is it a waste to rebuild a 5.2 magnum (318)?

[reek]

so I misread the vin on my 92 parts truck. I guess some designations changed after 1988 so what I thought was a 360 (5.9) magnum is actually a 318 (5.2).

I have a local shop ready to go for a complete rebuild. but the cost of a full rebuild on a 5.2 is about the same as a 5.9. would like to get a build to put out atleast 300 hp. I've heard you can get up to 400 out of a 5.2 magnum. is it worth it or do I just track down a 5.9 magnum block?

 

[gofishn]

Every car I ever had with a 318 got it yanked, for a 440 or 383.
I have never, nor known of anyone, who ever yanked a 318 out of a truck.
Every single one was left alone. This when 383's and 440's were plentiful as raindrops.

318's are solid. Reliable, Dependable.
One hellova of an Engine but not a let's build the **** out of it motor.

FYI, I have never been a 360 fan. Period.
Would much rather have a 318 than a 360.

 

[reek]

I think 360's got a bad rap early on in production as a low compression dirty pig of a motor. I would agree with you. the 318's and 360's I'm referring to are the EFI Magnum series. Significantly better in performance and reliability. Magnums were a lot better about not leaking after a few years.

my project truck is a play truck so would like some horses under the hood. Was looking at the ATK 5.9 efi or 408 stroker but for the same or less $$$ if I could get a local build from a guy I can talk to in person, I'd take a few less horses for that. just trying to figure out how to spend my money in the best way.

 

[pacofortacos]

You can stroke the 5.2 to 391 - same basic setup as the 408.

 

[crazykid1994]

I don’t know anything about the 360 but I had a 318 magnum MPI in my 97 and it was slow but that thing would rip some mud. All stock. I ended up putting in an mds blaster coil and opening the gaps up on the plugs and swapped out the plenum pan and gasket as it leaked so bad. No cats. After that was all done I could burn 33s pretty good. Thing never stopped running even after the plenum blew. The engine chugged so much oil... I ran a bottle of sea foam and hand cleaned the intake manifold when I changed the plenum pan. Truck never missed a beat at 160,000 miles
Edit: it chugged oil from the plenum blowing. Never had any other issues

 

[crazzywolfie]

i think you need to see how much it may cost for a 360 magnum core and then see if it is worth it. i think either way you will probably be happy with the end result. are you keeping it fuel injected or what are your plans especially with especially with the emission ****'s

 

[reek]

thanks for the input guys. did consider the cost of the 5.9 core. I do like the idea of stroking it out to a 391. thanks Pacofortacos.

My trucks are a 72 and 73 titles so no smog Nazis are involved.

I'm going to go to the shop and have a long talk with the builder. will research the 391 option before that. I think THAT may be a game changer.

 

[crazzywolfie]

could always search to see what it may cost for a newer hemi compared to rebuilding a 5.2. might be cheaper power to cost just because i know mopar engines can generally be more expensive to build with power. plus you could always go with newer transmission that way so it might get better fuel mileage while cruising.

 

[reek]

looked into a hemi. brand new motor rated at 383 hp and computer goes $7500. then the headers, engine mounts, headers, oil filter reloc kit about another $1000. then probably will have to rebuild the 46rh to handle up to 400-450, a few more bucks. all said and done, probably 9-10 grand.

If I can get a rebuilt motor for 5-6 grand, I'd rather go with that. I have 2 trucks I'm trying to get back on the road. add in the 7 year old chevelle project that needs a motor too. I may have to hang out on a street corner and start turning tricks....

 

[crazzywolfie]

but you could probably find a good running used hemi for cheaper than that. might almost even be better to buy a whole parts vehicle so you can get a transmission also. they can usually be bought cheap enough. i just figure the power to cost ratio you are better off with the hemi.

 

[reek]

I would consider the parts vehicle with a good motor if they weren't like unicorns around here. all parts hemis are usually 150,000 miles. wreck with low miles are still 5 grand just for the motor and ECU. throw in the cost of the trans and trans computer plus add in I'm doing a custom wiring job on the trucks so harness adapting will be a nightmare. Having said that, I am known to be browsing on craigslist every evening.

 

[pacofortacos]

No stock or close to stock hemi will pull like a stroked 5.2 on the bottom end - and you can stroke the hemi.

My 2016 5.7 is considerably weaker below 2000 rpms than my 5.9 was.

5.2 parts are plentiful and not expensive. Now on top end, there really isn't much of a comparison, the hemi heads just flow so well stock, the hemi block can take incredible power and not break, etc..

In the end, it depends on what you are doing with the truck - driver or drag racer.
I mean in reality, how many times are you above 3000-3500 rpms in normal driving?

 

[crazzywolfie]

is there anything wrong with the 5.2/46rh that you currently have? if not you could always just run it as is till you come accross a good deal on a hemi or something like that. higher mileage is not always a bad thing as long as it runs good and was maintained well.

 

[pacofortacos]

First he has to decide on what he is doing for tuning, there are not many options when stay with OBD 1

If he is staying with the stock system, it can only adjust to so much. If going carb or other system, then that opens up the options.

 

[crazzywolfie]

you don't need to tell me. i got a 93 with the same 5.2/46rh that he has. they are usually pretty tough engines and really not that bad stock. he would only have to figure out fuel and ignition system if he went and modified the engine away from stock. that is why i was thinking he could just run it as is if there is nothing mechanically wrong with it till he decides exactly what he would like to do with it engine wise.

 

[reek]

the 5.2 has 190,000 miles on it. runs a bit rough but runs. not reliable enough for daily driving. want to get anywhere from 300-400 hp at crank for backroad fun factor. it will be primarily my father's truck. he's old but still likes his fun. depending on the price quote for the 390 stroker vs a 318 'aggressive' build, I'd like to stick with the magnum and a much simpler Fitech EFI system. Seems a more straight forward build and would let me get the truck on the road sooner.

stroking the 318 was not even on the radar when I started this thread. now I'm kind of less hesitant about using the 318 for a build!

 

[crazzywolfie]

there is nothing wrong with building a 318. i just know older mopar engines are not as cheap to build power with especially if you end up needing new heads like the magnums are know for needing. if the 5.2 was not reliable best not to put it back in.

 

[reek]

the 360 magnum EFI crate motor by ATK is about $5500. as long as I come in below that, I'm good. The machine shop I spoke with has given me a rough estimate at $4500 for a 300-350 hp build. that's for a complete rebuild/magnaflux/etc. considering all of the new info I've been finding on the 318 magnums, I still need to go speak to the guy with details but would like the 318 Magnum built. Seems like even without going to a stroker, getting the compression between 9.5-10:1 with better heads will get me at or above 300 hp.

If all goes ok, have a 360 LA motor that would be next. If the ball park quote is way off, ATK gets my business.

 

[crazzywolfie]

but i think it really depend on what parts are used on the crate engine. if it comes with new heads then the $5500 it might not be a bad deal but if it is stock rebuilt head then no.

minus well just go with a 360 magnum. probably not worth rebuilding a 360LA unless it was for a numbers matching vehicle.