360-383 A-debate...max builds need not apply.

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  1. pishta

    pishta I know I'm right....

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    Came up in a different post about B'n an A-body. Realizing that the head flow number is pretty much the benchmark on what a moter can produce HP wise, I brought up the fact that the LA 915 J head with a 2.02 intake (stock stuff) outflows the B's 915 head with its 2.08 intake at the same .500 lift at 26 inches. The stroke of a 360 is longer than the 383's with only the 4.25 bore of the 383 eclipsing the 4.00 bore of the 360. Take in the weight penalty of the 383 and the small header selection of the B'd A engine bay and I say a 340/360 is a better choice in an A on multiple fronts. Take an honest look at the stock numbers on a 383 and a 340 (360 with large valve heads) just to keep the max effort builds out of the debate and the cost factor of a core 360 over a 383 today and i gotta ask is the 383 worth what it gives you...which is...? Let the debate begin. Try to back up data if you throw out numbers. I looked at Hughes website for flow numbers of stock heads and am not sure if their numbers were their results of bowl work or off the block tests. 915 A head was 20 cfm over the 906/915 B head at .500
     
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    • diymirage

      diymirage HP@idle > hondaHP@redline

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      It's not a fair comparison
      The 360 is the biggest baddest small block out there, with added benefits of a hydraulic cam in the magnum version

      The 383 is the grocery getter smallest of the big blocks, so it's just not worth the hassle to do the swap

      Just like you wouldn't bother pulling a slantie for a 318...it just doesn't make sense to replace the 360 with a 383
       
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      • 66fs

        66fs FABO Gold Member FABO Gold Member

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        You guys are funny. Did you ever race a HP 360 Duster against a 68-70 383 Road Runner? No contest in real time or by theoretical numbers. If you want to Bench Race, then who cares. You can make anything up, or make either win or lose. 360's were low compression, most 383's were high compression with about 0 decks. By the time they put the HP goodies on the 360 in 1974, J heads were long gone. What torque did a Road Runner 383 put out? 425 ft.lb. and revved like a good small block? Intake flow for stock 360 heads is roughly between 190 and 200 cfm while stock intake flow for big block heads is roughly between 220 and 230. Ask IQ 52 what is the potential for 906 or 452 heads.
         
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        • 318willrun

          318willrun Utube channel 318willrun

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          Short and sweet. 383 4bbl cars were faster than 360 4bbl cars from the factory. Roadrunner's ran 14.4's off the showroom with 383, what did the 360 4bbl run in the lighter A-body??
           
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          • DionR

            DionR Well-Known Member

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            You could be right.

            I have heard that the 383 was the base motor in some model E-Body, and the 340 an upgrade, but it seems like the 383 was always rated higher than the small block. Maybe just Dodge playing with the numbers?

            Couple of things I can think of that might throw things off:

            1. The bigger bore of the 383 might help with the intake valve flow, making things more even.
            2. The 383 is still more cubes, even if it is the smaller big block available.
            3. Valve train geometry is probably better on the 383.
            4. Dry intake. No coolant flowing through it to warm it up (or cool it down??).

            Wish the guy who used to post all the old road test data and drag tests was still around. I bet he could give us a comparison between a 383 and 340 Dart.
             
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            • rumblefish360

              rumblefish360 I have escaped the evil Empire State! FABO Gold Member

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              The B 383 is bigger than two of the other B series engines. The 2 smaller ones are the 361 & the 350. The only B engine larger is the 400. The only RB smaller than the 400 is the RB 383, long stroke, 3.75, & a small cylinder bore.

              Stock vs stock, It’s kind of a wash. Depends on how you go about looking at it all. And I mean everything from all angles. But here are my thoughts and comments.

              The best thing about a B series engine (or RB for that matter, but we’re discussing the B series here....) is the large cylinder bore that readily loves a better cylinder head. Enter an Edelbrock, ProMaxx/Pro Comp, Trick Flow or Indy or ..... Where the engine will really get to breath!

              The way I see things is any engine you get has a high probability of being in deep need for a rebuild so any compression concerns are none, nil & void. Unless you get a good 5.9 Magnum. But now your starting at a 9.0-1 ratio without any clear and easy or cheap way of getting more compression cheaply. Milling the heads will do well and cause other fitting issues you may not be so happy about fixing.

              Your focus is the end game result even if it is years down the line. There is no replacement for displacement and the addition of any bolt on parts or cam will just make it that much better. Then there is also turbo/super charging on top of it.

              The weight penalty of the B engine cam be reduced just like the LA/Magnum can. The weight savings is greater engine vs engine. But the B engine will generally speaking get as light as a stock LA/Magnum is. If you build the 383 with enough beef, it will easily over come the weight difference & then some of you so desire to go there.

              And it won’t be that hard to do ether. Your already 23 cubic inches greater with much better OOTB cylinder head choice.
               
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              • rumblefish360

                rumblefish360 I have escaped the evil Empire State! FABO Gold Member

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                @DionR I don’t know who told you that load of crap about the 340 being an upgrade. Weather you see it or not as so, the way it was done was strictly by the engines CID.
                 
              • DionR

                DionR Well-Known Member

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                Maybe I didn't state it correctly. Wasn't trying to say the factory saw the 340 as the better motor, only that I thought the 383 was the base engine for some E-Body model and that for a small price you could "upgrade" to a 340 4BBL. Can't figure out what model it would have been (not a T/A or AAR), so I must be wrong. Had it pointed out to me in a thread on a different forum and it seemed like I remember seeing that before, but didn't verify it then and couldn't just now either.
                 
              • DionR

                DionR Well-Known Member

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                • 318willrun

                  318willrun Utube channel 318willrun

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                  I see the 383 as a grown up 340. About the same stroke (3.31 vs 3.38 in favor of 383), but a lot more bore. Was there a small block mopar rated at 335 hp from the factory ???? :)
                   
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                  • DionR

                    DionR Well-Known Member

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                    • pishta

                      pishta I know I'm right....

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                      71 Roadrunner base motor was the 383/4 with the 340/4 optional. 1974 the 360/4 caught up
                      V8-360 4-bbl 4.00 x 3.58 8.4:1 245 @ 4800 320 @ 3600 45-65
                      V8-400 2-bbl 4.34 x 3.38 8.2:1 185 @ 4000 315 @ 2400 45-65
                      V8-400 4-bbl 4.34 x 3.38 8.2:1 205 @ 4400 310 @ 2400 45-65
                      V8-400 4-bbl 4.34 x 3.38 8.2:1 250 @ 4800 330 @ 3400 45-65
                      V8-440 4-bbl 4.32 x 3.75 8.2:1 230 @ 3600 350 @ 3200
                       
                    • DionR

                      DionR Well-Known Member

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                      Whew...just barely snuck it in there before you.

                      :rofl:
                       
                    • MOPAROFFICIAL

                      MOPAROFFICIAL FABO Gold Member FABO Gold Member

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                      I have written down #'s from testing a bone stock set of 906 heads 10 years ago and they bested 228 cfm stock. 2.08
                      I have a set of 915 j heads 2.02 factory that peak identical..228 cfm.

                      Worst 2.02 x or 915 j numbers I've seen were 212-222 cfm, x heads I had did 218cfm stock.

                      The 383 will make more power, the block is also more ridged, the heads have an easy potential of 280 cfm with a 2.08 and 300's with 2.18 ...shorter stroke. 383...It's the 340 of big blocks imo
                       
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                      • fishmens67

                        fishmens67 FABO Gold Member FABO Gold Member

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                        I'm going to stay out of this. lol
                        I think MOPAROFFICIAL, 318Willrun and Rumble have it covered.
                        only the young bucks that haven't been around a 383 mag call the 383 a taxicab engine. lol
                         
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                        • K.O. SWINGER

                          K.O. SWINGER Meeting in the alley since 1976

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                          Sorry but a 383 roadrunner would not handle a 340 dart with the same transmission and gear ratios the dart would win every time. My brother had a 70 roadrunner 383 4 speed and I had a 340 swinger and it broke his heart every time we raced. The 383 was rated at a higher horsepower because they did not want to have the 340 cars cutting into the b-body platform sales for that reason they kept the horsepower rating down on the 340 fact. that being said the 383 is still as mentioned a more rigid platform and will handle more horsepower
                           
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                          • 318willrun

                            318willrun Utube channel 318willrun

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                            Nice story, and thanks for sharing. Not a apples to apples comparison, two totally different cars so it proves nothing. I mean, both cars were dead the same weights? Both cars equally life and quality of life, in "as new" condition? Then you have driver variance, means they were both sticks. Anyways, it's 360 vs 383. By the way, I love 340's, 360's...... and 318's, 383's :)
                             
                            Last edited: Feb 22, 2021
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                            • fishmens67

                              fishmens67 FABO Gold Member FABO Gold Member

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                              The 340 Dart was known as the big block killer.
                              But the op is talking about factory 360 vs 383.
                               
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                              • 318willrun

                                318willrun Utube channel 318willrun

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                                In the end, a guy can make any of them fast...
                                 
                                Last edited: Feb 22, 2021
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                                • rumblefish360

                                  rumblefish360 I have escaped the evil Empire State! FABO Gold Member

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                                  The base engine in any Barracuda is the /6.
                                   
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                                  • K.O. SWINGER

                                    K.O. SWINGER Meeting in the alley since 1976

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                                    yes I guess I kind of got off track sorry, but I will say that by the time the 360 hit the street everyone with a 383 or 340 had had a few years to dial them in and going up against one on a Saturday night with the 360 well that could be real embarrassing. But after the guys started to learn what they needed to do to 360s to make them run hard they became their own legend.
                                     
                                  • 318willrun

                                    318willrun Utube channel 318willrun

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                                    I'll add to your point that the 360 was considered dog breath when it came to performance for quite a few years. It was 340 or go home. But as you pointed out we know that the 360 can be killer. 9 second 1/4 mile times in door cars with stock stroke. But today, we can fly with just about any engine with a few bills laid out.
                                     
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                                    • Seth Jones

                                      Seth Jones Well-Known Member

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                                      I’m pretty sure Car Craft had a project 74 360 Duster that went 14.5’s off the showroom floor.
                                       
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                                      • DionR

                                        DionR Well-Known Member

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                                        Seems like people are missing the question.

                                        Why is it worth swapping a 383 into an A-Body today rather than a 360?
                                         
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                                        • 318willrun

                                          318willrun Utube channel 318willrun

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                                          Not sure what "project" means. But even so then the 383 went a tenth faster in a heavier car.
                                           
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