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Jeb 10-03-2012 09:19 AM

Engine Upgrade
Hey guys. I got a 1998 Ram 1500 with the 3.9L V6. Was a good buy, but I am upset at the power, or lack there of, of this V6. I am thinking about upgrading to the 5.2 or even the 5.9 V8. What all must I change with one of these engine swaps? Mounting brackets, ECU, wiring harness, ect...?

Jeb 10-04-2012 12:13 PM

ok...can someone point me in the right direction to find the answers i seek?

Gen1dak 10-04-2012 10:58 PM

Brackets are standardized. The V6 and 5.2 are zero-balance, so that'd be an easy swap since you could bolt the 5.2 in with no external balance issues, not that the 5.9 is a big deal. You'll need the v8 engine harness-2 more injector wires (or just wire in yourself). Naturally the V8 exhaust manifolds. V8 fuel rails. Basically, V8 specific things that a v6 wouldn't have, like pipes for cylinders 7&8, and injectors. If your v8 doesn't have a distributor, you can use the v6 unit, just remember to swap on a v8 cap. Also, you will need a v8 flexplate for automatic or v8 flywheel for stick. It's so the crank sensor will see the proper number of cylinders and run correctly. I'm not sure if the v6 computer is wired for 8 cylinders and they just use 6 or if you will need a v8 unit. Will check around and see if I can find out.

RamTech 10-05-2012 08:56 AM

I would recommend locating a donor truck in a salvage yard where you can get the engine, trans, PCM, wiring and related hardware all in one purchase. The transmissions that were put behind the 3.9 are of the 42 series which weren't made to handle the torque of the V8 engines.

Gen1dak 10-05-2012 02:32 PM

The 42, aka, the A500, is an outgrowth of the 904-series Torqueflite. While the 904 was originally developed as the 3-speed automatic for 6-cylinder engines, it became standard equipment in Chrysler B-bodies (Charger, Satellite, Coronet) behind the 318 V-8 in 1969. Those are 2 ton cars. The 900-series Torqueflite was further developed into V8 car and truck models (998 and 999). The fact of the matter is that the 900-series is more than capable of handling anything a street smallblock V8 can dish out. Specially prepped 904 guts are even used behind Super Stock 426 Hemi Darts. These cars run low-10's in the quarter all day. The 900-series was used behind 318's and 360's in 2WD Ramchargers all day long. V8 torque, 5,000lb trucks. The problem with the 42's, as well as the 46's, is the common overdrive unit they share. It was originally developed to handle 400 ft-lbs input torque. Any of you guys kickin' out 400 lbs torque with your smallblock? Not many. The OD was an add-on, and coolant is critical. It comes down to this, keep the OD cool (and it tends to run hot), and the
transmission will live. My '89 Shelby Dak was the first with a factory V8 (318-only 270 lbs torque) and had the A500 - later redesignated as the 42RH, then 42RE. Six times it burned up and I never even towed anything. Just runnin' up and down I-10. Every time it was the OD. The original design of the "front three" that came from the 904 was always fine. The egghead-designed OD was what failed. Failures were much higher in the A500 because of the smaller coolant passages....something that was fixed in later models by Mopar, but leave it to the aftermarket to solve the problems and it did. Get an aftermarket valvebody kit and it'll be great. The valvebody kits make a huge improvement in lube and overall performance.
Not designed for? The 42 is more than strong enough. Wanna haul a horse trailer, get a 46. In HD everyday situations, the bigger clutches will take the abuse even longer, but it's the OD that's gonna be the weak link, and it's the same unit on the 42 and the 46.

Jeb 10-09-2012 06:52 PM

hmmm...i think i need to follow RamTech's advice. otherwise, it might be cheaper to get a new truck. i just love the look of the 2nd gen for single cab short bed. the newer models look better as ext cab, which i dont need. i might try to get with my local dealership to see if they can give me part numbers as to what all i need, and then i can search around and price this out. thank you all for the help. i dont make that much money, so this 'dream' might have to be scrapped

Jeb 10-09-2012 06:53 PM

unless, i rebuild a v6 for a turbo...hmmm

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