Intake Cam Failures - Materials, Design, or both?

[bmpcamry09]

Some info on VVL from my manual

I posted that same page up in one of my tuning threads. Proves that the VVL operation theory is backwards to what you would believe. Although I find it funny they mention “torque” when it’s 100 percent for emissions. Torque gains are far greater tuning the intake cam to advance earlier paired with better spark timing.

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[northernrider]

So both the outside lobes on cylinder 3 were wiped out on your JL? Then the center lobe on cylinder 1? Just want to confirm since most of these I’m seeing just the center high lift low failing. Just curious

I guess I worded that poorly. The inside lobe from cyl.5 and both lobes on cyl.3 were wiped.

 

[Remorseless]

I posted that same page up in one of my tuning threads. Proves that the VVL operation theory is backwards to what you would believe. Although I find it funny they mention “torque” when it’s 100 percent for emissions. Torque gains are far greater tuning the intake cam to advance earlier paired with better spark timing.

With those tuning changes where is the torque gain realized in the rev range? My reading of those lines in the manual are "We want juuuuuust enough torque lower in the rev range to keep you in 8th gear for MPGs"

 

[northernrider]

Are the PUG cams failing with the rollers still intact? My thought has always been it's cheap roller bearings failing and collapsing and then wiping out the cams, and that the rollers that are going are just in a less-well-oiled spot in the valvetrain. Couple that with Jeep struggling to get all the casting sand out of the engines over the years and cheap bearings getting gummed up in a spot where oiling isn't amazing, and that's a pretty plausible way for the cam to get wiped out.

The rollers on the three rockers that were worn on mine were perfect. The lifters seemed perfectly fine too, but I changed them anyway for cheap insurance.

 

[bmpcamry09]

With those tuning changes where is the torque gain realized in the rev range? My reading of those lines in the manual are "We want juuuuuust enough torque lower in the rev range to keep you in 8th gear for MPGs"

Part throttle torque available below 3000 RPM is 25-40 foot pounds increased with my tuning changes. Low end on 87 since spark timing has to remain stockish to keep cylinder pressure in check. But I can command and actually receive an extra 50 pound feet of torque under 3000 on 93 octane with the right part throttle spark mapping, torque management changes, and cam behavior. Can’t prove that low on a dyno easily but I see it in the datalogs on everyone I tune. And literally everyone I’ve done is surprised at how much they were lacking below 3500 on stock.

 

[bmpcamry09]

@Remorseless just let me tune yours already. Your such a loudmouth on this forum if I get you tuned right I’d have business for life

Then again if you don’t like it, I’d be doomed.

 

[Remorseless]

@Remorseless just let me tune yours already. Your such a loudmouth on this forum if I get you tuned right I’d have business for life

Then again if you don’t like it, I’d be doomed.

lol, maybe the 2.0 one day. The 3.6 in the truck is staying stock as can be. It's the family hauler/beach rig. I feel like my 2.0 would be more fun with a tune anyway.

 

[bmpcamry09]

lol, maybe the 2.0 one day. The 3.6 in the truck is staying stock as can be. It's the family hauler/beach rig. I feel like my 2.0 would be more fun with a tune anyway.

I need a 2.0 in person so I can get going on that. But all the GPEC2A ones are getting up there in miles now and I don’t think HP Tuners supports the newer ones yet.

I had a 2020 2.0, but was too busy doing Ecoboost stuff I never got around to it. It takes about 30 minutes of tuning and some 93 octane to make 50 plus extra HP/TQ on the Ford stuff. I’m sure this would be good too

 

[Remorseless]

I need a 2.0 in person so I can get going on that. But all the GPEC2A ones are getting up there in miles now and I don’t think HP Tuners supports the newer ones yet.

I had a 2020 2.0, but was too busy doing Ecoboost stuff I never got around to it. It takes about 30 minutes of tuning and some 93 octane to make 50 plus extra HP/TQ on the Ford stuff. I’m sure this would be good too

Well if you were in NC I'd volunteer. The 2 door with a tune would be fun as hell.

 

[northernrider]

Flat tappet cams have been used for decades without having constant failures so long as they are properly lubricated and not overloaded. So I wouldn't say that roller bearings are a requirement.

The lifter on a flat tappet cam can also freely rotate on the cam lobe. I wonder if that helps with lubrication. On the PUG the cam contacts the rocker in exactly the same place. I wonder if there is increased friction on the PUG as compared to a OHV flat tappet design.
I'm not an engineer or even a licensed mechanic. This is just a thought, I might be way out in left field.

 

[bmpcamry09]

The lifter on a flat tappet cam can also freely rotate on the cam lobe. I wonder if that helps with lubrication. On the PUG the cam contacts the rocker in exactly the same place. I wonder if there is increased friction on the PUG as compared to a OHV flat tappet design.
I'm not an engineer or even a licensed mechanic. This is just a thought, I might be way out in left field.

Hey don’t be hard on yourself. You are a certified forum poster, and that means something

Unless you ask what engine you should get in your Jeep. Those threads create wars.

But that definitely makes sense, I don’t believe the high lift side lifters move much, but I think there is a small port in the middle of them at the top to allow for oil flow.

 

[azjl#3]

As a visual reference for everyone. This is what I would expect from a cam failure with proper heat treatment, but lack of lubrication/overload condition.

But since we don't see that cracking of the surface hardening, that leads to spalling, I am questioning the hardness of the cams. Especially when the slipper on the followers seems to show much less wear.

agree.

I just watched a 3.6 teardown vid, I am amazed there seems to be no designed way to guide the arm, other than the roller following the cam lobe, and the camshaft holding it down, with zero guidance. Sure seems like it could develop some serious oscillation at rpm? Leading to wear.

 

[DaltonGang]

So, how much is an LS swap?? Problem solved.

 

[Fishdoc]

So, how much is an LS swap?? Problem solved.

I had it repaired, intake cam (right side) at 46k. If it happens again down the road, an engine swap is in my future. Never getting rid of the Jeep, bought brand new. It's been paid off for a while.

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