Electric Radiator Fan

[booster]

Originally Posted by sadpanda

To further muddy the water, interesting testing done by TBSS fellas: https://www.tbssowners.com/threads/f...-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.

Just a note on the shrouds for the mechanical fans.


I used to mess around with some pretty nasty engine muscle cars like the twin turbo 340 cid Dodge Challenger that I built in the late 80s with all homemade stuff for turbo setup with carb and then aftermarket EFI. 600hp/600tq on a 5 speed Richmond trans. It was wonderful engine but the engine compartment was stuffed with hot stuff so hard to keep cool at idle because the air couldn't get out. I used every electric fan they had in those days and none would do the job either with a 4 core copper/brass radiator or a Griffen aluminum. The Griffen was great once moving but the electrics couldn't cut it at idle. I went back to a mechanical clutch fan with factory shroud and still had some issues.



The "rule of thumb" back then was to have the fan half in and half out at the rear of the shroud and that is where I had it. Checking airflow I found nearly all the movement coming off the blade ends with very little straight back toward the engine. I moved the fan back toward the engine so that the blades were only into the shroud about 1/4" and idle cooling issues went away completely. The airflow coming out from under the car sitting running was noticeably higher.


Today's cars with mechanical fans always have them tucked completely into the shroud, presumably, and wisely, for safety reasons. It does appear to cut down the flow a bunch. What can be done safely is to window out sections of the rear of the should and cover them with finger safe mesh to let the air out.



I really don't understand why GM turns on their fans at so high a temperature. I went through this on my 1996 Buick Roadmaster wagon that has the old reverse flow cooling 5.7 engine. The reverse flow makes the sensors and thermostat read differently, I think, so they are really high at 215 and 227*F, when the engine on thermostat runs about 198*. You get a constant cycling up and down that hot at stoplights and it is warm enough that in hot weather the alcohol laced fuel starts giving stutters at stop sign leaving. I tuned them down to 204 and 210* with my tuner where the 204 is just a bit above what the sensor sees on hot days at highway speeds and now it runs great all the time.


The Buick runs the small fan continuously when the AC is on and it never goes above about 202* it the hot weather. My high van essentially never comes on. This is with a 1.25" thick single core radiator which is the middle thickness of ones they offered on different cooling packages.


One thing to consider is that for as long as I can remember vans always run hotter than their full engine compartment cousins like pickups and SuVs. The small van engine compartment just can't get the air out fast enough, it appears. There is a discussion on here about adding side fender vents to let air out of the engine compartment, and I have considered doing it, but haven't to this point.

[phantomjock]

I did a quick look a while back at the efficacy of installing side vents (in the fenders). I believe more body work hassle than benefit gained. In my Chevy 2500 there are several "layers." Not just metal, but also the obligatory "plastic" inner liner(s). Not to mention the engine is so far aft, no effective "venting" could be accomplished as it is virtually in the cab.

So, since my under hood cooling experience has been with race cars, I see 3 EXIT locations of reasonable merit. All located in the hood. The pic shows the 3 and the cabin air intake (as I understand it).



If I didn't have another ongoing (major) project, I (very briefly) considered picking up a used hood for about $100, doing some surgery, and providing some real answers. The alternative of doing a CFD study is still to involved for my workload. Perhaps someone else could be persuaded to cut some tin.

For a test protocol, my thought experiment identified a few key measurements; OAT, engine bay temp, various speeds, with baseline hood, then with modified hood, and modified hood with fans. Comparing bay temperature and temperature at the outlet and near the alternator(s) would be useful too. My data would be unrepresentative, as my modification eliminating the entire shroud and mechanical fan, and replacing with electric fans, would not represent a true baseline. Also, my Short Ram Air intake frees up a sizeable volume in the engine bat formerly used by the air filter canister and assembly. Also why I am seeking a smaller coollant reservoir.

CABIN AIR INTAKE (Area 4): The rubber gasket does seal the hood from the cabin intake, so the #3 area would still be a "last" choice, require some clever aero "shaping." Areas 1 & 2, however with some cleverly designed louvers, perhaps a couple of small pancake fans could provide much measured relief.

Perhaps adding additional air INTAKES could provide some relief? There would be a drag (and MPG) cost, but just like adding brake ducts in a race car similar devices could add atmospheric (not engine heated) air to the bay? A 4 inch hole saw and some drier ducting - Bob's your Uncle! Again I'd look for similar test protocols.

Any Takers?

Cheers - Jim

[booster]

Here is a link to fender vents, but be aware there is typo that says they are air inlets, when the really are exits that help the radiator fan push through the air out of the engine compartment.


Be sure to read down quite a ways as it comes back to vents again later on.


https://www.classbforum.com/forums/f...tml#post146233

[sadpanda]

Originally Posted by sadpanda

I have yet to find any CFM ratings on the tahoe fan setup.

Correction

VDO 7/9 blade FA70620 is listed as 2963 CFM
VDO 5/7 blade FA70618 is listed as 2712 CFM

For reference VDO site also states lauded crown vic fan as only 1562, old LS1 dual fans were in the same range.

Only way to get more CFM would be FlexALite claimed 3000 cfm 16 pullers but at $155 ea + shroud, it seems the OE solution would be the best bang for the buck

[phantomjock]

Just a few quick ones;

The Fuse Panel tap locations for the Extreme Electric Fan Controller (Stage 4) I installed:


Here is a quick shot of the controller mounted in a "Dry Location." OK it is under the hood, but I fabricated a weather resistant cover:


A diagram of the controller and the connections:

An observant reader will note I got my colors out of the crayon box mixed up The yellow/green are not coordinated between the 2 diagrams. To lazy to change it.


And as a finale; a paste up of a hood "concept" with a similar vehicle CFD. Note the lower pressure zone midway up the hood - that is without an opening. That region would "fill" and draw air from the engine bay. Just as the earlier versions 1 & 2 would.

[phantomjock]

Originally Posted by booster

Here is a link to fender vents, but be aware there is typo that says they are air inlets, when the really are exits that help the radiator fan push through the air out of the engine compartment.

Yes. And, I "get it." And, there might be some lower pressure to help vent those in that location. But as I survey the area, without pulling the fenders, and then opening the inner fender - to match, those will only be venting the space between the outer fender sheet metal and the inner fender - not the engine bay. Perhaps some ventilation of the wheel well - but also slight. I concluded this by looking through the open door to the inner/outer fenders. Plus on the 2500, there is a "lot of stuff" in those areas - air conditioning on pax side, ecu, brake cylinder, etc.. Vehicles may be different - but on a Chevy 2500 - the fenders would have to come off.

It would, in my opinion, be more profitable (small business op here?) to splash a carbon fiber hood, following testing of the sheet metal tests I proposed. That would be my approach. But then again, I am more of a 'Glass-man than a Panel Beater. And, it would keep the vehicle in service longer.

Cheers - Jim

[sadpanda]

Im assuming you have seen this:
https://www.sarona.com/Chevy/Express...per_cowl/Hood/

or better still, this looks like your desired design, just needs cut open
https://weldtecdesigns.com/product/w...berglass-hood/

ironically the most reasonably priced thing I've seen from them

[phantomjock]

Originally Posted by sadpanda

Im assuming you have seen this:
https://www.sarona.com/Chevy/Express...per_cowl/Hood/

Nope - never seen those before on an Express Van. I've seen that one on other cars. Sometimes called a "snout" or, a snorkel. These were on some of the muscle cars like the Pontiac Firebird, for one.. As a forced air intake, it could be good for a ram air for power/performance, and some additional fresh air into the bay. But, then the challenge of exhausting that air is what increases underhood drag, and reduces MPG with little change in underhood heat. Nice looking, though.

Originally Posted by sadpanda;148297or better still, this looks like your desired design, just needs cut open
[url

https://weldtecdesigns.com/product/wtd-chevrolet-express-fiberglass-hood/[/url]

ironically the most reasonably priced thing I've seen from them

WoW! Not cheap at all. Looks "cool" but for removing underhood heat, would definately need to be opened.


As presented, both of these appear to me as; styling items. They are offering look and more form than function. This second one, with the left and right 'flats' on the hood opened judiciously, could offer look and function.

For example;


But for now, these are just my opinions.
Testing and temperature measurements would be useful for decision making.
There might be some business op here.

Thanks for bringing those in.

Cheers - Jim

[phantomjock]

A quick sketch if I may:

[booster]

Originally Posted by sadpanda

Im assuming you have seen this:
https://www.sarona.com/Chevy/Express...per_cowl/Hood/

or better still, this looks like your desired design, just needs cut open
https://weldte
cdesigns.com/product/wtd-chevrolet-express-fiberglass-hood/ ironically the most reasonably priced thing I've seen from them

I have not looked at all that they have to offer, but the front to rear slotted bulge hood would certainly what I would pick to evacuate the engine compartment, rather than pressurize the inlet like the other options. Of course you would open the sides of the bulge to pull out the air compartment air.

Airflow is very picky a thing and getting it to help you can be a big benefit, but if it hurts you it makes things worse. Been there, done all of those options.


The other pics of the front scoop hood would be good for force feeding the air inlet to the engine but not for compartment cooling.

[booster]

Originally Posted by phantomjock

A quick sketch if I may:

That would work, but IMO you would need to turn the louvers around to the face the rear if you want to evacuate air from the engine compartment. Putting more air into the engine compartment is going to reduce the air through the radiator and that is not a good thing.

[phantomjock]

Originally Posted by booster

That would work, but IMO you would need to turn the louvers around to the face the rear if you want to evacuate air from the engine compartment. Putting more air into the engine compartment is going to reduce the air through the radiator and that is not a good thing.

That is just an illusion created by my crappy shetch. Those lines are hastely drawn, to show what may be a viable location for louvers - areas 1 & 2. Those are indeed exhaust louvers - not intakes. They must be facing aft to allow flow out of the engine bay. Additional high pressure in the engine bay would - yes interfere with radiator cooling (unless ducted elsewhere for exit) and cause a major decrease in fuel economy.

I felt no need to make a CAD correct presentation - just a "Quick Sketch" regarding placement. I thought this image in the earlier post made that orientation clear:


There are a number of after-market louvers that could be purchased for this.
I still believe a test would be worthy before committing to an expensive modification to a $700 fiberglass hood!

Good fun and some information clarified - I say.