Electric Radiator Fan

[phantomjock]

Found several posts on this topic; one was a Van for sale with electric fans, another was a comment about engine idling to generate power for air conditioning:

1) https://www.classbforum.com/forums/f11/im-selling-my-class-b-low-low-miles-and-affordable-495.html
2) https://www.classbforum.com/forums/f23/propane-free-onan-free-7187-3.html​

And, of course, booster has been down this track before... including an HP Tune (something I am also considering - but that for later).
A couple of other members have commented regarding electric fans--Dicktell and tillard23, and Hondo gave a link that looks very compelling.
I'm curious, has anyone taken a "bite" on this one:
https://www.ebay.com/itm/CHEVY-EXPR...216470?hash=item19e7079616:g:LUgAAOxyRhBSxwqt

Their information moves me toward removing the mechanical fan...hmmm.

Seems to be a sensible idea, as I currently have the shroud out and off for an alternator upgrade. I also note there are 2 radiators on my RT, one is black and well forward and the other larger is aluminum and aft of the forward one. Plenty of space to add between or aft. Not concerned about "power" as it is a 400A alternator, and I'm adding a couple of drops in the engine bay. Could add the fans later, but; "Hey! While I'm at it..." so much for a "Phased Approach..."

As an aside, my RT has the Tow/Haul mod. Haven't chased lines, but is it possible one of the 2 radiators is a transmission cooler?

Again, I'm looking to be able to lower coolant temps at idle, while charging. As booster mentioned in his postings, there is other work to be done to improve at highway speeds.

Thoughts/Comments - as always, much appreciated.

Cheers - Jim

 

[booster]

Found several posts on this topic; one was a Van for sale with electric fans, another was a comment about engine idling to generate power for air conditioning:

1) https://www.classbforum.com/forums/f11/im-selling-my-class-b-low-low-miles-and-affordable-495.html
2) https://www.classbforum.com/forums/f23/propane-free-onan-free-7187-3.html​

And, of course, booster has been down this track before... including an HP Tune (something I am also considering - but that for later).
A couple of other members have commented regarding electric fans--Dicktell and tillard23, and Hondo gave a link that looks very compelling.
I'm curious, has anyone taken a "bite" on this one:
https://www.ebay.com/itm/CHEVY-EXPR...216470?hash=item19e7079616:g:LUgAAOxyRhBSxwqt

Their information moves me toward removing the mechanical fan...hmmm.

Seems to be a sensible idea, as I currently have the shroud out and off for an alternator upgrade. I also note there are 2 radiators on my RT, one is black and well forward and the other larger is aluminum and aft of the forward one. Plenty of space to add between or aft. Not concerned about "power" as it is a 400A alternator, and I'm adding a couple of drops in the engine bay. Could add the fans later, but; "Hey! While I'm at it..." so much for a "Phased Approach..."

As an aside, my RT has the Tow/Haul mod. Haven't chased lines, but is it possible one of the 2 radiators is a transmission cooler?

Again, I'm looking to be able to lower coolant temps at idle, while charging. As booster mentioned in his postings, there is other work to be done to improve at highway speeds.

Thoughts/Comments - as always, much appreciated.

Cheers - Jim

I do have electrics on ours but in front of the radiator and the mechanical clutch fan is still in place. The fans actually sit off the radiator a bit with the big tranny coolers in between the fans and the radiator so the coolers get forced flow. This setup with the oversize 8.1 radiator from the previous generation would keep the engine and trans better but not great on our test climb up into Rocky mountain National park. These are twin Spall 2500cfm each fans that pull over 25 amps each. I have never found any fans that beat Spal in the past, but anything is possible.



All that said it was not really enough even with the mechanical in place so very leery of what it would be without.



Once the reprogramming of the trans was done, the hot trans and engine went away. That is with the trans on just the standalone coolers so the engine gets lots of extra cooling from the big radiator. This is with the electrics off as they haven't been needed since we did the reprogramming unless I turn them on at low speed to help cool the alternators if I have it charging at 180 maps continuous for over 15 minutes.


You do save some energy with electric over mechanical, but it isn't all free as the alternator is going to have to come up an extra 50 amps of continuous power and that also takes fuel and will reduce your battery changing.

 

[phantomjock]

Electric Fans!

Originally Posted by booster:
You do save some energy with electric over mechanical, but it isn't all free as the alternator is going to have to come up an extra 50 amps of continuous power and that also takes fuel and will reduce your battery changing.

And, you are correct. I note the losses from an electric fan set up are about 5HP, and the setup I'm looking at draw about 30 amps at max, so maybe a bit more. But, the clutch operated fan takes between 20 and 40HP at 6000 RPM. Mind you, I won't be operating there! [Does give a comparison though.]

I'm going to pull the trigger on the FF Dynamics dual fan setup. Nice email chat. The setup I'm going for will be a good match for my towing requirements - and any HP boost will be welcome as well. Later I'll look at a "Tune."

I'll pull the stock shrouds and the fan after the parts arrive. I expect I'll duct the radiators (as time permits) to seal lost flow around the sides. This is not a race car - but there are areas of experience that will lend to improvements.

Today, I should drop in the 400A alternator. That is why/how I came to write this thread.

Once again, the plan takes a turn...

Cheers - Jim

 

[booster]

Interesting that they are only 30 amps total, which seems a bit low for 5000cfm, but of course what motor style they are, and even more what discharge pressure and suction negative pressure points they are rated at. Lots of the, particular off, brands tend to cheat on the rating points a lot compared to big OEM also manufacturers.

The big issue in vans tends to be that getting air into the engine compartment is much easier than getting it out. This is the same issue I had in my 1970 Challenger with the twin turbos on it that blocked a lot of air from getting out the bottom. As I am sure you know, there are lots of 70s vintage muscle cars driving around with the hood to cowl seal out to keep them cooler.

Another item that you probably have on the race car is to seal up all the air bypasses around the radiator, and there are a lot of them, especially the gap down under the van that is before the radiator at the bumper top. I sealed up all of that kind of stuff and also added extensions to leading edge of the front wheels wells to stop the turbulence and backpressure of the air going into the wheelwells. Getting it all done did help the cooling quite a noticeably and especially how quickly the extra temp gained at a stop light goes back down as soon as were are moving.

There is also one thing you might want to that I did when I found the power steering/hydroboost factory fill of oil get black fairly quickly in the first couple of years. GM put a small lip spoiler on the low edge of the front end and it goes right in front of the trans cooler, blocking the air. On the Roadtreks it is behind the front bumper skin but visible through some of the cutouts. I windowed it out in front of the cooler and the power steering fiuid temp did go down. I now has Reline Dex4 ATF in the PS/hyrdoboost system and it stays clean and also smoothed out the steering some and improved the brake boost a bit.


If you really want to go weird like I did on the cooling, you can change to a GMC grille instead of the Chevy one. The GMC has something like 20-30% more open area to let air in.


I have been contemplating, but stalling I think, putting in pair of the fender side vents that are allegedly made specifically for the Chevy/GMC vans. Need to cut out a hole in the fender to put them on and either get chrome ones, which I think they make, or paint them to match and anything you only get one chance at, like hacking big holes is kind of scary sometimes. Fender vents are said to be of good benefit as that is a quite low pressure area and will suck out air from the engine compartment.

 

[phantomjock]

Lunch Break!

I had to do a quick back of the envelope and, yep. The chevy grill blocks out 28.6% of the grill area. It would be a mess to try and cut it out and keep it looking good, so the GMC grill is a good thought. On my list.

Those fender grills (on eBay) also look interesting. Not as radical as on a race car, but the flow around a wheel in motion does wrap up and then forward, so you'd get some relief from under hood pressure. (It begins to recirculate, but if you let it out, benefits!)

It is smart tolook at engine bay drag as it is 10% (at least) of the total drag of a vehicle. Given the size and shape of a Class B, there some gains to be made.

For optimum evacuation of the engine bay - we'd have to be really radical:

But optimum side evacuation ( caries a penalty, as it would block-off/isolate any cooling from the already heating-up alternator. No free lunch! -- Oops - back to work.

Cheers - Jim

 

[booster]

Lunch Break!

I had to do a quick back of the envelope and, yep. The chevy grill blocks out 28.6% of the grill area. It would be a mess to try and cut it out and keep it looking good, so the GMC grill is a good thought. On my list.

Those fender grills (on eBay) also look interesting. Not as radical as on a race car, but the flow around a wheel in motion does wrap up and then forward, so you'd get some relief from under hood pressure. (It begins to recirculate, but if you let it out, benefits!)

It is smart tolook at engine bay drag as it is 10% (at least) of the total drag of a vehicle. Given the size and shape of a Class B, there some gains to be made.

For optimum evacuation of the engine bay - we'd have to be really radical:

But optimum side evacuation ( caries a penalty, as it would block-off/isolate any cooling from the already heating-up alternator. No free lunch! -- Oops - back to work.

Cheers - Jim

Nice diagrams, haven't run across those before.


I think you I may have missed in describing the wheel wheel dam. It goes down from the underbody only in the area of the wheelwell and is a bit lower than the rest of the chin. The goal is prevent the upper air path you show in the side view that goes back up into the wheelwell and pressurizes it some which reduced air evacuation from the engine compartment. The goal would be to only have the bottom 3 dotted lines in the diagram so air is running along the ground and making the wheelwell a negative pressure area to pull air out.


The side vents I am interested work a bit different than I think you are used to. Think old Buick port holes in the outer fender, not the inner one. The vans have enough room to do that kind of vent. Here is a link and they would pull in a good area to allow more air to the alternators.


https://www.sarona.com/Chevy/Express_Van/2007/Side_Vents/

 

[phantomjock]

Nice diagrams, haven't run across those before.

That's OK - as an Aero, there is a lot I don't know about "sparky-stuff."

I think you I may have missed in describing the wheel wheel dam. It goes down from the underbody only in the area of the wheelwell and is a bit lower than the rest of the chin. The goal is prevent the upper air path you show in the side view that goes back up into the wheelwell and pressurizes it some which reduced air evacuation from the engine compartment.

Ah- like an AIR DAM, or Air Curtain, to direct flow, as a vane for directing flow to where you want it. Easily fabricated out of lawn edging - or similar material. Wears if you hit something, and it flexes. An Air Curtain uses air (flow) to direct air. The vane would do the same. Got-it.

The goal would be to only have the bottom 3 dotted lines in the diagram so air is running along the ground and making the wheelwell a negative pressure area to pull air out.

Exactly what you'd like. And helps air flow through the brake stack - at our "high speeds!"

The side vents I am interested work a bit different than I think you are used to. Think old Buick port holes in the outer fender, not the inner one. The vans have enough room to do that kind of vent. Here is a link and they would pull in a good area to allow more air to the alternators.


Custom Chevy Express Van 2007 Side Vents - Sarona

Good link - saw same idea on eBay. Just did a tap on the fender - and there is a lot of stuff in my engine bay - so might not work. But, the vanes/air dam - yes.

BTW - here is a YT test (Dyno) of HP loss from mechanical fan.

I went back to my "rad-Files" and found this one. Could be useful for understanding those hot days and high temps:

Cheers - Jim

 

[tlillard23]

HP tuners and adjusting the transmission shifting has likely cured my heat issues while moving.
The issues as OP stated, when sitting at idle there is too much heat underhood. I have read the previous posts, on my short list are sealing up bypass air, adding an old spahl fan on the trans cooler and some sort of engine hot air venting.
I was thinking hood vents, like on the race car, Booster reminded me that will allow hot stinky engine air to be sucked in to the ventilation system. Soo that's no good. The side vents are being seriously considered. I look forward to seeing what happens!

*one thing that hasn't been mentioned, the electric fan will RESTRICT air if it's on while at speed, so there needs to be some sort of speed lock out. The factory electric fans shut off after somewhere around 50mph (uncertain at what speed)

 

[booster]

HP tuners and adjusting the transmission shifting has likely cured my heat issues while moving.
The issues as OP stated, when sitting at idle there is too much heat underhood. I have read the previous posts, on my short list are sealing up bypass air, adding an old spahl fan on the trans cooler and some sort of engine hot air venting.
I was thinking hood vents, like on the race car, Booster reminded me that will allow hot stinky engine air to be sucked in to the ventilation system. Soo that's no good. The side vents are being seriously considered. I look forward to seeing what happens!

*one thing that hasn't been mentioned, the electric fan will RESTRICT air if it's on while at speed, so there needs to be some sort of speed lock out. The factory electric fans shut off after somewhere around 50mph (uncertain at what speed)

I am not an aero, but only a lowly mechanical/manufacturing but the hotrod stuff has been great in teaching me some of that stuff! One thing I found of particular interest was the best location of a mechanical fan in the shrould. It is not what the mfgs tell you, based on my testing, but is more hazardous to do. Having the fan almost completely out of the shrould worked way better in my testing as a lot of the air comes of the end of the blades that way and it is thrown under the car where it can be moved away. Of course now they put them all inside the shroud to prevent finger clipping at the penalty of less cooling.


The vents in my link seem to locate in the semi sweet spot on the upper fender just forward of the hinge. At this point there are probably two layers of steel, but they are close together and above the wheelwell proper. I did a bunch of guess/measuring of the location when I found these vents and it looked like they would fit well if done carefully.

 

[tlillard23]

Been looking for fender vents. The sarona that Booster posted need some sort of mounting, that I assume comes with it for $300. what about some generic "hood"/"fender" vents placed on the fender? I have not looked at the fender to see where the sweet spot is.

Like these?
https://spikedperformance.com/collections/hood-vents/products/fender-vents

or?

https://trackspecmotorsports.com/universal/small-angular-universal-hood-louvers

 

[booster]

Been looking for fender vents. The sarona that Booster posted need some sort of mounting, that I assume comes with it for $300. what about some generic "hood"/"fender" vents placed on the fender? I have not looked at the fender to see where the sweet spot is.

Like these?
https://spikedperformance.com/collections/hood-vents/products/fender-vents

or?

https://trackspecmotorsports.com/universal/small-angular-universal-hood-louvers

I think anyone who is looking at doing the fender side venting needs to carefully look at how that area of the Chevies is constructed. I just went out and looked at ours again, as it has been a while, to confirm the basic structure.


The fenders are double layer with an outer and inner fender with a gap in between them. To complicate it more than that, the inner and outer are open in the front so frontal air will be pushed into that gap at speed.



If you just put a vent in the outer fender, it will probably do no good at all for cooling as it will only get air from the front of the van and may actually even take some radiator air away.



If you cut the outer and inner and put a vent in the outer only you might actually make things worse for cooling because at speed the frontal air might actually flow into the engine compartment and pressurize it slightly as it has nowhere to go (that is what you are trying to reduce with fender vents).


The only ways I could see it working would be to have a vent in the outer fender that is fed by a duct through the inner fender so the low pressure of the outer fender skin pulls directly on the engine compartment. Or the other way would be to put a vent in the outer fender and a hole in the inner fender but seal up all other air that could get between the inner and outer fenders, if that is even possible to do decently.


When you look at the pix of the Sarona, it appears they have a built in depth to them, which I would hope matches the depth of the distance between the inner and outer fenders so you would pull air only from the engine compartment, but there are no pix of the inside of the fenders to confirm that. I would certainly call first before I ordered to ask that question, though.

 

[sadpanda]

OE fan option

New here but wanted to chime in - I had good results retrofitting the '05+ Tahoe OE dual fan on my '03 suburban (had fan control enabled when I had trans tuned with HP Tuners) and am considering the same swap on my 3500.

Direct swap, great AC performance at idle in the SC heat, never had an issue towing a 7,500 boat through the mountains of hwy 26 / 40 / 75

Avalanch HD lists an 'enhanced' fan that has a 9 blade/7 blade setup instead of the standard 7 blade.

 

[tlillard23]

I know electronic fan control is an option in HapTuners on the '07 Express, but not sure that there are any wires coming out of the computer. do you have to add pins to the main connector on the ECM? I don't think any of the vans had electric fans did they?

 

[phantomjock]

I know electronic fan control is an option in HapTuners on the '07 Express, but not sure that there are any wires coming out of the computer. do you have to add pins to the main connector on the ECM? I don't think any of the vans had electric fans did they?

Todd - I'll answer from my install experience:
I added a Fuse Tap(s) to the main fuse panel for the Electric Fan installation. Not to the ECM proper. One went to the fuel pump fuse (as I recall) to provide an "On/OFF" signal to the fan so it wouldn't run 24/7. I added several other Fuse Taps for other bits under the hood - like the High Idle power, etc.

I'll get some pics and add to complete my threard.

Have a happy 4th of July!
Cheers - Jim

 

[tlillard23]

thanks phantom jock and sad panda I found this post which details the ECM wire editions.
https://www.gmtruckclub.com/threads/my-project-e-fans-on-my-6-0-savana-cargo.87079/

 

[sadpanda]

I know electronic fan control is an option in HapTuners on the '07 Express, but not sure that there are any wires coming out of the computer. do you have to add pins to the main connector on the ECM? I don't think any of the vans had electric fans did they?

Yep. You will need to depin /cut some pigtails from the bone yard (any similar year gm will do) or buy the terminals /seals/crimper from a supplier like digikey

 

[sadpanda]

A conversation with booster on a different topic got me thinking: my experience with moderate towing in my suburban may be vastly different than someone running a class B... Even on the steepest hills I was never below 45mph. In fact the trick was either maintain 70+mph to keep it in 4th (note I had the tuner enable full throttle 4th gear) or end up at 3000 some odd rpm at 55mph the whole way up.

The only time a clutch fan really shines is when you are stuck with heavy load and no airflow.

To that end I may try a different solution: EV clutch fan. Can be commanded full on regardless of temp, can free wheel when airflow is good and can still provide a monsoon of CFM when you are stuck climbing at low speed.

There are pitfalls though - once cooled after shut down the fluid will firm up essentially locking the clutch until it warms enough to flow back into the reservoir (usually within 3 min). They also pose a maintenance issue as the fluid tends to escape - a run of poor quality OE fans lead some diesel guys have said F-it and revert to standard thermo clutch fans and programming out the ECM fault codes.

For donor vehicle my first thought was Duramax, however they run a much larger shaft (43mm?) vs the 36 mm on the 6.0L. I may drop a line to Hayden but here is what I have found that is close:
Stock fan - 10x1.5 on 3.25 circle, 1.75 clutch to flange
'09 Trailblazer SS - 8x1.25 on 3.81 circle, 1.54 clutch to flange
'10 Mercury Mountaineer - 6x1.0 on 7in circle, 2.62 clutch to flange

 

[booster]

A conversation with booster on a different topic got me thinking: my experience with moderate towing in my suburban may be vastly different than someone running a class B... Even on the steepest hills I was never below 45mph. In fact the trick was either maintain 70+mph to keep it in 4th (note I had the tuner enable full throttle 4th gear) or end up at 3000 some odd rpm at 55mph the whole way up.

The only time a clutch fan really shines is when you are stuck with heavy load and no airflow.

To that end I may try a different solution: EV clutch fan. Can be commanded full on regardless of temp, can free wheel when airflow is good and can still provide a monsoon of CFM when you are stuck climbing at low speed.

There are pitfalls though - once cooled after shut down the fluid will firm up essentially locking the clutch until it warms enough to flow back into the reservoir (usually within 3 min). They also pose a maintenance issue as the fluid tends to escape - a run of poor quality OE fans lead some diesel guys have said F-it and revert to standard thermo clutch fans and programming out the ECM fault codes.

For donor vehicle my first thought was Duramax, however they run a much larger shaft (43mm?) vs the 36 mm on the 6.0L. I may drop a line to Hayden but here is what I have found that is close:
Stock fan - 10x1.5 on 3.25 circle, 1.75 clutch to flange
'09 Trailblazer SS - 8x1.25 on 3.81 circle, 1.54 clutch to flange
'10 Mercury Mountaineer - 6x1.0 on 7in circle, 2.62 clutch to flange

I also have considered going to an electric clutch fan in the past but haven't worried about it lately as our cooling issues have been resolved by all our changes to the cooling system, but mostly because of the reprogramming I did to the PCM so that the transmission is in lockup more of the time. We have the 4 speed 4L80E in our 2007. 2010 and later with the 6 speed do run in lockup nearly all the time and do not overheat like the 4 speed ones do.


In my looking in the past, finding one to fit was not readily apparent, but I was looking primarily at Horton products and not trying to find from existing vehicles.


I would imagine that the clutch fans are hard on the shaft and bearings because of the sudden loading when they activate. The is probably why they also use the viscous clutch to lessen the shock.

 

[sadpanda]

Unlike heavy duty diesel fans, these all seem to be 3 wire PWM controlled so you can dial in engagement percentage. Also the fluid may be somewhat slow moving - in the same posts I was reading where Duramax guys were having failures and going standard clutch some were complaining that even with a new clutch, the fan would not achieve full lock until mid way up a hill and not be able to 'catch up' resulting in high engine temps. One suggestion was to add an override switch to request full lock well ahead of the hill.

I'm still thinking a lot of this was due to poor OE design on that gen and that subsequent replacements from companies like Hayden probably resolved those issues. My brother has a 2012-14 ish dmax and has never had any cooling issues even towing a maxed out enclosed trailer with weight distributing hitch - and his AC is icy cold at idle.

 

[sadpanda]

To further muddy the water, interesting testing done by TBSS fellas: https://www.tbssowners.com/threads/factory-ev-fan-measurements-vs-measurements-of-ls1.14101/

of note poster recorded in excess of 10,000 max CFM from the EV fan @3,000 rpm engine speed but despite this, TBSS was still prone to over heating... Easy to guess why though, TBSS has a tiny radiator - 18x26 - and a poor shroud design, whereas tahoe/suburban has same size as express - 34x17 - a 23% increase.

Back to 05+ tahoe setup, to resolve any doubts I had about the swap I performed a number of tests right after install. Normal Charleston morning with 89F and 80% humidity I idled the truck with AC off and fans disconnected. Eventually after 20 minutes or so the ECM finally commanded high speed but truck never overheated, just held 220. I then played with different relay and motor failures (standard 3 relay series/parallel setup) and even one fan on low was enough to keep it from overheating with the AC on full.

Either way, it seems tuning and shroud sealing (which I did a lot of) is key.

My fan tune was copied from stock tahoe which if I recall correctly called for low on @ 195, high on @ 210, low on AC request, high on AC high pressure, fans off over 45mph. I have yet to find any CFM ratings on the tahoe fan setup.