How Big can a 5.2 get?

Magnum Engine Swaps

  1. toolmanmike

    toolmanmike FABO Staff Staff Member FABO Gold Member

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    That's pretty! No really!
     
  2. rumblefish360

    rumblefish360 so close yet so far away

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    A sonic check will tell the machinist how far he can bore out the block safely.
    stroker cranks can go larger than 4 inches. The largest I have read about in use is a 4.25 from Rod Bloomer.
     
  3. MopaR&D

    MopaR&D Nerd Member FABO Gold Member

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    I don't think it needs a stroker kit based on what you're doing. Sure it would be nice to have all that torque but you're also throwing gas mileage out the window, 5.2L up to 6.4L. Kind of nice to have in a grocery getter especially with European fuel prices, JMO
     
  4. Dusterfreak

    Dusterfreak Well-Known Member

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    Thats what I thought and decided not to stroke. I want decent street manners and best possible gas mileage, RON 98 is 1,50€/ litre here, that means its 6,50$/ gallon :D I also decided to feed the engine with Pro-Flo4 fuel injection to support those things. Engine is slowly getting somewhere, next thing to do is to measure piston to head clearance, pistons are sticking .018" up from the hole so with Fel-Pro 8553 gaskets I should get Quench around .035".
    51623630_10213103279358819_8742935689454157824_o.jpg?_nc_cat=100&_nc_ht=scontent-arn2-1.jpg
     
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    • MopaR&D

      MopaR&D Nerd Member FABO Gold Member

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      Wow, fuel prices here are literally one-third of that, fuel station near my house has 91-octane (RON+MON)/2 for I think $2.25/gallon? Even still I'm happy my engine will only be 9:1 compression I should be able to run 85-octane regular gas or at the very least 87-octane midgrade. Too bad I can't ship you a barrel of cheap American gas :lol:

      With good quench and compression like you're building for, those heads which have good air velocity esp. with the smaller intake valve, and the Hughes roller cam, I bet that engine will run great at all speeds and have a nice fat torque curve for the relatively small displacement.
       
      Last edited: Feb 10, 2019
    • AJ/FormS

      AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s FABO Gold Member

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      Our gas prices have been dropping this winter which is highly unusual. With an exchange rate of 1.33; the price equivalents of 87E10 are from as high as 6.49 per USg last fall, to currently 4.79 per USg.
      Just to compare; a 2 liter bottle of Coke costs the equivalent of 8.96/USg.
      And jug of milk is 9.68/USg equivalent, of which I buy 3 per week,minimum, of which I drink 2 by myself. I love milk!
       
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      • rumblefish360

        rumblefish360 so close yet so far away

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        Well that explains a lot!!!!

        Seriously.... I’m just glad I don’t drink as much milk as my truck drinks gas!
         
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        • Dusterfreak

          Dusterfreak Well-Known Member

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          Wish I could get a tanker!
          :thumbsup:
          Seriously, thats what Im aiming really, a strong pulling engine that reacts immediately.
           
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          • MopaR&D

            MopaR&D Nerd Member FABO Gold Member

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            Might be the surplus of American oil, first time in history the U.S. is producing more oil than it needs and the oil companies don't know what to do besides keep processing and selling more of it. Which isn't a great idea since there are still leaking pipelines and offshore rigs that need to be fixed but that's another discussion lol.

            Wait you're saying a 2-liter of Coke costs almost $9 in Canada and here I can buy one for like $3? And a gallon of whole milk (milk fat is good for you if you're active and eat heathy) is $1.99 before tax at the local grocery... I sure hope your minimum wage and mean household income is higher than ours!
             
            Last edited: Feb 11, 2019
          • AJ/FormS

            AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s FABO Gold Member

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            No; a 2liter jug sells at the rate of 8.96 USgallon, so you can compare it directly to gas. The bottle itself is 3.70C per 2 liter bottle or 1.95C per liter.Smaller quantities out of refrigerated coolers cost way more comparatively, and I only buy by 2liter bottle.
            As for milk I buy a 4L jug (3.64USg) at the convenience store for a tic over 8.00C, or about 5.50C to 6.50C at the big box grocery store. These also cost comparatively way more in smaller quantities, and are taxed. Many things we buy are taxed in smaller quantities/ exempt in bulk;the idea being that smaller quantities are a convenience for a well-to-do person, whereas someone buying a jug of it is buying it for his poor family, so deserves a break. Hey I didn't make this system up.
            A typical wage for a trained common-tier tradesman or laborer, is about $18 to $20 per hour. So that breaks down to average about 4gallonsImp per hour of average gross wages. But I gotta tell ya, gasoline still seems reasonably priced,when figured this way. In 1969 gas was 37 cents a Canadian gallon and I was making 1.50 per hour minimum wage; this then being 4 gallonsImp per hour's wage. Gas is about the only commodity to have remained like this.
            We are lucky to NET 70/75% after income-taxes.
            Our combined Provincial and Federal sales taxes is another 13%.
            Milk is sales tax exempt in 4L jugs.
            Gasoline, Alcohol, and Tobacco are taxed to the extreme.
             
            Last edited: Feb 11, 2019
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            • MopaR&D

              MopaR&D Nerd Member FABO Gold Member

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              Good to know, thanks. Like with a lot of things there's a lot more to it than what's on the surface. Smaller quantity goods tend to be a little bit pricier here in U.S. but that's just the companies making up for production costs, they aren't taxed any differently based on size. The main economic problem here is the wage gap keeps increasing (rich getting richer etc.), cost of living and goods keep going up, but all the "mortals" are still making the same money or less compared to 20, 30, 40 years ago (accounting for inflation of course). I think it's kind of the same deal around most of the developed world though.

              Sorry got off topic lol... back to Scandinavian small block Mopar builds :D
               
            • Dusterfreak

              Dusterfreak Well-Known Member

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              Well, this didnt go as planned... Somehow Ive got piston to head clearance everything between .038 and .047 .038 is good but .047 is not... Dont know wtf should I do, block is decked allready and crank balanced.
               
            • AJ/FormS

              AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s FABO Gold Member

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              ouch :(
               
            • Dusterfreak

              Dusterfreak Well-Known Member

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              Tell me about it... Ive been trying to figure this out all day, I could get 4 pistons shaved and then use thinner gasket, but how about my balancing then? .008 shaved off a piston, how many grams is it?
               
            • AJ/FormS

              AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s FABO Gold Member

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              You say the pistons are .018 above deck. I assume you mean all of them.
              I reread the thread but I got no smarter; Are those heads closed chambers?
              When you measured the deckheights did you measure across the center of the piston and rock it to find the lowest number. If the piston-crown was not dead-parallel to the deck it will skew your deck height measurement, and if you are using math to find the P-H clearance, it will skew that as well.
              In any case your range of P-H clearance AKA Quench , is well within the range of acceptability.
              But if you find the deck heights changing from front to back or side to side, and the range on one side is different than the range on the other side, then the decks have been machined crooked, unless you also had the block line-honed,and or the rods resized, then there could be some error there.
              But if one entire side is about the same from front to back, as is the other side, just different, then you just have one taller deck. So now you can either machine the taller one down to match the other side, or, since the range is .009, you can just even it up by gasket selection.
              The thing is, if you also had your rods resized, then they can be the culprits.
              What I did was take one assembled rod and piston, and stuff it in each hole marking the deck-height on the deck surface. THis found me the deep and shallow holes.
              Next I picked one hole and one piston and and checked the deck height with each of the 8 rods. This found me the long and short rods
              All my KB-107 pistons were within .0005 on the cd, so I could put any piston on any rod,except for valve-pocket orientation.
              Then I put the longest rod in the deepest holes,with the proper piston, orienting the squirter holes as I went. The rods don't care where they go, except recheck the side clearance when you are done, and maintain some minimum clearance, I forget the spec.
              Then I assembled it all, and remeasured the deck heights. I ended up with one tall one and the rest fell within .003 inch, so in my case I was good to go. My deck height ended at .005 +/- .0015, except for the tall one was a thou or something, higher, I forget.
              There was a lot of time involved, but I was running out of machine shops. I tell you one thing; if there is a next time, I'm going with custom pistons no matter what the cost; I don't care. By the time I ended up with all that machining, I couldda had money left over with custom pistons.

              I hope this gives you some ideas.
               
              Last edited: Feb 16, 2019
            • Dusterfreak

              Dusterfreak Well-Known Member

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              Machinist said 0,47mm, thats .0185", I thought he meant they are all the same.
              And yes, the EQ heads are closed chamber.

              I didnt have access to right tools so I had to improvise, also this is my first enginejob so Im learning, every day is a schoolday.
              I put solder (is this the right word?) tinwire.jpg
              on both sides of the piston, so it cant rock. Then I put headgasket and cylinderhead on and tightened it to specs. Turned the engine one full turn, took the head off and measured the flattened solder. I did this three times for accuracy, numbers below are averages of the three.

              This is what I got for quench:
              1. .039
              2. .043
              3. .045
              4. .047
              5. .039
              6. .045
              7. .043
              8. .038
              (these are also converted from millimeters)

              I decided NOT to do anything, since there is really no cheap or easy way to fix this... maybe its because the crank has been grinded down years ago to .030 on 1 and 2 and others are .010, or the rods arent the same size or what ever...
               
              Last edited: Feb 18, 2019
            • txstang84

              txstang84 Well-Known Member

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              Weird-almost sounds like rod C2C lengths inconsistent?
               
            • Dusterfreak

              Dusterfreak Well-Known Member

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              Might be, I used magnum rods and KB pistons are press fit.
              After a week of hard thinking Ive decided to give it a try. Ill get three pistons shaved for .006. That brings my quench in .043-.047 range with 8553pt and then I can use a thinner gasket and get final quench of ~.033 to .035
               
            • txstang84

              txstang84 Well-Known Member

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              Well, regardless of magnum or LA rods, they should still be 6.123" C2C. The only dimensional difference I'm aware of between LA and magnum rods is the small end width; magnums are slightly narrower.

              I hope it works out for you, I'm anxious to hear about the performance level as I'll probably go a similar direction with my 5.2.
               
            • Dusterfreak

              Dusterfreak Well-Known Member

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              Not much progress here, pulled three pistons and noticed there were strange scratches in 1st rod bearings. Now I have to find out what caused it, rod is in machineshop and theyll measure it. If its round, then its must have been dirt what caused it, but I have to find out.

              But hey, I got my Proflo4 :thumbsup: 54257944_10213276290203982_1666070590676533248_o.jpg?_nc_cat=108&_nc_ht=scontent-arn2-1.jpg
               
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              • rumblefish360

                rumblefish360 so close yet so far away

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                I have well considered that set up. Let us know how that goes will ya?!?!
                 
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                • high.rev.trev

                  high.rev.trev Well-Known Member

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                  Hi. Your in Finland ?? 2 options: 1 isn't a 'Magnum' Block but Scrounge around for a wornout 240 or 250hp Chrysler Marine Sterndrive engine: its a thick bore/casting H/duty Block with ALL the goodies ( & I mean ALL the factory H/duty goodies: bushed/floating small end ",Truck/Industrial Rods High Pressure oilpump, 273ci Commando Single Plane 4bbl Intake , big 4bbl AFB, STEEL crank, etc etc) OR if some Intl freight isn't out if your Budget there's an Engineering Business in Australia that makes Custom overbore size pistons with pins & rings supplied.
                  JP Engineering try google jpengineering.com or jpengineering.co.au I know the owner Laurie - Tell him Trev from NZ sent you. He'll make you Std +080" block savers or any feasable overbore req.
                  I read in a Hotrod mag Magmun blocks didn't like much over +030"_ +040 without sonic testing & your pushing it: Suggest a Welded up offset ground Stroker Crank done locally with a Custom Compression height piston to match: +.060" 318 takes you to 327cubes, did 1 with smooth flattops: not valve reliefs & pocket ported heads & that was a Stormer , IF you find an ex Chrysler Marine they've also got a high torque H/duty Starter Motor, which is a cheap way to get something to swing the project over + save those Intl EBay type Shipping costs :-/
                  Goodluck .Trev

                  Screenshot_2019-02-26-21-20-05.png
                   
                • high.rev.trev

                  high.rev.trev Well-Known Member

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                  Semi-delete that last reply of mine: I replied to a muchvEarlier post of yours...but, how high are you going to spin that. 318 ?? - that's a high Rev midrange torque manifold like hovering around 4'500 rpm constant like circle track. + things can't be TOO expensive in Finland if you've got KB pistons & proflow injection. ,( not as tough as here in NZ, we pay near 45% extra to $US with exch rate + the high cost of Shipping 9,000+ miles, then there's the +15% GST which then incures another $176+ flagfall in customs' creative surcharges.
                  Cheers anyway. T
                   
                • Dusterfreak

                  Dusterfreak Well-Known Member

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                  Yes I live in cold Finland, near russian border.
                  Not much marine engines here to use, I believe there hasnt been so many and whats left nowadays are rotten.
                  This Magnum is 1993 from a Grand Cherokee and the block is in great shape, got it bored .030 over and cant think how it wouldnt manage that.

                  Well, im thinking the engine should easily rev to 6000 and with my gears, Im in 2700-2900 range at highway. The intake is a bit overkill, I know. But thats what edelbrock has decided to offer to this set. There isnt much options for mopar EFI intakes, in fact super victor is the only one :D
                  But in MPI the manifold has to provide only air, not atomized fuel so maybe it isnt the same as with carbs? Perhaps someone can lighten this a bit??

                  We have to pay 24% tax from everything including shipping, so 375usd KB pistons cost me 589usd and 1895usd fuel injection costs 2644usd when delivered.
                  But, ive decided to do this once, and dot it properly and when its done its done.
                  I can divide the cost to 10 year or 15 year period and then it isnt so much after all... You know, theres many ways to cheat your mind.
                  :rofl:
                   
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                  • stixx

                    stixx FABO Gold Member FABO Gold Member

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                    Smart calculation method you have there... :)
                     
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