Bullet proofing the 6.7

[cerberusiam]

https://www.dieselworldmag.com/diesel-technology/bomb-proof-top-end-for-the-6-7l-cummins/

 

[Jim W]

What HP/TQ are they running in that engine with the upgraded components? For the standard run of the mill user I see no need to spend the money on this update for the 6.7L Cummins. As an example I have been running sine 2009 on my 6.7L Cummins 60HP/120ft-lbs over stock with no engine life issue. Unless you are drag racing or sled pulling with your truck I see no need to spend the dollars or time to upgrade the engine.

Most of the Diesel rags are always trying to advertise/fix for a perceived issue of some sort for all three of the manufactures for diesel engines! This is how they sell the magazines! I have never seen this recommendation in the publication for TDR since I have been a member.

Just saying!!!

 

[Wiredawg]

I tow heavy with mine and would never consider any of these mods. I ran level 5 on my 09 Ram 4500 for 8 years and never had any issues pulling heavy most of its use. I see it the same way Jim W does, these upgrades maybe needed for sled pulling and drag racing. I'm not sure I've seen any issues from Ram 6.7L Cummins owners even with heavy duty cycles on their engines.

EDIT: IMHO, the 6.7L Cummins in our Rams is already fairly bullet proof.

Interesting read, though.

Cheers, Ron

 

[cerberusiam]

Far from racers only, these are the absolute needed mods for daily drivers and heavy tow machines that are running tuned and\or deleted. HG's are a known weakness, have been from the first day these engines rolled out, along with a few other problems that will eventually cause problems. Been there done that, once you pull the safeties and the buffers the emissions provide it is a different story.

The 4500 is a completely different tune and setup, no comparison to the 6.7 in the LD trucks. The 6.7 is far from bulletproof, that has been proven time and time again. The best one can say it is decent platform at stock tuning and running with emissions intact. Tune it, work it hard, delete it, any combination thereof and the failures multiply, there is no safety overhead left in the stock design.

If it was so bulletproof Haisley and Sheid's would not have developed and market a package like they have. More and more shops are now offering the fire ring machining service because the demand is there. Any engine builder worth their price is going to fire ring while tossing and replacing the problem internals if one wants anything OTHER than a stock engine, nobody wants do-overs on an expensive engine. The positive aspect is as many 6.7's that are going thru the shops, the numbers of the other makes are 2-3 times as high.

 

[TFucili]

Cerb, have any of these weaknesses been addressed with the CGI engines?

 

[Wiredawg]

My 4500 was deleted and ran a Mads 90HP tune pulling 21KLb 5er. I've run a 2003 Ram 2500 on level 9 for 5years, A 2002 Ram 3500 same and no blown HG.

So, my experience does not match yours with HG failure or other components for that matter in 20 years of Ram Cummins ownership.

Thanks again for the info tho.

Cheers, Ron

 

[cerberusiam]

My 4500 was deleted and ran a Mads 90HP tune pulling 21KLb 5er.

Different programming, different platform, different results. You started with less emissions equipment, less aggressive fueling and tuning and better gear ratios. It all makes a difference in the end, still not a Ram 2500/3500 where the bulk of the issues are.

Your experience not matching thousands of others doesn't mean much as the problems are real and many go thru it. Pick any diesel forum with a lot of traffic on mods and deletes and you will see 2 or 3 active threads on HG problems almost constantly.

The 6.7 is not a 5.9 and definitely not a 12 or 24V, huge differences in design and engineering in the blocks and heads. The 5.9 was as close to bulletproof as they come and still have plenty left for uprating without issue, not a 6.7 though.

Cerb, have any of these weaknesses been addressed with the CGI engines?

Depends on if they re-engineered the heads to get rid of the steam port issues blowing the HG, balance issues with the rods, ring gaps too tight for emissions, and quality and style of main bearings used. No info on internal changes other than they went away from the previous style of rods to better forgings and of course to hydraulic lifters for NVH. There are probably a lot of the gotchyas still left in there and probably more with the new design. Likely the simaesed cylinders and HG issues will continue to be an issue unless cylinder pressures and temps are tightly controlled. The tendency of the block and head to expand\contract at different rates with the cylinders going egg shaped and the stock cooling system flow problems are at the root of a lot of issues, that has to be addressed with casting changes. Have not seen any in-depth analysis if the blocks yet, bit to new for someone to torch apart.

 

[TFucili]

Thanks.

 

[Wiredawg]

So you are saying THOUSANDS of Ram 6.7L Cummins trucks have blown HGs?

I guess it's possible, especially if folks arent smart about performance upgrades. My experience was planned to NOT have failure... not so with a lot I've read.

The take away is do the upgrades you posted if you are deleting and doing big performance upgrades. Makes sense.

 

[AHutson]

I believe like many issues, the nut behind the wheel can be a big contributing factor. I do understand the desire to upgrade if you have it apart. I did a lot of reading before I decided to put head studs in when I upgraded my 2001's turbo. Probably wasn't necessary but I operate on the better safe than sorry principle. In all my reading the one's popping head gaskets were pushing the engine hard. Also, either a 5.9 or 6.7 seems to pop the stock gasket at the same power level (over 500hp). 6.7 starts with more so doesn't take much adding to hit that level sooner. That all being said, the Cummins is very popular in performance circles so no surprise to me these mods are getting more common. I am in the same boat on this as Wiredawg and Jim, unless going for big and/or all-out performance the upgrades seem a bit overkill.

 

[cerberusiam]

The bulk of the 6.7 HG issues are happening at way less than 500 HP, like stock and little more. Back in the day when the delete kits and tunes first came out there was a steep learning curve, lot of HG issues with the early tunes on deleted trucks. Still a lot on just basic 50 HP daily drivers let alone track performance engines. At one point the shops around here were 1 or 2 per week on stock trucks being worked hard, the tuned\deleted were just part of the statistics.

The reason for deleting and tuning drives the HG issues as does a turbo that is kinda the red headed step child of these engines. Ona 5.9 never really started worrying about HG issues until the build broke 1000 HP and it was all in. The 5.9 HG's have a fire ring in the gasket, 6.7's do not. The 5.9's do not have steam ports exceeding close to the cylinder sans a fire ring. If you don't think a deleted 6.7 on a 425 HP tune at 80% load cannot generate enough heat and pressure to take out an stock HG, or, a failed HE351VE generating 110 lbs of back pressure won't take out a stock HG then you just been lucky.

No matter, you can't fix the engineering problems with the right foot. Once you tear one of these engines down and really start going thru it you see where the issues are and how they affect operational stability.

 

[Wiredawg]

Cerb,

Still learning here, so are you saying the Cab and Chassis 6.7L motors are more robust than the HD pickups? That my gearing helps prevent extreme boost and head pressure? I would think I might would be building MORE head back pressure with my gearing since my 4.88s keep me from running TH with my EB solo due to it being uncomfortably agressive.

I have to say I tend to blow off threads I read where folks delete and tune without planning limits or building the motor to them. Also, I guess the diesel performance businesses selling performance tuner/delete kits don't mention fire ringing and new head bolts recommended.

My own research on my previous 5.9s and my robust 09 Ram 4500 apparently paid off as I never experienced HG problems. I exceeded Aisin transmission max input TQ at the time of 730 LbFt by 80 lbft, which worked with no problems.

You seem to be an expert on this subject, so are we correct in saying the top end upgrades should be done if you ate going to build 60PSI boost or more, or are you saying you recommend these upper end upgrades to everyone, even the completely stock rides?

Thanks for the info, Ron

 

[cerberusiam]

If one is building a 600-700 hp street performance truck and want to use that HP then the fire rings are a need not a nice to have. At that point the VG turbo is gone, bigger injectors, advanced fueling and a lot of other changes that warrant extra work. No disagreement there and there are definitely instances with just minimal mods that some people could break and anvil in a sandbox. No disagreement there. LOL!

However, there are aspects of stock and slightly modified applications that emulate the same scenarios a high HP application does, chiefly high cylinder, high cylinder temps, and the ever present heat soak problem. The question about how those situations occur and the effects took more than few years and some experience to actually work out by trial and error. A lot the issue were on the programming side, it took time to gain experience on the 6.7 because it simply is not the same as a 5.9, the injectors react differently, the siamese cylinders and restricted cooling system create a black hole of unknowns that cause problems.

I referenced one instance of the back pressure out of control. That is NOT saying back pressure blows head gaskets, it is a symptom that in certain leads to the real root cause. On a stock tune the feeling is all calculated to create the best HP and still keep emissions in check. That means the engine is always running stoich rich and the EGR is dumping somewhat expended exhaust back into the cylinder. You can only pull fuel back so far until it effects the TQ, but, what you can do is fuel hard down low then roll it back based on boost and conditions for high emissions along with adding EGR input. The problems ensure when the mechanicals file to a degree and the electronics do not know it and cannot compensate. High back pressure means the VGT is closed too far, either by programming design or some type of internal failure that does not set and DTC's. If back pressure is high that means boost is high and the ECM is still fueling based on boost and throttle input so more fuel than is really needed is present. The high back pressure is cutting down cylinder scavenging of exhaust and leaving unburned fuel in the cylinder along with the additional air and fuel. Plenty of air with plenty of fuel is going to go stoich and stoich lean which bounces temp and pressures way higher than intended in-cylinder. This flows back into the cooling system in the form of heat that takes more circulation to dump but with a restricted flow now you have heat soak into the block and head, quite possible flashing to steam in places further heat soaking the block and head unevenly.

The HG blows in these conditions not because of the cooling system pressure or boost or back pressure, rather because the cylinder pressures and temps have created imbalances in the block and head expansion\contraction rates. That causes the MLS gaskets to break contact with the leaves, head and block leaving a path for high cylinder pressures to to leak. With a tru fire ring in the gasket and steam port cooling passages so close to the pressures the end result is inevitable.

That is just one aspect of even stock programing that can cause problems. Comparatively, the same general things happens if the EGR is deleted and tuning tries to reset to a stoich condition and the load or right foot demands the fueling and air. If everything works correctly the HG holds, but, the inherent weaknesses are still there waiting for the right conditions.

The intent of the article was Bullet Proofing the 6.7 top end, not what conditions it is needed in or causes. The used an example of street performance wants because that is pretty common and itr grabs attention. Same principles apply to the daily driver tow pig multi-use variant trucks, it is about bulletproofing an inherent weakness. Does one need to run out and pull the head and have it done? No, whatever conditions that apply to keeping the HG intact keep on doing them. However, when ti comes time and an HG does actually blow then consider a more permanent bulletproof fix.

The MD trucks with 4.88's may run more rpm and carry more weight but the real variables that affect things are in the demanded load and actual heat\pressure generation. Lower gears give better leverage and even though it take 200-300 rpms to hit speed as compared to a 3.73 truck the overall engine loads will be less, fueling less, and the in-cylinder variables that really count will definitely be less, much less in a lot of cases. IIRC, a 90 HP tuner on an MD engine doesn't even get past 400 HP where the same tune on an LD truck is into the danger zone.

 

[Wiredawg]

Thanks! One LAST question, what is the approximate cost to do all the work listed in the article you linked to? I'm WAGing ~$3-4K.

Anyhoo. information is power, so appreciate the time/effort to explain.

Cheers, Ron

 

[cerberusiam]

We had the block done for $500, the fire headset is about $300, the ARP stud kit is between $300 and $400. A lot of places will say put the ARP 625+ stud kit, that is $1000-1200 depending on where you source it.

Thee head recondition and planing cost us about $400 with new seals and valve job, IIRC. If you do freeze plugs and seats it will be more but that really is a performance mod.

The extra cost will be the machining for the fire ring and special headset.

 

[Jim W]

The bulk of the 6.7 HG issues are happening at way less than 500 HP, like stock and little more. Back in the day when the delete kits and tunes first came out there was a steep learning curve, lot of HG issues with the early tunes on deleted trucks. Still a lot on just basic 50 HP daily drivers let alone track performance engines. At one point the shops around here were 1 or 2 per week on stock trucks being worked hard, the tuned\deleted were just part of the statistics.

The reason for deleting and tuning drives the HG issues as does a turbo that is kinda the red headed step child of these engines. Ona 5.9 never really started worrying about HG issues until the build broke 1000 HP and it was all in. The 5.9 HG's have a fire ring in the gasket, 6.7's do not. The 5.9's do not have steam ports exceeding close to the cylinder sans a fire ring. If you don't think a deleted 6.7 on a 425 HP tune at 80% load cannot generate enough heat and pressure to take out an stock HG, or, a failed HE351VE generating 110 lbs of back pressure won't take out a stock HG then you just been lucky.

No matter, you can't fix the engineering problems with the right foot. Once you tear one of these engines down and really start going thru it you see where the issues are and how they affect operational stability.

Cerb, I respect your knowledge but sometimes you do go too far on some issues! Such as the need to Bullet Proofing the 6.7L Cummins engine!

I had a similar debate with Harvey B. back around May of 2012, about deleting and the head gasket issues on the 6.7L Cummins. What I am basing my thinking on is what MAD'S put out in writing about their testing and the Smarty S67 tuner/programmer, in years past. I believe there might have been some failed head gaskets on the 6.7L Cummings that do apply to being deleted. But this was mainly on vehicles that used other programmers and tuners that where not extensively test before being released to the market place for sale. Such as H&S, Bully Dog and so, forth. In the Cowboy days of the earlier 2007 thru 2009 there were a lot of companies that were selling kits to delete the diesel emissions on all diesel trucks. Most of these kits that offered programmers/tuners that did not do the testing that is required to refine the characteristics of the tuner/programmer to the 6.7L Cummins engine. That is buying trucks and testing them with their tuner/programmer installed to find the failure mode and the cause and effect! MAD'S did! Other causes were the users themselves, who would purchase the delete kits and jack-up the HP/TQ above the safe limits to use for every day driving.

MAD'S pointed this out in their literature, that the SMARTY S67 had nine levels of programs (CaTCHER Levels). These provide different power levels in HP/TQ and their needs to either refine the engine and transmission for safe levels of operation. If my memory severs me right anything above level 3 needs to have changes made to operate the vehicle for longevity otherwise it will fail. Most users, but not all ignored the advice and simply jack-up the program and then suffered the consequences of powertrain failures. They then went on the internet and complained about the radiality of the powertrain and said the Cummins was unreliable. But never providing the information on what cause the failure! This is the problem with the Diesel Rags for sale too.

I do know this for a fact! My older son and his two friends had a Diesel Performance Shop called "No-Limit", as a part time business, in the early days, but it is now out if business (life got in the way). They had several customers who destroy their trucks in less than 24 hours by doing stupid stuff. Such as doing power burn outs at CaTCHER level 9 on a Smarty, or some other tuner set to the maximum. They would than come back and complained that the tuner/programmer cause the powertrain to fail. Little did they realize that the ECM recorded the power level that was used on the trucks (at least with the Smarty). They would fix their trucks but the customers would pay for the fix!

Others who did the deletes in the early days, did not use gauges to monitor the engine parameters at this time, as this added to the expense of the delete. They did not see the need! You do need to monitor the Boost, and the EGT's once you do a delete. I know I do and I drive by the Boost and EGT's when towing. I try and keep the Boost pressure under 30 Max and the EGT's under 1,100 Max when towing my trailer. I have done this since 2009 and I am still have the stock HG intact.

Another thing I have done and most people who have deleted have not done is to leave the EGT cooler on the truck. But block the ports so, no crossover tube to the AIR HORN exist. MAD's point out that the EGT cooler could be left on the truck and did not have to be removed just block the ports with no ill effects. Which I did!

This is my $0.02 on the matter!

 

[cerberusiam]

Again, the title of thread is BULLETPROOFING not whether it is needed for every truck, every driver, every situation. There is no such thing as "too far" in a BULLETPROOFING, the whole goal is to address an inherent weakness with a permanent solution. Same thing we have been doing for some 30 years.

The question of is it too far is an interesting, at what point does that happen? Is it one HG replacement? 2? 3? Where is that magic point at which something is "too far" or "not far enough"? Have you ever changed one of these heads, let alone another trip to the engine shop for maybe more planing, change the oil, flush the cooling system and generally get all the pieces back together and functioning? It is flat out a fair amount of work on some heavy pieces, how many times before the cost I quoted is NOT "too far".

Best bonus of all, the peace of mind to know that particular job is DONE and done right. Now the tuning window is wide open. No longer have to worry about defuel vs fueling parameters, timing advance curves, boost thresholds and the ever present heat soak that happens on a heavy tow vehicle. I submit your "too far" assumption is simply lack of experience with the realities inherent in deleting and modified engines.

Let's compare, you have no failures while I have had 2. We know have 2 engines and 2 failures, all else being equal. Of course, all else is NOT equal so we really do not have a good comparison point. Remember, this is not brand new ideas and problems. This something that is hitting the mainstream for a reason, what other reason could it be than there is a lot more failures of HG's on 6.7's than anyone wants to admit. The root causes and fixes have been pretty much nailed, the article is just the culmination. If you have a 6.7 it ALL applies, you aren't THAT special and your engine isn't either.