Anyone run a Ram 3500 with 6.4 Hemi?

Bedlam wrote:
Cylinder deactivation on the 6.4 Hemi when used in Ram's Class 4 and 5 trucks is only used for PTO operation. They do not deactivate while driving. If you drive a Class 2 or 3 always loaded, you will rarely see it deactivate cylinders.

Mine was in 4 cylinder mode a lot today with no trailer. I went 500 miles.

Cylinder deactivation on the 6.4 Hemi when used in Ram's Class 4 and 5 trucks is only used for PTO operation. They do not deactivate while driving. If you drive a Class 2 or 3 always loaded, you will rarely see it deactivate cylinders.

Thanks for the information guys. I've decided to keep what I have and buy the large TT. I wasn't really sure about pulling a 36ft travel trailer, but with my truck and a wd/anti- sway hitch it will be fine. Plus I won't lose the use of my bed. I'm sure the 6.4 would work, but I don't think I would be happy with it coming from 12 years of driving a diesel.

Yeah, that's why I said it wasn't related FW towing. Just putting more info out there for the OP to show the capabilities of the truck.

Understood, and thanks for the links. As I read them I also see that Truck Camper Magazine drives often below the speed limit making their gas mileage numbers even worse for somebody hauling the same size and weight camper at 65 or 70 mph. I own a Ram 3500 Cummins 3.73 axles and carrying a camper that weighs about 4000 pounds routinely gets 13-14 mpg at 65 mph; substantially more than their 6.4. However, empty the 6.4 can get around 17 as it has cylinder deactivation. Loaded is where the mileage drops. Had thy gotten the 4.10 axles their mileage could actually be slightly better driving relatively slow as they do and the engine working less hard for cylinder deactivation to occur more. Lots of options to consider. The 6.4 has the same warranty as the Cummins and is sold as a medium truck gas engine and I suspect will last at least 200,000 miles. But when put under a load the fuel mileage is not a bragging issue.

Up to the Ike tunnel for about eight miles the 6.4 towing around 12,000 pounds got 2.8 mpg; their Cummins test with 17,000 pounds behind in a trailer got 5.8; twice the mileage, 5000 pounds heavier and about 15 mph faster. There is a difference between a gas engine and a diesel even though some of the 6.4 owners tend to minimize that fact for what they tow. Maybe they tow light trailers. Maybe they never towed their trailer with a diesel.

How often do you pull up a hill without traffic in the way. When you are following two semis side by side going 18 mph it doesn't matter if you have 300 or 3000 hp.

Yeah, that's why I said it wasn't related FW towing. Just putting more info out there for the OP to show the capabilities of the truck.

Not directly related to FW towing, but Truck Camper Magazine seemed pretty happy with their 6.4L 3500 Dually when it was loaded with their 4700 lbs camper.

It appears they were very happy with the truck except the gas mileage. They are more concerned with how much the truck can carry and stay within the payload and GVWR. And Ram has a huge payload (like up to around 7000 pounds) in some of it's 3500 dually models.

Not directly related to FW towing, but Truck Camper Magazine seemed pretty happy with their 6.4L 3500 Dually when it was loaded with their 4700 lbs camper.

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ib516 wrote:

I'm assuming you are referring to me as the "optimistic owner" :)

I agree that the other trannys (Ford) have better ratios for the gas engines, especially 2nd gear. However, it seems the numbers from actual tests share my optimism :W -- the Ram/6.4L Hemi still outperforms - other than the high altitude towing one where the software limits performance. It clearly makes more power as the specs say it does.

Yes, the 6.4L did perform well in acceleration tests loaded and unloaded, but towing grades while keeping speed seems to be the 6.4L weakness according to PUTC, TFLTruck, and TruckTrend to name a few. I have also read some in the Ram forums I belong to say the same thing that it bogs pulling grades at much lower altitudes than that Ike Gauntlet test. I don't think that software has anything to do with it. If the ECM kept kicking the the transmission up a gear to make it bog down then I would agree with you, but in those Ike tests it held first gear so you can't blame it on software.

My main point is that some 6.4L owners will tell you that it will tow anything(just as some Cummins owners will). However, like anything it has its limitations and I think those limitations are well below what Ram states especially pulling hills. With my limited experience with the 6.4L Hemi towing, I would do 13-14K tops if most of my towing was on flat ground, up to 12k if there were slight grade, and up 10k if there were major grades and maybe a little less if it were high altitude. If the OP is pulling that 13K on the grades, then I would do like the rest as say a Cummins would be the optimal choice. Of course this is towing by my expectations and others may be different.

They are all pretty good, doubt you could tell the difference between any of them without a stopwatch.