[3inthedirt]

Anyone know where I can see the torque curve for this stock motor? I need a little more pull for the trailer (only about 2,000lbs) and am considering a towing cam. Any sugestions on cam? It's rare to run much over 22rpm. I already have the 3.55 limited slip rear.

Thanks

 

[dodgefan360]

5.2 hp/tq graph here: http://allpar.com/mopar/318.html
If the trailer is only 2000lbs I wouldn't bother upgrading the cam. The 5.2 and 3.55 rear you can pull around 5K with no problems. Most cams will require more engine modifications and a custom computer flash to make the engine operate correctly. Needless to say if you want some additional towing oomph your best bet is to upgrade the exhaust and intake. There are several threads on here that discuss upgrading cams, if you really want to go that route be sure you do a thorough investigation.

I'm sure you meant to say "2200rpm" instead of "22rpm". Depending on the highway speed you were traveling at and the size of your tires, your rpms will vary.

 

[3inthedirt]

Truck has Mopar performance PCM, cat back exhaust and K&N intake. It also has 245 series tires. Plate in door says stoock is 225 so I know my gearing is no longer 2.55. Next set of tires will be 235s. Main issue is while in OD, where the gearing is too high to maintain speed on a gentle uphill. Yes, the tranny will kick down but it seems to be working too hard. It just should have more guts and yes it is 2200 rpm. Guess I'll deal with it the little I pull a trailer. I believe the truck is rated for 8200 lbs.

 

[dodgefan360]

Well, two things that might help then: first is to increase (yes increase) tire size to a 265 width tire (or 31" height) if the 15" rims can take it. Second - tow with the OD off unless you are on level terrain so the trans can stay in the power band of the engine and the truck won't feel as weak. I imagine if you tow with the OD off with the 235 tires you'll be around 3300rpm on the highway which isn't bad. The larger tires (31" height vs 29" height) will reduce your rpm with the OD off and it will help somewhat with fuel mileage. Don't forget that the magnum V8's make peak torque at 3200rpm. Unless you upgrade to roller rockers I don't suggest keeping rpm's above 3500rpm for any prolonged period. However, Gen1 D's are not rated to tow in excess of 7300lbs. 5.9 with 3.92 gears can tow 7300lbs max. The 5.2 with 3.55 is around 5000lbs, give or take 500lbs. As you mentioned you don't pull a trailer very often and the truck will be more than able to handle 3000rpms on a constant basis. I've towed cargo and landscape trailers with weights from 2800-5400lbs and at 62mph (100km/h) the engine turns over at 3100rpm. It's a bit noisy but it keeps trans temps in check and doesn't lug the engine when I run into hills. Generally I try to tow at 50-55mph if the speed limit allows, so the engine is turning over at 2500rpm; a more manageable speed and still able to pull the trailer up hills without down shifting.

 

[3inthedirt]

Sounds right except for the rpms. At 70mph (which I know is off by about 10%) the tach is at 2200rms in OD. I guess I'll go no OD and slow down a bit......

 

[gramol]

go no od don't worry about slowwing down............3000-3500 all day is no problem............engine will take it AND he's right about the tranny temps staying way lower............

 

[3inthedirt]

Thanks for the replies.

 

[stev]

I can tow a loaded 4,500lbs trailer without any big issues with the 5.2L/318cid Magnum and the 3.92 rear. Plus, this is in a loaded 12-passenger van that's towed well in the Pocanno Mts. in east PA too!

I had the 3.55 rear in the B1500. Both the 3.9L Magnum and the 3.55 just squeeked by towing on flat highways and was murder on the hills.

Your best bang for the buck is to swap in a 3.92 rear. You can boost the Hp some and maybe the torque, but the rear is the key for getting those revs in tune for towing.

 

[3inthedirt]

With 3.92 gears, at what mph does the OD kick in? Currently it is about 47mph. I don't know if it goes by rpm or speed but believe it is speed.

 

[razman131]

With 3.92 gears, at what mph does the OD kick in? Currently it is about 47mph. I don't know if it goes by rpm or speed but believe it is speed.

45 or so sounds right and it is speed. gotta luv these 46RE trannys,,,

 

[dodgefan360]

When I'm gentle with it (30" tires as well) my OD kicks in at 58km/h (37mph).

 

[charlie1935]

My o/d kicks in as low as 30 MPH. The converter will lock up as low as 44 Mph. Thats with 3.55 gears and 265x70 x16 tires. :gr_patrio

 

[stev]

With 3.92 rear gears, OD kicks in around 42~50mph using Yokohama 235/75R16 tires. The slower I ramp up to speed the sooner OD kicks in.

Also, going uphill at 50mph or so, it will kick off while towing.

 

[3inthedirt]

Thanks again for the replies. Not sure if I'll do it myself. Depends on what the dealer wants..............

 

[razman131]

what are ya plannin on the stealership doin.....

 

[3inthedirt]

I would like to change the gears in the rear from 3.55 to 3.92 but I have to be sure that I keep the limited slip component. I can do it myself but don't have the time......

 

[sully75]

just because the door jam sticker says 225/75r16 does not mean that it came with those tires. My 98 sticker says 225/75r16 but the window sticker from when it was bought new says that the optional tires 245/75r16 was purchased for $130.00. window sticker also says equiped with 5.9 and 3.55 axle ratio max payload 1,610lb max trailer weight 7,700lb Gvwr 6,400lb and gcwr 12,500lb but my truck is a quad cab with 6 foot bed 2wd and I have pulled my 2005 36 foot travel trailer that weighs 8,500lb with my bone stock truck without a problem.

 

[3inthedirt]

Intersting info, thanks. i did notbuy the truck new so I don't know the original size.

 

[sully75]

if you want send me your email and I can email you my window sticker