Some basic M-body magnum swap questions/information

[8v-of-fury]

Hey there guys,

I am planning on one day doing a 5.9 magnum engine swap to the 88 Chrysler. I may actually this weekend be picking up a loaded 1998 Jeep Grand Cherokee that I will be using as the donor.. So I will have EVERY single LA and Magnum piece associated with the swap.

From what I can see it looks like I only need the 360 oil pan and an (or both) engine mount(s) to drop this in my M-body in place of my stocker-318. Now I am thinking it would be best to keep the v-belt setup as it has not once in its current 313k km life ever given any issue This would then necessitate the use of the LA timing cover/waterpump and all associated pulley/accessories, which is fine because I have them all anyway.

Hmm, in my reading it seems you need to change out the harmonic dampener on the magnum because it is integral to the pulley. It would seem that using the magnum flex-plate (balanced) that one would not need to use a balanced dampener as the flexplate balances the engine.

 

[80mirada]

You need both a weighted damper and flexplate for an external balanced engine. The flexplate only balances the rear half of the crank. The damper balances the front, but its main job is to dampen vibration that would kill the valvetrain. Replacement early magnum 5.9 dampers cam be had cheap.

 

[80mirada]

Dorman harmonic balancer runs about $65usd or $85usd for the manual trans one.

 

[8v-of-fury]

Ohhh ok. yeah I read about some aftermarket ones that allow you to use the v-belt setup with the balanced dampener..

Would a stock 360 LA dampener and pulley be the right one to use? I have a big mopar junkyard near me, where I think I could easily source the 360 LA parts I would need.

 

[slant6billy]

Are you running an electric fuel pump? Did a magnum drop in a Valiant about 10 years ago on a budy's car. The swap was everything- motor, RH46, computer, harness. We added an electric fuel pump and the little Valiant 100 with a once 170 slant was alive with fierce fire. My budy drove that Valiant as a daily driver for 4 years brutally and then lost it in the rain. Don't know where it landed

 

[80mirada]

The Magnum 5.9 and the LA 360 have a different imbalance in them, so it has to be the correct damper. They used a separate damper and pulley for quite a few years. It seems that all of the parts houses have superseded to the one piece later unit. Professional products makes one with changeable weights, http://www.summitracing.com/parts/pfs-80012 . Otherwise look for an early magnum 5.9 up through about 96-97.

 

[8v-of-fury]

The only reason I ask about the 5.9 magnum is because they are routinely popping up on Kijiji in my area for under $1500.. However the 5.2 magnum stuff is even more common around the $600 area.. However this whole time I have been looking towards JEEP's as my donor vehicles, I totally forgot these engines came in Dakota/Ram too! DOH! They are even cheaper, but tend to be a much more abused vehicle.

I think the added hassle of going to the 5.9 over the 5.2 would just be unneeded for my intended application, which in the end is mostly cruising.. but also a light duty warrior out of this car right here;

I'd like for this to be in the 400bhp area as the end goal, looking exactly like she does pictured! :happy6: Wire wheel covers, normal-ish sized tires.. Stock-ish sounding exhaust, maybe a small grumble.

 

[Monkeyed]

http://www.campbellenterprises.com/318-stroker-kit-mopar-318-5.2-stroker-kits.

Have you checked that site out? If you're looking for that kind of power, a well built stroker is one way to go.

 

[kkritsilas]

Don't even have to stroke it. Get some good heads, more compression, a better cam, and you are pretty much there. See:

http://www.hotrod.com/how-to/engine/113-0304-318-small-block-build/

I don't know which is the most cost effective way to go, though. A good 5.9/360 Magnum, or a 318 with a performance rebuild. I guess it really depends on what the relative costs are in your area, and what your exact goals are.

 

[8v-of-fury]

oooh a stroked 5.2 magnum.. sounds beastly!

And with EFI (also the game plan) because I absolutely dislike the variances with running carbs lol

 

[8v-of-fury]

The MAIN reason I would swap to a magnum engine is for the EFI system I would swipe with the engine from the donor vehicle. In pulled-from-donor form it puts out 100hp more than my stock 318 engine, and is going to have less than the 313k kms my 318 has on it now.

I would need to do anything I do to the magnum to the 318LA anyway.. so shouldn't those mods be spent on a more worthwhile powerplant?

Kkritsilas, I have read that article by David Freiburger about a dozen times and it is what originally set me on this path. That pathway requires total engine tear down and machine shop work.

 

[kkritsilas]

If you want 400 HP, you are going to have to rebuild something. Whether it is a 5.9L Magnum (275 HP factory rated), or your own current 318 LA (120-160 factory rated), neither are close to what you are looking for; the 5.9L Magnum has a lot more torque, just from the displacement increase, which is always good on a street engine.

Alternatives to this are a 360 LA (displacement & torque increase, better heads), which has fewer issues with mixing and matching some external bits. The rebuild costs for any of the engines will be similar, so the biggest bang for the buck would be the bigger engines (360 LA or 5.9L/360 Magnum). I wouldn't think about porting the LA heads, of any type; get the EngineQuest heads for any of these engines. They aren't cheap, but porting can get very expensive very quickly, and in the end, you still don't have the flow of the EngineQuest heads (you will need different pushrods, length will be off). They are also not prone to cracking between the valves like the factory Magnum heads are. From that point, KB167 pistons to improve compression ratio, and maybe a slight shaving of the block deck or simply use the thinnest head gaskets you can. Go with whatever rings and bearings you or the re-builder likes, camshaft as per camshaft manufacturer recommendation. Good set of headers, and you should be good to go.

P.S. I don't know what engines are going for in your area, but they are $179.99 +$29.99 Core charge for any engine at Pick-n-Pull. Obviously, these are just long blocks, but that is for any engine, including 5.9L Magnums; condition is an unknown. Quite a long way from the $1500 you are seeing.

 

[8v-of-fury]

Oh that is very true my good sir, I do not mean to question your knowledge

The 400hp benchmark is an end goal for sure, likely not this year or even next.. lol! I would very much love to have a fire breathing 300k km smog-318 to tell people about though, as that would be loads more interesting and shit than just a magnum swap. I don't plan to race the car in any shape or form it will purely be for driving pleasure.

I thought I had read in that article they machined the block the 0.050" to bring the pistons near TDC? Now I read they had the heads milled the 0.050" to bring the compression up that way.. That is much more feasible to me because then I do not have to remove the block, and can slap on some aftermarket heads in one swift effort.

 

[kkritsilas]

With 313K Km on the car, you are going to need a rebuild. It is somewhat dependent on the care and use that the engine has had, but 313K Km, (close to 200K Miles), and probably getting close to what the life of the engine can be reasonable be expected. Engines do wear out, no matter how well they have been taken care of.

Adding anything high performance on an engine with that many miles on it may not be the advisable, specifically with trying to raise compression, as the rings has seen some use, and may not be sealing as well as they did they day they left the factory. Same goes for valve guides, valve seats, etc. Car is yours to do as you see fit, but by definition, higher horsepower levels will put more of a strain on an engine than the standard factory parts. In an older engine, it will just bring forward the time to do a rebuild.

Whether you machine the block, or heads, or just use thinner head gaskets, you are reducing the size of the combustion chamber (combination of volume aboe the piston at TDC, and the open volume in the head), so compression goes up. Machining the heads won't bring the pistons higher, it will reduce the open volume of the head. Machining the block will reduce volume of the open space above the piston at TDC; same happesn with thinner head gaskets. Either way, the combustion chamber size is reduced, so compression goes up. In both cases, other changes will need to be made (pushrod length changes, machining the mating surfaces of the intake manifold, etc....). Still not as simple as it may appear.

As for the fuel injection with the Magnum, you will need a high pressure fuel pump, and most likely, some fuel injection computer work. It is not a disconnect 318, pull out of car, plug in Magnum, reconnect hoses and wires, and go. It would be easier if the Magnum were brought back to a carb set up.

Third party fuel injection would be another way to go.

Even with a Magnum, keep in mind that those engines are fairly long in the tooth as well, last factory OEM one being made over 10 years ago, and they also have the well known cracking issue.

I am in the same situaion as you, but with my J bodies. I am leaning towards a rebuilt Magnum 5.9L/360 from a Ram truck, with the EngineQuest heads, a streetable cam, headers and either a Street Demon carb or a QFI fuel injection system.

Another article here using the 318 LA and EngineQuest heads: http://www.hotrod.com/how-to/engine/0810phr-chrysler-318-engine/