Author Topic: PT 525hp C13 - Driving up steep grades (6% - 9%)  (Read 3959 times)

rkevincarson

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PT 525hp C13 - Driving up steep grades (6% - 9%)
« on: September 17, 2021, 05:12:42 PM »
Just wondering how different folks drive up steep grades with a toad?   We have a 525hp PT 2006 and seem really struggle on the steep grades.  Pretty heavy with a toad (Equinox) on the back.   Maybe just incorrect technique?  On smaller grades we get 41-45boost but on the steep grades is seems to be down in the 29-35 range. 

Fred Brooks

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Re: PT 525hp C13 - Driving up steep grades (6% - 9%)
« Reply #1 on: September 17, 2021, 06:12:00 PM »
   Kevin,
The sweet spot is approximately 1800 rpm probably in 3rd or 4th gear dependent on % of grade. The whole idea is to NOT lug the engine and make it overheat. Experiment next time out and find out where she wants to be so she is happy and you are smiling. Fred
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Mike Shumack

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Re: PT 525hp C13 - Driving up steep grades (6% - 9%)
« Reply #2 on: September 17, 2021, 08:08:35 PM »
I just left north-eastern Tennessee (Mountain City and Shady Valley area) and drove some pretty steep and long grades - for the east coast (about 7-1/2% was the steepest).

I was just giving it full throttle all the way up. No special technique.  RPM ran around 1800. Transmission downshifted when it needed to. On one grade my max speed was 35mph in 3L (that was the slowest I saw on the trip. Mostly I was able to do the posted speed limit). Boost hit 49 psi with engine load reporting 99% (I don't think the Aladdin has a 100%), exhaust temp got up to 750 degrees (measured after the turbo). Temps never went over 195. On the downhill side (Jake in Hi) I never had to touch the brakes.

Over all, I was very impressed with the C13 performance. I don't tow anything, but I am carrying a motorcycle on a hyd lift.


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Re: PT 525hp C13 - Driving up steep grades (6% - 9%)
« Reply #3 on: September 17, 2021, 10:51:14 PM »
Suggest you DO NOT run grades at full throttle with a side radiator coach. Your wax valve is controlling fan speed so running at full throttle is only generating excessive and unneeded heat. Drive coach to maximize toque, not engine RPM. As Fred noted around 1800-1900 RPM is normally the sweet spot. Downshift as needed to keep this RPM.
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Carl Boger

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Re: PT 525hp C13 - Driving up steep grades (6% - 9%)
« Reply #4 on: September 18, 2021, 03:36:35 AM »
While I do not have the luxury of 525 hp, I have found that I often have to lock the Allison transmission down into 5th or sometimes lower to maintain the proper RPM range and make the Cat 3126 happy.  If I notice that the engine is lugging on a series of hills I will go ahead and lock it down into 5th.  The torque is better, the engine runs cooler, and it no longer slows down toward the top of the hills.
Carl

98 Beaver Patriot Savannah
330 hp Cat 3126

Eric Maclean

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Re: PT 525hp C13 - Driving up steep grades (6% - 9%)
« Reply #5 on: September 18, 2021, 02:25:23 PM »
Kevin
On your Allison automatic shift counsel the mode button will change the shift schedule in the transmission when the mode button is pushed the schedule will be set for economy mode which will try to keep the transmission in the highest gear possible eliminating the down shift to 5th on the rolling hills and improving fuel mileage .however when climbing larger hills this is counter productive as it will hold the shifts too long and doesn't allow the shift down soon enough which inturn lugs the engine RPM down to a point where the turbo can't spool up effectively.
I like Carl am stuck with the 330 HP 3126 and when in hilly terrain  take the trans out of economy mode allowing the transmission to down shift earlier which keeps the engine at peak torque longer but in the end just like driving your car the vehicle can't see the hills coming so it falls on you to try to speed up a bit and carry some speed and momentum into the hill . often the terrain is such that you come down one hill on the exhaust  or jake brake only to head right into the next heavy climb this is when it is important to get off the brakes as soon as possible and get into the accelerator to get the turbo spooled up before the RPM is pulled down too far , there are still times when a manual down shift is called for but thats not often .
The best way to maintain maximum torque is to monitor your boost pressure as you climb and the engine looses RPM there will be a point where the boost starts to drop off this is where the engine has dropped below is peak torque ( usually 1600 to1800 RPM ) and will loose RPM more quickly if you don't get it a lower gear to get that RPM back up into its torque curve .
You know your getting everything you can out of your engine when your climbing and the RPM is holding at or around 1800 RPM
And the speed and boost are holding steady . On a 7 % grade with our 30000 lb coach and 3300 lb toed the 3126 with is 850 foot lbs of torque is usually 3rd or 4th gear at approx 35mph it sure would be nice to have another couple hundred HP but it is what it is .

Sorry for the long winded answer
Hope this helps
Eric
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Dwight Wilson

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Re: PT 525hp C13 - Driving up steep grades (6% - 9%)
« Reply #6 on: September 20, 2021, 08:50:02 PM »
HI Kevin,
I regularly drive our PT through the Rockies and find that I get the best performance on the hills at around 1700 to 1800 RPM. I typically shift down to 4th going up and down the higher grades with stage 1 or 2 as needed of the Jake employed. Just keep an eye on your engine RPM to be sure to keep it under 2000 RPM going down. I pull a Ford Edge and can typically maintain 50MPH going up an 8% grade as long as I am maintaining 1400 to 1500 RPM when I start to climb. I have never seen the temp exceed 196 Degrees on the engine so the fan seems to be keeping the heat out.
Dwight Wilson
Calgary, Alberta
05 Patriot Thunder C13 Cat

rkevincarson

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Re: PT 525hp C13 - Driving up steep grades (6% - 9%)
« Reply #7 on: September 20, 2021, 10:05:12 PM »
To all that replied...   thank you very much.   On a 7% grade I think I was letting it drag a little and not getting it up in the 1700-1800 range and thus the boost was low.   We will give it another go this weekend.

Again, thank you to all that took the time to reply.

Ken Pruitt

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Re: PT 525hp C13 - Driving up steep grades (6% - 9%)
« Reply #8 on: September 20, 2021, 10:16:35 PM »
525 horsepower? I'm surprised you don't have to Pedal the throttle to keep from slipping the rims inside of the tires. 8)

Bill Lampkin

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Re: PT 525hp C13 - Driving up steep grades (6% - 9%)
« Reply #9 on: September 20, 2021, 11:48:47 PM »
2005 Patriot Thunder Lexington, 3 slides
40' tag axle (short wheelbase)
525 hp C13

"Goin where the weather suits my clothes..."
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Keith Moffett

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Re: PT 525hp C13 - Driving up steep grades (6% - 9%)
« Reply #10 on: September 22, 2021, 06:27:51 PM »
We have the C13 as well and am currently in the Petersens CAT getting a fuel filter changed and a computer print out for just the reasons mentioned in this thread.
Driving up the hill from I-84 above Biggs Junction OR I shifted down to 5th and that perimeter change showed a 5 mph or so boost up hill.  Long steep (6% plus). Never dropped below 40.
2nd fuel filter was on so hard I couldn’t get it off so it has too many miles.  Hope to see a further boost in power now.
2007 Patriot Thunder
45' C-13
2006 Explorer Ltd.
DW is Carol
Safe travels and
May God bless!

Keith Moffett

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Re: PT 525hp C13 - Driving up steep grades (6% - 9%)
« Reply #11 on: September 23, 2021, 05:23:39 AM »
Here is the update after our computer analysis.
There are three control heads under the valve cover.  These regulate the intake valves.  There is one sensor for all three heads.  There is an O-ring in this sensor which maintains oil pressure to the sensor.  When this O-ring fails or begins to it tells the ECU that oil pressure has dropped and this causes a D-rate.  Ours shows it has begun to fail due to a low voltage report.
As we start out the oil is cooler and the O-ring holds better pressure but as oil heats and thins out the O-ring no longer does its job and so a D-rate begins.
A new sensor will help so long as the control heads are functioning properly.  Each one is about $800.

Hope this info is useful and that Dave will chime in with his opinion here.
2007 Patriot Thunder
45' C-13
2006 Explorer Ltd.
DW is Carol
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May God bless!

Lee Welbanks

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Re: PT 525hp C13 - Driving up steep grades (6% - 9%)
« Reply #12 on: September 23, 2021, 03:29:02 PM »
Out west here we have plenty of steep grades to test out your motor, with my 06 PT/C13/525 the max torque is around 1500 rpm, 49 psi boost, it will pull down to around that rpm and really go to work, just have to watch the temp gauges. Most all grades it will pull in 4th gear depending on the outside temp, I've run the temp up to 205 and then shift down and cool the motor off, my fan shifts to high speed around 196 degrees, i can hear it when it shifts. One thing to note I clean out the radiators every year so there is no crap blocking the air from passing through them.
All so the altitude will make a big difference in you motor performance the higher you go the thinner the air, pulling I-70 in Co your lucky to get 40 psi boost.
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Bill Lampkin

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Re: PT 525hp C13 - Driving up steep grades (6% - 9%)
« Reply #13 on: September 23, 2021, 07:19:49 PM »
I had the CAT dealer do an 'overhead' service on our C-13 last year. I wonder if these 'O' rings Keith mentions are routinely replaced as part of an overhead service??
2005 Patriot Thunder Lexington, 3 slides
40' tag axle (short wheelbase)
525 hp C13

"Goin where the weather suits my clothes..."