Pushing the 6.4 to its Limits

6.4 Hemi 4X4 CC 3.73 gears - 11K 5th wheel up over Oregon Hwy 26 through Government Camp - Mt. Hood. I believe the hwy peaks at around 4500'. It's a pretty sharp climb going from roughly 1200' to the 4500' in about 10-12 miles.

Was running mid/premium gas (1/2 tank 89 octane, 1/2 tank 92)

Through the weigh station near the base:

Steer Axle - 4250
Drive Axle - 5900 (Yep, over my GVWR by 150# and the tires didn't explode and I didn't get arrested )
Trailer Axles - 8300

So, I'm 150 over my GVWR, roughly 1000 under my GCWR, 600 under my RAWR, 1400 under my rear tire rating (each rated for 36xx)

I hauled my old 8000# TT up the same hill several times and this was definitely more of a challenge. I have to say I was more pleased than discouraged. I maintained highway speed up the entire hill. Never dropped below 50 and was able to accelerate (gradually) after slowing for turns.

I have to say this Hemi is a towing beast but I was pretty near the max of what she had to offer. I fear if I got slowed below 45-50 on a steep part of the hill I'd have a hard time getting back up to the meaty part of the power in 2nd (thanks again Ram engineers for the CRAPPY 1-2 ratio gap on the 66rfe).

In the end it's was a success. Part of me almost wishes it had just died beside the road so I could justify a Cummins

A re-gear would help a lot of things and still may be in the cards at some point.

Grade braking coming down today was good but certainly no diesel. I had to use my brakes a couple times heading into sharp-ish curves (35-40MPH type). Never felt bad though and never felt any loss in power or excess heat.

MPG micro-managers cover your eyes - 6 up but nearly 10 coming home.

Overall, this is a a damn good gas truck. I get shivers up my spine wondering how great it could be with a decent transmission.

Nice! Thanks for the report. Glad she hung in there tough for you. That's quite a steep grade with a lot of weight. My truck is identical to yours in specs so that's good info. The heaviest I plan on towing with mine is around 8k so i should be good to go. Good stuff!

I've done that stretch of road as well. Good info!

With a properly geared and beefed up 8 speed, oh yeah!

Yeah, I think some new gears would improve that already excellent drive train.

Great test for the 6.4. glad it did well.

tjfdesmo said:

With a properly geared and beefed up 8 speed, oh yeah!

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So much this! With a properly geared 8 (or maybe 10) speed behind the 6.4 and standard 4.10s with optional 4.56s, Ram would have one hell of a gas tow rig. As it stands, it's just very good. But then a properly geared 6.4 might hurt sales of the Cummins a little lol.

I have towed 84 the length of OR. Is it similar in the length/altitude of passes & grades?

Yeah the 8 speed would be a hugh improvement IMO. Even the mid strength rating version is like 516 foot pounds so should take the 429 foot pounds of torque rating 6.4 quite well. It would tow noticeably better and get a jump in mileage.

I would think with some 4.10s it would be sweet.

I was thinking the same with the 4.10 gears but yeah the 8 speed will be the cat meow.

VernDiesel said:

I have towed 84 the length of OR. Is it similar in the length/altitude of passes & grades?

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The west end of the gorge is pretty flat but I know out east there are some pretty good mountains. I'm not too familiar with that end of it. I know in the winter that can be one of the worst stretches of driving anywhere in the country. Routine ice storms make it just about impassable.

The worst drive I ever had (no RV thankfully) was coming up some big hills in the east gorge in the ice passing a bunch of trucks. Coming down the other side I could barely see past the hood of my truck but had to keep going or was going to get run over by all the trucks I had passed as they barreled down the hill.

Good honest report.

I tow a 14k toy hauler with a 3500, 6.4 with 4.10 gears in the mountains of MT. Not going to win any speed contests when it gets steep at elevation, but it gets there.

You are right about getting below 45-50 mph. The thing just dies. I think part of it is torque management. Mine doesn't seem to pull as hard as it should in 1st gear even at higher rpm. The computer nanny is holding it back below about 45 mph. My 5 star tuned V10 was stronger below 45 mph, 6.4 rules above that speed for the most part.

Ram has the potential for the baddest gas powered tow rig ever. As we all know it needs a better tranny. Better cooling system for the engine. Less computer nanny influence. 4.56 or even 4.88 gears.

I don't know why Ram hasn't went to the 8 speed behind the 6.4. I Transport TTs for the Mfgs. 320,000 miles to 9,000 pound TTs no issues with the trans.

My ED has a modest tune that bumps it to 480 Foot pounds of TQ point being it's more than the 429 the 6.4 puts out. The truck is lighter but has been to 15,300 combined and taken that load over 5 & 6 percent grades and up the grape vine in Cali.

So I don't see why it would not work and reliably making it a better tower more fuel efficient etc. I presume it's no royalties on the existing trans and not having to meet fuel economy regs on the HDs.

They would sell more 2500s if it had the 8sp or atleast a different transmission. I would have one no question.

I would upgrade my 2500 if they came out with the 8speed as well. When I trailer with my1500 and then my 2500 the 8 speed is just so much better at everything.

I'm very happy with my current truck. That said, a properly geared 8+ speed tranny is the ONLY thing I would consider trading for any time in the next 10 years. Outside of that, there's nothing I would want that this truck doesn't have or do. I'd bet a lot of people are of a similar mind so unless these things turn into total turds with higher mileage, if Ram wants to get current customers trading up 6.4s they need to get on this. I bet you'd see a lot of current 6.4 owners trade out for new 6.4s with 8 speeds. The downside is the resale value of the older 6.4s with 6 speeds would take a massive dive I think.

I think you are right for the most part gustheram. I am very happy with my rig overall, and would be completely happy if I did not tow heavy in the mountains and wind. The tow last weekend was quite enjoyable. It was cooler and temp seems to change performance a lot. But every time I am down to 30 mph, with the engine revving in 1st gear and not going any where, I tell my wife to NEVER let me buy another gasser to tow with. It's just that I don't want a diesel when the trailer is not hooked up.

I'm towing a similar TT @ 9000#. You guys notice the torque converter unlocking and locking between gears? I pull up and down lots of long hills in the northeast and at first I thought the trans was slipping but no codes are thrown. I've read on other BB's it's normal with our transmission. Just wondering if anyone has had the same experience.

Yeah, I'm good with mines but for what I have heard that they are suppose to be working on putting a 8 speed in the 6.4L, just not sure were I heard it from.

The transmission does need another gear between 1st and 2nd.

I purchased a 2017 2500 ram 6.4 semi a little over a year ago. 90% of my miles are pulling a 31 FT TT and I noticed that I have almost no throttle response until I get up to 35-40 MPG.
I love the way the truck pulls and handles but it is very frustrating when I get into a steep pull especially when starting from a stop (leaving a fuel stop, rest area, etc). Been looking at the "pedal commander throttle response controller). Anyone have any Ideas on that product?

Also, when pulling a TT as much as I do, should I stick with the recommended 0w40 oil or use something else.
Any and all replies appreciated.