Trem has a good point. If you can "seal" a large fan and pull air across the hex you should get good air flow without a lot of fancy construction. If you can create space between the hex and fan you get a better plenum. You can then add flaps/etc. to reduce recirculation as others have done. This is why years ago you saw large radiator fan housings with the fan close to the engine and maybe 4 more more inches from the fan to the back of the radiator. That was back in the days when there was room in the engine compartment.

In the server business - space is everything. This is why HP and other companies want high performance small fans. This doesn't mean small fans are good for all applications.

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Attaching cradle-bracket to tub. Using 3/16” diameter pop rivets with 3/16” – 1/4” grab. Gel epoxy goes in holes put in tub and on rivet-shafts. Am looking to seal tub’s exposed metal (in bores.) Idea = prevent bores from rusting---at least significantly delay rusting. For '80 911... is in good condition rust-wise. Seeking to keep it so.


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"90" typically serves hex screw driver heads. Got 3/16” hex drill bit. To get contraption into wheel well and squarely against bracket... minor surgery. Rivet gun in wheel well... managed tiny increments of squeezing out rivets (so no need to modify handle length.)


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Short length added to air-valve intake works---inlet faces tub at inward flare of wheel well without touching tub. iPhone batt ran out while testing fit so no pics at this stage. Will get pics of fit later. (HC notes bends being air-flow's enemy---agreed. On this subject, it would have been nice to angle air-valve's intake to reduce air-passage-angle when valve is open/operating. Is complex joint-cuts of tube but needed to sort cuts out anyway. Problem in doing this "better angle" is duct real estate. To improve air flow from air-valve to main duct, valve duct's angle eats up more & more real estate as air-flow angle improves. That space does not exist without raising stack and therefore increasing angle of stack's top bend. Is no-win. Fortunately just enough spare space existed in stack to fit 3" air-valve diameter. The sound transition from main intake to air-valve being open is such that's there's no missing a blocked main intake. Assuming air-valve will rarely if ever activate---since I'll now more aggressively avoid plastic bags and seemingly deep puddles---decision to angle air-valve's intake duct at 90 degrees to stack was no-brainer.)


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With stack-wrangling in wheel well done, am doing final valve door install. Initially thought slip-in/slip-out valve system would be good idea but canned that plan. Premise for canning = air-valve should not be high maintenance part. Challenge with valve is spring & mandrel's install on pivot rod being from back side of doors. In order to remove doors... have to tether spring & mandrel first or they end up at tip of Madonna’s boob (per your abstract vision Bob!)... or, can go fishing for those parts. Tether is better. Would like to think it was good decision to can "slip" program.


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HP server cooling modules are received. One turbine (extracted from module) is heading to bucket-system as #2 unit. Purpose for #2 is to increase air volume delivery to bucket/condenser. Other two modules are spare parts in reserve. Reducer couplings & clamps are not in yet. (If you know news and my location... you know progress may experience slight delay.)


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Was going to run 16awg from ESC to single brushless motor. Addition of second motor ups amps to 30 vicinity over an estimated 10' cable length.

Treme... if you're suggesting a large fan in the air bucket pushing air out the condenser, or, a fan outside condenser sucking air through... both were considered with space being an issue either way. If you're suggesting a fan only and forget the bucket... this project formed on exploring the possibility of taking cooler air from ahead of rear wheel and delivering to a condenser behind it. At no time am I pizzing on Spal-on-condenser program---I know personally that this config works. This experiment serves to discover & test new ideas and techniques that may be applied elsewhere. Good example is sound barrier material you brought to light.

Yeah... remains questionable whether these server coolers are suited for Porsche AC app. Few things have been proven: it's possible to get a brushless motor running ON and OFF in 12v system, is possible to get reasonable CFM at condenser (killer CFM was unfortunately a misconception,) with only one turbine only marginal air exists---2 turbines makes air-to-condenser viable. Assuming there's no impossibility to running 2 turbines, next unknown is durability. If system runs nicely for long time, I'll disassemble at some point to see what's going on regardless of such performance.

Testing two brushless motors on one speed controller

Is something technically unique about brushless motors sending “back EMF” to speed controller (ESC) operating the motor that ESC is attached to. I’ve yet to study exactly what "back EMF" is so can only say it being some sort of reading a speed controller acquires concerning its associated motor. To run two brushless motors on one speed controller… questionable whether this config works but possible. Having found reference to config working so am testing it for empirical purposes (given plan to include second motor in system.)


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#2 and 1 are connected to single 40amp Turnigy ESC… power OFF here.


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Power ON. #1 ramps up and achieves 80% full speed as programmed. At same time, #2 stutters… stops… stutters… stops… stutters. My take = is back EMF confusion at ESC since ESC is being asked to sort out EMF from both motors (and can’t.) Why one motor runs according to program… ??? If you know, pls explain.


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Been a few seconds now since power ON. After stutter-stopping a few cycles, #2 has almost caught up to 1 but not according to program’d ramp up sequence. Is wrong enough at this stage to disconnect power…


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Before cutting power, #2 stutters again then stops… motor whisp'ing smoke. Remove #2 from circuit and test #1---Arduino, ESC and #1 are good. Perhaps there’s ESC out there that'll run multiple brushless motors of this kind. Would be possible to buy a bunch of ESCs & motors and keep testing to maybe find combo that works. Could get costly. With potentially low probability of finding combo that works and time to invest… not going there.

Simpler path = provide each motor a dedicated ESC. Am proceeding with this believing two (or more) ESCs can be correctly signaled from one Arduino. Electrical plan has to change to accommodate this mod. Can see elec-plan in head but need to sketch it out to make sure mind-pic is genuinely functional---trusting mind-pic is risky. Will post sketch later.

With each component addition, system’s complexity increases. Question: where does one pull the plug? Until a brick wall is clearly faced... surrender's not happening. If you're new to thread and thinking... "Put 12x12 condenser with Spal in fender and call it quits.” We already know that works---here, we’re looking into unknown (repeating mission now: purpose being to find out what’s required to get a reasonable volume of air from ahead of the wheel to condenser behind it. (Pardon me for restating journey mantra if you already know it.)

This Slipknot classic, which you are familiar with, KinkyKarl, fits well with the above!

PS - another round of props for forging ahead with such gusto, bro!

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Probably "timing"'. And no, a set of cams and a new chain won't help.
Read up on synchronizing poles with brushless motors.
You might explore two PM motors with one ESC; I have this set up on my kicker heater blower motors. If you go PM you may want to explore your fan blade profile.

You probably sensed that a few pages back, KISS is always the way to go, but that is not why you are still here; solve the problem.

Great muzac RonO! Love the energy those guys generate. Saw Mom in vid. :D


PM motor seems whole other universe. Is new fodder for info grist mill---TY Charliemnon. That said, am more than kneedeep with HP coolers in hand. With summer burning off, gona make bold attempt at having AC running before mid Oct. Correct me if I'm wrong but charging AC system works better the hotter the ambient is. If true, would you explain why?

#2 Turbine Config in Duct

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Burned motor next to “adjusted” replacement. Adjustment = cowlings, cowling fastener points, and footers are cut off casing. Is necessary in order to fit casing into rubber reducer couplings (being used to fit this turbine into duct line.)


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#1 Turbine

Compared to mounting turbine inside 4” aluminum tubing---as was done with #1 unit---this is simpler approach. Reason for mounting turbine #1 inside aluminum tube on rubber fenders is to reduce turbine noise. Having bench-run system, seems minimal benefit from this config since noise comes out ends of system regardless of what envelops turbine. Noise control here seems primarily matter of running motor(s) at a chosen speed level.


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Current thinking = position #2 connected to bucket. Slight turn in duct needed (as duct approaches bucket) may be possible to create with rubber couplings. Test fit in fender will answer if this is possible. If push comes to shove… inlet to bucket can be modified to make turn. Another option, position motors head-to-tail where #1 is currently positioned. Not inclined to this as result will surly be lower CFM at condenser.

Second ESC is ordered. When it comes, will assemble system and bench. Added hard duct and #2 turbine will eat up half the existing length CEET duct currently occupies. Point being to dump as much high friction duct as possible. How two inline turbines affect each other… unknown to be answered.

Always amazing work in your threads Uncle Karl.

Reasons to evac and charge at higher ambient:

Evac - water (moisture) 'boils' off more easily at higher ambient.
For example, boil off starts 86F ambient starts at 28.67 inHg. If you were at 64F ambient it would require a deeper vac down to 29.32 inHg. Hence the preference to use digital gauges vs. analog needle to start off at those reading levels, then you would want a micron gauge to read further down, say anything under 29.87 inHg. So, its simply a matter of taking advantage of higher ambient assist with boil off; and my 2 cents on importance of equipment type.

Charging - A few issues here.
A) Typically your mechanical thermostat will make contact above 55F.
B) If you charge by P&T (pressure and temperature) on the high side, say a 65F day,
although your high pressure, say 156 psi, may look good (in theory) and your vents are cold, there is no way to insure that charge will perform as well or better on a 90F day; which would be near 230 psi.

In summary, you can evac and charge in cool temps however always best to toss the gauges back on system on a warm day and recheck the numbers.
"Set it up on the dyno and tune it on the street".

Commentary appreciated Charliemon! http://forums.pelicanparts.com/support/smileys/wat6.gif

Detail on hot/cool day charging is enlightening---TY! Baring a catastrophe, will have system charged soon---in the hot.

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Version 2 wiring plan accommodates addition of second Electronic Speed Controller (ESC.) Only one 5v power wire runs from either ESC to turn Arduino ON. Is theoretical that Arduino will correctly signal both ESCs with two 5v signal wires (running from pin 8 in this case.) I don't believe there's a problem with this---bench will confirm one way or another. 5v wires provided by ESC are Battery Elimination Circuit (BEC) wires = white, red, black / signal, power, ground. Wheel well junctions = waterproof. Will now tap into AC ON/OFF circuit in cabin somewhere rather than by compressor.

Hopefully you won't have any EMP's or sunspots where you are driving.

Same here - turbo powaaa' tunage, for sure!

Hilarious about yer Mom in the vid - love it! :D

Just a reminder to fuse your wires every time the gauge decreases...If you have, say, two 10awg wires coming off that main relay and they are both protected by a single 40A fuse, the fuse might not blow if one is shorted, and the wire can burn.

For splicing power to the arduino, etc, you can probably get away without fusing if it's a short splice that is in no danger of touching the chassis. I don't really know how the ESC delivers power.

FUSES

That stuff is limited to Jersey. Gotta keep shades on :cool::cool::cool::cool:

Gorrilla's in the mist :D

Killer electro-tidbit Treme! I would not have done this. TYBT!

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16awg stranded 4-wire cable (suited to single ESC config) next to 16awg stranded 6-wire needed for dual-ESC config. Both cables are same 3/8” O.D. Am going heavy duty on this as it will run exterior as well as near engine. Not sure if center tunnel is way to run this through cabin or just lay it on floor board. Source = ProWireandCable.com . 3-wire cable needed for where 6-wire splits to serve each motor... believe HomeDepot has that.


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Making sure ESC #1 and #2 mode settings match. These settings are now applied to both ESCs. Looking at card, am wondering if "music" would be good to have turned ON. There are different tunes that ESC plays to signal status. Would be indication of ESCs working (or not.) Something to think about.



Testing two brushless motors now with dedicated speed controllers

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Wiring is as last sketched/posted (minus 12v 40amp relay and AC circuit connection.) Power is supplied by 12v motorcycle batt. Will update sketch to include fuses Treme input and post later.


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Power OFF.


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Power ON. #1 is ramping up and #2… nothing… half second later #2 starts and ramps up without stuttering. 5v power for this test-run was served to Arduino (to turn Arduino ON) from ESC #1 only. Is that causing #2’s delay? Switched 5v power for Arduino to come from ESC #2 and… no difference in start up… #2 still delays half second. Disconnected #1 from system altogether and tested #2 alone. It ramps up as it should.


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Ran start sequence few times and result is always the same.* Both motors seen above are at full speed---“full speed” for time being is at 80% of motor’s capacity. Faster than 80% and turbine-whine becomes a bit much as heard when benching units. In car… things may be different. (If not well secured… these quickly have a mind of their own. As HColes mentioned earlier, HP developed these turbines to deal with the greater heat their new blade servers were generating. Looking into this, I found that an HP executive was/is an RC enthusiast and it was he who introduced idea of Electric Ducted Fans (EDFs from RC jets) as a potential solution to company's blade server cooling needs. HP intentionally altered RC EDF design to their more robust solution. Result is brushless turbine being applied here.) HP units tested are "reconditioned" costing $9.99 each NI shipping. My take on "reconditioned" is there's no telling how many hours a given unit has run. Or, what reconditioning constitutes in terms of actually mechanically servicing a unit. Provided system installs in car as planned, and provided there's durability of blades given permanent 1/8" particle filter---Glen-filter (TY Glen)---installed... if there is blade durability, plan is to replace "reconditioned" units with new. New HP cooling modules are priced anywhere from $25 to $95 on eBay. Takes seconds to remove turbine unit from module. Then each unit must be "trimmed of certain appendages" to fit into system.

* Given consistency of #2's delay and correct operation of both motors following start... no concern with this scenario here. Beyond bench, have to ask how delay will work in assembled system with #2 few feet behind #1? Am not seeing any issue with this. If you do... pls say so.

Air speed comparison at bucket inlet

Air speed into bucket is measured at end of duct, just before air enters bucket. Anemometer is positioned at center point of duct for each read. CEET duct here is not yet shortened as will be necessary provided turbine #2 is installed just ahead of bucket. Few inches of extra CEET for this test doesn’t matter. Unlike prior air speed test, CEET duct is bent for this test. Bend is not exactly as it will be in fender but close enough to simulate resistance generated from bend. Both motors are programmed to run at same speed. (Is possible to program Arduino so one motor runs faster/slower than other.)

When looking at results, should bear in mind each turbine is ducted differently. There’s a “house’d” version and “reduced coupler” version. Look back a few posts if you’re interested in differences.

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House’d turbine positioned just after intake stack. This config was previously air speed tested. Speed here is fairly close to test result done days ago with straight CEET duct and smooth bore metal duct. Slight speed loss here. Bend in CEET ductis likely cause. (22.0)

Not looking to split hairs where measuring air speed is concerned. What’s of interest is any significant delta.


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House’d turbine followed head-to-tail by reduced coupler version. Combo is positioned just after intake stack. Would be difficult if not impossible to fit this config into fender (due to total straight length measure of combo unit.) Is possible to shorten head-to-tail total length but doesn’t matter given obvious inefficiency compared to other results. (25.0)


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Reduced coupler turbine positioned just after intake stack. (27.2)


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Reduced coupler is connected to end of CEET duct for this test (so exhaust side of coupler is "end of duct.")

Reduced coupler turbine positioned just before air-bucket. Triple checked this reading to make sure reading repeated. It did. (71.5) Went back to triple check result when this turbine is positioned just after intake stack. (27.2) Is correct.

EDIT: Is now day after these air speed tests were done. At moment this config---turbine just ahead of bucket---is preferred. Set this up again now to confirm air speed and reading was 50 mph. Having tested multiple times yesterday with same reading in 70 mph area... something's changed but cannot see what yet. Delta here is too much to ignore. Answer needs finding.

EDIT: Answer to air speed anomaly = multiple variables at play:

1. Clock position at turbine's exhaust where meter is held... it matters in this case---With system in operating position (as if installed in car) and looking at exhaust side of turbine and 12 o'clock at top, highest speed (72 mph) reads at 4 o'clock. All other clock positions are lower and relatively even. Rotated turbine 180 degrees on duct... highest speed remains at 4 o'clock. Is is CEET duct and/or bend in CEET?
2. Where meter is positioned at exhaust matters greatly. For this study, center of meter's impeller was aligned directly with exhaust areas of turbine. (This was also done for yesterday's test.) Because motor occupies center area of turbine, cannot position meter at center as is possible when measuring ducted air speed. Will comment on anomaly & findings status in new post.

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Same as prior... Reduced coupler is connected to end of CEET duct for this test (so exhaust side of coupler is "end of duct.")

House’d version just after intake stack and reduced coupler version just before bucket. Another triple check. Reading confirms. (71.7)


What air speeds reveal:

1. Bend in CEET reduces air speed slightly where house’d version exists ahead of it. Speed reduces dramatically where reduced coupler exists ahead of CEET (likely in combo with CEET’s interior wall friction.)
2. House’d turbine version = very inefficient. My guess: exhaust air is returning to intake through gap* where fenders are.
3. House’d turbine offers no added value when positioned ahead of reduced coupler.
4. Reduced coupler turbine---when positioned just ahead of bucket---significantly outperforms house’d version.
5. “Assisted gain” didn’t happen. Would it happen with both turbines wearing reduced couplings? Is this config worth creating? Is single reduced coupler turbine better by default than two of them---as in less-is-more?
6. Updated CFM: 71 mph = 6,248 fpm X 0.0872 = 544 CFM. Does not account for duct’s interior friction (as noted by HColes.) Should be noted that CFM does not stand alone is regard to system's thermal performance. Air temp as delivered to bucket/condenser is also performance factor---the crucible of this journey.
   EDIT: Is day after these tests and original post. Set system up with reducer coupler turbine just ahead of bucket to confirm air speed. 70 mph (as read over three tests yesterday) is not duplicating today. 50 mph is today's air speed. Am looking for answer as to what has changed.
7. Domino affect on hand. **

If you’re following details and see anything missing or off-base, your input would be appreciated.


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* Gap between turbine housing and 4” duct. Is good example how benching reveals what minds-eye doesn’t see. In this case, am at fault in this design for thinking more of noise insulation and not enough about air flow. Also learned that mounting this EDF inside aluminum tube does little-to-nothing in terms of turbine noise reduction. This sort of ed nicely justifies exploring unknowns IMHO.


** Dominos

Increased speed does domino onto deflector, filter and air valve---none of these parts being designed with 70+ mph air flow in mind. Thin gauge deflector construct reads doable given added bracing. Filter (with 1/8” diameter hole & hole count in cone) provides more open area than does area of 4” duct itself. Increased friction at filter?…yes, is evident by air-valve opening. Air valve needs to be adjusted. Before making any refinements, must decide on final turbine config. Reduced coupler version positioned just before bucket offers best air for minimal hardware. Have to think if there’s ANY benefit to having two turbines before dumping 2nd unit. If you see this differently, pls say so.

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Anemometer used.

I'm fascinated by this thread but have so little to offer.

But yesterday, while blowing off my driveway, I was once again "blown away" with how much air this sucker moves. I know the voltage isn't right, but I thought it might be an "outside of the box" solution that could lead you somewhere. I think it's 400 CFM.

Dave... fine OOTB thinking! Am betting leafy blower has a ducted fan (EFD) in it! Assuming it does sport an EDF, would be interesting to see how robust the turbine blades are. It could indeed lead somewhere. Right now am too far down the pike to change turbine gears. Fact is, these HP motors & blades are unproven so must keep options open. You do have something to offer if you're willing to get in for a look-pic-post of the blades in your blower and motor size. If blades are robust and motor is a working fit, would be possible alternate direction on the table for next summer. Appreciate input regardless of you diving into your blower or not. TY :)