Mod idea - good or bad???

[skippy]

ok my 2 cents is that by cutting a hole in the bonnet i mean hood you decrease the amount of air that will flow through the radiator?
yes some heat will escape through the holes but there is a reason why there is a shroud around the fan?
also the rain as doug said could cause some other issues?
it will be interesting to find out the results!
i have thought about this mod for along time!

 

[theBroken]

I got you Skippy.

Bonnet = Hood
Boot = Trunk
Saloon = sedan
Caravan = RV
Drop-head = convertible

I can pronounce Nürburgring and Bathurst properly also.

 

[skippy]

Thanks Brodie I have had it all week no one can understand me

 

[HUMMER INVESTMENTS]

:corn:

 

[LagunaH1]

I got you Skippy.

Bonnet = Hood
Boot = Trunk
Saloon = sedan
Caravan = RV
Drop-head = convertible

I can pronounce Nürburgring and Bathurst properly also.

Bowser = fuel pump

 

[LagunaH1]

Did you have similar issues with the clutch driven fan? If not, then I'd very seriously think about reverting back to the stock setup

 

[rsc]

ok my 2 cents is that by cutting a hole in the bonnet i mean hood you decrease the amount of air that will flow through the radiator? yes some heat will escape through the holes but there is a reason why there is a shroud around the fan? also the rain as doug said could cause some other issues? it will be interesting to find out the results! i have thought about this mod for along time!

I think you might be confusing a few things. There are areas of high and low pressure around the vehicle as the air passes over/around it. Air vent intakes are places at the base of the windshield because that is a place of high air pressure like the front grill and at the base of the windshield as the air has to hit the windscreen and be directed upward, over the vehicle. The same principles apply at the front of the hood where the air vent will go. As air comes over the front edge of the grill Bernoulli's principle takes effect and causes a low pressure area at the front of the hood. We are trying to tap into this low pressure area to "suck" the air out of the engine compartment throuh the hood vent instead of letting it out underneath the vehicle or spilling out around the edges of the hood.

http://www.gmecca.com/byorc/images/liftdownforce.gif

 

[rsc]

Found this while looking for pictures of the pressure zones on cars. Everyday, laymans terms with scientific measurements to back up his backyard guesses and attempts.
http://www.oman4x4.com/hoodvents.htm

I'm looking at this more and more, now I need to find a decent full coverage hood louver or make one at work that will look good and still look like stock.

 

[Steve #1]

True, but the isue with the H3 comes when not moving or moving very slowly. The pressure zones arn't in play.

 

[bebe]

Some info I gathered from my conversations with the Ron Davis folks.

The fan shroud is very necessary to direct the flow from the OEM Fan. The e-Fan is sitting right on top of the fins so it should be ok as is.

However, when I asked RDR about using an e-Fan on my new set up, they said absolutely not. His explanation was that the e-fans cfs's are anywhere between 4000-6000 cfs. The OEM fan runs about the same, but when the fan clutch kicks on it's running at 7000-10,000 cfs. The e-fans can't do that.

He said the measurement of the cfs on the e-fans are usually done on a bench, not on the truck while moving, the directional flow coming into the vehicle actually reduces the cfs of the e-fan. He also said the mechanical fan is the best way to cool an engine and trans, he made the point "If e-fans were so great, every manufacturer would use them". They were originally designed to be used as auxiliary fans, not a primary.

Notice on many of the race vehicles they are used on - they are not in a direct air flow position, they are usually located out of the engine bay, on top of the back of the vehicle, this allows it to suck air with the down draft.

I hope I'm making sense. :giggle:

 

[bebe]

Let's try looking at this from a different angle. I understand that the Efan uses a pretty high cfm rating so airflow across the radiator core might not be the entire issue. The transmission cooler is located inside the radiator for more efficient heat transfer to cool the transmission, but that also heats up the engine coolant more- 250F vs 200F for the two fluids. At 100F+ ambient temps I notice the radiator is getting to the limits of it's ability to shed heat, especially noticeable when running the A/C. Above 105F I have to cycle the A/C to balance engine temps with interior comfort around town below about 55 mph. I agree that hood louvers will shed engine bay heat, but by also adding an inline transmission cooler you might be able to shed some of that transmission fluid heat before it heat soaks the radiator. ???

I have noticed my Fan clutch kicks on at about 215-225 depending on speed/airflow. I just replaced my thermostat and it is stamped 190*. I run the recirc all the time (I don't think I have ever actually hit the little snowflake button).

Another direction from RDR is that the new Radiator they are designing for me will keep the integrated trans cooler like OEM, and they have beefed it up, plus it being all aluminum, should make it more reliable. (I shouldn't say should, it WILL be far more reliable). The radiator will have a higher air flow and cooling capacity, but they are still recommending I run the Aux cooler in addition to the integrated. We ran mine like Brodie did, with the cooled fluid going into the trans.

The fact remains we drive bricks, these in-lines run hotter, the auto trans runs hotter, and when we add all our gear, bumpers, racks etc, it increases load which makes it run hotter, and then when we throw a big winch in the front, we limit air flow which makes it run hotter.

A better radiator (not saying the OEM one is bad) will increase cooling capacity, make what air flow we do have more efficient., therefore allowing us to add all our crap and help increase engine life and reliability.

 

[rsc]

Some info I gathered from my conversations with the Ron Davis folks.

The fan shroud is very necessary to direct the flow from the OEM Fan. The e-Fan is sitting right on top of the fins so it should be ok as is.

However, when I asked RDR about using an e-Fan on my new set up, they said absolutely not. His explanation was that the e-fans cfs's are anywhere between 4000-6000 cfs. The OEM fan runs about the same, but when the fan clutch kicks on it's running at 7000-10,000 cfs. The e-fans can't do that.

He said the measurement of the cfs on the e-fans are usually done on a bench, not on the truck while moving, the directional flow coming into the vehicle actually reduces the cfs of the e-fan. He also said the mechanical fan is the best way to cool an engine and trans, he made the point "If e-fans were so great, every manufacturer would use them". They were originally designed to be used as auxiliary fans, not a primary.

Notice on many of the race vehicles they are used on - they are not in a direct air flow position, they are usually located out of the engine bay, on top of the back of the vehicle, this allows it to suck air with the down draft.

I hope I'm making sense. :giggle:

Thanks Bebe, I learned something new today. I knew the e-fan wasn't quite as effecient as the mechanical fan, but didn't know why. It seems counter-intuitive that incoming airflow would reduce the fan's airflow, it should take some of the load off of the fan and free up some rpm's. Much like measuring propellor rpm on the ground vs. inflight where the prop "unloads" and speeds up gaining rpm and airspeed

 

[bebe]

Thanks Bebe, I learned something new today. I knew the e-fan wasn't quite as effecient as the mechanical fan, but didn't know why. It seems counter-intuitive that incoming airflow would reduce the fan's airflow, it should take some of the load off of the fan and free up some rpm's. Much like measuring propellor rpm on the ground vs. inflight where the prop "unloads" and speeds up gaining rpm and airspeed

I think it's because they are electric and can be affected more by the turbulence created by the incoming air flow than a mechanical fan would.

Also, he said most fans, mechanical and e-fans are really only effective at speeds below 20 mph, after that unrestricted flow is the most effective for radiator efficiency.

Paladine - you could always put your mechanical fan back on for a comparison of effectiveness.

 

[Paladine71]

I've been thinking about that. Still undecided. Thanks for the info, Bebe.

 

[theBroken]

Some info I gathered from my conversations with the Ron Davis folks.

The fan shroud is very necessary to direct the flow from the OEM Fan. The e-Fan is sitting right on top of the fins so it should be ok as is.

However, when I asked RDR about using an e-Fan on my new set up, they said absolutely not. His explanation was that the e-fans cfs's are anywhere between 4000-6000 cfs. The OEM fan runs about the same, but when the fan clutch kicks on it's running at 7000-10,000 cfs. The e-fans can't do that.

He said the measurement of the cfs on the e-fans are usually done on a bench, not on the truck while moving, the directional flow coming into the vehicle actually reduces the cfs of the e-fan. He also said the mechanical fan is the best way to cool an engine and trans, he made the point "If e-fans were so great, every manufacturer would use them". They were originally designed to be used as auxiliary fans, not a primary.

Notice on many of the race vehicles they are used on - they are not in a direct air flow position, they are usually located out of the engine bay, on top of the back of the vehicle, this allows it to suck air with the down draft.

I hope I'm making sense. :giggle:

Most vehicles with engines that are mounted in sideways have Efans.

You should have RDR design that new core so it's not as tall and have it mounted about 1" shy of the bottom of the condenser. This will keep mud/dirt from building up between the condenser and radiator. And since your talking to them ask if they can use brass ends on the sides of the cores instead of aluminum.

 

[Portager]

I agree, the easiest way to test this is to switch back to the mechanical fan, but to get valid data you need to test each approach in nearly identical conditions and you need hot weather otherwise the thermostat will mask the results. Therefore, you should wait until a very hot day when your truck over heats and switch back to the mechanical fan before the weather changes and retest with a mechanical fan. Of course in Iowa the weather is famous for changing every 15 minutes, so you better be fast.

 

[bebe]

Most vehicles with engines that are mounted in sideways have Efans.

You should have RDR design that new core so it's not as tall and have it mounted about 1" shy of the bottom of the condenser. This will keep mud/dirt from building up between the condenser and radiator. And since your talking to them ask if they can use brass ends on the sides of the cores instead of aluminum.

You are correct...and....

Those vehicles usually are much lighter than an H3 and they have 2 fans - one for cooling and one for the A/C.:wink:

Making it shorter would require modifying the mounts, and the goal is for it to be a direct OEM replacement. There is a pretty good mud and dirt trap in between the condenser and the rad, but I guess since you and I have both discovered that we can make sure our Hummer brothers and sisters are aware of how important radiator cleaning is as regular cooling system maintenance

[video=youtube;I-thGyh_W6c]http://www.youtube.com/watch?v=I-thGyh_W6c[/video]

I can ask them about the Brass ends but I'm sure they are trying to avoid making it more expensive for the consumer. I'm sure if someone wanted something really fancy (trick, badass or whatever) a custom radiator shop would be happy to oblige.

RDR has had some great success over the many years they have been in business with their all aluminum product, it's just what they do. There are other manufacturers out there who may be comparable, but most of the best in our industry use RDR.

 

[Hunner]

Huh, so an auxiliary set of double E-fans laying flat where the louvers that are not louvers are but with some type of modded version or vent or removable cowl for extreme heat conditions while at slow trail speeds with minimal wind shear across the fans, set up to exhaust heat upwards assisting in the natural tendency for heat to rise and the stock fan drawing in fresh air across the radiator might work to help the heated air escape???
post 14

 

[bebe]

LOL - That was your original idea right?

 

[Hunner]

Well, yeah but then I thought maybe it sounded too Redneck for some people.:emb:

 

[bebe]

Your sitch is a lot like mine, lots of added weight, creates more work for the motor and trans. It needs more efficient cooling not necessarily more cooling.

But whatever works for you and your application may not work or apply to everyone else. It's not redneck for you, but may be for a guy in New York who only wheels to the ski slope.

What we have to do is make sure it's applicable and advantageous. We get held to a higher standard because we own and wheel these rigs.

There are plenty of snake oil salesmen out there.

 

[Hunner]

I think there are starting to be people catch up to our vehicle "gross" weight. Paladine is carrying some baggage also. It adds up quick. I just loaded mine up and will try to weigh the H3 in the next day or two.
Beadlocks and 35's with rock rings are 135#! each!
What do those 37's weigh?

 

[bebe]

38's and they are 87lbs Hutchinson/Tire Combo.

 

[Hunner]

Whoa I better check my scale. Heck maybe "I" did lose some weight??
edit I checked on that
I got the 135 with it all mounted.

67lbs Cooper STT 315 manufac. stated weight
46lbs Hutchinson weighed wheel
113lbs
16lbs dual rock rings
129 lbs
or there abouts, according to cheap bath scales, just wondered, guess I got rocks in there somewhere.

 

[Paladine71]

Whoa I better check my scale. Heck maybe "I" did lose some weight??

I'm doing P90X right now, Hunner you could jump in on that... :horns: