those of you with th400's and 4l80e's that use a fuel pressure regulator to drop cooler oil pressure (and thusly converter charge pressure) does this restrict or otherwise degrade cooler flow and oil cooling capability? I have read about guys with a bypass solenoid so converter feed is only restricted at WOT / raised RPM, but no one ever mentions pressures, temperatures or anything else.

thanks and please correct my understanding of this set up if I have it wrong.

 

using a fuel pressure regulator is really the wrong way to go about it.
A. on a th400, you should run a pump restriction paired with a regulator valve that is TEED into the cooler line.
B. On an 80e...take a look at what that pressure is when in stock form. You'll be surprised. There is no need to run a regulator on an 80e. If you are worried about thrust issues...take a look at every single 6.0/4l80e truck ever and let me know if the thrust is really an issue.

Yes, it will obviously affect cooler flow. A restriction will reduce flow...that's the whole point. And using a regulator to redirect fluid to the pan will also mean that fluid isn't getting to the cooler.
Now...is it an issue...hardly ever. Adequate cooler and a properly sized restrictor for the application and you'll be fine

 

I completely agree with this.
The 4L80E cooler circuit was intentionally designed so that it would not mimic the way in which the THM400 does.

I see a ridiculous amount of vehicles at the Strip that are running External-Regulators from some big Transmission-Shops.
It might not be a bad idea to try and sell some of them on changing things up.

Anyone going to the next NHRA National-Event in Norwalk, OH, June 24th - 27th?
I'll be there if any of you guys are around...
Since i can no longer pass a FAA physical to drive my Funny-Car; I will be testing some new potential drivers for the car.
I would be nice to meet any of you guys.

 

that's why I ask---with several customers asking about it I figure someone is talking it up.

I wasn't logging cooler pressure before, only line pressure. Now I will have data.

 

It sure would be nice to put faces to names!

 

IMO the 400 gets unfairly blamed for thrust failure in light of improper installation of the converter or the thrust bearing itself more often than it actually being the culprit.
That being said charge pressure does still need to be manipulated on bigger power setups but more so for converter control. 1000+HP I would jet every 400 pump i did, and anything below that power with a turbo.

On to dump valves/regulators themselves: IMO there is no need for an external fixed adjustable regulator, jet the pump and eliminate 1 less thing you have to worry about failing or leaking(I see the fixed ones leak alot).
Electronic dump valves definitely serve a purpose when used correctly. Spooling a laggy setup that makes big power is the most popular reason for needing one. I have also recommended to several throttle stop racers that race at wildly varying elevations. The dump being used at higher elevations to make the converter looser to compensate for the loss in power due to elevation. Its also becoming more popular in no prep situations where power management options might be limited. The one thing I see them used often for adjusting for a converter that is too tight or too loose as well and I think this is a bad practice. Instead get the converter adjusted properly and allow yourself the option to use the dump as a tool to better your setup, not to band aid a problem that needs to be addressed.

 

I'll have to disagree on the "no need for an external regulator"
in some setups...just a jet in the pump is adequate. If you monitor pressures and they are ok...that is fine

but there are many instances where an external regulator will help take away the "spikes" of pressure that can be seen on most every setup.

 

In my thrust bearing research I found data from GM stating that the LS thrust bearing was designed to handle to 140-150psi constantly and could handle spikes 180-220psi. BUT i can't seem to find this article anymore to reference and it was posted on the internet so take that info at face value if you like.

 

those numbers are close to accurate. Close enough for the conversation
Run the math, 1.885" hub diameter (that's the total availible area for reaction of thrust)
2.79 in^2
let's say 200lbs thrust force is going to be our constant load rating
that's 72psi of charge pressure to reach 200lbs thrust

so...there is a reason most regulators I install are 65psi

I have other documentation where GM states 800lbs thrust is acceptable for clutch manufacturers. This doesn't assume constant loading and I doubt hardly any clutch manufacturers use a spring that heavy.
In reality...I know BBC, SBC, LS, SBF, can all take extended periods of 130+ psi thrust and not have issue.

The majority of issues with thrust bearing issues are NOT converter charge related. Period.
BUT...that doesn't mean the trans builder should be negligent and just ignore it