Does WOT really help the Pentastar?

[Fatbob Frank]

my 3.6 psi is around 31 psi or so when driving under 2000 rpms. I agree tho I don't really just let it idle for any length of time.

I guess I really don't see a problem with 31 PSI when the engine isn't under load...
Thin weight oil nearing 200 degrees with non-gummed up oil channels you wouldn't think there'd need to be a lot of pressure...
The Magnum 5.2L in my 1999 Dakota only had like 15psi at idle running 10w40...
It probably only broke 30psi at 3K or higher...

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[jadmt]

I guess I really don't see a problem with 31 PSI when the engine isn't under load...
Thin weight oil nearing 200 degrees with non-gummed up oil channels you wouldn't think there'd need to be a lot of pressure...
The Magnum 5.2L in my 1999 Dakota only had like 15psi at idle running 10w40...
It probably only broke 30psi at 3K or higher...

my thoughts too. 30+ psi seems fine to me.

 

[Zandcwhite]

I guess I really don't see a problem with 31 PSI when the engine isn't under load...
Thin weight oil nearing 200 degrees with non-gummed up oil channels you wouldn't think there'd need to be a lot of pressure...
The Magnum 5.2L in my 1999 Dakota only had like 15psi at idle running 10w40...
It probably only broke 30psi at 3K or higher...

The 5.2L had a 9.6-1 compression ratio and made peak power (just 230hp) at 4100 rpm. The pentastar has an 11.3-1 compression ratio and doesn't make peak power until 6200rpm, well past the redline of the 5.2L. It very much needs that 2 stage oiling system at those rpms and pressures. Apples and oranges.

 

[Fatbob Frank]

The 5.2L had a 9.6-1 compression ratio and made peak power (just 230hp) at 4100 rpm. The pentastar has an 11.3-1 compression ratio and doesn't make peak power until 6200rpm, well past the redline of the 5.2L. It very much needs that 2 stage oiling system at those rpms and pressures. Apples and oranges.

I didn't mean to imply they were- just using it for a point of perspective that 31psi isn't an insignificant amount, especially considering ( as you mentioned) the oil pressure goes up dramatically when the engine needs it..

 

[jadmt]

I didn't mean to imply they were- just using it for a point of perspective that 31psi isn't an insignificant amount, especially considering ( as you mentioned) the oil pressure goes up dramatically when the engine needs it..

ditto, at idle and below 2000rpm under low load 31psi seems plenty...punch it and it goes up instantly according to my gauges. mine also shoots up on initial start up for brief bit.

 

[roaniecowpony]

Does WOT really help the Pentastar?

Define "help".

 

[Brad Hearing]

The pentastar design engineer says yes, do it.

Nice! As an former Pentastar design engineer I am slightly bias but the engine is really high quality. Few points from the development using tens of millions of dollars in analysis and testing regarding the oil and durability..... The lighter oil was chosen mostly for fuel economy BUT engineering is the science of compromise. You help one thing but hurt another. A thicker oil will reduce timing chain and tensioner wear because the center timing chain idler doesn't go fully hydrodynamic till about 1650rpm on 5w-20. So, a thicker oil will lower that number slightly and with general loads/speeds the engine spends a lot of time around 1500-1750 rpm with the 8 speed. So thicker oil is a win there. Additionally, the earlier engines had what was called the "McDonald's Arches" in the idler bearing which was intended in making a more uniform distribution but in actuality acted as a knife edge. This design was changed around 2014 to a smooth bearing. So overall timing chain issues will likely follow the 2011-2014 engine years more than 2014+. Where you lose.... The head is very complicated with a Type II valve train. Meaning lots of things to pressurize and pump up at start up. A thicker oil didn't do so well here (on long sit times +cold start) and contributed to a overall increased engine wear especially in the head and cam bearings. Last point. This engine needs occasional WOT runs if you want it to last. Granny cycling is bad for it. So bad for it we actually created a new granny cycle test during the cylinder #3 misfire issue. The highest wear is in the valve guides, because of tight valve stem seals (for emissions, reduce oil burn). They basically dry out. When you go WOT/high rpm/load you get some fresh oil in there and this keeps the wear down. Thicker oil might not help this condition but we also change the valves/guides/seals in 2014+. Not sure the impact. Cheers! Kevin PS. Turn off stop start and do not run e85 if you are concerned about engine wear. Eats the engine alive.

Question:

whats the difference between going full throttle and just running at a normal speed with a really low gear in terms of effect on engine as you describe above?

 

[Old Dogger]

Question:

whats the difference between going full throttle and just running at a normal speed with a really low gear in terms of effect on engine as you describe above?

The full throttle (WOT) is only recommended on occasions to help flood the VVT systems in the cylinder heads with additional engine oil, for better lubrication of the system. Many of us feel that some of the rocker arm cam failures, would be prolonged with more oil flow to them. Particular to the upgraded intake rocker arms that no longer have a roller, but rather a metal-to-metal wear factor applied drag.

 

[roaniecowpony]

WFO or 1/2 throttle don't affect oil volume or pressure. Since the oil pump is connected to the crankshaft with a chain, RPM is the only relevant variable controlling oil flow.

 

[jadmt]

WFO or 1/2 throttle don't affect oil volume or pressure. Since the oil pump is connected to the crankshaft with a chain, RPM is the only relevant variable controlling oil flow.

but the WFO is much more enjoyable

 

[Brad Hearing]

The full throttle (WOT) is only recommended on occasions to help flood the VVT systems in the cylinder heads with additional engine oil, for better lubrication of the system. Many of us feel that some of the rocker arm cam failures, would be prolonged with more oil flow to them. Particular to the upgraded intake rocker arms that no longer have a roller, but rather a metal-to-metal wear factor applied drag.

thanks for the answer but i dont quite follow. please understand i know nothing about how engines actually work and can only conceptualise the parts you mention and not how they interact. ie I know what a camshaft looks like, no idea what it does.

if I drove my car to work in second gear when it normally needs 4th, am I not giving it an italian tune up?

 

[Old Dogger]

if I drove my car to work in second gear when it normally needs 4th, am I not giving it an italian tune up?

Yes, the higher RPM generated will help the oil flow..IMO

 

[Brad Hearing]

Yes, the higher RPM generated will help the oil flow..IMO

ahh but it will lubricate the seals or whatever like what you said when you go WOT? in otherwords is it for all intents an purposes the same as going WOT?

 

[jadmt]

ahh but it will lubricate the seals or whatever like what you said when you go WOT? in otherwords is it for all intents an purposes the same as going WOT?

if your oil pressure is up 75psi sure you are getting it done. if you have never did a WOT run you should just to see how good it feels...and contrary to what some people think it will not hurt your vehicle...just do it it in a safe place with no one around.

 

[Old Dogger]

ahh but it will lubricate the seals or whatever like what you said when you go WOT? in otherwords is it for all intents an purposes the same as going WOT?

It will help some, but it is not going to flood the vvt overhead the same way that WOT will. This is why, the Design Engineer recommends WOT.

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