360 HP estimate???

Discussion in 'Small Block Mopar Engine' started by Dubs Chops, Jul 12, 2018.

  1. Dubs Chops

    Dubs Chops Well-Known Member

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    Hey guys the 68 dart I just bought has a great sounding motor. Taking it to the track tomorrow night and was wondering if anyone may be able to help me with the HP estimate

    360 .60 over
    Kb 10.5-1 pistons with stock 72cc heads
    Xe274H cam
    Open headers
    Stock intake
    Holley 600 carb (going to an airgap and 750 holley DP soon)
    Electric water pump and fan
    Msd6al
    Pro billet dist

    The car itself has 28x9 slicks
    Ladder bars
    2600 stall
    Manual valve body 727
    8.75 rear axle with 4.56 gears i believe

    Anyone wanna guess the ET also? Let me know if i left anything out. 20180702_190649.jpg
     
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    • rumblefish360

      rumblefish360 so close yet so far away

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      Car race weight, shift kit/trans brake/suspension parts/valve sizes/port work/header size,
       
    • 273

      273 Well-Known Member

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      375 hp @ 5400
      420 lbs-ft @ 4000

      With airgap and 750.

      Stock 1.88 Heads limiting factor here.
       
    • crackedback

      crackedback FABO Gold Member FABO Gold Member

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      Engine if tuned right should make 325ish on a good day

      ET is all hook and converter. Should go mid 12's pretty easy as long as it hook and tuned well.
       
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      • KosmicKuda

        KosmicKuda Well-Known Member

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        Weigh the car and calculate HP based on MPH
         
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        • B3422w5

          B3422w5 Well-Known Member

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          Gears will help, but i bet it wont run mid 12’s. Maybe real low 13’s. Maybe. My guess would be 13.30’s or 40’s
           
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          • Dubs Chops

            Dubs Chops Well-Known Member

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            FB_IMG_1532804011034.jpg
            Great guess, the car ran a best of 13.29 at 101mph last night every pass 60' was 1.94 I need to get that down. Also I was out of the power in 3rd by the 1000' mark and it basically quits pulling the rest of the way. I didn't have time to play with jets, I think with good air and the carb turned well it has a 12.90 in it. After i get it to that point I'll have to decide where I want to get more power from. My head options are limited with the 10.5-1 KB pistons to motor has in it so I'm thinking I'm may just give it a bottle.

            Also the car weighs in at 3044 without me in it. The fiberglass front end should help but I'm sure when I add a cage it will take all that back.

            Photo Credit to Charles Judd photography. He is always at the track and does awesome work.
             
          • crackedback

            crackedback FABO Gold Member FABO Gold Member

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            Soggy 60'... it's at least .1 to .15 off based on MPH. Get it down and that's .2-.3 at the other end. Laying over at 1000' another .2-.3 and that took a bunch of MPH out of it too.

            About 250hp at the tire which seems low to me. My Dart with less engine went 103 at a slightly higher weight. 60', Carb and tune should get it there. Find a good 750DP for it! Fuel delivery issue is likely why it laid over.

            Unless that 600 has a metering block in the rear, upping only the primary is a waste of time. You want to step up jetting in all 4 holes.
             
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            • nm9stheham

              nm9stheham Well-Known Member

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              I'd guess fuel-air delivery, too. Numbers with that tire diameter and top end speed works out to 5500-5600 RPM with a 4.56 rear gear. So something is choking it off; 600 cfm ought to do better than that.

              Why not go with a bigger cam to take advantage of the higher CR pistons and then you can go to better heads? Can you confirm that these are KB190 pistons? (Which show as 10.5 at 72 cc's...)

              You can use better heads if you work it out. With those pistons and stock deck height, and a .075" thick Cometic head gasket, Edelbrock 60779 heads should give a good quench gap and a DCR of around 8.1 with a 282 advertised cam. You can tune around that for sure. Just check the piston-to-deck height if they are KB190's, to make sure the piston to head clearance is adequate. If the block has been decked, then look at the Edelbrock 60179's with the .060" recess and vary the head gasket thickness.
               
            • Dubs Chops

              Dubs Chops Well-Known Member

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              I did get a quickfuel 750dp brawler and added the rpm airgap. I think it's in my jetting. I went 76/81 and I think its rich at idle and its having to burn off the extra affecting the 60'
               
            • Dubs Chops

              Dubs Chops Well-Known Member

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              What are the cc's of those eddy's? I'm afraid the static would be way too high for pump gas if they are in the 60's cc range. It has an xe274h cam.
               
            • crackedback

              crackedback FABO Gold Member FABO Gold Member

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              Rich at idle is ALL tune up. Get the proper initial timing on it so it's clean down low. Should have somewhere around 16-20 maybe more. If it's timed using total, that may be why it runs like junk at idle.
               
            • Dubs Chops

              Dubs Chops Well-Known Member

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              16 at idle. I don't have a dial back so I'm not sure of total yet.
               
            • nm9stheham

              nm9stheham Well-Known Member

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              63 cc's for the 60779 closed chamber ones and 65 for the 60179 'open chamber' ones. You have to use a combo of head AND head gasket like I listed to make the clearances work, AND do some measuring.

              If you are not comfortable with measuring things and setting clearances, then don't go down this road. I just wanted you to be aware that it can be done with the right parts and measurements. The warnings to not use Edelbrock heads with the KB190's are for the knuckleheads who just want to slap things together.... that WOULD be problem!

              DCR is what you care about; SCR is just part of what goes into DCR. The numbers I gave you are worked out for a 282 cam. If I plug in your xe274 cam and set the cam timing for dot-to-dot timing, then DCR comes up to 8.3. Still quite manageable with quench and AL heads, and it's not all that different from what you have now with that cam and piston and head combination and a thinner head gasket; I think you have around 8.0 DCR right now. Care in tuning IS required either way. But the idea to go to a larger cam is to get even more top end HP and use the larger heads better. You have the pistons to support that.
               
            • Dubs Chops

              Dubs Chops Well-Known Member

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              Thanks, this is exactly the reason I come to people with more knowledge than me. This is a very helpful post. However I am thinking a bottle might be simpler and cheaper to get the car into the 11's after I get the carb dialed in. But heads would definatley bring more all the time HP to the table

              What kind of piston to deck measurement do I need to make sure this combo will work? I was assuming my static was like 10-1 with the current setup assuming stock deck height.
               
            • AJ/FormS

              AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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              Well, one thing I can tell you is if you get the pressure up to 185 to 195 with a 223 to 230*cam, you will get such a grin on your face it will take all winter to get it off.
              The KB 190s are a great start

              To run N2O usually requires more ring-gap, and more skirt clearance.Which is kindof the wrong thing to do on the street,especially long-term.
              But if you are gonna make it a dedicated track car, then N2O makes sense; sorta.
               
            • MOPAROFFICIAL

              MOPAROFFICIAL Well-Known Member

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              Get a 750 dp on there, that will feed it past 5000 rpm, upping the peak torque beyond where it lays down now.
              The heads need work too.

              With the right carb and heads that flow 190@.300,
              225@.400,
              252@.500
              For instance

              You'd be into the low 12's.
               
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              • Dubs Chops

                Dubs Chops Well-Known Member

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                I do have a quickfuel 750dp on it now. I think I just need to jet and tune it a little better
                 
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                • mderoy340

                  mderoy340 Well-Known Member

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                  You are correct, tune what you have first. The 60' and top end mph/rpm is off for the package you have now. You more than likely went lean at the top end. Look at fuel delivery, bump up initial timing, and jet carb.
                   
                • 318willrun

                  318willrun Stomper 4x4... we kept energizer in business

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                  nice car. some mis-matched components. Honestly, in my opinion is you have some tuning to do, because your car should be deep in the 12's. my thoughts are these.....
                  • Too much gear for your combo. I went from 4.30's to 3.91's in a 360 Dart and the E.T. or MPH didn't change any at all. I think your car would go faster with something like a 4.10 or 3.91. just my opinion.
                  • You are correct, get the 750 on there...
                  • I would "fine tooth comb" the tune. Timing and jetting could be leaving a half a second on the table.
                  • I see your combo, with a little tuning, going 12.30's.
                   
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                  • nm9stheham

                    nm9stheham Well-Known Member

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                    For some long term thinking.......

                    If you go to NOx, you are just adding in more oxygen so you can add more fuel. That will raise the cylinder pressures and move towards detonation. So you probably aren't going to go with much NOx safely without higher octane fuel, because the present setup is already moving towards the limit for detonation on pump fuel with just the natural intake of oxygen via the carb.

                    The present setup is not optimum for fighting detonation anyway:
                    • The present piston to head gap is likely in the range of .110" + or -, and that will give you no quench effect.
                    • This large gap presents a larger, slow burning open chamber style area. Slower chamber burns increase the probability of detonation.
                    • The head are iron, which does the same thing.
                    • The DCR is already up there.
                    • More ignition advance needs to be done with care here IMHO due to this setup. Listen closely for detonation. (I've been in this territory before.)
                      • The prior owner may have found this out already. Let us know where you find the ignition timing setup as-is. BTW, you don't need a dial-back timing light to find you timing; just accurately extend the marks on the damper or put on a timing tape and use a regular timing light.
                    Moving to a closed chamber head like an Edelbrock with the right head gaskets will give you several advantages:
                    • AL heads that fight detonation
                    • A good quench gap that does the same
                    • A closed chamber where the burn is faster overall. Fights detonation and does not need as much ignition advance.
                    • Better flow that will help all over the RPM range.
                    The DCR is not going to increase very much with the change, so it is an improvement all over.

                    One thing to note is that if you go with Cometic head gaskets to get the piston-to-head clearance right for Edelbrocks, then the head and deck finish has to be in the right ballpark (50 RA) to hold the Cometic gasket. Just something to be aware of. It would be good to hear of anyone else using Edelbrocks out of the box with Cometics; we have, but that is just a sample of 1, and I did not check surface finish like I should have.

                    The key measurement is to find out how far the tops of those pistons stick above deck when at TDC. Head has to come off to do that... maybe a good thing when you put on that AirGap? Ooops.. too late! If you do that, then the present head gasket can type can be found out. (Or maybe you can get that info from the prior owner.) That will help firm up the details of what you have now.

                    And, of course, there are other options in heads.
                     
                  • AJ/FormS

                    AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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                    When you think about it; running near 200psi compared to 140 typically....
                     
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                    • Hot Metal

                      Hot Metal '69 440 Cuda

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                      All depends on how far you wanna go ET wise, but here are some specs and on track times from my street/strip '71 340, 3550+lbs Cuda.

                      Stock 2.02 heads no porting, 10:1
                      .484/284 hyd purple cam
                      MSD6A..NGK 6's
                      factory rockers
                      stock 3.55's + 8x26" slicks
                      3500 verter
                      ally dual plane, 750DP
                      small tube hdrs
                      all stock suspension
                      just long shocks +snubber
                      13.29@101 = 303fwhp.
                      max rpm 5900
                      _______________________

                      Stock T/A heads with W2 rockers (worse than stock heads)
                      .590" sft purple cam
                      NGK 7's
                      adj. rockers
                      4.30's, 10x28's
                      H-Strip Dom int.+2" open spacer
                      850DP 4781 with milled down choke tower
                      1.3/4" race hdrs
                      4200 verter
                      same suspension
                      12.39@108 = 367fwhp
                      Limited to max rpm of only 6200
                      cos of valve train .

                      +N20 11.01@122
                      early to mid 80's

                      Just some real info on specs /weight from the track to add to the overall mix of parts
                      and what they can do.
                       
                      Last edited: Jul 29, 2018
                    • Dubs Chops

                      Dubs Chops Well-Known Member

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                      Did you do anything to the ring gap for the giggle gas?
                       
                    • Hot Metal

                      Hot Metal '69 440 Cuda

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                      No, we built it as an NA motor with replacement TRW pistons/ring gaps. Then we discovered N20, we made several passes with a cheater system@125/150 hp jets and just that 1 pass with 250 jets (11.01), but we ran it on motor 90% of the time. Cheater solenoids only have a .093 orifice, so the 110n/110f jet 250 tune wasn't 250hp and the jetting on the kits was very rich back then. We encountered no problems at all with plugs (NGK7's) and we ran a lot of timing (36 total), with the 98oct leaded pump fuel we had.
                      If your gonna get a bit serious with it and run 200hp+tunes frequently with todays clean 5>10 smaller size fuel jet tunes, watch your timing and run 100oct fuel as its timing that kills motors with a lot of N20, then I would open your ring gaps some, otherwise I wouldn't bother if your only gonna run it every now and again with max 150hp tunes.