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Hey, just wondering if anyone else is seeing very high boost (46 psi) like I am while pulling a heavy load? I can't get the thing above 32 psi while empty but when I am pulling my trailer & track loader @ 23K lbs I have to baby it to keep the boost down. EGT's are fine only seeing 1150 deg no matter what. I have talked to H&S about it and it sounds like my truck is just a freak and needs some special code written to ignore the P0471 code that pops up when it hits the 46 psi of boost. I think it's safe to say the stock head bolts and gaskets are good to at least 46 psi because my truck has seen that quite a bit over the last 3 weeks!! :shock: I am running a Dipricol Boost Guage off the intake with a "Boost Bolt" so I know my readings are accurate. Anyone have a comment?? Buhler....Buhler....anyone.......
 

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i have hit 41 at WOT but then backs off to hold about 35, with your intercooler and tubes it is not unreasonable to hit 46, you will gain a couple of PSI with the cooler and tubes, what do you sustain at? just be happy i guess, most guys here will be jealous.:lol4:
 

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Hey, just wondering if anyone else is seeing very high boost (46 psi) like I am while pulling a heavy load? I can't get the thing above 32 psi while empty but when I am pulling my trailer & track loader @ 23K lbs I have to baby it to keep the boost down. EGT's are fine only seeing 1150 deg no matter what. I have talked to H&S about it and it sounds like my truck is just a freak and needs some special code written to ignore the P0471 code that pops up when it hits the 46 psi of boost. I think it's safe to say the stock head bolts and gaskets are good to at least 46 psi because my truck has seen that quite a bit over the last 3 weeks!! :shock: I am running a Dipricol Boost Guage off the intake with a "Boost Bolt" so I know my readings are accurate. Anyone have a comment?? Buhler....Buhler....anyone.......
46 psi seems to be really pushing it with these 6.7's. I would get that addressed before towing again or setting the tuner to a lower setting.
 

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How many other XRT users are able to handle over 40 psi on stock head bolts without popping a head gasket?
It doesn't matter which tuner you are using. 40+ PSI on stock head bolts is a bad idea...low 40's is ok. 45 seems to be the magic number for popping the head gasket. Time for studs.
 

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It doesn't matter which tuner you are using. 40+ PSI on stock head bolts is a bad idea...low 40's is ok. 45 seems to be the magic number for popping the head gasket. Time for studs.
Sure it matters, as every tuner will have different characters with timing and such that could greatly effect cylinder pressure. That and the fact that the majority of reported blown head gasket users have been using a different programmer thus far.
 

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Sure it matters, as every tuner will have different characters with timing and such that could greatly effect cylinder pressure. That and the fact that the majority of reported blown head gasket users have been using a different programmer thus far.
I disagree. Pushing 45 psi is a bad idea. A lot of the head gasket issues have been from guys taking off the turbo speed sensor and hitting about 45 pounds.

I say not a good idea no matter what tuner you have. all it takes is one wrong accelleration and see ya head gasket.
 

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I am under the impression that the 6.7 head studs are the same as a 5.9. If that is the case, if it were my own truck, I would not hesitate to run 50 PSI with stock head studs. I have had many a 5.9 with bigger turbos that would peak at 55+ and sustain 50. I am not saying this is safe for everyone, but I think that around 40+ PSI for shorter bursts would not be a problem. There is a lot more into the equation than just boost #s. Timing will have a lot to do with it. But if it was me I would not be running the higher tune pulling that much weight. But again that is just my opinion.
 

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I am under the impression that the 6.7 head studs are the same as a 5.9. If that is the case, if it were my own truck, I would not hesitate to run 50 PSI with stock head studs. I have had many a 5.9 with bigger turbos that would peak at 55+ and sustain 50. I am not saying this is safe for everyone, but I think that around 40+ PSI for shorter bursts would not be a problem. There is a lot more into the equation than just boost #s. Timing will have a lot to do with it. But if it was me I would not be running the higher tune pulling that much weight. But again that is just my opinion.
Putting timing aside, the head studs may be the same as a 5.9, but more displacement creates more cylinder pressure. It was posted that the gasket design was not that good.


I think studs are going to be required at lower boost numbers than the 5.9.
 

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I will go with you on the cylinder pressure being a bit higher. Only time will tell I suppose on how they hold up on a 6.7. Who posted that the gasket design was not that good? I myself have not done one yet, and any knowledge out there would be great to hear. I would think Cummins would assume that the 6.7L will have the same if not more cylinder pressure, and wonder why they would send out a product with a less quality head gasket than the 5.9. If they did, shame on them for downgrading!
 

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I will go with you on the cylinder pressure being a bit higher. Only time will tell I suppose on how they hold up on a 6.7. Who posted that the gasket design was not that good? I myself have not done one yet, and any knowledge out there would be great to hear. I would think Cummins would assume that the 6.7L will have the same if not more cylinder pressure, and wonder why they would send out a product with a less quality head gasket than the 5.9. If they did, shame on them for downgrading!

Erick Brown of Browns Diesel posted that along with the cylinder pressure.
 

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Discussion Starter · #13 · (Edited)
Let me just interject my experiance on the subject being discussed. I owned a 2006 and a 2007 3500 with the 5.9L engine and both saw 55 psi. before I installed ARP studs. So I can personally say the 5.9L head gasket and bolts worked great under pressure (pun intended). As for the 6.7L engine I would hope that Cummins engineers had the forethought to see there would be higher cylinder pressure based on the increase in displacement alone. I don't see a problem running the 120 program while towing (which is what the truck was bought for) since the EGT's are well below what one would expect in a tune like that. My truck has easily seen that 46 psi a few dozen times already over the past 1,200 miles. The only issues I have are why is mine spiking to 46 psi and then holding 40 when others are not and then why is that setting a pressure sensor code. It could be the combo of parts on the truck is helping increase the boost psi but it just seemed a little high looking at other peoples posts. I also wonder just how many XRT guys have pulled a load as heavy as the one I do all the time (it is my work truck). :confused013:
 

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I wouldn't worry too much about running 46psi with your XRT at this point as almost all of the recent head gasket failures have been from Smarty users alone, one was only running SW5 (90hp) level. The Smarty defensive line would like everyone to believe otherwise, but the numbers don't lie and head gasket failures seem to have increased since the Smarty's release.

I'd still like to hear of other XRT users that are running over 40psi without failure, and even those XRT users that have experienced head gasket failures so we can put this whole head gasket debate to rest.
 

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Discussion Starter · #15 ·
I wouldn't worry too much about running 46psi with your XRT at this point as almost all of the recent head gasket failures have been from Smarty users alone, one was only running SW5 (90hp) level. The Smarty defensive line would like everyone to believe otherwise, but the numbers don't lie and head gasket failures seem to have increased since the Smarty's release.

I'd still like to hear of other XRT users that are running over 40psi without failure, and even those XRT users that have experienced head gasket failures so we can put this whole head gasket debate to rest.

I hear ya! I would be more concerned if I was getting a "over boost" or "turbo over speed" code. Since I am not I am going to keep using the 120 and hope Casey can send me a patch to eliminate the the CEL & P0471 code. If that happens I'll be happier than a pig in mud....:hehe:
 

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I wouldn't worry too much about running 46psi with your XRT at this point as almost all of the recent head gasket failures have been from Smarty users alone, one was only running SW5 (90hp) level. The Smarty defensive line would like everyone to believe otherwise, but the numbers don't lie and head gasket failures seem to have increased since the Smarty's release.

I'd still like to hear of other XRT users that are running over 40psi without failure, and even those XRT users that have experienced head gasket failures so we can put this whole head gasket debate to rest.
There is really no debate because it is too early. Of the 4 or so that have blown a head gasket, 1 has had a blown a gasket before the Smarty came out and 2 disconnected the boost sensor.

How many people are running the XTR 175 tune? 20? How many people have the Smarty 170 tune? 2000? Can you hit 45psi with the XRT 120 tune?

Give it some time and we will get a better picture.

I run around with the Smarty maxed out and have not had a problem. I don't break 40psi. The vast majority are not having trouble.

This thread is trying to determine if the OP should be able to run at 46 pounds and the answer is mixed. Casey suggested not to run the 120 tune while towing, which is soild advice.
 

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The drive pressure is what I would be concerned about, that little vgt will have a lot of it at that boost level. I am not sure but I think it was designed in the 20-30 range, I am for sure it is way out of its map at 40+
 

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Discussion Starter · #18 ·
The drive pressure is what I would be concerned about, that little vgt will have a lot of it at that boost level. I am not sure but I think it was designed in the 20-30 range, I am for sure it is way out of its map at 40+
I agree, the poor little ******* is probably about to go "POOF" in a big way. But I look at it as the reason I'll then have to dial up LoveFab and order a set of twins.....:headbang:
 

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I am under the impression that the 6.7 head studs are the same as a 5.9. If that is the case, if it were my own truck, I would not hesitate to run 50 PSI with stock head studs. I have had many a 5.9 with bigger turbos that would peak at 55+ and sustain 50. I am not saying this is safe for everyone, but I think that around 40+ PSI for shorter bursts would not be a problem. There is a lot more into the equation than just boost #s. Timing will have a lot to do with it. But if it was me I would not be running the higher tune pulling that much weight. But again that is just my opinion.
I was running 50-52psi for awhile on stock headbolts, this equated to 616WHP with our Twins setup. The truck was as smooth as can be, no timing rattle. Only when I installed larger injectors, CP3, and ARP studs did I spit out a gasket. However, the larger injectors introduced a TON of timing and I was getting rattle at higher RPM levels. Should've backed it down because next week another HG is going in.

As long as you don't have ANY timing rattle(120 XRT tune should have none on stock fuel system), I wouldn't worry about 50psi.
 
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