Toying with the idea of a magnum swap

Engine Swaps

  1. ChryslerCruiser

    ChryslerCruiser Well-Known Member

    Messages:
    70
    Likes Received:
    7
    Joined:
    Jun 27, 2019
    Location:
    Morrisville VT
    I just saw an advertisement for a 95 1/2 ton 2 wheel drive P/U for sale locally for $700, 130K and supposed to run good. The ad got me thinking that it would be the simplest way to improve compression, efficiency, and general street manors...

    It seems to me that the engine and transmission could be swapped as one, and get an updated drivetrain w/out the hassle and added expense of finding bits and pieces here and there.

    To do the job, it seems that a timing cover, oil pan, Intake, and electronic fuel pump would handle most of the engine side of the swap... and figuring out how to control the overdrive, and converter lock up, would be take care of most of the transmission puzzle...

    Then to source a rear end that has something like a 3.55 or 3.73 gear ratio...

    What are your reactions to this line of thinking. Am I nuts to wonder if it is the easy and economical way to add 100 HP/100 LB-Ft?
     
    brotherGood and SuicideRider like this.
  2. Duke5A

    Duke5A Well-Known Member

    Messages:
    767
    Likes Received:
    296
    Joined:
    Apr 6, 2018
    Location:
    Michigan
    DO IT.

    It's not just the added peak power. Power over the entire curve is better and you're going to gang gobs of streetability.

    Is this just a cruiser? Grab the entire thing. Computer, harness and use it all. Don't change the intake. Just crack the motor apart, inspect and regasket. Reuse your old exhaust manifolds.

    You'll need a fuel system and surgery to the transmission crossover to get it to fit. Something that has been done plenty of times here.
     
    MBDale and brotherGood like this.
  3. ChryslerCruiser

    ChryslerCruiser Well-Known Member

    Messages:
    70
    Likes Received:
    7
    Joined:
    Jun 27, 2019
    Location:
    Morrisville VT
    Thanks for the encouragement Duke. I will keep moving forward on this.
     
  4. Duke5A

    Duke5A Well-Known Member

    Messages:
    767
    Likes Received:
    296
    Joined:
    Apr 6, 2018
    Location:
    Michigan
    ....and for a little more encouragement.





    The above is a guy who swapped a 5.2L Mag motor, factory fuel injection and all, into a 1983 Fifth Avenue. That is exactly what you can expect. Only thing he left out was the 518.

    What axle do you have in the car?
     
    MBDale likes this.
  5. Camtron

    Camtron Well-Known Member

    Messages:
    470
    Likes Received:
    167
    Joined:
    Apr 25, 2019
    Location:
    Chicago
    Easily the best bang for your buck. No reason to not do it.
     
    MBDale likes this.
  6. ChryslerCruiser

    ChryslerCruiser Well-Known Member

    Messages:
    70
    Likes Received:
    7
    Joined:
    Jun 27, 2019
    Location:
    Morrisville VT
    Pretty sure it is an 8.25 W/ 2.2:1 gears... so that won't work real well with an overdrive... It might be nice to put some 3.73's although a 3.55 might be a better option on the interstate.
     
    MBDale likes this.
  7. brotherGood

    brotherGood Well-Known Member

    Messages:
    814
    Likes Received:
    102
    Joined:
    Mar 31, 2013
    Location:
    Urbana OH
    As someone with just the magnum heads..its night and day difference. Especially when upgrading the rear along with it.

    I agree with the above..if it's for driving (not racing) grab everything to switch over to the MPFI. I'm strongly leaning toward aftermarket FI for my 360 magnum, yet it's going to be raced as much as just driven around
     
  8. kkritsilas

    kkritsilas Well-Known Member

    Messages:
    1,826
    Likes Received:
    352
    Joined:
    Jun 21, 2012
    Location:
    Calgary, Alberta, Canada
    Magnums don't have MPFI (which I am reading as Multi-Point Fuel Injection, A GM term for port fuel injection). They are throttle body injection.

    If you are doing a Magnum engine swap, get the 5.9L/A518 combination, if possible. Nothing wrong with the 5.2 Magum, just that if you are going to go to the time and effort of an engine swap, it doesn't take any more effort to swap in 5.9L/tranny than a 5.2L/tranny, so go with the 5.9L.

    Also, if you are going to open up the engine, check for cracks in the heads (specifically, between the intake and exhaust valves). Magnum heads are notorious for cracking at that pioint.
     
    MBDale likes this.
  9. brotherGood

    brotherGood Well-Known Member

    Messages:
    814
    Likes Received:
    102
    Joined:
    Mar 31, 2013
    Location:
    Urbana OH
    The magnums are MPFI..each cylinder has it's own injector. The last of the LA engines in the truck were TBI, and that may have bled over into the first year or two of the magnums but I cant see a newly designed engine using an old fuel delivery system that it wasnt designed to use in the first place.
     
  10. Duke5A

    Duke5A Well-Known Member

    Messages:
    767
    Likes Received:
    296
    Joined:
    Apr 6, 2018
    Location:
    Michigan
    Throttle body injection is where the injectors are built into the throttle body itself. MPFI is an injector per intake port fed by a common fuel rail. All Magnum motors are MPFI and the previous three years worth of LA motors in trucks and vans were throttle body injected.
     
    brotherGood likes this.
  11. Mikes5thAve

    Mikes5thAve Well-Known Member

    Messages:
    199
    Likes Received:
    59
    Joined:
    Mar 3, 2020
    Location:
    Canada
    I always thought that would be a nice swap to do especially to get fuel injection. But lately I've been toying more with idea of hemi swap.
    I agree on the 360 bit. Especially since you're changing everything out it's the same amount of work but get a better power increase and with fuel injection should be better mileage then what the older 360s got.
     
    brotherGood likes this.
  12. ChryslerCruiser

    ChryslerCruiser Well-Known Member

    Messages:
    70
    Likes Received:
    7
    Joined:
    Jun 27, 2019
    Location:
    Morrisville VT
    Did the '95 half ton trucks come with anything other than the A518 (which I believe to be a 727 with overdrive, is that correct?).
     
  13. brotherGood

    brotherGood Well-Known Member

    Messages:
    814
    Likes Received:
    102
    Joined:
    Mar 31, 2013
    Location:
    Urbana OH
    Honestly, same here. Issue is, I've got about 85% of what's needed to put the 360 magnum in my car. So unless a Gen3 Hemi is practically gifted to me (or I find another vehicle-almost happened last week) I'm sticking with the 360
     
  14. BudW

    BudW Moderator Staff Member

    Messages:
    4,326
    Likes Received:
    1154
    Joined:
    Mar 4, 2012
    Location:
    Oklahoma City
    The ½ ton pickups could have come with an A500 or an A518. The A518 is an overdrive A727. The A500 is an overdrive A904/A999.

    To be more exact (in 1995 terms):
    A904/A999 = 32RH (3spd, 2 (out of 10) torque rating), Rear wheel drive, Hydraulic).
    A500 = 42RH (4spd, 2 torque rating, Rear wheel drive, Hydraulic).
    Front 2/3rd of transmission is mostly the same.

    A727 = 36RH or 37RH (3spd, 6 torque rating, Rear wheel drive, Hydraulic)
    A518 = 46RH or 47RH (4spd, 6 torque rating, Rear wheel drive, Hydraulic)
    Again, the front 2/3rds of transmission is mostly the same.
    The 37RH and 47RH are for diesels/V10's only and will not attach to a small block without some major modifications.

    I would say the ½ ton pickups made in '95 would have a 60% chance of a V8 having the 42RH and a 40% chance of having a 46RH (my observation – but no hard data to back this up).

    Newer trucks went to 42RE, 46RE and 47RE (E referring to being more computer controlled than the H's were). The RH's are better suited for FMJ's unless you are also using the donor trucks computer system

    The easiest way to tell a A904, A998, A999, A500, 42RH or 42RE (vs. the A727, A518, 46/47RH/RE) would be to look at the oil pan
    904 pan gasket.jpg
    This is looking up underneath the transmission with arrow facing forward.
    727 pan gasket.jpg

    I hope this helps.
    BudW
     
    ChryslerCruiser likes this.
  15. MBDale

    MBDale Well-Known Member

    Messages:
    319
    Likes Received:
    82
    Joined:
    Aug 20, 2015
    Location:
    Winnipeg Manitoba Canada
    The 5th ave video is a good one. Good luck on the swap, grab that truck!!

    I’ve got a 1980 Volare 2 door I might magnum swap. Slant 6 out, 5.9/46RH in! I’ve met a guy who 5.2 magnum swapped a ‘69 Dart and gave it to his daughter. Even put a command start in!!

    B2F6EB09-88CD-4F12-A01D-5A82D99E8E23.jpeg
     
  16. ChryslerCruiser

    ChryslerCruiser Well-Known Member

    Messages:
    70
    Likes Received:
    7
    Joined:
    Jun 27, 2019
    Location:
    Morrisville VT
    Thank You Bud. Great info. I will commit those oil pan outlines to memory before going to see the truck. Need to call him and get the ball rolling!
     
  17. AJ/FormS

    AJ/FormS Well-Known Member

    Messages:
    1,149
    Likes Received:
    257
    Joined:
    Apr 26, 2016
    Location:
    On the Circle of the earth, Southern Man,Canada
    AFAIK; Magnum truck engine mounts are different from LA engine car mounts.
    That might slow you down some.

    Assuming you already have a 318;
    the power difference in the 5.2, over the 318, is in the compression ratio, the better heads, and the bigger cam. The short blocks are similar enough that you could call them the same except your 318 already fits in your car.
    If you were to pump up the Scr on your 318 and install the Magnum heads and upcam, then you would have the same or similar output as the Magnum. You just wouldn't get the roller cam, which IMO, in NOT a big deal.
    But
    There are better than Magnum, aftermarket heads, already available for the LA; and FTH cams are cheap.

    The really big deal is getting rid of the FA hiway gears in favor of more performance oriented mid-3 series gears, like 3.23 or 3.55.

    If you are unlucky enough to be stuck with 2.20s, then 3.23s would increase your TM (Torque Multiplication) by 3.23/2.2= a whopping 46.8%, making your engine feel that much bigger, everywhere in the rpm band.
    If your FA has 2.45s then 3.23/2.45=plus 31.8%

    Your next performance improvement, and perhaps this should be the first; is the TC (Torque Convertor).
    The TC is so much more than a Fluid Coupling. It actually multiplies the torque coming into it to a higher level as it leaves. This ratio can be as high as plus 80% at zero mph, to as little as plus 8/10% in top gear at high speed. It does this automatically. And best of all, they can be tuned to start from a low rpm to at a higher rpm.
    This is good to know because you can choose that point off your power curve to go from dead sucked-out to holichit is this still my old 318.......
    Below is a 5.2 Magnum power curve.
    Up the left is the torque scale, and the red line is torque output.
    Check out the maximum available ftlbs torque; at WOT
    at 1800, I read 270ish; this is 92hp ; the base amount
    at 2200, I read 280ish; this is 117hp, or +27% over base
    at 2400, I read 285ish; this is 130hp, or +41%
    at 2600, I read 290ish; this is 144hp, or 56%
    at 2800, I read 293ish; this is 156hp, or +70%

    Ok so let's think about this. If your current TC was "stalling" at 1800/92hp which is dead sucked-out with 2.20 rear gears, then for a few hundred dollars you could be blasting off with horsepowers of; 117/130/144/156; or up to 70% more power .
    But it gets better.
    If you put those two together, namely stall and gears
    Let's see how this plays out. Now I know your LA is not gonna put these Magnum numbers out there but the results when applied as percentages will approximate the same, so I'm gonna down size the Magnum torque numbers to 70% to approximate the 318 power/torque.

    Lets say your engine currently has an 1800TC, and
    let's say you have a trans with ratios of 2.74-1.54-1.00, and lets say your car has 2.45 rear gears .

    From the above numbers 1800 is 270 maximum available ftlbs, downsized to 70% or 189 in the LA. Then at the rear wheel ignoring powertrain losses, you could see;
    189x(2.74x2.45)=1269 ftlbs. But at zero mph the TC could multiply this to as high as 1289x1.8=2320 ..As the car begins to accelerate this ratio immediately begins to diminish to an eventual low of 1289x 1.3ish so say 1676.
    But the torque is rising with rpm so by 3200 (earlier in the LA) it might peak at
    (293x.7)x(2.74x2.45)x1.3=1790

    Ok so now lets swap out that slowazz TC and get rid of the slowazz 2.45s
    Instead lets get that 2600 and 3.23s.
    At 2600 we read 290 ftlbs, x 70%, downgrades to 203 in the LA, so on the start line at zero mph the new combo predicts;
    203x(2.74x3.23) x1.8=3234 ftlbs, diminishing to
    203x(2.74x3.23) x1.3=2336.. At peak torque, this would then be
    (293x.7)x(2.74x3.23)x1.4=2541

    Next let's analyze this;

    currently;
    2320@0mph, dropping to 1676, peaking @1760
    Predicting;
    3234@0mph, dropping to 2336, peaking @2541
    By percent;that is plus 39.4%, plus 39.4%, plus 44.4%
    And we never even touched the engine.

    The penalty of course is your hi-way cruise Rpm has risen; 3.23/2.45=plus 31.8% . And that could translate to a fuel-economy loss of half that or 16%. Is the penalty worth it to you? Only you can answer that.

    Still same 318 under the hood.

    BTW
    your current engine, according to the numbers I worked out in BLUE, At 2320 max available footpounds could possibly break the tires loose. But it doesn't have the sustained TM to continue beyond the chirp.
    Whereas, with the new numbers of 3234 in purple, this should easily break the tires loose, and there is plenty of sustained TM that should carry the tirespin for a respectable distance.




    power-318.gif
     
    Last edited: Mar 18, 2020
  18. Duke5A

    Duke5A Well-Known Member

    Messages:
    767
    Likes Received:
    296
    Joined:
    Apr 6, 2018
    Location:
    Michigan
    AJ, do you just copy/paste the same reply into every thread??? Some of that information is just wrong.

    • Do not expect to increase compression bolting on a set of Magnum heads. Those 302 casting LA heads have a smaller chamber vs the Magnum. You'll drop compression.
    • All Magnum motors have the LA mounting ears cast into the block, for the entire production run.

    Smogger era LA motors suck balls until you rip it apart to the point of replacing the pistons and putting better heads on it. You can skip the Frankenstein setup and just toss a complete, factory Mag motor in the car to get the desired result and benefits. Use the same trans and converter out of the truck. It was all designed and optimized for a chassis that weighs 1000# more than your M body. Compensate for this by running a low numerical gear with the OD (trucks usually had 3.9:1 gears), or use a tire frying higher gear - your choice.


    OEM reliability. Simple as...
     
  19. ChryslerCruiser

    ChryslerCruiser Well-Known Member

    Messages:
    70
    Likes Received:
    7
    Joined:
    Jun 27, 2019
    Location:
    Morrisville VT
    Agreed, the charm to this swap is that the engine tranny and converter are all in one piece. Not sure the stock 904(?) transmission would be happy behind a magnum 360 for long, especially with 2.2 rear gears.

    I assume the truck rear axle is quite a bit wider than the M body, but it would be fun to have 3.91 gears for a time.. maybe even forever..
     
  20. 80mirada

    80mirada Well-Known Member

    Messages:
    1,163
    Likes Received:
    341
    Joined:
    Sep 3, 2012
    Location:
    Wisconsin, West Bend depends
    Magnum 5.2 and 5.9 have taller compression height pistons. Your LA motor mounts will bolt to the Magnum Block and you just need a car oil pan and pickup to get the proper fit on the bottom. The trans is where the fitment work is. I have pictures in my 80 Mirada build of how I made the 518 fit