Re: Why still rear radiators? (was: Rear radiator shroud vs a "Louve

[Keith Bowers]

'I will be interested in the'pressure balance' with and without the fans running at road speed   say 55 MPH.My scientific fluid-flow knowledge leads me to suspect the engine compartment under the bed is a substantial NEGATIVE pressure to that just aft of the Charge cooler. If my assumption is valid, the engine driven fan efficiency (air pumped through radiator and charge cooler) will decrease significantly as coach speed increases.
I just sold my '86 30' Sierra Sahara (name is Sara BTW) so I am unable to run the differential pressure test with a simple clear plastic manometer tube.I had planned to retrofit an underbody air scoop to increase air pressure in the engine compartment if it is a Negative pressure relative to the aft side of the charge cooler.
The 'factory' engine driven fan is grossly inefficient because it has way too much blade tip clearance and not nearly enough shroud length surrounding it.  The amount of noise it makes also supports my theory of fan inefficiency.

On Fri, Jun 1, 2018 at 8:55 PM, dewey2501@... [Safarifriends] wrote:
 
I posted a picture a few weeks ago of the rear of my rig with 2 electric fans on the rear of the radiator to help push the air out past the fins.  The anemometer I ordered finally showed up, so I have some air flow readings to show the difference so far.  At idle with the meter on the fins, I'm pushing 6.1 knots of air past the meter.  With the fans on, the airflow increases to 13.8 knots of air, so almost double what the engine driven fan pushes out.
I'll know more once we head out on vacation in July, but so far they are doing exactly what they were installed for - moving the air out of the engine compartment past the radiator.  I did discover with them on that you have to work at it to raise the bed - you can feel the pull on it when they are running.

I tried to figure out other readings on the meter that would make more sense, but the meter is smarter than I am.  I might try it again using the ft/min setting and see what it comes up with just out of curiosity.
Duane96 30' Sahara, 250hp Cat, Allison 6spdSpokane WA

--
We sleep soundly in our beds because rough men stand ready in the night to visit violence on those who would do us harm.   -Winston Churchill- '

[Bill Edwards]

' That is more of that engineering that everyone references, done while building these coaches. A lot of common sense was deleted during the phases of design and construction.

On Saturday, June 2, 2018, 12:51:20 PM MDT, Keith Bowers kebowers47@... [Safarifriends] wrote:

 
I will be interested in the'pressure balance' with and without the fans running at road speed   say 55 MPH..My scientific fluid-flow knowledge leads me to suspect the engine compartment under the bed is a substantial NEGATIVE pressure to that just aft of the Charge cooler. If my assumption is valid, the engine driven fan efficiency (air pumped through radiator and charge cooler) will decrease significantly as coach speed increases.
I just sold my '86 30' Sierra Sahara (name is Sara BTW) so I am unable to run the differential pressure test with a simple clear plastic manometer tube.I had planned to retrofit an underbody air scoop to increase air pressure in the engine compartment if it is a Negative pressure relative to the aft side of the charge cooler.
The 'factory' engine driven fan is grossly inefficient because it has way too much blade tip clearance and not nearly enough shroud length surrounding it.  The amount of noise it makes also supports my theory of fan inefficiency.


On Fri, Jun 1, 2018 at 8:55 PM, dewey2501@... [Safarifriends] wrote:
 
I posted a picture a few weeks ago of the rear of my rig with 2 electric fans on the rear of the radiator to help push the air out past the fins.  The anemometer I ordered finally showed up, so I have some air flow readings to show the difference so far.  At idle with the meter on the fins, I'm pushing 6.1 knots of air past the meter.  With the fans on, the airflow increases to 13.8 knots of air, so almost double what the engine driven fan pushes out.
I'll know more once we head out on vacation in July, but so far they are doing exactly what they were installed for - moving the air out of the engine compartment past the radiator.  I did discover with them on that you have to work at it to raise the bed - you can feel the pull on it when they are running.

I tried to figure out other readings on the meter that would make more sense, but the meter is smarter than I am.  I might try it again using the ft/min setting and see what it comes up with just out of curiosity.
Duane96 30' Sahara, 250hp Cat, Allison 6spdSpokane WA






--
We sleep soundly in our beds because rough men stand ready in the night to visit violence on those who would do us harm.   -Winston Churchill- '

[Colin Caldwell]

'Duane,I'm impressed with your fan set upLooking forward to hearing how it works out on your vacation.Please post your results.Thank youColin97 Sahara

Sent from my iPhone

On Jun 1, 2018, at 6:55 PM, dewey2501@... [Safarifriends] wrote:

 
I posted a picture a few weeks ago of the rear of my rig with 2 electric fans on the rear of the radiator to help push the air out past the fins.  The anemometer I ordered finally showed up, so I have some air flow readings to show the difference so far.  At idle with the meter on the fins, I'm pushing 6.1 knots of air past the meter.  With the fans on, the airflow increases to 13.8 knots of air, so almost double what the engine driven fan pushes out.
I'll know more once we head out on vacation in July, but so far they are doing exactly what they were installed for - moving the air out of the engine compartment past the radiator.  I did discover with them on that you have to work at it to raise the bed - you can feel the pull on it when they are running.

I tried to figure out other readings on the meter that would make more sense, but the meter is smarter than I am.  I might try it again using the ft/min setting and see what it comes up with just out of curiosity.
Duane96 30' Sahara, 250hp Cat, Allison 6spdSpokane WA



'

[Tom Williams]

'HI there; Interesting discussion on engine heating as I have had this same problem, and still do to some extent. We have a Cat 3125e 330 horse rear mount radiator in a 2003 Winnebago Journey (formerly a safari owner and miss the Sahara sometimes) I have always wondered if there should be some added cooling on this as we encounter high temps in SO Cal as well as high stress such as going over the grapevine on I5. Appreciate any advise or pics etc of what you folks have done and any suggestions.
Thank you all for your help.
Tom Williams2003 Jpurney. Cat 3125e with Alllison 6sp. pulling 2015 Wrangler .  Tom Williams, Realtor Keller Williams Realty Eastern Ventura County and Northern Los Angeles County Office: 805-915-5152 Cell: 805-368-2500 Email: propertytw@... DRE Lic #00836034 http://www.kw.com/kw/agent/propertyman'

[nanandpete@q.com]

'I f you have done a "louverectomy" on the rear doors, put an aluminum filler above the radiator to fill the big gap, have a new thermostat, checked the water pump belt for tightness and cleaned the radiator properly, you should never need electric  fans. We do the Salt River climb and north out of Phoenix to Flagstaff in July with toad, make that 110 F. outside.  Sure, it gets up to 220 but not a problem. Pete, '99 Sahara, 3126 Cat, 140,000 Mi. '

[technolog1]

'hi, are your fans on all the time or on a thermastate. i would like to see your pict of how you installed them. I have 2 of them i want to install this weekend. your pushing the air over the rad right?Craig 93 cont. 8.3  6sp'

[Duane Buck]

'Attachments :

1. [url=file:///D:\---.safarimotorhomes\Attachments\SafarifriendsDatabase\Attachments\Safarifriends\Fans01.jpg]Fans01.jpg[/url]

Craig,I installed a thermostat to turn my fans on when the radiator gets to about 170 (give or take), with them drawing power via relay from the house batteries.  They are pulling the air through the radiator, and when I turn them on, you can feel a definite increase in the flow of air out the back end.  This past fall when we fixed the diaphragm on my Pac-brake, we had my bed lifted to monitor it, and my brother stated that he could feel the change in airflow when those fans turned on (and if they are on when sitting idle, it's almost impossible to lift the bed top now).

Duane96 30' Sahara, 250hp CatSpokane Wa

On Thursday, March 21, 2019, 5:40:37 PM PDT, technolog1@... [Safarifriends] wrote:

 
hi, are your fans on all the time or on a thermastate. i would like to see your pict of how you installed them. I have 2 of them i want to install this weekend. your pushing the air over the rad right?Craig 93 cont. 8.3  6sp '

[TD]

'Duane,

Is there an air flow difference felt while the engine is running at
higher rpm, say around 1,700 rpm to simulate road speed rpm?


John
'95 Safari Serengeti 38ft, 300 Cummins 8.3CTA, Allison
6spd.


On 3/21/19, Duane Buck dewey2501@... [Safarifriends]
wrote:

> Craig,I installed a thermostat to turn my fans on when the radiator gets to
> about 170 (give or take), with them drawing power via relay from the house
> batteries. They are pulling the air through the radiator, and when I turn
> them on, you can feel a definite increase in the flow of air out the back
> end. This past fall when we fixed the diaphragm on my Pac-brake, we had my
> bed lifted to monitor it, and my brother stated that he could feel the
> change in airflow when those fans turned on (and if they are on when sitting
> idle, it's almost impossible to lift the bed top now).
>
> Duane96 30' Sahara, 250hp CatSpokane Wa
>
> On Thursday, March 21, 2019, 5:40:37 PM PDT, technolog1@...
> [Safarifriends] wrote:
>
>
> hi, are your fans on all the time or on a thermastate. i would like to see
> your pict of how you installed them. I have 2 of them i want to install this
> weekend. your pushing the air over the rad right?
> Craig 93 cont. 8.3 6sp

'

[Duane Buck]

' John,We did a mid throttle test when we were playing after installing the fans and saw some increased airflow when we turned them on, but I don't remember how high we went on RPM's. You could feel an increase even at the higher RPM's, but I don't remember if we used the anemometer to test them that way or not in all honestly to see how much of a difference.  I know there was increased airflow, but who knows how much.  The biggest test for me was when we went up the I-15 grade from Vegas to Barstow - the thermostat stuck and delayed them turning on until we were starting up the grade, and we went from about 215-220 degrees and dropped down to 205 and lower going up that long, long grade.
Duane96 30' Sahara, 250hp CatSpokane Wa

On Thursday, March 21, 2019, 8:10:02 PM PDT, TD sdjhtm@... [Safarifriends] wrote:

 
Duane,

Is there an air flow difference felt while the engine is running at
higher rpm, say around 1,700 rpm to simulate road speed rpm?

John
'95 Safari Serengeti 38ft, 300 Cummins 8.3CTA, Allison
6spd.

On 3/21/19, Duane Buck dewey2501@... [Safarifriends]
wrote:
> Craig,I installed a thermostat to turn my fans on when the radiator gets to
> about 170 (give or take), with them drawing power via relay from the house
> batteries. They are pulling the air through the radiator, and when I turn
> them on, you can feel a definite increase in the flow of air out the back
> end. This past fall when we fixed the diaphragm on my Pac-brake, we had my
> bed lifted to monitor it, and my brother stated that he could feel the
> change in airflow when those fans turned on (and if they are on when sitting
> idle, it's almost impossible to lift the bed top now).
>
> Duane96 30' Sahara, 250hp CatSpokane Wa
>
> On Thursday, March 21, 2019, 5:40:37 PM PDT, technolog1@...
> [Safarifriends] wrote:
>
>
> hi, are your fans on all the time or on a thermastate. i would like to see
> your pict of how you installed them. I have 2 of them i want to install this
> weekend. your pushing the air over the rad right?
> Craig 93 cont. 8.3 6sp
'

[technolog1]

'Thanks but i am misunderstanding. The engine fan pulls air through the rad. U said you can feel the air coming out the back so your pulling air not pushing it??? In to the rad. Sorry if i am not following  you. ThanksI am not a electrician  so next question  is why do you put in a relay and not just a fuse?Thanks for explaining things. Craig93 cont. 8.3 6sp


Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: "Duane Buck dewey2501@... [Safarifriends]" Date: 3/22/19 1:07 AM (GMT-06:00) To: "TD sdjhtm@... [Safarifriends]" Subject: Re: [Safarifriends] Re: Air flow increase with electric fans on rear of radiator
 
John,We did a mid throttle test when we were playing after installing the fans and saw some increased airflow when we turned them on, but I don't remember how high we went on RPM's. You could feel an increase even at the higher RPM's, but I don't remember if we used the anemometer to test them that way or not in all honestly to see how much of a difference.  I know there was increased airflow, but who knows how much.  The biggest test for me was when we went up the I-15 grade from Vegas to Barstow - the thermostat stuck and delayed them turning on until we were starting up the grade, and we went from about 215-220 degrees and dropped down to 205 and lower going up that long, long grade.
Duane96 30' Sahara, 250hp CatSpokane Wa

On Thursday, March 21, 2019, 8:10:02 PM PDT, TD sdjhtm@... [Safarifriends] wrote:

 
Duane,

Is there an air flow difference felt while the engine is running at
higher rpm, say around 1,700 rpm to simulate road speed rpm?

John
'95 Safari Serengeti 38ft, 300 Cummins 8.3CTA, Allison
6spd.

On 3/21/19, Duane Buck dewey2501@... [Safarifriends]
wrote:
> Craig,I installed a thermostat to turn my fans on when the radiator gets to
> about 170 (give or take), with them drawing power via relay from the house
> batteries. They are pulling the air through the radiator, and when I turn
> them on, you can feel a definite increase in the flow of air out the back
> end. This past fall when we fixed the diaphragm on my Pac-brake, we had my
> bed lifted to monitor it, and my brother stated that he could feel the
> change in airflow when those fans turned on (and if they are on when sitting
> idle, it's almost impossible to lift the bed top now).
>
> Duane96 30' Sahara, 250hp CatSpokane Wa
>
> On Thursday, March 21, 2019, 5:40:37 PM PDT, technolog1@...
> [Safarifriends] wrote:
>
>
> hi, are your fans on all the time or on a thermastate. i would like to see
> your pict of how you installed them. I have 2 of them i want to install this
> weekend. your pushing the air over the rad right?
> Craig 93 cont. 8.3 6sp

'