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Quote:
Originally Posted by Discseven View Post
BTW... if anyone wants to "partner" with me on the scripting side for this project...

.
TY for contact John!
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Karl ~

Current: '80 Silver Targa w /'85 3.2
Prior: '77 Copper 924. '73 Black 914. '74 White Carrera. '79 Silver 930. '79 Black 930. '79 Anthracite 930.
Old 09-26-2016, 09:24 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #301 (permalink)
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Quote:
Originally Posted by billybek View Post
Some filled gauges have a tiny little lever that you flip to vent the inside of the gauge for use and then flip it back for transport or storage so they don't leak.
I would just go ahead and use it. Low side gauges are just an indicator anyway and micron or vacuum gauges give you the real inside pressure.
Here is a little trick if you believe that you have a good or very good vacuum pump. The pumps pull their best vacuum level after an oil change. If you have a hose bib fitting on the discharge, take a short section of hose and put the discharge of the running pump into a small container of water. If there are very few or no bubbles being discharged from the hose over a period of time, that is about as good as the pump can pull. In the old days we would test our pumps on a very good analog vacuum gauge that was very very sensitive and expensive. If the pump proved good, we would use the above test as an indicator of vacuum. Not really bang on accurate but a good indicator.
Do not leave the hose in the water and shut off the pump!
If you were going to recommend a Micron gauge which gauge would it be? I looked at several and the reviews went from bad to horrible for many of the gauges.
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Old 09-26-2016, 10:02 AM
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Quote:
Originally Posted by Discseven View Post
^^^

Not much static difference. Enough to question consistency & accuracy of manufacturing & testing.


Replacement = left. Original = right.

Waste of valuable time. Will sort out plan B.

.
Well, before you buy a "gauge" you need to ask the manufacturer what their accuracy is, and in terms of "scale". Just like a torque wrench, you would not use a 0-150 lb wrench to torque a bolt requiring 10 ounce inches of torque.

With regard to micron gauges, do you want NIST traceable?
When you are looking at your micron gauge, and say for example it reads 600 microns. Do you consider that to be:
A) the holy gospel at the point of measurement, or
B) that is the best your pump can do on the system, or
C) you got a leak somewhere?
D) you have residual refrigerant migrating from oil in the system?
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1987 911 cab, modified
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Last edited by kuehl; 09-27-2016 at 03:45 AM..
Old 09-27-2016, 03:41 AM
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Quote:
Originally Posted by kuehl View Post
With regard to micron gauges, do you want NIST traceable?
When you are looking at your micron gauge, and say for example it reads 600 microns. Do you consider that to be:
A) the holy gospel at the point of measurement, or
B) that is the best your pump can do on the system, or
C) you got a leak somewhere?
D) you have residual refrigerant migrating from oil in the system?
These are all good points.
600 microns with a system with as much rubber tubing as the 911 has would be pretty darn good in my opinion.
One of the Vacuum pump manufactures was doing a demo at a wholesaler years ago and I remember him using charging hoses from the mechanics trucks for the demo.
He would draw down on a new unused charging hose and blank off the pump leaving the vacuum gauge and the hose in a deep vacuum. Just the rubber out gassing would raise the micron reading over a minute or two. The used hose from the mechanics truck would increase dramatically in a short period of time from oil/refrigerant in the rubber.

To answer an earlier question, I have a Supco vacuum gauge.
It is not as accurate as the Yellow Jackets vacuum gauges that we have at work but it is a pretty good indicator. It is also significantly cheaper.
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Old 09-27-2016, 04:39 AM
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Quote:
Originally Posted by billybek View Post
These are all good points.
Well, thank you!

Quote:
Originally Posted by billybek View Post
600 microns with a system with as much rubber tubing as the 911 has would be pretty darn good in my opinion.
600 is okay, not great, but can be easily done if you have good sealing (system and service set connections; a good pump is standard). The purpose of multiple evacuations and purges with gas or nitrogen is remove all "out gassing". Most auto ac techs don't run across 911/930 variants often. They think they can trust their automated recovery-evacuation-charging machines to do it all, without thinking. Got 2 phone calls this week from tech's who could not figure out why they had normal system operating pressures (with lousy vent temps) while there was only 1/3 turd of the required refrigerant in the system. When I asked them what they used to evacuate they said "a brand new bobby-air". When I asked them how long they think their machine pulled a vacuum for one stated 10 minutes and another 20 minutes; either time value is insufficient for 40 feet of hose, 2 condensers and evaporator.

AC Help Basics
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Old 09-27-2016, 05:34 AM
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Nicely written CG.
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Current: '80 Silver Targa w /'85 3.2
Prior: '77 Copper 924. '73 Black 914. '74 White Carrera. '79 Silver 930. '79 Black 930. '79 Anthracite 930.
Old 09-28-2016, 06:04 AM
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Arduino-based AC control system has picked up momentum thanks to “Dr. J’s” / John’s collaboration. His experience with Arduino sketching… impressive.

Long story cut short = visible mod in this case is an LCD added just below the existing stock AC control knobs (located at the top of the center console --- ’80 911.) At this moment, a 4D 3.2” unit is proposed. Damm fine equipment if they do say so themselves. I have to confirm this gizmo fitting well where intended... and... John has to approve it technically. Sensors feeding into this system are noted in post #299.

Rather than convolute this “Black Death” topic with digital jibber, will detour to a new “Arduino” thread. That thread will cover the digital system’s development. When that’s completed... will return here to pick up charging and what follows.

At moment, John has hardware references to look over. As soon as he gets back to me with approval, I’ll get on with plan-drawings and hardware buys. In meantime, my AC system may be setting Guinness World Book of Records for holding a vacuum. Will publish "hours held" downstream. (Will likely have ya on this one Rono )
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Current: '80 Silver Targa w /'85 3.2
Prior: '77 Copper 924. '73 Black 914. '74 White Carrera. '79 Silver 930. '79 Black 930. '79 Anthracite 930.
Old 09-28-2016, 07:17 AM
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Arduino AC control is in final stage of proofing. Arduino - Digital AC control system for '80 911. Am back to dealing with AC hardware here. Plan was to reinstall cleaned rear fender serpentine condenser… now, that's not happening. Is not worth risking the serp being out of sorts in any way. Am going with a new 14" x 12” parallel flow instead.

Location of new condenser's fitting don’t match prior unit’s---while hoses can be connected, it's not looking good---hoses are possibly in space tire occupies. Will move ports later.




Instead of using spal-like fan from prior serp condenser, air supply is being rethought. Plan at moment is to “bucket” condenser. Air would be sourced from ahead of rear wheel. Will duct air over wheel and dump it into bucket. Am in cardboard model stage. Final version of bucket… fiberglass or sheet aluminum.






Tested this 4” bilge blower. 200 cfpm seems good. Make & model = Rule 240. Is very noisy---needs insulation. Wants 7 amp fuse. More waterproofing (than it comes with) seems called for. Will remove mounting feet---they're of no use here. (How long this thing will endure... questionable.)






Rear-lid-release-cable-tube is only existing attachment for ducting and blower. (Drilling holes in car = not appealing.)






Air intake would locate in this area.

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Old 07-09-2017, 01:21 PM
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Cousin Karl,

The 12" Spal pushes 865 cfm static, laying against the condenser.
The boat fan (aka drier vent fan) you go there is 200 cfm "static".

You are going to have a major pressure drop in the design due
to the length, turns and ribs of your air tube. Kinda like trying to blow out a birthday
candle on NY side of the Lincoln Tunnel from the Jersey side.

Think Karl, Think.
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https://griffiths.com/
Old 07-11-2017, 02:16 PM
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^^^ Didn't realize Spal did so well... TY for enlightenment CG.

Will re think
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Current: '80 Silver Targa w /'85 3.2
Prior: '77 Copper 924. '73 Black 914. '74 White Carrera. '79 Silver 930. '79 Black 930. '79 Anthracite 930.
Old 07-11-2017, 04:12 PM
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Some explanation…

This and other projects I take on are done so for the sake of functional purpose that sometime goes beyond mechanical function. Bottom line, having sold my design firm in 2005, I’m at a significant loss for creative challenges without clients and having to consistently deal with the creative process. Couple that with an insatiable design-build addiction---handed down by my fine father---am genuinely unhappy without something in the making. (Baking cookies just doesn’t do it for me as it does for some of us… am referring to Wild Boar baking duo.)

Is this air-bucket necessary? Maybe, maybe not. The 3 condenser system in my ’80 911 as it was with the Spal moving air over the fender condenser delivered 33 dF at the vent. So why mess with system? Because I can / because feeding my creative addiction is mandatory for contentment. Do I ignore PPF input? No. Reason to post this and any design-build is both for input and to share ideas and techniques. In all of this I assert it being better to be a proclaimed idiot and be looking for more info than to consider one’s self a genius---am definitely taking “proclaimed idiot” path… so input is ALWAYS welcome.

Am also sensitive to not stepping on anyone’s toes. In particular, that means you CG. Again, 33 degrees at the vent with Kuehl parts and guidance/support---even after almost 10 years after purchase of some components… add to that all the info you provide us here in PPF… ADMIRABLE to say the least CGmon! And thanks for it all! So, while this air-bucket is unnecessary to the already proven performance of my AC system… I trust it’s somewhat understandable to all (see explanation above) why I go down the paths I sometimes do.

One last comment on my compressor failure then I’m moving on. In 2014 I did a variety of tests where my AC system was charged and evacuated several times. How much oil remained in the system after all was said and done was unknown. IMHO, all that testing came at the price of the compressor’s failure (and subsequent work to bring the system back to life.) It’s all good.

----

Bucket build from yesterday. Stainless steel sheet is used.



Started joining seams with Alumiweld. Weld/braise flows at 730 dF. Works on this thickness sheet BUT… way this piece sets up along with thickness of sheet, Alumiweld is not a good seam-joining option here. Perhaps someone expert in controlling heat across the wide areas of metal to the narrow sections (where there may even be 2 joints near each other) could Alumiweld this. I’m using this stuff for the first time here and so a total Aluminoob. After a few goes at it… I switched to epoxy gel to make joins.

Air stack before being cut.




Stack is also epoxy gel’d in.




Attached top with slight outside overhang.Will file this lip flush to side.






Seam between air-stack and top panel… does that need to be filled? Technically no---it’s air tight. Going to fill it anyway with Plumbers Epoxy Putty to see how that stuff handles. Found that given roughed metal surface and if putty is pushed hard enough and dragged slightly… this putty has good bond to metal. Hardens like rock. Is drillable and sandable. Cures quickly---in about 3 minutes it’s hardening. Section below is what I could manage in that time frame.




Putty sands easier before it’s fully cured. Right side has been sanded here. Left side is raw.




Both ports need to be relocated. Plan to get to that later today.

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Current: '80 Silver Targa w /'85 3.2
Prior: '77 Copper 924. '73 Black 914. '74 White Carrera. '79 Silver 930. '79 Black 930. '79 Anthracite 930.
Old 07-12-2017, 05:39 AM
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Karl, it looks like you are having fun with this project. I totally understand the engineering and fabrication fun. Much like building a project car or doing the Griffiths AC system upgrade I did to my 911 back in 2007. With no doubt the AC upgrade was the best most enjoyable thing I have ever done to my car, and car. It made it very comfortable to drive in the hottest weather. I really enjoyed learning about AC systems and making them work.

My wife has a compost barrel (think 55 gallon plastic barrel) and she wanted wheels on it. She bought some silly 40 pound capacity casters that lasted a few weeks. She then told be to fix it. I told her she has a choice, she can tell me how or I can do it my way. She let me have at it. It took me several hours, but she now has a caster system we could give rides around the neighborhood on pulled behind a car. Lets just say they are over-engineered my way.

You are coming up with your own solution to a problem Griffiths solved long ago. His solution is very easy but not cheap. Yours is costing time and money, but it a fun learning project.
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Old 07-12-2017, 06:18 AM
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Cousin Karl,

Not being critical. I enjoy playing outside of the box as well. Your cowl design is interesting, but simply you need more lungs.

Only comment on the sheet metal.... expansion and contraction as temperature change are going to challenge the bond you make.

Keep going ...

Griff
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Old 07-12-2017, 06:19 AM
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1) Put the SPAL fan inside the cowl, and give it a cold air intake instead of putting the fan at the end of that tube
2) Why does your condenser have 90 degree bends at the fittings? Every generic 12x14 Chinese parallel tube condenser I saw (which is the same manufactured part from dozens of sources) has straight out fittings.


I actually have a 12x14 condenser which I shelved, since it wouldn't fit in the front fender well. Do you want it? I would trade that for some sort of fan control for my car, since right now I only have 1 speed.
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Old 07-12-2017, 06:36 AM
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Quote:
Originally Posted by GH85Carrera View Post
...I totally understand the engineering and fabrication fun.
Nice to have to with me on this Glen!


Quote:
Originally Posted by kuehl View Post
... Your cowl design is interesting, but simply you need more lungs.
Indeed. Tested Spal next to blower (hooked up to hose and air-bucket.) Spal won. Expansion/contraction note appreciated. Rethinking... again. Been looking at Spals. There's 13" that does 1710 CFM. Min Current Draw: 18.0 Amps
Max Current Draw: 19.5 Amps --- will that run on existing fan wiring?


Quote:
Originally Posted by Pazuzu View Post
1) Put the SPAL fan inside the cowl, and give it a cold air intake instead of putting the fan at the end of that tube
2) Why does your condenser have 90 degree bends at the fittings? Every generic 12x14 Chinese parallel tube condenser I saw (which is the same manufactured part from dozens of sources) has straight out fittings.

I actually have a 12x14 condenser which I shelved, since it wouldn't fit in the front fender well. Do you want it? I would trade that for some sort of fan control for my car, since right now I only have 1 speed.
Mike... am switching to Spal and considering how to config it. Interesting thought you have. You're direction may well hit drawing board. TY for input

You're astute on ports. They were indeed originally pointed straight out. I put 90 degree ports in to see if existing hoses would reach. They did but config didn't work. Hoses were too close to tire if not within tire's space. (Another reason for the 90s was to minimize the total length of the finished unit.)

Thanks for 12x14 offer. That's condenser size I'm working with. 1 speed!?---hopefully it's HIGH! Rather than a condenser, I could use an evap.
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Current: '80 Silver Targa w /'85 3.2
Prior: '77 Copper 924. '73 Black 914. '74 White Carrera. '79 Silver 930. '79 Black 930. '79 Anthracite 930.
Old 07-12-2017, 03:51 PM
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Quote:
Originally Posted by Discseven View Post

Been looking at Spals. There's 13" that does 1710 CFM. Min Current Draw: 18.0 Amps
Max Current Draw: 19.5 Amps --- will that run on existing fan wiring?
1710 "cfm?"... maybe 1710 "m3/h", 1 m3/h = .589 cfm; or 1007 cfm.

Typically, with 10-13" fans, with the depth footprint you are working with, using a 19 to 25 mm thick coil, you are limited to 'low profile' fans which are 52 mm or 2" nominal thick. The pancake motors on these units usually don't draw 19.5 amps, more like 7 amps running, on start up you have a higher draw, and the cfm's are more near 1000 nominal static. If you move up to a 'medium profile' or 62 mm thick unit, cfm's are near 1168-1186 static; Spal may have other designs however these are the most common used for this application .

To get more cfm with the same nominal diameter you need to increase the depth of the blades or pitch perse; look at the 964/993 front condenser blower blade and the size of its motor.

We have tested thicker coils, say 50 to 60 mm, and thicker fans. You usually run into issues with your depth. The fan needs to be on the outboard side and when placed too close to the inside of the outer fender you'll end up choking the air supply and lose your air mass; something to consider if you intend to enclose the fan/condenser unit in a 'box'.

There is a point you will reach of "no additional benefit" as you increase cfm of fps, you have to model and test each condenser and fan combination.

The Kuehl circuit you are using taps off the "Tail fuse box" in the engine bay. That 3 fuse panel has two 16 amp circuits and one 25 amp circuit; any of which can provide power to the Kuehl AC relay; the relay is a common 12vdc 5 pin SPDT with a minimum 25 amp rating. Wire gauges are 16 awg. The fan circuit is fused. Wire gauge is 16; length of the circuit is good up to 30 amps. This circuit has been used for over 16 years powering single Kuehl Condensers and the optional Duehl Kuehl.
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Old 07-13-2017, 05:05 AM
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^^^ Great info. Thanks Charliemon

Today's progress notes...

Tested fits of various Spals (by dimension) mounted inboard of condenser. High profile did not fit at all. Low profile was a squeeze. Being on inboard side of condenser... "plastic" fan would be just next to and above catalytic. Called Spal and asked what max ambient temp their fans will survive in. Tech advised 176 dF. This answers whether Spal can be mounted inboard on the outside of existing air-bucket---Not happening.

Putting fan inside air-bucket per Mike's suggestion... is possible. BUT, the way existing bucket is rivet-configured, any issue with fan and bucket has to be de-rivited to get to fan. I believe Spals are superdurable but still... idea of making fan difficult to access is tough nut to swallow. Could make new bucket with screw config. Before going down that path, will see if existing bucket can be used intelligently.

Spal could be positioned ahead of rear wheel. "Collection bucket" would be needed. Begs question if making new air-bucket to accommodate internal fan is in order. More thinking to be applied here.

Ducting. The "air-inhibitor hose" I had with blower... was wearing idiot shirt picking both of those parts. Looked for smooth bore duct online. Some beautiful and expensive stuff is available. Went to Home Depot. They stock 4" econo-mode smooth bore and related articulating joints. Credit to CG for smooth-bore move.


CG---I hear you on expansion & contraction potentially affecting hard media.
If epoxy putty cracks/falls off... lesson learned. Internal epoxy gel will hold stack in place.
Do admire your attention to detail.

Going to check fit of 12" Spal positioned ahead of rear wheel. Unit is 1275 CFM unit.

Have ordered Super Alloy 1 (to compare it to Alumiweld.) Supposedly it joins any white metals, even dissimilar metals. Alumiweld flows @ 730 dF. Super A1 @ 350 dF. Would make joining sheet metal much easier.

.
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Prior: '77 Copper 924. '73 Black 914. '74 White Carrera. '79 Silver 930. '79 Black 930. '79 Anthracite 930.
Old 07-13-2017, 03:11 PM
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I have a Spal 30100374 10 inch pusher on my rear condenser, which is a 993 unit.
Dual 993 a/c condenser system

Dimensionally, the 993 unit is very close to the 12x14 parallel flow units, but it's about an inch thicker. IIRC, the 10 inch Spal fits beautifully on the 12x14 condenser. A bit of sheet metal and you'd have a shroud to force the entire condenser surface to get air, I didn't bother.

That fan pulls 5-6 amps at speed, and *maybe* twice that at startup inrush. It sounds like an airplane when running, even under the fender.

I actually have two of them, since I have two fender condensers. There is noticeable noise when they are both running at idle, but not once the car is moving (the exhaust is much louder).
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Old 07-13-2017, 07:11 PM
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Don't expect a strong joint with a low temperature brazing material such as 350F; that is only good for You Tube beer can stunts.

Ideally you'd want to either:
A) TIG some sections or spots equally spaced and then fill/bond the joint with a higher temperature material,or
B) use a few 90 degree angles, equally spaced, riveted, and then fill/bond the joint with a higher temperature material.
"B" will be the easiest because of the thickness of the aluminum sheet you are using.

In terms of higher temperature materials something like This link you will find helpful.

Once again, on the flat fans you need to maintain a minimum distance between the inlet side of the fan and any surface adjacent to that flow side otherwise you will not have enough mass (air flow). You can test this by either observing the amp draw on the motor or placing a anemometer on the outlet side to measure velocity.

And, plastic fans and motor windings don't like direct radiant heat.
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Last edited by kuehl; 07-14-2017 at 04:43 AM..
Old 07-14-2017, 04:40 AM
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Quote:
Originally Posted by Pazuzu View Post
I have a Spal 30100374 10 inch pusher on my rear condenser, which is a 993 unit.
Dual 993 a/c condenser system

Dimensionally, the 993 unit is very close to the 12x14 parallel flow units, but it's about an inch thicker. IIRC, the 10 inch Spal fits beautifully on the 12x14 condenser. A bit of sheet metal and you'd have a shroud to force the entire condenser surface to get air, I didn't bother.

That fan pulls 5-6 amps at speed, and *maybe* twice that at startup inrush. It sounds like an airplane when running, even under the fender.

I actually have two of them, since I have two fender condensers. There is noticeable noise when they are both running at idle, but not once the car is moving (the exhaust is much louder).
Be interesting to see pics of both units Mike. Am curious how they're configured.
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Prior: '77 Copper 924. '73 Black 914. '74 White Carrera. '79 Silver 930. '79 Black 930. '79 Anthracite 930.
Old 07-14-2017, 05:20 AM
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