YODAONE

1998 - 2000 LS400 upper radiator hose is very durable and wall thickness does an excellent job of containing coolant pressure without bulging.

Two ~ 90 degree bends cause excessive flow and pressure drop.
See:
http://www.thermopedia.com/content/577/

The upper radiator hose on a 2001 LS430 employs two ~ 45 degree bends.

Several images from thermopedia link:


Figure 1. Schematic diagram of a double spiral flow in a bend: a) longitudinal section; b) cross-section (rectangular section); c) cross-section (circular cross-section)

Figure 2. Total pressure contours in a U-bend of a bend-to-pipe diameter ratio of 24; Reynolds number = 236000

Figure 3. Bend loss coefficients for a pipe.


Anyone have info on OEM upper radiator hose wall thickness for LS400.and LS430?

I.D. appears to be the same....

Thanks.


LS430 upper radiator hose routes coolant more directly without 90 degree bends..


LS400 upper radiator hose employs two 90 degree transitions....abuts the throttle actuator motor, shrouds the cam pulley cover. However, do like the heatshrink tubing.


Stewart components offers "Advanced Cooling System Basics" :

https://www.stewartcomponents.com/index.php?route=information/information&information_id=14




See also:

https://www.clublexus.com/forums/ls-1st-and-2nd-gen-1990-2000/802539-ls430-water-inlet-housing-in-ls400.html

1998 -2000 LS400 and 2001-2006 LS430 water inlet housing. Two 90 degree bends were removed. to improve flow characteristics. Straightening of radiator hose reduces pressure drop and increases flow...or less engine power to flow coolant

Losiracer2

I think they added the increased 90 deg. bends to clear the fan blades? does the LS430 have the same style cooling fan blades or does it use an electric fan instead of the thermostatic fan and clutch?

Also what about the throttle body motor? that seems to be in the way for the LS400 configuration whereas the LS430 doesn't have that.

YODAONE

The image suggests the LS430 hose will not interfere with the throttle body motor, in fact will divert 195 F hose away from it.

Also allows clearance for left cam cover

As to the radiatot fan and shroud, it appears to clear with plenty of room to spare.

Will advise..

YODAONE

A few images of new 1998-2000 LS400 and 2001-2006 LS430 upper radiator hose courtesy of McGrath Lexus.

The LS430 hose offers better flow, lower turbulence and pressure drop but no ignoring the closer proximity of the LS430 hose to the fan blades.

Resolving hose-fan clearance leads to another cooling system deficiency solution.

The radiator cooling fan reside 80% outside of its radiator shroud.and has plenty of clearance to move forward. A fan more efficiently draws air residing in a venturi or fan shroud.

A 25 mm spacer will place the fan blades more fully within the fan shroud, but not all the way...in case I'm missing something.
This will increase cooling system efficiency.
There is more than ample space (too much in fact) between the blade tips and shroud to avoid interference with engine movement

See hydro fan images...

https://www.clublexus.com/forums/ls-...options-3.html

The Hydro fan blades sit entirely within the fan shroud and blade tips sit squarely and in close proximity to the shroud venturi - made possible because the blade hub is fixed to the fan shroud thus does not move with engine torque...tighter blade - venturi clearance equates to more efficient air movement.


LS400 and LS430 hose thickness is same.

Side by side image io new LS400 and LS430 upper radiator hoses. (courtesy of McGrath Lexus) The LS430 hose offers better coolant flow, lower pressure drop and significanyly less turbulence. The LS430 hose will settle too close to fan blades, so employing a spacer between fan clutch base and fan bracket hub will resolve two problems.


Same alignment..

LS400 radiator hose navigates around the fan blades with 90 degree bends

Another angle

The fan blades reside mostly outside of fan shroud. Very inefficient.

A spacer between the fan clutch and fan bracket hub would move the fan more fully inside the shroud and provide comfortable clearance between fan blades and LS430 hose. Not just a flat spacer however.





Backside of fan clutch...a spacer will require a conical shape positioning pin, ndex and inverse conical shape to mate with fan bracket hub... Standard fan clutch used from early model LS400s. Unsure why not modified to better position fan blades within shroud venturi area, as does hydro fan.



Front of fan bracket hub has conical.interface with the fan clutch flange to insure precise alignment, so not as simple as machining a flat spacer with 4 holes... Happily I know a machine shop that can handle it. Not gonna be a $100 part however.

YODAONE

Aside from trimming the upper radiator hose 1" on the water inlet side, it fits like a glove.

Clearance between fan blades and LS430 hose is only 1/2"..but it does clear. Not ideal..so...

Have removed the fan bracket bearing and fan clutch to fabricate a spacer.


Initial fitting.radiator side...Hose bulges to the left with slight kinking on inner radius...so trimming 3/4" to 1" on the water inlet side resolves this

Fan blade clearance at closest point is not ideal.

Another image depicting clearance. Notice how far the blades reside outside the radiator shroud.. Using a custom spacer between the fan bracket hub and fan clutch flange will move blade assembly slightly forward into the shroud while increasing hose - blade assembly clearance.

Blade - hose clearance after trimming. Does not touch throttle actuator motor


1" section of hose removed.. The LS430 upper radiator inlet tube positions slightly to the right facing engine over LS400, so shortening hose solves this. Took two lesser cuts to remove exact amount of hose.

bradland

Soooooo without any real data like the flow rate (GPM) of the 2 hoses, to actually establish one is superior to the other, it would appear all you've done is install the equivalent of a generic fit (Gates Dayco etc) rad hose. An $11 investment...

Stroock639

lol yodaone is the best at solving issues that've already been solved

he should've just extrude honed the existing coolant line

YODAONE

Arguably Toyota removed the two 90 degree bends in the upper radiator hose for a reason. They also removed two 90 bends in the water inlet housing. Why do you believe they did so?
This is not a Gates non-fit aftermarket hose. It is a thick-walled OEM quality hose, which explains why I initially inquired about wall thickness, and that's why an OEM LS430.hose was used.

Am ecstatic to be able to use a quality OEM part and have it fit so well with only slight trim. LS400 and LS430 are different vehicles after all

My water inlet housing was replaced several years ago with an LS430 unit. See diagram. This information comes from Toyota and suggests removing 90 degree transitions offers improvement.
If you don't agree with the physics or Toyota, then I can't help you.

Should you wish test data, then feel free to purchase one of each hose, locate and pay a test lab to perform flow and pressure drop testing, otherwise let the physics guide you.

sdls

"If it ain't broke, fix it until it is"

YODAONE

Proactivity is my motto.

Can't name one Auto manufacturer that doesn't evolve yet remained in business.

sdls

Well yeah but it was more of an incremental improvement afaik because the LS has a huge frontal area for cooling and air intake and I’ve never heard of the LS having inherent overheating issues. I think you also introduced additional failure modes via stressors (edited, autocorrect struck again) to the radiator plastic neck. How old is your radiator?
See how the hose kinks to the right in the after picture?

Chasing a lower Reynolds number but introducing a new stressor to an aged component beyond design spec is a recipe for possible failure.

my 96 LS with 250-300k (my life of ownership) with a stock and original OLD radiator hose never overheated (monitored via Scangauge) even when supercharged for two years.

JMO and I appreciate your Kaizen efforts.

btw, industry experience talking, it’s mainly cost reduction that drives changes in what is called “sustaining engineering” (not new product development) if the old design was not defective.

please note that I’m not here to put anyone down, I want to learn and a healthy and respectful exchange of views is part of the learning experience.

YODAONE

A few years since the 1999 LS400.water inlet was replaced with an LS430 unit.

You understand this type of testing is not always practical, so unless Toyota did it first, then it is difficult to quantify results.

Efficiency, emissions or performance gains can be incremental. Enough of them start to add up.

Located technical article entitled:

"Pressure Losses in Multiple-Elbow Paths and in V-Bends of Hydraulic Manifolds".

Fluid flow within a double elbowed bend:


This screenshot fairly depicts coolant flow charachteristics within a double bend elbow of a LS400 radiator hose.

Article .pdf will not attach to this post because it exceeds size limit, but you can Google title above.

"Abstract: Hydraulic manifolds are used to realize compact circuit layouts, but may introduce high pressure losses in the system because their design is usually oriented to achieving minimum size and weight more than reducing the pressure losses."

Yamae

It would be more authentic if actual measurement results were shown.

YODAONE

Agreed.

Can you inquire whether Toyota engineering department performed testing as a basis for modifying the double elbows (two 90 degree transitions) of the LS400 design in favor of straighter upper radiator hose before use on production of the LS430.

bradland

YODA many of the mod write-ups you submit could be great, but without application (LS400) specific data they are basically incomplete assumptions.
No one is arguing the fact that two 90 degree bends would impede flow. We don't need a diagram to understand that. The question is how much? The LS is one of the most beautifully engineered cars ever produced and the cooling system is by no means lacking. So the real question here is DOES THE 430 HOSE PROVIDE A 2% INCREASE OR A 20% INCREASE? This is a simple mod so there's not much at stake. Readers need to know a mod will actually make a discernible difference before they spend money on a part and commit to the labor involved. Cost vs Benefit is normally a simple equation.
You said "Let the physics guide you", physics with only generic data assumptions, not specific to the application, is not necessarily valid science.
I won't apologize for being so critical because discerning readers are expecting more than "This is better BECAUSE I SAID SO..."