Magnum: 5.2 vs 5.9

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Sinister.

Sinister.

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I'm highly considering putting a Magnum engine into my dart. I will be staying with EFI. It will be my daily driver but will see the seldom day at the track. I've done a little looking myself but want to see what you guys know about them.
What are the pros/cons of the two engines? Also, what would be my options as far as transmissions go?
How are after market parts for each?
 
If you want to go with a 5.2 (318) look for a pre-95 model because I think 95 was the year that the motor mount bosses disappeared on them. The 5.9 had them up until end of production in 2003. Tranny depends on your skills as a fabricator and willingness to cut up the floor of your car. The regular 904/727 will work on either engine but with the 5.9 you will need the later model balanced flexplate and a neutral balance converter. May need to redrill a couple of holes also. If you stay with the EFI then by all means go with the A-518 (pre-98) OD unit. ITs tough, can be built to take hi HP and will give you a decent cruise RPM with the OD and lockup. Makes the EFI swap easier too. But thats the one that entails the floor mods. The Upper crossmember part of the tranny hump must be cut and spread apart about 4 inches and then the floor modified to conform to the change in the crossmember. This gives you about an inch all around the tailshaft of the 518 and plenty of room so the VSS unit won't hit the floor. Lot of work but the end result is great.

Larry
 
5.9 definitely !!!! 250 hp and 345 #ft. of torque in a Dart is nothing to sneeze at!!

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fstfish66 said:
what did they use if the motor mount bosses dissapeared ?
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All of the 92 and up trucks use the bosses located in the side of the block about halfway back. When the Magnum 5.2 first came out it was basically the roller LA block from the late 80s and the castings still had the front bosses like the LA. For some unknown reason MOPAR did away with the bosses after 95 or maybe late 94 on the 5.2 blocks yet kept them on 5.9 block. No one has come up with a reason for it that I know of. I know that since the 5.9 block is used for all the drate engines then maybe thats the reason.

Larry
 
So is there no real benefit of the 5.2 being internally balanced? What problems would I run into if I used a modern automatic transmission?
 
Sinister. said:
So is there no real benefit of the 5.2 being internally balanced? What problems would I run into if I used a modern automatic transmission?
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If you can get a 94-96 Ram, B series van, or (if you are lucky) a Dakota R/T with the 5.9 and A-518 OD tranny COMPLETE then the swap isn't too hard. Lots of wiring to interface between the EFI and the old dart harness. You will need to have an electric fuel pump that will put out at least 40 PSI, A Schumaker engine swap motor mount set, and a lot of patience. Other than the tranny its a bolt in for the engine and a relatively easy swap for the electronics.

The tranny is the problem. If you go with an older tranny then you can pretty much forget about using the factory EFI setup since the ECM needs input from the tranny to work correctly. The advantage to the newer tranny is the OD and TC lockup. I have 3:23 gears in my dart and cruize at 70 MPH at 2000 RPM but around town it is the same as a 727. Problem is that there is no way to correctly shoehorn in the tranny and get the proper engine angle, etc., without doing the tunnel mod since the tailshaft of the 518 is much larger in diameter than the 727. I have heard of people using the stick shift ECM to get away from the problems with the ECM vs. tranny input (basically VSS signal) but I haven't tried it.

Larry


Larry
 
lhearold said:
All of the 92 and up trucks use the bosses located in the side of the block about halfway back. When the Magnum 5.2 first came out it was basically the roller LA block from the late 80s and the castings still had the front bosses like the LA. For some unknown reason MOPAR did away with the bosses after 95 or maybe late 94 on the 5.2 blocks yet kept them on 5.9 block. No one has come up with a reason for it that I know of. I know that since the 5.9 block is used for all the drate engines then maybe thats the reason.

Larry
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I think the 5.9's were cast in mexico. I remember posting on another thread about how horrible the casting flash was on a set of 5.9 heads, and the general response was that they were Mexican heads.
 
lhearold said:
If you can get a 94-96 Ram, B series van, or (if you are lucky) a Dakota R/T with the 5.9 and A-518 OD tranny COMPLETE then the swap isn't too hard. Lots of wiring to interface between the EFI and the old dart harness. You will need to have an electric fuel pump that will put out at least 40 PSI, A Schumaker engine swap motor mount set, and a lot of patience. Other than the tranny its a bolt in for the engine and a relatively easy swap for the electronics.

The tranny is the problem. If you go with an older tranny then you can pretty much forget about using the factory EFI setup since the ECM needs input from the tranny to work correctly. The advantage to the newer tranny is the OD and TC lockup. I have 3:23 gears in my dart and cruize at 70 MPH at 2000 RPM but around town it is the same as a 727. Problem is that there is no way to correctly shoehorn in the tranny and get the proper engine angle, etc., without doing the tunnel mod since the tailshaft of the 518 is much larger in diameter than the 727. I have heard of people using the stick shift ECM to get away from the problems with the ECM vs. tranny input (basically VSS signal) but I haven't tried it.

Larry


Larry
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when you use harness and computer from a manual tranny car they dont have to see any thing from the tranny to work. so i would get a manual tranny engine and computer etc and then put in whatever tranny i want. i would go manual anyway lol.
 
That's something I hadn't considered. Thanks Tyler.
Can anybody confirm a speed sensor on the manual trannys?
 
Sinister. said:
That's something I hadn't considered. Thanks Tyler.
Can anybody confirm a speed sensor on the manual trannys?
Click to expand...

There is a Mopar part that hooks to the speedo drive on a transmission that provides a VSS signal & lets you use a cable driven speedometer. I'm hunting for the part number now.

Okay! I found two numbers:

Speed Sensor 56027015
Speed Sensor Adapter 9400012

I have this on my AMC with EFI that uses a Mopar 998 transmission (904 derivative) & Jeep transfer case. The standard speedo drive & gear are the same as those used on a Mopar trans so this should be a straight bolt-on. I had to do a bit of searching to get a speedo cable with the two correct ends for my application but it wasn't a big deal.

Here's a pic of the 2 parts together about to be mounted to a transfer case. As I understand it, these are factory Dodge truck parts. You can't really see it but there is a place behind the speedo cable in the pic where the wiring harness from the EFI plugs in.

129_0309_efi_09_z.jpg
 
IMHO a 5.2 or 5.9 Magnum is the best small block in stock form. A 5.2 running through the factory air filter, exhaust manifolds, cat, muffler and tailpipe makes slightly more power than an early 340. Upgrade the exhaust, intake and flash the ECU and it will run even better. The 5.9 is slightly better.

My 98 Dakota ran high in the 14.7 range without touching the computer or any engine mods. It weighed just over 4000 pounds with me in it. In an A-body with a set of headers and no cat, 13's should come pretty easy.

FWIW, the bosses are still on the 5.2 blocks up to 98 at least, they are just not drilled. I just ran out to the garage and checked.
 
As far as dropping the engine in, would it just require a new oil pan and pickup? I'll probably stick with the serpentine setup with electric fans on a more modern radiator.
 
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