", but anybody could buy them. I believe this was also the case in '76, but not later.

    As I recall, Chrysler didn't really get fully involved in emissions hardware until 1974, when they got "real" egr valves rather than "floor jets", for example. No doubt, their hardware became more sophisticated and refined, which might have resulted in more rated power than when the standards got tighter a few years later.

    The weakest 360 2bbl was the 1980 model year, when the horsepower sunk even lower than a 318 4bbl. Main reason, best I could tell, is the Carter BBD 2bbl carb, "318 size" on the normal 360 2bbl intake manifold. Different mounting pad. I have one of those cars.

    CBODY67
     
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  13. Moparwilks

    Moparwilks Active Member

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    I always thought it was the wimpy cams in the 360s 2bbl & the 400 2bbls to create smooth luxury emissions friendly power. I think most heads 383/400. 318/340/360 are pretty close in specs. It’s a mild camshaft roadrunner/commando/340 can that wakes them up. I could be wrong. That’s why im here. To get educated most the time. Lol
     
  14. CBODY67

    CBODY67 Senior Member

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    As I recall, the cam specs on the 360 2bbls and the pre-'68 383 2bbls were 252 degrees and .390 lift, which pretty much goes back to the first B/RB motors. Some of the 4bbls had something a little wilder, back then. but the '58 Sport Fury 2x4bbl 350 had that same cam spec. The 340 cam and the 360HO (4bbl) cam were pretty much the same, with the latter possibly having a few more degrees of timing and possibly a little more lift. As lower compression ratios and such came online, Chrysler put a little more duration and lift into the cams to help compensate and minimize horsepower losses from the compression ratio. Plus possibly some larger cross-section exhaust manifolds, which looked like the prior ones, just a bit bigger for more flow, but NOT as much as the prior HP manifolds. LA and B/RB motors.

    ONE thing Chrysler did was design "package motors", rather than what might have looked good on paper. That meant the carb was the correct size for the head flow, which matched the cam specs, which matched the exhaust flow. It all worked together synergistically. As things evolved, some improvements were made yearly (in the '60s) for better performance and such. Put any ONE thing out of the "spec window", and it didn't work as well . . . unless you started changing everything else to work with the new part. This was the BEAUTY of the Mopar Performance/Direct Connection recommended parts. If you followed their recommendations/directions, I suspect you'd be to the "85%" level of ultimate performance. The rest would be tweaking the combination AND the chassis to get the desired 1/4 mile performance. With GM or Ford, it was "trick of the week" in the car magazines, by observation. A well-finessed Chrysler OEM combination of engine parts and pieces can be a very formidable competitor, as many in our Mopar Club (who did this) found out when they did it. Follow the factory specs and you'll get there.

    Now, in some cases, a slightly larger carb will make more power on the dyno. There's a Nick's Garage YouTube video of him doing this on a 440/375 rebuild. Using the OEM carb that came on the motor and his "dyno" carb, which was a little bigger. Not much additional power from the larger carb. AND it hit the factory hp ratings, too!

    Welcome and enjoy!
    CBODY67
     
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  15. PeugFra

    PeugFra New Member

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    That's interesting. That would mean that the 1974 engine was already fitted with a catalyst. All the more amazing how that was accompanied by an uptick in the ratings!

    So the Chrysler emissions hardware was not the performance killer, it were the ever more tighter emission standards?
     
  16. traintech55

    traintech55 Senior Member FCBO Gold Member

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    Remember, 1974 did not have a catalytic converter, 1975 did. ONLY difference between the two years.
     
  17. PeugFra

    PeugFra New Member

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    I do not quite get it. Same certificate, valid for 1974 and 1975, yet for 1975 with a significant change in the set-up of the exhaust system.

    I can see only two possible explanations for this contradiction. Either the converter was considered a running change under a valid certificate, or the 1974 certificate was obtained with the converter installed in the test engines/cars for the purposes of the certification process only. I think the latter explanation is more likely. But I'm guessing here, which I had hoped to avoid.
     
  18. CBODY67

    CBODY67 Senior Member

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    As for emissions hardware, EGR isn't supposed to happen at WOT. Retarded ignition timing was usually on the lower rpm ranges, not WOT. Leaner fuel curves were part-throttle and not WOT. One of the earlier articles I read on emissions tuning was that the systems were designed to work with the IM240 driving cycle, but that normal calibrations were usually in effect over 3000rpm, which would also be when "cylinder pressure" was in a higher range than it was at lower rpm levels and mixture/timing would be more normalized, generally.

    In those orientations, where the main impact of emissions controls were in the lower-rpm and part-throttle operational modes. With EGR, throttle response was not as crisp, by observation. Less total ignition timing could result in less response than in prior times, but still valid response.

    I'd say the real "power detractors" included the lower compression ratio (which had some engineering implications, but also resulted in a significantly hotter exhaust flow. When comparing our '72 Newport 400 2bbl and '66 Newport 383 2bbl, the exhaust was much cooler on the '66. If camshaft timing was altered, it was usually "to the positive" with a little more lift and duration, to get more air into the cylinders and then out of them, with a little more overlap in the mix. I never did hear of any Chrysler monkeying around with "retarded cam timing in the cam sprockets" as I did with Chevy and Ford, though. But such a move would tend to help top end power, I suspect, while bleeding off a little low end torque.

    IF the flow through the catalytic converter was sized properly, that MIGHT have had some affect, but NOT as much affect as going from dual exhaust to single exhaust (and one converter) where previous engines would have had real dual exhaust. There was one road test of a '75 small Fury with the 400/190 engine. The testers noted a drop in power above 4000rpm, which they attributed to the single catalytic converter and single exhaust. In general, their acceleration numbers were not nearly as good as I'd suspected they should have been. Later, they did a two-car test of a 440 Coronet police package and a civilian Coronet 400 4bbl. Numbers still seemed a little "weak", all things considered, as the internal specs hadn't changed that much, to me. Other thing was that these were the acknowledged TWO most powerful police packages in existence, back then.

    ONE observation, in general, was that Chrysler's factory calibrations of TorqueFlite shift points was that they were a little low. This got them into "high gear" sooner, but at a detriment to road performance, by observation. Prior to the part-throttle downshift in about '71, this was especially noticeable in fast-moving traffic situations!

    When we got our '66 Newport 383 2bbl, when the '67s came out, it was one year old and had 7100 miles on it. Compared to the prior 6-cylinder '61 BelAir, it was powerful as it was. I had the tuning finessed and was happy with it. Until . . . I took it to college in Lubbock, TX. I'd driven it in DFW metro traffic with no problems. But that time, I'd learned to do a manual 3-2 downshift at part-throttle to better merge into freeway traffic (mimicking the later part-throttle downshift), but out there, it was much more of a "stop light grand prix"! Normal throttle left me "in the dust" as the other cars roared off. More throttle didn't help, so I tried manually shifting the trans, which worked better.

    After consulting with the old-line Chrysler service manager at home, I put two more turns of pre-load into the kickdown linkage at the carb. Worked MUCH better as it raised the shift points a few mph. Engine felt happier, too!

    I test-drove a traded-in '85 Dodge 1/2 ton pickup we had. The 318 4bbl had equivalent power to the 305 4bbl pickups I'd been driving, so I wanted to compare them. The Dodge felt doggier as the trans upshifted too soon for best acceleration in part-throttle. WOT felt comparable, but part-throttle didn't. Manually upshifting helped a good bit.

    Initially, I think it was more about smooth and torque-based acceleration until WOT was really needed. But as traffic speed patterns changed, so did the needs of the cars. WOT power was not always appropriate, but a part-throttle downshift (as GM and Ford automatics did) WAS a good fix. Yet, even then, the shift points were a little low. In later years, when the emissions specs were "grams/mile" rather than "parts per million", those lower shift points might have helped get them past the emissions testers, but did no favors in on-road driving situations. Moving the shift points up as I did with the kickdown linkage adjustment, meant "more acceleration with less throttle input", which made things feel much more efficient, to me. Wasn't "on the converter" nearly as much when the needed gear reduction was in the more efficient "gear" downshift orientation.

    In a Newport with a 2.76 rear axle and H78-15 tires. The min-throttle upshift could be at about 27mph, which would have put the engine back at "idle speed" at that road speed. Any acceleration would have been "on the converter" in high gear. Works fine if you're not in a hurry. Generally too low of a road speed to really need WOT, too. A little more throttle in a Ford or GM automatic would have resulted in a downshift into 2nd and then later to 3rd as acceleration needs decreased. NOT until '71 for Chrysler, though. But even then, they still had shift point calibrations that were a little "conservative", by observation.

    AND, as "exact" as the kickdown adjustments might need to be, that SMALL ALTERATION did NOT affect trans durability one iota! If anything, a "gear reduction" is less heat-generating than a "on the converter" acceleration where the torque converter slips MORE rattler than less.

    Did similar things on my '80 Newport 360, but with a smaller black wire tie. They moved the kickdown road adjustment "under the car" to possibly lessen tampering desires?

    More acceleration, less throttle, "happier" car . . . better feel and keeps the carb out of the power mixture. Win, WIN to me.

    Just some thoughts,
    CBODY67
     
  19. CBODY67

    CBODY67 Senior Member

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    Over the years, there were comments about the A.I.R. systems hurting WOT performance with their added air volume in existing exhaust manifolds. A possible situation, but I also believe that those systems were oriented more toward lower-rpm operation and didn't add that much total air into the exhaust flow at higher rpm levels.

    Still, though, when we got catalytic converters, there was generally ONE, which meant a single exhaust system. These were later upgraded with dual-outlet mufflers, for a more performance image, but a normal single exhaust in front of that. To me, the best of that configuration was on the L69 Camaros. Single pipe going into the muffler was 2.75" diameter, rather than the more normal 2.25" or 2". One converter upstream.

    Chrysler still built dual-converter dual exhaust systems on their HO engines, though.

    One night, I got to check out the "power-robbing" single exhaust single-converter situation. One evening, on the way home on the freeway, I noticed that when I'd take throttle out of my '77 Camaro 305 2bbl, the tach needle would go to "idle" at 60mph, then quickly return when throttle was added to maintain speed. That was not normal. I pulled to the shoulder and stopped. All gears would still engage, BUT upshifts would not happen short of WOT. With a 2.56 rear axle ratio, driving in 2nd made it a 4.10, so no real problems. I made a swing by our service manager's house to get his thoughts on the issue. "Don't worry, it's uner warranty" (it had about 3000 miles on it at that time). It was more sporty with it staying in the lower gears in town and such, but not "right".

    When I got to the highway, as I had to manually shift it, I put it in "1" and nailed it, just to see when it'd take an upshift. Well, that tach needle swung normally past 3000rpm, then 4000rpm, 5000rpm, and hadn't stopped or slowed down by the time it hit 7000rpm, so I upshifted and it went into 2nd. NO power loss at the higher rpms that could be related to a single catalytic converter, from what I could see! 7000rpm from a 2bbl was surprising, plus that power didn't feel to drop off either! Obviously, the GM "bead converter" on that car was sized more for a larger engine, as cold start emissions were not really measured back then?

    Turned out that the check ball seat in the direct drum was flaky. The ball check ball was laying the oil pan. Warranty fixed it. NO problems later on, engine or trans.

    Kind of disproved the "power-robbing, emissions-choking" emission control argument a little weaker.

    CBODY67
     
  20. PeugFra

    PeugFra New Member

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    Thank you for these detailed comments! Maybe I did not understand every aspect of it, but that's my problem.

    So we should get away from the idea that the AIR and EGR affect the power ratings negatively. And the power-robbing effect of the catalyst would be only mild. So far, so good. Lower compression ratio sure left its mark on the ratings, as it was lowered from 8.8 to 8.4 from 1972 to 1973, exactly where you see a 5 hp loss.

    But it remains unclear how the 10 hp uptick in the ratings between 1973 and 1974 should be accounted for. The compression ratio remained at 8.4, for instance.

    Here's the table once more:

    year power torque compression
    1971 175@4000 285@2400 8.7
    1972 175@4000 285@2400 8.8
    1973 170@4000 285@2400 8.4
    1974 180@4000 290@2400 8.4
    1975 180@4000 290@2400 8.4
    1976 170@4000 280@2400 8.4
    1977 155@3600 275@2000 8.4
    1978 155@3600 270@2400 8.4