Dyno Testing Bolt-ons On The 4.0

[GoldenGorilla]

You can read about people having cracked/broken skirts in stock engines here and other forums. It seems to be more common in these 4.0s than any other stock engine that I've messed with. I haven't had the issue, so I’ve never had to go down that rabbit hole figuring out why. From what I've been told and read, skirts tend to break because of bad/wrong material and/or excessive tolerances (rocking).

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Get to know the Porsche 911 996 and 997.1 generations. They don't break skirts but they have alot of bore scoring and piston slap issues for the same reasons, plus IMS bearing failures. Followed by eye watering repair costs.
I don't think the 4.0 is exceptionally bad about this. Cast iron block and a cast aluminum piston are not exactly a match made in heaven. But I think late 2010s and 2020s engines are going to be looking even worse with time as they've made compromises on rings and pistons to gain marginal reductions in friction losses while at the same time extending service intervals too far.

 

[Brianj5600]

I wonder what percentage of broken skirts are cold starts and how far away from where from where it was parked?

 

[MikeE024]

I don't have a good way to test lockout hubs. I would need a 4wd dyno for that. The 248 I have is 2wd only.

@astjp2

FWIW, I noticed zero improvement with power output or MPGs after switching to lockout hubs a few years ago. I figured it might help a little bit, but that was not the case for me.

 

[SkylinesSuck]

Only one 4.0 on this forum that has skirt issues...

I thought he had a 4 popper? Maybe not.

 

[Steel City 06]

Was that high enough to start floating the valves?

Surprisingly it kept powering through all of that. Through 5,500 there really isn't all that much drop really.

That said I don't go past 5,300 in normal use since there are rumors of a camshaft resonance issue starting around 5,500.

 

[Steel City 06]

Damn no respect....

I was known to rev my 4 angry squirrels up to the redline more than once... But I did say most members... But then I guess the members who are watching this thread aren't "most" members... I'm just going off the number of people who say they never rev their 4.0 above 3K RPM's and wonder why it's so slow.

I drive in ways that would annoy just about any older manual driver. I basically shift like a modern automatic is tuned. Cruising at low load? 1,200 to 1,500 RPM is all you need. Passing someone? Skip two gears and redline it.

 

[Wildman]

I drive in ways that would annoy just about any older manual driver. I basically shift like a modern automatic is tuned. Cruising at low load? 1,200 to 1,500 RPM is all you need. Passing someone? Skip two gears and redline it.

I can't say what I'd drive like anymore.... I flogged my 4 angry squirrels is all I can tell you. And while not a powerhouse I never felt like it was super slow...

 

[srimes]

I drive in ways that would annoy just about any older manual driver. I basically shift like a modern automatic is tuned. Cruising at low load? 1,200 to 1,500 RPM is all you need. Passing someone? Skip two gears and redline it.

Likewise. Low revs under light load gets better mileage, and that dang fan is a lot quieter.

I also do a lot of clutchless shifting in the summer. Meant to ask if other folks do and if there are any issues doing that.

 

[NashvilleTJ]

I thought he had a 4 popper? Maybe not.

Once again I stand by my humor, not necessarily my accuracy…

 

[lBasket]

I also do a lot of clutchless shifting in the summer. Meant to ask if other folks do

I never do

 

[BlueC]

I also do a lot of clutchless shifting in the summer. Meant to ask if other folks do and if there are any issues doing that.

Randomly I'll float a gear in town, but it's rare. Potential issues are damage to synchros and shock loading, it really depends on how you're doing it. Slow and easy with no load probably won't hurt anything. Hard and fast, and she ain't going to be happy, just ask your wife.

 

[ColoJeep]

Randomly I'll float a gear in town, but it's rare. Potential issues are damage to synchros and shock loading, it really depends on how you're doing it. Slow and easy with no load probably won't hurt anything. Hard and fast, and she ain't going to be happy, just ask your wife.

I find it easier to float the occasional gear in a CH-465 than a AX-15. Why bother , it's a car transmission .

 

[BlueC]

a AX-15. Why bother , it's a car transmission

Out of habit when driving normally I use my clutch, but I instinctively rev match or get close, probably close enough to float 'em. Two finger, buttery smooth shifts, my transmissions probably love me in those situations.

 

[srimes]

I find it easier to float the occasional gear in a CH-465 than a AX-15. Why bother , it's a car transmission .

So I can leave my foot resting on the rock slider. I'm lazy like that.

 

[BlueC]

So I can leave my foot resting on the rock slider

That kind of stuff bothers me. I used to know a guy who lost his left arm after he was T-boned. He always rode with his arm hanging out, and then she was gone. I have family members who work in various medical field position, and I've heard/seen of people being messed up bad after a wreck simply because they had their foot in the wrong place, like up on the dash. Big no-no in my vehicles.

 

[srimes]

That kind of stuff bothers me. I used to know a guy who lost his left arm after he was T-boned. He always rode with his arm hanging out, and then she was gone. I have family members who work in various medical field position, and I've heard/seen of people being messed up bad after a wreck simply because they had their foot in the wrong place, like up on the dash. Big no-no in my vehicles.

Still much safer than a motorcycle. I bring it in when there's traffic.

 

[Rickyd]

Still much safer than a motorcycle. I bring it in when there's traffic.

An open jeep gives that out in the wind experience while letting you wear a seat belt.

But in a serious wreck i doubt I'd be able to keep limbs inside anyway. Oh well

 

[ColoJeep]

An open jeep gives that out in the wind experience while letting you wear a seat belt.

But in a serious wreck i doubt I'd be able to keep limbs inside anyway. Oh well

Somewhere between riding a twin turbo unicycle and strapping in like a Nascar cup car is the balance .

 

[Steel City 06]

That kind of stuff bothers me. I used to know a guy who lost his left arm after he was T-boned. He always rode with his arm hanging out, and then she was gone. I have family members who work in various medical field position, and I've heard/seen of people being messed up bad after a wreck simply because they had their foot in the wrong place, like up on the dash. Big no-no in my vehicles.

https://www.toyota-4runner.org/off-...your-hands-feet-inside-vehicle-all-times.html

 

[Wildman]

Not to steal @Jezza thunder but here's Part 2 in his video series...