DOD Delete - "Stock" or stage 1 cam? VVT Delete?

[thefrey]

Getting a list together for a DOD delete.

Looking like things can get real expensive real quick depending on what your scope ends up being.

I figured while I'm putting in a new cam, might as well put an upgraded cam in, but it's where things get messy. I am trying to figure out if a stage 1 cam will need a VVT delete, then I get to the question if I should keep VVT.

Then, a stage 1 cam is going to need special tuning. Seems like an upgraded cam ends up being an extra $1000 from all the goodies for maybe 20-30 hp gains unless I am missing something. I don't know if an aftermarket engine + transmission tune is worth it for me...


I would ideally like to keep a stock profile and add just a little bit of power. I don't want to take a big hit in MPGs.


Thoughts on stock vs upgraded cam and/or VVT delete?

 

[Marky Dissod]

I would ideally like to keep a stock profile and add just a little bit of power. I don't want to take a big hit in MpGs.

No such thing as a cam that improves MpGs. IFF I'm wrong, it'd be a cam that improves low-RpM torque at the expense of high-RpM ...
and your 6L80 might need to get upgraded to withstand the extra power released by the cam, regardless of where the extra power happens on the tach.

So far as I know, only mod that can possibly improve MpG: axle gearing.

 

[thefrey]

No such thing as a cam that improves MpGs. IFF I'm wrong, it'd be a cam that improves low-RpM torque at the expense of high-RpM ...
and your 6L80 might need to get upgraded to withstand the extra power released by the cam, regardless of where the extra power happens on the tach.

So far as I know, only mod that can possibly improve MpG: axle gearing.

Yeah, by no means am I expecting an increase in MPGs. I just don’t want to end up getting a bigger cam if it means I end up with a 3-5+ mpg loss.

I figured the 6L80 with a new or upgraded torque converter could handle a little bit more power over stock, but maybe that’s incorrect.

 

[rdezs]

I think everyone weighs that option when preparing for an AFM delete.

I guess the answer is what your intentions are for the vehicle. And of course the added money. The 6L80E is the primary concern.

The most affordable option and what probably results in the most reliability and longitivity of the drivetrain, is basically keeping it in stock trim without the AFM, but keeping the VVT. And that pretty much means picking up a camshaft for the same engine that was used by GM prior to implementing AFM. (For the 6.2 L94 for example, you would want an L92 or L9h camshaft)

That will end up with you retaining the same horsepower and torque. I think the money spent on getting that extra 30 or 40 horsepower, would be better spent on replacing the OEM torque converter, maybe some rebuilt fuel injectors, etc.... if your goal is long-term longevity and reliability. The diablosport predator 2 for GM will turn off the AFM, it also has a canned tune 87 octane that usually gives you between 1 and 1.5 mpg increase. There's a few options for the transmission as well that tightens up the shifting, resulting in less slippage and lower temperatures, which should prolong transmission life. (There's also a tune to add more horsepower as well) Last time I checked the Diablo was between $350 and $400, but it's probably the most user-friendly for the novice and simple to get done what you want done. By contrast the HP tuners is a lot more money, but let you get down into intricate details and involves a learning curve.

You are on the right track by reading the forum and doing research before deciding on the plan.

 

[Scrappycrow]

The diablosport predator 2 for GM will turn off the AFM, it also has a canned tune 87 octane that usually gives you between 1 and 1.5 mpg increase.

Do you (or anyone else) know how they're tuning to stay on 87 and get that MPG increase? One would think there wasn't much margin to achieve that, or else GM would have already done so.

 

[thefrey]

I guess the answer is what your intentions are for the vehicle.

At this point, I've basically come to the conclusion that doing a DOD delete and keeping this truck alive is going to be cheaper/better in the long run for me, rather than trying to find a replacement that I have no idea what issues it has. Plus, replacing it isn't exactly cheap. Figured I would put another 50-100k on the clock before I give er' up...

I don't know if the cam is worth it from what it seems like. I also have e85 near me, so it might make more sense to just get some extra power through something like a Diablo running corn rather than a bigger cam.

I think I want to pull the engine since it'll be easier to work on the engine outside the car, but it'll make replacing the TC easy also. So it's just kind of a two birds with one stone type of deal. Not sure if it would be easier to just drop the trans to get to the TC and do the delete inside the car.

But, I may try to address the cam bearings if I pull the engine. I don't know if I want to touch the rods/mains (or any bearings for that matter)... this is all new territory for me, so I don't want to bite off more than I can chew and lock up my engine. I guess if it ain't broke don't fix it type of deal...

I have dreams of putting a turbo kit on it in a couple of years when I don't need the reliability. Nothing too crazy, just a few lbs of boost to give it a little pep. Doubt it'll happen, but it would be fun.

 

[Joseph Garcia]

At this point, I've basically come to the conclusion that doing a DOD delete and keeping this truck alive is going to be cheaper/better in the long run for me, rather than trying to find a replacement that I have no idea what issues it has. Plus, replacing it isn't exactly cheap. Figured I would put another 50-100k on the clock before I give er' up...

I don't know if the cam is worth it from what it seems like. I also have e85 near me, so it might make more sense to just get some extra power through something like a Diablo running corn rather than a bigger cam.

I think I want to pull the engine since it'll be easier to work on the engine outside the car, but it'll make replacing the TC easy also. So it's just kind of a two birds with one stone type of deal. Not sure if it would be easier to just drop the trans to get to the TC and do the delete inside the car.

But, I may try to address the cam bearings if I pull the engine. I don't know if I want to touch the rods/mains (or any bearings for that matter)... this is all new territory for me, so I don't want to bite off more than I can chew and lock up my engine. I guess if it ain't broke don't fix it type of deal...

I have dreams of putting a turbo kit on it in a couple of years when I don't need the reliability. Nothing too crazy, just a few lbs of boost to give it a little pep. Doubt it'll happen, but it would be fun.

Sounds like to me, you still don't really know how you want to proceed.

My suggestion to you is to get a remote BlackBear Performance tune (~$800), which will disable the AFM, not kill your mpg, give you the additional pep that you are looking for, and will make your transmission operate much more efficiently (and lengthen its life). And, you won't have to pull your motor apart, or spend extra money on the related hardware. For a small fee, you can make future tune adjustments, as needed, if you eventually decide to make some other mechanical improvements to your truck, so you lose nothing in terms of future mods.

Give them a call and discuss your needs. Their reputation is stellar and many folks on this Forum have BlackBear Performance tunes.

 

[rdezs]

Do you (or anyone else) know how they're tuning to stay on 87 and get that MPG increase? One would think there wasn't much margin to achieve that, or else GM would have already done so.

Considering it was done at the same time as the AFM delete, some of the increases probably due to the delete itself. As the AFM system gets older it is not as efficient and fuel mileage suffers. Hard to say what is contributing the most to the mileage increase

 

[thefrey]

Sounds like to me, you still don't really know how you want to proceed.

My suggestion to you is to get a remote BlackBear Performance tune (~$800), which will disable the AFM, not kill your mpg, give you the additional pep that you are looking for, and will make your transmission operate much more efficiently (and lengthen its life). And, you won't have to pull your motor apart, or spend extra money on the related hardware. For a small fee, you can make future tune adjustments, as needed, if you eventually decide to make some other mechanical improvements to your truck, so you lose nothing in terms of future mods.

Give them a call and discuss your needs. Their reputation is stellar and many folks on this Forum have BlackBear Performance tunes.

I think I know what I want to do, but I don't how exactly to do it, that's my issue.

I think I am going to need a DOD delete in the future. I have a tick and it concerns me because it feels like a ticking time bomb... I also really don't know where or why it's happening. I can only assume it's a lifter. I took this video in slow mo and you can hear the tick. I haven't checked the driver side because it sounds like it's passenger, but perhaps it's some sort of echo.

That brings me to the thought process of well, if it's ticking, I might as well bite the bullet and do a DOD delete now.

I just constantly have a worry of "mistrust" with it... I am going to most likely be making a 2500 mile road trip here in a couple of months, and I would like to take this car. I can only assume it would be fine w/ a lifter ticking considering it's ticked on and off for the past 15k miles, but I don't know if I want to find out.


I already have AFM disabled via a Range disabler. I guess I wouldn't mind if I didn't delete the AFM and just left it disabled, just the constant tick without any misfiring is what scares me because I don't know where exactly it's coming from or how long I have. My only concern is I think the AFM system is bleeding pressure somewhere. I have 20psi idle and maybe 35 cruising.

It's just what options should I go with if I do a DOD delete (scope creep lol) and what makes sense for long term.

 

[Joseph Garcia]

I think I know what I want to do, but I don't how exactly to do it, that's my issue.

I think I am going to need a DOD delete in the future. I have a tick and it concerns me because it feels like a ticking time bomb... I also really don't know where or why it's happening. I can only assume it's a lifter. I took this video in slow mo and you can hear the tick. I haven't checked the driver side because it sounds like it's passenger, but perhaps it's some sort of echo.

That brings me to the thought process of well, if it's ticking, I might as well bite the bullet and do a DOD delete now.

I just constantly have a worry of "mistrust" with it... I am going to most likely be making a 2500 mile road trip here in a couple of months, and I would like to take this car. I can only assume it would be fine w/ a lifter ticking, but I don't know if I want to find out.


I already have AFM disabled via a Range disabler. I guess I wouldn't mind if I didn't delete the AFM and just left it disabled, just the constant tick without any misfiring is what scares me because I don't know where exactly it's coming from or how long I have. My only concern is I think the AFM system is bleeding pressure somewhere. I have 20psi idle and maybe 35 cruising.

It's just what options should I go with if I do a DOD delete (scope creep lol) and what makes sense for long term.

Well, then get a mechanic's stethoscope and pinpoint the location of the tick. It might be a relatively easy fix without tearing the entire motor apart, and, when you locate the source of the tick, it may not even be related to a lifter.

20 psi oil pressure at idle for a hot motor is perfectly fine. 35 psi oil pressure at 'cruising' may be a bit low, depending on what your cruising rpms are.

 

[thefrey]

Well, then get a mechanic's stethoscope and pinpoint the location of the tick. It might be a relatively easy fix without tearing the entire motor apart, and, when you locate the source of the tick, it may not even be related to a lifter.

20 psi oil pressure at idle for a hot motor is perfectly fine. 35 psi oil pressure at 'cruising' may be a bit low, depending on what your cruising rpms are.

It's in time with the cam, so I can only assume it's a lifter at the moment. I have no idea what else would be able to make a sound like that... Unless I can fix it with a slightly longer push rod or something? I don't know...

That's cruising at about 75-80, so I think around 1800-2000rpm if I recall correctly? I get like 45 cold, it'll spike to 50+ on cold revs. It just seems like I should have almost double what I have right now if I do a DOD delete. My pressure drops to about 15 if I'm coming right off the highway.

I think I need to go spend the 8 bucks at Harbor Freight to get a stethoscope to try to pinpoint the tick...

My only guess is maybe the new head gasket the last owner put on is slightly thinner than the old one and causing some extra slack in a rocker. But I don't know if that's how that would work with the hydraulic lifters lol.

 

[Joseph Garcia]

It's in time with the cam, so I can only assume it's a lifter at the moment. I have no idea what else would be able to make a sound like that... Unless I can fix it with a slightly longer push rod or something? I don't know...

That's cruising at about 75-80, so I think around 1800-2000rpm if I recall correctly? I get like 45 cold, it'll spike to 50+ on cold revs. It just seems like I should have almost double what I have right now if I do a DOD delete.

I think I need to go spend the 8 bucks at Harbor Freight to get a stethoscope to try to pinpoint the tick...

My only guess is maybe the new head gasket the last owner put on is slightly thinner than the old one and causing some extra slack in a rocker. But I don't know if that's how that would work with the hydraulic lifters lol.

Yes, it could be a bent rod and not a bad lifter, but, either way, if you isolate the source of the noise, you may only have to remove 1 head to fix it.

35 psi oil pressure at 1800-2000 rpms is not bad at all, but yes, over 40 psi oil pressure would be more reassuring.

 

[thefrey]

Yes, it could be a bent rod and not a bad lifter, but, either way, if you isolate the source of the noise, you may only have to remove 1 head to fix it.

35 psi oil pressure at 1800-2000 rpms is not bad at all, but yes, over 40 psi oil pressure would be more reassuring.

I checked two of the pushrods that synced up with the noise on that side of the engine in that video. They were both straight and didn't have any issues. I am just confused because I am having trouble finding what the problem actually is.

The low(er) oil pressure concerns me a bit, so that's another thing driving me towards a DOD delete.

 

[rdezs]

The complexities of the AFM system can easily create oil pressure issues by itself. (Beyond the normal items like the pickup tube o-ring, oil pressure relief valves and such) On your engine valley you have the VLOM plate. To make matters worse, most of the time you will find at least half of the bolts holding it down loose. For some reason GM decided not to use loctite on the bolts. When you look at the underside of that plate, and realize the crazy concoction of routing oil that exists and the many places for it to leak and bleed off pressure.... You will really start to question the wisdom of what engineer designed the thing.

This is the underside of one removed and around 170,000 miles. The clean areas where you can actually still see aluminum are obvious places oil had been spraying out. Although the gasket looks like originally it was some type of rubber, it was very hard and brittle.

Don't forget you also have a metal screen underneath your oil pressure sending unit. It's known to collect crap, preventing the sending unit from receiving the full oil pressure. So for starters you can swap out the sending unit and replace the little screen under it ...see if your oil pressure comes up.

You will want to be 100% sure you don't have an exhaust leak. I guarantee you that many of them sound exactly like a lifter ticking. Make sure all your manifold bolts are in place. A smoke machine does wonders when trying to locate a leak between the head and the exhaust manifold.... Or there's the old school way with that big cigar. (Probably frowned upon by the EPA these days!)

If it's a lifter, doing the delete is pretty much a no-brainer. I can't imagine anyone wanting to spend the money to repair the AFM system, knowing it's reliability is in doubt.

As for the AFM lifters themselves, wait till you see the big spring on the end of it.... And just ponder how long that supposed to last!

Lifter on top is obviously the AFM lifter. The one below is a normal lifter.

The whole design raises many questions.... Nobody ever talks about the overall balance of the valve train..... But this setup makes one ponder that as you have several lifters that weigh a lot more than the other lifters. I have my own theory as to why AFM equipped engines go through cam bearings faster than the non AFM engines.... And it involves this very item.

 

[thefrey]

The complexities of the AFM system can easily create oil pressure issues by itself. (Beyond the normal items like the pickup tube o-ring, oil pressure relief valves and such) On your engine valley you have the VLOM plate. To make matters worse, most of the time you will find at least half of the bolts holding it down loose. For some reason GM decided not to use loctite on the bolts. When you look at the underside of that plate, and realize the crazy concoction of routing oil that exists and the many places for it to leak and bleed off pressure.... You will really start to question the wisdom of what engineer designed the thing.
View attachment 472304
This is the underside of one removed and around 170,000 miles. The clean areas where you can actually still see aluminum are obvious places oil had been spraying out. Although the gasket looks like originally it was some type of rubber, it was very hard and brittle.

Don't forget you also have a metal screen underneath your oil pressure sending unit. It's known to collect crap, preventing the sending unit from receiving the full oil pressure. So for starters you can swap out the sending unit and replace the little screen under it ...see if your oil pressure comes up.

You will want to be 100% sure you don't have an exhaust leak. I guarantee you that many of them sound exactly like a lifter ticking. Make sure all your manifold bolts are in place. A smoke machine does wonders when trying to locate a leak between the head and the exhaust manifold.... Or there's the old school way with that big cigar. (Probably frowned upon by the EPA these days!)

If it's a lifter, doing the delete is pretty much a no-brainer. I can't imagine anyone wanting to spend the money to repair the AFM system, knowing it's reliability is in doubt.

As for the AFM lifters themselves, wait till you see the big spring on the end of it.... And just ponder how long that supposed to last!

Lifter on top is obviously the AFM lifter. The one below is a normal lifter.
View attachment 472305

The whole design raises many questions.... Nobody ever talks about the overall balance of the valve train..... But this setup makes one ponder that as you have several lifters that weigh a lot more than the other lifters. I have my own theory as to why AFM equipped engines go through cam bearings faster than the non AFM engines.... And it involves this very item.

I am sadly all too familiar with the VLOM. I cut the gaskets on mine since I had a lifter collapse, and then I took a circular plug and blocked off the passage to the VLOM. Just ends up being a 3x fail safe with the disabler, cut gaskets, and plug. This itself gave me a good 5+ psi...

All from CPR's lifter release kit.

I ended up using AI to help me create a plan of diagnosis LOL. I'm sure a lot of people might frown upon that but it seems to have given me a solid plan... but it makes sure I don't drive everybody on this forum absolutely nuts with the amount of questions I ask. Basically going to get a mechanics stethoscope and utilize that to check for the usual exhaust leak or lifter tick, then check the lifter preload to see if I have a lifter that is bleeding off... we'll see if that gets me anywhere. I just wanna diagnose the issue before I spend a ton of time + money with a DOD delete. My current guess is that I have a tired AFM lifter that's bleeding off pressure.


Interesting thought as to why the cam bearings are getting trashed quicker. Makes sense in my opinion. I wonder if they get trashed more on one side of the bearing than the other given the slight displacement of the camshaft when it's pushing heavier lifters.

 

[rdezs]

I'm actually amazed the subject has never really come up that I have seen. I guess the bottom line is.... Would you even build an engine with half your lifters weighing twice as much as the rest of them? What engineer would publicly say that's a good idea?

And yet here we are 15 years later, and GM has doubled down on the idea and made it even more complex. Yeah, no way I'd buy one of the new ones.

 

[Marky Dissod]

Yeah, by no means am I expecting an increase in MpGs. I just don’t want to end up getting a bigger cam if it means I end up with a 3-5+ MpG loss.

I figured the 6L80 with a new or upgraded torque converter could handle a little bit more power over stock, but maybe that’s incorrect.

As said, only mod that MIGHT improve MpGs is more axle gear.
Don't know which axle gear Denalis tend to come with; I'll assume 3.08, since that's the base gear for 5.3L suvs, and CAFE is a byatch.

3.08 to 3.42 improves tow rating, meaning city MpG would also very likely improve (unless you trade MpGs for smiles per gallon).
Improving tow rating is also another way to say that the vehicle can apply more power to the ground (even though the engine is not making any more power),
so if you were to race another 6.2L XL with lesser gear, even though your engines may make about the same power, YOU WIN!
More axle gear also takes some of the strain off the transmission when you're NOT flooring it.
Not exactly an 6L80HD rebuild, but easier on the 6L80 than adding more horses to the engine with weaker axle gearing.
3.42, by the way, is the GM OE tow pack axle gear for 5.3L suvs.

If you feeln froggi, 3.73 is the GM OE axle gear for 2500s.

 

[hagar]

I'm actually amazed the subject has never really come up that I have seen. I guess the bottom line is.... Would you even build an engine with half your lifters weighing twice as much as the rest of them? What engineer would publicly say that's a good idea?

And yet here we are 15 years later, and GM has doubled down on the idea and made it even more complex. Yeah, no way I'd buy one of the new ones.

Factory installed LS bearings look pounded out right from brand new, some worse than others. When gm builds an ls/lt engine, they install the cam bearings, then align hone the cam bearings instead of the cam bearing bores. It depends on each engine and how much core shift it has during casting, but it's not uncommon to take a brand new gm engine that has never been ran, and have cam bearings with copper showing through like they are worn out already. If you get an ls/lt engine with a particularly bad core shift, then put in new cam bearings, it can sometimes be hard to even put a cam back in, and often times is hard to even turn the cam by hand.
I cant see the extra weight of a lifter causing extra bearing wear, the affect of the extra weight, in comparison to the massive spring opening forces from normal operating, would be minimal if anything.