How many sub 4K rpm street trucks did NOT upgrade valve springs

I was going to ask... how much reversion is there in a boosted application?

It seems weird theres soot in the intake with a direct injected application, does it not? That would make me instantly think valve float. IDK, i'm not an engine builder nor a diesel mechanic.
 
Pretty simple enough boost and the valves will open when they are not supposed to and bad, not so bad, or catastrophic things may occur.
 
JBradley500 said:
was going to ask... how much reversion is there in a boosted application?

It seems weird theres soot in the intake with a direct injected application, does it not? That would make me instantly think valve float. IDK, i'm not an engine builder nor a diesel mechanic.
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You got it right...just kinda mixed up.
The valve float allows reversion to happen.
Another way: when the intake valves don't close all the way soot can travel back through them into the intake tract (reversion)
The redneck way: that chit done moved backerds....yup
 
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yeah, but where on the map of the cam? between exh/intake stroke? I cant see it happening anywhere else
 
UNBROKEN said:
You got it right...just kinda mixed up.
The valve float allows reversion to happen.
Another way: when the intake valves don't close all the way soot can travel back through them into the intake tract (reversion)
The redneck way: that chit done moved backerds....yup
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yeah i can understand that... i guess i wouldnt call it reversion though, just valve float. I think of reversion as air backing up the intake tract because of air with "momentum" running into a wall (the valve) and needing a place to go.
 
There's bound to be reversion during overlap when you have a large differential between drive and boost.

Its unlikely boost is opening the intake valves....any time you have the "big boost" you have the big drive to match that, and the other side of the valve is seeing that.

Where the few have seen power gains from springs is likely from drive contamination during cylinder fill and where the cylinder comes as close to a negative pressure.....more likely at higher rpms..... Rpm's being the larger factor when it comes to destructive float.
 
Think about this mathematically for a second. Boost is measured (and drive as well for that matter) in Pounds/Square Inch
Spring pressure is measured in Pounds
So when boost reaches a pressure that pushes on the exposed area of the intake valves that is greater than the pressure the spring puts on the valve, it is going to crack open. I'm not sure of the area of the valve that boost is going to push on, or I would run the numbers. Once that valve cracks open though, math gets real crazy because you will also have to have enough flow to keep it open and maintain increasing pressure to open it further.
 
You have to account for the pressure on the other side of the valve as well. Compression-combustion-exhaust stroke....all high pressure conditions relative to boost.
 
Joesixpack said:
There's bound to be reversion during overlap when you have a large differential between drive and boost.

Its unlikely boost is opening the intake valves....any time you have the "big boost" you have the big drive to match that, and the other side of the valve is seeing that.

Where the few have seen power gains from springs is likely from drive contamination during cylinder fill and where the cylinder comes as close to a negative pressure.....more likely at higher rpms..... Rpm's being the larger factor when it comes to destructive float.
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So BP can create this issue? Maybe thats how I get away with 80 plus? I have less BP...
 
I kinda doubt you're running less back pressure than boost at that pressure but you might have some secret voodoo under the hood too...

Wait a min...."2006 triple turbo dodge"....been away awhile need catch up on some reading....

On my 64/480 there is a real sweet spot around 50psi, were on every data log comes up with a little more boost than drive.

However at 5500 rpm and even with internal gates wide open on the secondary (13cm exhaust housing) I've seen 60 psi drive higher than boost....not ideal LOL
 
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DGRIZZ said:
It would have to be when boost pressure is stronger than the resistance of the spring, right?
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For the most part the only time boost presure is higher then the pressure in the cylinder is during the intake stroke, and that's only the case because of the resistance of flow through the head.

Think drive pressure though...

Paul
 
CC12V said:
Its called reversion. 70,80ish psi with stock springs ,the exhaust valves can push open.
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Exactly. Drive pressure will push the exhaust valve open when the intake valve is open.

Paul
 
UNBROKEN said:
Just like the title says....who does NOT run upgraded springs?

2nd question...everyone says you just HAVE to have upgraded springs. Why?


Just stirring up some discussion......
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I'm waiting till I wear my stock springs out. :bigsmile:
 
This is just a thought, but with my truck..I can see a slight aggitation in the boost gauge when 60+ psi is reached. I have 60lb springs. Was thinking this was the exhaust valves starting to float..
 
Not sure about float, but I know 12 valve springs will start to pull the locks through the retainers after 4400 rpms. Ask Nick about it haha I tried to tell him.
 
I wonder if the valve guides will play a part in this. I have been told by several cam guys that I should start looking for spring at 55+ psi and anything over 3200 rpm. Although I have seen some guys on here that are running stock springs with high rpms and boost pressures.
 
I had my head off so I did it just in case. I wanted to run nitrous, and with a balanced rotating assembly I feel safer climbing to the rpm I need springs at. But you're right, below 3500 rpm I don't see the need.
 
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