What rpm do you like on the freeway

[wanderer]

As it says. I guess too that it should be linked to speed. Which out here in CA is like 75- 80 (or they’ll shoot you).

Trying to figure out whether to regear or not. At 80 with stock gears 410s turns just a shade over 2000 in 8th which means 8th is hard to hold except on flats. But. 488 will turn 2600 at 80 in 8th and that seems too high. Where as 80mph turns 2444 in 8th So for you who have regeared what are your thoughts? Is 2666 rpm too high?

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[MrZappo]

Too high based on what? It's not over redline, it's not going to damage anything, it's lower than the rpm that you would see when towing at 70 when the transmission stays in 7th and sometimes 6th depending on the load.

This is a small block, lower displacement engine that makes its horsepower with higher rpm's. Redline is 6500.

2600 is very close to 2000 honestly.

This engine would run all day long at 4000 rpm without damage if you asked it to.

Other than that it feels higher than you might like what is your basis for saying that it seems too high?

All that being said, I have 4.10 gears as well and the constant shifting out of 8th in the highway is a pain in the neck for sure.

I know that @ShadowsPapa on here had a code update done and I think that I remember him saying that it settled down the trans a little but I don't know the details.

I have considered asking my dealer for the same code update in hopes that it would help that very issue.

I can say that at 75 or 80 when it down shifts on a slight incline I never feel like it really needed to honestly. It all seems a bit over sensitive to me.

 

[DJ_Rubi]

trade it in for the diesel - cruise at just under 2K @ 73 plus torque is amazing

 

[Mr._Bill]

I have a stock Overland with the 3.73 gears. It runs around 2000 rpm with the cruise set at 78 mph. It doesn't seem to have any problem holding 8th gear.

 

[ShadowsPapa]

I have a stock Overland with the 3.73 gears. It runs around 2000 rpm with the cruise set at 78 mph. It doesn't seem to have any problem holding 8th gear.

But you are driving the salt flats, right?

Here, it's all hills, everywhere unless you are in NW Iowa, or parts of western IA. And it's almost always windy (that means 10 - 15 mph a lot of the year, a calm day is 5mph winds.)
Since the PCM flash, mine doesn't jump into 8th as quickly - which is GREAT as that means it won't have to downshift as often. Before the flash, it would go to 8th, then I'd hit a mild incline and it would drop back a gear - or TWO, then as quick as I hit less of an incline, it would jump into 8th, then any mild acceleration or anything other than totally flat ground, it would downshift again, it was up and down up and down up and down. Mild hills it never held 8th for more than a few seconds, then it would be back down again. Now it doesn't go to 8th as quickly, staying in 6th or 7th longer as if making sure it's ok to upshift.

A LOT LESS up/down/up/down since the flash. It's almost as if it's more of a sport mode than granny mode like it was before.
I wish it was more like my Silverado - push a button and it all but locked out the OD gears unless you were on really flat ground - trailer tow mode.

It still isn't perfect - it really sucks that it thinks it's ok to be running 1500 RPM here in Iowa because the thing simply can't take our hills at that RPM, so still kicks down a lot. Better, but way too much 8th gear nonsense.
I wish there was a way to get rid of 8th gear with some switch and use it only in Nebraska or eastern Kansas. 8th is worthless here.
And may as well totally lock it out of 8th when towing. I'd love it to sense a trailer back there and skip 8th completely. You can't make that 3.6 pull any load on a hill at the RPM range it seems to like.
How can you push a brick along the road at 1500 rpm? No power, no torque, and yet it seems to like that RPM range and still hits 8th when it should not.

Seriously, they really need to re-map the transmission and what the heck is up with pushing a truck on hills at 1500 RPM? These are not long stroke engines with high torque down low.

 

[DAVECS1]

I could go on for days. The transmission mapping isnless than stellar. I have spent months on mine. This last month I actually put the torque converter and shift schedule maps from my 2019 RAM. It was great at low speeds but any quick driving led to way to many shifts. I have about 120 revisions on the gladiator shift schedule. I like to keep the trans, in a gear that puts the engine around 2200 to 2500 rpm. This seems to make the gear transition at part throttle the most smooth and imperceptible. I have 4.10s and I am supercharged. I barely have it going into 8th unless there is no grade or wind. 8th has no torque capability in this engine and why make this engine lug ot already has high cylinder pressures so your just asking for misfires. It should have a tow mode. They were just lazy and did not fill in the maps and wire up the button. I have thought about doing it but have not. My boggest issue at the moment is tuning for low speed cornering. I would like ot not to shift qhile cornering, but with the torque map it absolutely insists on a lower gear when any amount of posotive torque is applied. My current strategy is to get it in a lower gear before the corner so you do not have an awkward back shift when accelerating out. The drawback is you get a bit of unnatural engine braking before the corner.

 

[Tufelhundin]

I found a way to completely take away 8th. Put 35's on it. Mine really never stayed in 8th when stock, all it would take is a slight incline or any type of head wind, for the most part 7th was the norm. I did ask the service department about any new PCM flash shortly after you @ShadowsPapa posted they flashed yours and they went out with their little tablet and hooked it up and said there was nothing showing concerning a new flash. I traded in my Diesel Canyon for the Gladi and I do love my Jeep but I certainly miss my little diesel engine. Right now Im considering a re-gear to 4.56, its a cheaper alternative then getting hosed for a trade -in. My only problem is that there are not many re-gear shops around and the one that has been recommended to me down in Baton Rouge will not respond and Im trying to throw money at them....

Sorry about the side track of the post. I never travel 80mph down here and I actually hate going over 65 due to mpg. I posted pics on the forum of my MPG hit from 60 to 65 and it was like 3 mpg less and it stayed in 6th which is the norm unless no wind or tail wind.

 

[wanderer]

i just think that lower rpm is better, quieter less wear over hundred thousand miles, i think 2200 to 2500 is optimal but that is just my thought. c orrect me if i am wrong but as i recall the engine ramps up hp to about 2000-2200 then the hp flattens out with significant gain in HP As i said correct me if i am wrong post the HP and torque curves. If I am not wrong the why run at higher rpms for not much gain?

 

[ShadowsPapa]

i just think that lower rpm is better, quieter less wear over hundred thousand miles, i think 2200 to 2500 is optimal but that is just my thought. c orrect me if i am wrong but as i recall the engine ramps up hp to about 2000-2200 then the hp flattens out with significant gain in HP As i said correct me if i am wrong post the HP and torque curves. If I am not wrong the why run at higher rpms for not much gain?

Still a lot of gain of HP past 2,000 - that's hardly the peak and not really close to it.
You even gain torque to a fair degree well past 2,000
Charts I've seen show you gain another 50 pound/ft of torque up to about 4400 rpm.
HP keeps climbing even more. Torque is pretty flat for a small gas engine, but far from FLAT FLAT.
HP keeps going up to about 6300 or so, I think.

 

[LaterGator]

I have 37's on my truck. Before i regeared it would constantly hunt between 6th and 8th on any incline. I am in houston so it's pretty flat and the gear hunting was annoying. After I swapped to 5.13 gears from 4.10, the truck really settled down. It accelerates better. has better mileage and doesn't hunt for gears. It will get to 7th and 8th quickly and stay there unless passing or hitting a steep incline. The 5.13 gears are much more pleasant to drive. And driving 75-80 is no problem.

I don't think the 4.10 gears are very good with bigger tires. the 3.6 needs more rpm to get into the middle of the power band at typical highway speeds.

 

[Mr._Bill]

i just think that lower rpm is better, quieter less wear over hundred thousand miles, i think 2200 to 2500 is optimal but that is just my thought. c orrect me if i am wrong but as i recall the engine ramps up hp to about 2000-2200 then the hp flattens out with significant gain in HP As i said correct me if i am wrong post the HP and torque curves. If I am not wrong the why run at higher rpms for not much gain?

For fuel economy, you want the lowest RPM needed to maintain speed without lugging the engine. It is calibrated for the default factory tire size. The larger tires can use regearing to maintain the factory ratios and keep the RPM down. Other than pedal response, there is no advantage to the higher RPM on the highway, and it just burns more fuel.

 

[ShadowsPapa]

For fuel economy, you want the lowest RPM needed to maintain speed without lugging the engine. It is calibrated for the default factory tire size. The larger tires can use regearing to maintain the factory ratios and keep the RPM down. Other than pedal response, there is no advantage to the higher RPM on the highway, and it just burns more fuel.

Welllll. Depends on the load and the hills and the wind (which equates to load)
For me, the low RPM sucks as you have no power to pull, hit a hill and it bogs until it downshifts.
I'd rather be above the 1500-1600 rpm it keeps wanting to stick around.
The engine bogs, lugs, before it finally downshifts unless you drive aggressively or manually shift and hold lower gears. They have it on the edge of too low.

 

[wanderer]

You are running 37s with a 410? That is what I am on but no way does mine want to stay at 1500 -1600 rpm. On freeway. 65 -80. Shifts into 8th and will hold that if no load at 2055. And in 7th 2500 ish

 

[DAVECS1]

I have tuned mine so ot stays in 6th until positive torque surpassed 15 percent of the shift into 7th speed. I run about 2600 RPM at 65 then ot drops to 2200, and stays in seventh unless I go over 40 percent throttle and 30 percent negative torque. It will flip into 8th on flat ground or down hill grades I tried to set it so ot would not shift back until 20 percent negative torque and 30 percent pedal, bit there is an override that kicks it back sooner that I dont have access to. My guess is a clutch torque limit issue. It runs about 1900 rpm in 8th at 65. With my 7th delay you do not even feel it shift. It just clicks over to the next gear and away you go

 

[Mr._Bill]

You are running 37s with a 410? That is what I am on but no way does mine want to stay at 1500 -1600 rpm. On freeway. 65 -80. Shifts into 8th and will hold that if no load at 2055. And in 7th 2500 ish

He and I both have Overlands with the 3.73 gears. He runs Rubicon take-offs in the winter and stock Overland tires in the summer. I run the stock tires year round. Most of my highway travel is around 78mph, which results in the RPM around 2000. It usually downshifts and climbs to 2500 when going uphill.

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