i wanted to say this awhile ago but neverless i'll admit it now.......i tore the tag off my matress.

 

Not yet. Started this thread talking about possible delays due to a second house purchase, and that just got active again this last weekend.

 

Thanks for the update Hutch - I can certainly appreciate having other projects going. By the by, I am offshore and cannot get a measurement I am looking for: the ID of the shroud on 03 - 1500 w/4.7 (should be the same across the hemi as well) AND the diameter of the factory mech fan. I need to compare this diameter to the e-fan I want to purchase. I am sure you know if you don't get your shroud close to the fan blade ends that you will lose a lot of air flow. What are you thoughts on this?

And last ... most of you notice this is only my second post. I admit to watching things for awhile before jumping in on a topic which was of interest to me. I read through the entire Gen 3 forum before I decided this was a forum I wanted to join. Here's an intro:

Truck: 03 1500 w/4.7L, red
Tires: Yoko at/s
Susp Mods: front Edelbrock IAS, no rear change yet
Engine Mod: TPS @ .75v, IAC w/4.7kOhm resistance added, Autolite 3923 plugs
Exhaust mod: glass pak 3 in/out --- stock pipes
Intake mod: K&N filter

cheers,
rovman

 

You do need to have the shroud close to the blades for best performance, but the placement of the shroud vs the outer fan tip distance is going to be a bit different for every fan. From some of the preliminary testing I've done, doesn't seem like these fans really perform well when pulled back from the radiator. Not sure on what your dimensions are for your truck, only really looked at second gens and 1st gen Durangos so far.

At this point, I'll post here when I have a real update, but unfortuneatly the house thing is going to take up a lot of time in the coming weeks. Have to admit the stuff I'm doing specific for Rams is getting pushed back because I've already made the decision I'm not doing the mod for my truck this summer. Only real factor I wanted the fan for was better a.c. performance, and realized in the last few weeks my a.c. is screwed up and needs more serious attention. Haven't had time to look into what's wrong with that yet, and since all my trips are under 5 minutes, can't really justify making it a priority to fix right now. Plus, late Sunday was out looking at a house, and when i kicked the truck down to merge it started pinging...so that's one more thing to do...lol

 

Very interesting point you make about distance from the radiator. I have noticed the pitch on the blades is much different on e-fans ... I had assumed this was because e-fans typically get mounted "radiator close" due to space requirements but had not considered this design and unintended effect moving the fan away from the radiator.

Considering blade design, I have made a couple of observations. The mechanical "flex-type" fans are often made with a flat leading edge. In other words, the pitch begins further back on the blade, as if a 1/4 or so of the blade is parallel to the radiator. However, the stock fan blades on a clutch fan begin the pitch of the blade on the leading edge.

Considering blade/shroud relationship, I am sure there is fairly precise relationship that should occur ... any source material recommendation you can make I would be willing to review and study. Observing the stock fan relationship, the entire fan blade "is not" fully inserted into the shroud ... apprx 3/4 to 7/8 of the blade is inserted. I would expect that this is to relieve "back pressure" created on the exhaust of the blade.

Again, this is just all my speculation and pondering. I don't have a background in fan design or application but have worked with a number of engines in my background.

I am curious about a point you have made a number of times ... that one of the manufacturers was "honest" with you. Was the extent of the honesty that they admited to their fans performance being below advertised spec when static pressure was above zero? I ask because you noted that they tested a Perma-Cool fan and it was far below stated output. Have you discussed their testing method and setup to see if it matches or simulates your setup which appears in your description to be thorough a applicable to automotive application?

Thanks for the discussion,
rovman

 

I'm not sure how much good source info is out there. Only aware of what I have, but those are books that are specific to my license and not readily available. You make very good observations, and seem to have a goood understanding of this.

Regarding the factory fan/shroud, I don't have source info on the specific design, but yes, having the back out ensures the fan has no real back pressure so the extent of the fan 'work' will be pulling air. If it was fully within the shroud, it would create some back pressure and have limitations on the fan.

As far as the one truthful manufacturer...when I sent my initial emails to the manufacturers, it was asking a simple, blunt question about fan performance at '0' s.p. They were the only one who immediately responded with something along the lines of 'it's fake, we know, here's what we can show you'. They were willing to send me fan performance charts on their stuff @ .1-6" s.p. They stated they stand by their numbers as accurate and have a full research and development staff, something many fan manu's don't have.

They did not say our stuff is perfect, but Perma-Cool is bad...or anything like that. When they were honest with me, I was honest back, and said I planned to start testing fans to verify performance. They never tipped me to any competitors. I chose the fans I did initially because I knew they were answering my first inquiry with a lie or misleading statement, which lead me to believe they could be doing the same in other areas. After I told the 'honest' guy the fans I planned on testing, they said they'd be very interested in what I found because they could only get 'x' amount out of it.

I've done more with this then I've posted, only really showing the Ram specific stuff here. I will say I've tested more fans then I initially posted here, just not putting anything out there right now. At a point now where I have contacted the manufacturers of fans I know cannot produce the numbers they state at '0' to request documentation they possess to prove it can. Asked for specifics on how they've tested their fans and am willing to recreate their specific test before moving on to the next step.

What I'm going after in my non Ram related stuff is readings at 0 s.p. I know they are fake from the stand point of a fan installed can't be at 0 s.p., so in that sense, every manufacturer is using some misleading advertising. (However they are truthfully advertising '0' s.p., and taking advantage of the fact that no one knows what that means.) What I'm more interested in is checking the accuracy of their advertised '0' cfm reading, because if that's not accurate, I have a legitimate case of false advertising. I won't publish anything related to that here since it's probably headed to court, but will say I've tested multiple fans from 6 manufactures, and had over a 40% 'fail' rate. I am classifying something as 'fail' if they are missing the published cfms by more then 20%, which I feel is a generous spec to hit.

It should be noted, what I posted about Perma-Cool was what another manufacturer said, and while I've tested the fan, I have not shared those readings with anyone.

 

wow, gettin pretty serious

 

I fear our friend Hutch may soon be reported missing after angering the electric fan mafia.

 

Hutch - thanks for indulging my curiousity. I am sure you are aware that, minus an industry standard for testing, it would be difficult to prove false advertising unless you have precisely duplicated their testing protocol, particularly if they can repeat their findings in their testing. Considering your entire posting, I know that is what you are trying to acheive is a testing "standard".

I too believe that the market has "oversold" on the volume of air required to cool engines. This becomes even more suspect when you look at the design of the fans and the placement of the fans. The designs rely on rotational speed ... fan placement increases static pressure and/or air turbulence created by close proximity to the radiator.

Why is this? I suspect since electric fans were first utilized as a "space-saving" alternative to the mechanical fans. For a long time electric fans have been used by the small car market and the fans were always thought to be cheap and unreliable. As manufacturing techniques allowed better and more powerful performing fan motors, larger applications could be applied (i.e. larger engines). However, the "space-saving" mentality dominated and fans are produced to mount right against the radiator ... in some cases with a poor or no shroud. When cars started utilizing clutch fans, the most important factor in proper performance was and is the shroud.

Capturing this technology, I believe if I mount a fan in the factory shroud, duplicating the position of the factory mechanical fan/shroud relationship, I can get performance equal to or better than the mechanical clutch fan. I believe that having the fan blade away from the radiator lessens the air turbulence and static pressure. I believe the key to moving air is first blade pitch and rpm, then directed incoming air (shroud), and then exhaust of air flow which minimizes exhaust restriction.

As I stated before, I am not in the profession of engineering fans but have been able to pick up what I have with some study and some practical experience with cooling applications in the oil and gas industry. What I do have question on, in my particular proposed application, is the distance from the radiator. I know having the fan too far with too large a shroud area will minimize the air velocity coming across the radiator coils ... having it to close will create higher static pressure and turbulence. So without testing gear, I am looking at a trial and error project.

I will say this ... having looked at all the postings of people who have applied e-fans, people install fans w/o knowing cfm ratings and get by just fine. Fan manuf's tell us very little about what is "needed" without bias to their products or "product kits". Hence my interest in your project ... to obtain practical general principles which can be applied to our specific applications. Think about the whole "cat-back" thing. All this amounts to is a free-flowing muffler with pipes you don't really need ... just by the muffler and keep your pipes. Same thing with the e-fan market.

Just rambling now ...
cheers,
rovman - louisiana

 

You assume that those manufacturers have done any actual testing. I think many of them simply use estimates based on fan blade area and motor speed and really haven't done any actual CFM tests for their ratings.