Big suprise this week!

[CUMMINZ]

Thanks in advance for all the responses coming forth and dire warnings.



Every since I installed my Smarty and have done extensive testing towing and empty: We filled her up this week and drove mostly interstate for 101 miles. When we pulled into the town where our RV was parked and filled up. I had set the Smarty switches all on #1 except for the turbo setting and it was on #4. The power setting was on #7= 130hp. The overhead mostly hovered around 20. 5 & 21. 5... It took just over 4 gallons. That averaged out to be 21. 4mpg. That is absolutely the best we have gotten on our 07. 5 with 62,000 miles on it. The overhead has always been real close.



We hooked up to the RV today and towed by 35 miles to the house and the overhead mostly showed 14. 5 to 15mpg. That is the highest reading I have gotten. On our next trip I will check the mpg hand calculated. I never saw EGTs over 1200 degrees.

 

[HBarlow]

Let us know how the transmission rebuild goes.

 

[CUMMINZ]

HB,



I think you told me 6 months ago the transmission would go when I switched off the torque management. If you drive like you have some sense it will be OK.

 

[HBarlow]

Cumminz,

No, it wasn't me who said that. I don't have any experience with either the 68RFE or the magic black boxes. I just fear a very expensive failure when the boxes are turned up and a big, heavy trailer hung on the back.

 

[CUMMINZ]

Quote:



Cumminz's reports and the discussion in this thread makes me cringe with concern for broken parts and a very expensive repair bill.



Good luck. I hope you get away with it. I lack the courage to do that.

__________________

Harvey Barlow



2008 Ram 3500 SLT QC & Chassis w/ CM bed

2007 HitchHiker Discover America 32 LKTG

2010 Goldwing XM/Nav

 

[Jim W]

Cumminz,

Hi, what was your boost pressure before you towed and after? Have you installed ARP head studs? I always monitor my boost pressure and keep this under 30PSI. So I am wondering what you are seeing?



There have been several posts in other sites where several users think the VGT driver pressure is causing the head to lift and the head gasket will fail. They are quoting the drive pressure between 1. 5 to 2 times the boost pressure. So with no wastegate on the 6. 7L VGT as you approach 30 PSI you could see as high as 60 PSI drive pressure, if you go over 30 PSI the drive pressure is even higher.



My son is into high performance diesel and rebuilds them as a side job, is after me too install head studs so I do not fail the head gasket. So I have been watching and reading these threads so I can understand the issue before I make up my mind.



So please watch the boost pressure and let me know what you see.

Thanks

Jim W.

 

[RonD]

Thanks in advance for all the responses coming forth and dire warnings.



Every since I installed my Smarty and have done extensive testing towing and empty: We filled her up this week and drove mostly interstate for 101 miles. When we pulled into the town where our RV was parked and filled up. I had set the Smarty switches all on #1 except for the turbo setting and it was on #4. The power setting was on #7= 130hp. The overhead mostly hovered around 20. 5 & 21. 5... It took just over 4 gallons. That averaged out to be 21. 4mpg. That is absolutely the best we have gotten on our 07. 5 with 62,000 miles on it. The overhead has always been real close.



We hooked up to the RV today and towed by 35 miles to the house and the overhead mostly showed 14. 5 to 15mpg. That is the highest reading I have gotten. On our next trip I will check the mpg hand calculated. I never saw EGTs over 1200 degrees.

I don't think one example using 101 miles, then 35 miles will give a very good reading, report back after 10,000 miles and we will have a better idea.

 

[CUMMINZ]

Cumminz,

Hi, what was your boost pressure before you towed and after? Have you installed ARP head studs? I always monitor my boost pressure and keep this under 30PSI. So I am wondering what you are seeing?



There have been several posts in other sites where several users think the VGT driver pressure is causing the head to lift and the head gasket will fail. They are quoting the drive pressure between 1. 5 to 2 times the boost pressure. So with no wastegate on the 6. 7L VGT as you approach 30 PSI you could see as high as 60 PSI drive pressure, if you go over 30 PSI the drive pressure is even higher.



My son is into high performance diesel and rebuilds them as a side job, is after me too install head studs so I do not fail the head gasket. So I have been watching and reading these threads so I can understand the issue before I make up my mind.



So please watch the boost pressure and let me know what you see.

Thanks

Jim W.

Jim,



I don't have a boost guage. I do watch my EGT guage and shift accordingly. I usually don't let my temps get above 1250 degrees. With it set up this high I take it real careful.

 

[CUMMINZ]

I don't think one example using 101 miles, then 35 miles will give a very good reading, report back after 10,000 miles and we will have a better idea.

Ron,



When I have never gotten about 18mpg ever it is a good indication of what I may expect. The towing mileage is a different story. That will come later this summer.

 

[BruteForce]

I tow heavy using my Black Maxx tuner on MILD setting (+60hp) and now have just under 50,000 miles with no transmission issues.

GVW = 28,000 pounds.

 

[CUMMINZ]

I tow heavy using my Black Maxx tuner on MILD setting (+60hp) and now have just under 50,000 miles with no transmission issues.



GVW = 28,000 pounds.

Thanks BF, I normally tow at 60hp and have had no problems. I usually gross 26-27k but I do tow a lot in the mtns. of NC. We will be towing there in the next couple of weeks. I plan to leave it on 130hp and will be taking my Smarty with me. I have a couple long hills before I go up hwy. 226 which is tough. I plan to watch my EGTs very closely. Thanks for your input.

 

[CBlack]

Was having a discussion with a gent yesterday about this. I wouldn't think towing in 130hp would matter too much if you use Tow/Haul if you keep an eye on RPMs.

 

[JJPage]

Thanks BF, I normally tow at 60hp and have had no problems. I usually gross 26-27k but I do tow a lot in the mtns. of NC. We will be towing there in the next couple of weeks. I plan to leave it on 130hp and will be taking my Smarty with me. I have a couple long hills before I go up hwy. 226 which is tough. I plan to watch my EGTs very closely. Thanks for your input.

CUMMINZ, Right up front I'll admit I have no personal experience with the 6. 7's.



Something you may want to watch as close as egt's is coolant temp. The 6. 7 should have a larger coolant system than the 5. 9's, I just do not know. What I do know, is when I tow around 100hp over stock my egt's stay below 1200*, but on long pulls, or against a hard head wind, my coolant gauge will exceed the normal 200* mark and move rapidly towards the end of the black scale.



I have always caught the coolant temp before it became a problem, just trying to give you a "heads up", if you are going to tow that heavy and with that increase in fueling, there are other systems to consider besides just egt's. (trans/diff temps).



Glad the Smarty is performing positively for you so far. Jess

 

[AH64ID]

Those are pretty good numbers, I am especially surprised at the mileage and EGT's for stock timing (goes to show how aggressive the turbo is on 4).

 

[CUMMINZ]

CB & JJ, Thanks to both of you . I do watch the coolant temp and the transmission temps when I tow. I will assure you both that with the graduated hills on I-40 before I get to Marion, NC and hit 226 north will tell me real soon as to whether I will pull over and back down from the 130hp mark. I have always driven my 68rfe using the gear shifter paddle. Thanks again

 

[AH64ID]

Something you may want to watch as close as egt's is coolant temp. The 6. 7 should have a larger coolant system than the 5. 9's, I just do not know. What I do know, is when I tow around 100hp over stock my egt's stay below 1200*, but on long pulls, or against a hard head wind, my coolant gauge will exceed the normal 200* mark and move rapidly towards the end of the black scale.



I have always caught the coolant temp before it became a problem, just trying to give you a "heads up", if you are going to tow that heavy and with that increase in fueling, there are other systems to consider besides just egt's. (trans/diff temps).



Glad the Smarty is performing positively for you so far. Jess

2003 = 24qt system

2005 = 29. 6 qt system

2007 5. 9 = 29. 6qt system

2007 6. 7 = 22. 7 qt system

2010 6. 7 = 22. 7 qt system.



Apparently the cam and timing on late model 5. 9's made some heat!



The 3rd gen trucks (5. 9 and 6. 7, from what I can tell) use a 190° thermostat. This thermostat opens at 190°±3°, and isn't full open until 207°, with a max allowed temp of 225°.



When I am pulling steep hills I will see up to 215° with my current setup in 6th gear, 5th tops out at about 211-213°, as read on a OBDII reader. 200° is not even full open and nothing to worry about.



The 4th gen's use a 200° thermostat, and I can't find any info from Cummins on it, but if it holds the trend of 2nd and 3rd gen thermostats it will be full open about 215-217° and have a max allowed temp of 235°.



On the other side, min operating temp for full power operation in 160° for all models and thermostats.

 

[Jim W]

Cumminz,

I would suggest that you invest a little money into a boost gage and boost bolt. When I towed in NC towards Ashville NC. , I went up I40 near Black Mountain. I think my EGT's were over 1200F and the Boost was about 25PSi. I down shifted to 5ft gear and EGT's went down but the Boost pressure went up. So I took my foot out of the accelerator and lowered the RPM's a little slowing to about 50 or 55 MPH.

I was towing with the Smarty on level 3 all parameters set to default except TM which was on 2.

Just my $0. 02

Jim W.

 

[JJPage]

2003 = 24qt system

2005 = 29. 6 qt system

2007 5. 9 = 29. 6qt system

2007 6. 7 = 22. 7 qt system

2010 6. 7 = 22. 7 qt system.

Thanks AH, that's quite interesting, especially the increased capacity in 2005 and up with the 5. 9s. I would have never guessed the 6. 7s would have a coolant system with a capacity less than the 5. 9s.

 

[AH64ID]

Thanks AH, that's quite interesting, especially the increased capacity in 2005 and up with the 5. 9s. I would have never guessed the 6. 7s would have a coolant system with a capacity less than the 5. 9s.

I am guessing the capacity went up with the 04. 5 motor change. I too was shocked the 6. 7 has a lower capacity, it didn't even increase with the HO.

 

[CUMMINZ]

Cumminz,

I would suggest that you invest a little money into a boost gage and boost bolt. When I towed in NC towards Ashville NC. , I went up I40 near Black Mountain. I think my EGT's were over 1200F and the Boost was about 25PSi. I down shifted to 5ft gear and EGT's went down but the Boost pressure went up. So I took my foot out of the accelerator and lowered the RPM's a little slowing to about 50 or 55 MPH.

I was towing with the Smarty on level 3 all parameters set to default except TM which was on 2.

Just my $0. 02

Jim W.

Jim,



Do you think I should back off the turbo #4 to #1 when I have it set on 130HP?