RHO Cuts Power and Boost

[itsmekylep]

on the 2 pages of gauges, next to each gauge on the top right there's a little box, hit that

Nice. Learn something new every day with this turd. Lol

 

[Silver RHO]

View attachment 15346
View attachment 15347
80° this morning.

The difference in horsepower I could assume is due to my elevation at a mile above sea level even though it’s forced induction. In your boost video is that through redline? I can’t tell. Mine you can see it pulls boost back.

 

[itsmekylep]

The difference in horsepower I could assume is due to my elevation at a mile above sea level even though it’s forced induction. In your boost video is that through redline? I can’t tell. Mine you can see it pulls boost back.

Actually you’re right. I should have waited until it shifted. Back to the streets!

 

[gram10]

I haven't looked at mine, but I would be very surprised if these hold 28 psi until redline. Not sure I've ever seen a manufacturer do that. Generally, peak boost will be at peak torque and taper down. Manufacturers generally use smaller turbos to reduce turbo lag and increase torque down low. The smaller turbo(s) fall out of it's efficiency area on its compressor map and would just be blowing incredibly hot air and overspinning the turbo if it tried to hold boost all the way to redline. If we had bigger turbos it certainly could, but then people would complain even more about lag. Plus, being this is a truck and can be used for towing, it is more important to have low end torque then high end hp.

 

[itsmekylep]

I haven't looked at mine, but I would be very surprised if these hold 28 psi until redline. Not sure I've ever seen a manufacturer do that. Generally, peak boost will be at peak torque and taper down. Manufacturers generally use smaller turbos to reduce turbo lag and increase torque down low. The smaller turbo(s) fall out of it's efficiency area on its compressor map and would just be blowing incredibly hot air and overspinning the turbo if it tried to hold boost all the way to redline. If we had bigger turbos it certainly could, but then people would complain even more about lag. Plus, being this is a truck torque and can be used for towing, it is more important to have low end torque then high end hp.

This makes sense.

 

[Silver RHO]

I haven't looked at mine, but I would be very surprised if these hold 28 psi until redline. Not sure I've ever seen a manufacturer do that. Generally, peak boost will be at peak torque and taper down. Manufacturers generally use smaller turbos to reduce turbo lag and increase torque down low. The smaller turbo(s) fall out of it's efficiency area on its compressor map and would just be blowing incredibly hot air and overspinning the turbo if it tried to hold boost all the way to redline. If we had bigger turbos it certainly could, but then people would complain even more about lag. Plus, being this is a truck and can be used for towing, it is more important to have low end torque then high end hp.

From what I read about altitude and turbocharged vehicles a lot of this matches. For me at 5000+ feet the turbos have to compensate by increasing speed to accommodate the desired psi when ambient pressure is lower than sea level. Say 12psi vs 14.7 at sea level. Sounds like that would only work until psi is maxed and then I am down by the ambient psi difference. In this case say 2.7 psi. Otherwise the turbos would be overspinning and pushing much hotter air resulting in horsepower loss and potential damage. Thanks for the explanation. I figured these were smaller turbos to reduce lag unlike those high hp aftermarket turbo vehicles that have big turbos but have huge lag and really only produce a shit ton of power in the upper power band. That makes sense why psi would max after the peak torque curve when they have reached peak efficiency and then lower psi after. The only thing I still get confused about is the compensating and what happens when you max out. For instance mine goes to 28 I wonder if my turbos are working harder than those at sea level since they have to compress more air to get to 28 absolute psi at 5000 ft.

 

[Attakracer]

Yikes if thats true and its dropping 7psi everytime its over 4500rpms assuming each psi is roughly 10-15hp then its down about 70-105hp when its in its supposed powerband (over 4500rpms)

If this is rams short term solution while they figure things out its still pretty bad but if its their long term solution as many other members pointed out, thats class action lawsuit time.

That's crazy

What exactly are they trying to fix with this flash that robs the power and top speed ??? (sorry if I missed the answer to this earlier) !!

 

[Myers1981]

What exactly are they trying to fix with this flash that robs the power and top speed ??? (sorry if I missed the answer to this earlier) !!

I dont know I think I was wrong how I interpreted this. It seems the 98mph thing is a real issue (that we all hope they're working to resolve) but I haven't seen any definitive proof that any of the trucks were robbed of power or not making the advertised 540hp.

That said no one has been on a dyno to prove it one way or the other.

 

[Myers1981]

I saw one of your own this morning while in the trx!

 

[jschulman]

Thanks. I was wondering if it could be pulling timing due to knock detection and was going to try and find 93 gas somewhere to test. We really don’t have 93 in Denver because we aren’t supposed to need it with the elevation we are at.

I am also in Denver and my dashboard HP never reads above 460hp. My center screen shows 380hp. I'll need to check PSI next time out. It is so difficult to know what true power is supposed to feel like in this big heavy truck with large tires and 91 octane. Truck has not been in for service and can say that it has the original factory claimed top speed.

 

[Silver RHO]

I am also in Denver and my dashboard HP never reads above 460hp. My center screen shows 380hp. I'll need to check PSI next time out. It is so difficult to know what true power is supposed to feel like in this big heavy truck with large tires and 91 octane. Truck has not been in for service and can say that it has the original factory claimed top speed.

Yeah I can’t tell if it’s just losing that much power at altitude which is bad, or if there is something wrong. I didn’t mention to dealer as I don’t want it to sit there forever with them having no idea how to address it.

 

[jschulman]

Yeah I can’t tell if it’s just losing that much power at altitude which is bad, or if there is something wrong. I didn’t mention to dealer as I don’t want it to sit there forever with them having no idea how to address it.

Totally, I'm trying to figure out how much I care. I did a single 0-60 run the other evening when it was somewhat cooler. The performance page said 5.20s. factoring in power loss due to high altitude and 91 octane, i'm guessing that seems fine? My other car is naturally aspirated and i've driven it at sea level. I know it has a larger effect for NA, but I can say running that car with a tune, race filters, and lightweight full exhaust at altitude feels pretty much the same as the car did when it was stock on 93 at sea level.