Reid, PM and e-mail sent.SmileWavy
Thank you!

KelogGes. Very interesting concept. It was literally 130 degrees in the shade here in Baghdad today. Makes me think my anemic vent temps won't be so bad when I get home.

Regardless fixing my AC is on my to-do list and this could be the final piece i'm missing. Already have the rennaire hoses, evap, compressor, procooler but after about 30 minutes my AC stops blowing cold.

I noticed that it doesn't seem to be designed to fit the 87-89 Carrera or am I missing something?

Modifying The rock-guard
 

THE ROCK GUARD NEEDS MODIFICATION
http://forums.pelicanparts.com/uploa...1312375665.jpg

I have not talked about this before so I thought it was time I bring up this subject and now you have at least a pretty good idea about what will be needed to modify your rock guard and so you can still use it.

This is just a quick primer to let you know one way you still can use your old Rock Guard with a little modification, I will come back to this and show you in the future better how to modify your rock guard yourself or have someone in a shop you can find for not much cash to help you. For the welding and cutting off of the bracket ends to the rock guard, I doubt you can use MAP Gas but I am not sure, however I know Oxy/Acetylene torch works fine using an old coat hanger metal rod for the filler material for the welding or even brass rod, because I have an Oxy/Acetylene torch I have used to modify many damaged steel rock guards after they have been damaged by parking lots and wiping out several condensers of mine not being careful enough when parking UPPSSSS he he he

However I am sure some of you may also want a custom one made for you and if I get enough requests I probably will make new ones avalible I will make for you custom; mybe in stainless; or steel, anodized, plated, or powder coated etc if you want a closer body color match to go extreme coolness :)


If you use one of my Front Condeners THE ROCK GUARD NEEDS MODIFICATION because as you can see in the pictures I posted my condenser is a little larger; and planned this way very carefully increasing surfice area more then OEM demensions, and pushing these demensions to the limit of the limited avalible space more then Porsche did with their BEHR condenser

http://forums.pelicanparts.com/uploa...1312376330.jpg


if you look closely you can see that my front condenser is just a little too big to fit the OEM Rock guard in lengh and width; note also how much smaller the width is too.

The ROCK GUARD IS Steel this makes it easy for most people to modify it or get help modifying it fairly easy.

it would be best to unbraise or grind off the welds that holds the steel metal brackets from the rock guard and set them aside

next you will see a slightly bent end on one side of the metal to the guard, this can be Pounded flat (put it on a concrete sidewalk and get a ballpin hammer and flatten just the bend out so its flate on the one side of the guard

now try to put the end with the hose fittings on the end that is open, and the other end of the condenser inside where the metal is boxed in.

you should now notice that you can cut down the width of the rock guard to fit the new condenser buy just leaving enough width inside that works out the best between the square holes and still leaves an edge on the open end that is just a little more then the condenser that will be inside srewed into the lower pan body of the underside front of the car between the wheels where through moving it around gives you the best fit in relationship to your hoses connecting to the condener fittings.

again when i get time I will show you what I am talking about better what I mean using one of the work benches at the shop and a car on the lift rack nearby

It appears that your condensor extends BEYOND the lid airflow opening quite substantially. Wouldn't, might, the "excess" CSA with no source of airflow be "gathering" radiant heat from the engine compartment rather than dispersing it into the air stream...

Well, it is still quite new, but so far no problems. I suspect at idle you may see some of that, but even then, that fan moves a lot of air and I suspect the temperature in the engine compartment (and the condenser) is pretty close to outside ambient temperature.

There was a comment about air bypassing the condenser in various directions and again, so far no issue. There is not as much space around as you might think from the picture and the air has to follow a fairly tortuous path to get around the condenser, so I think the vast majority of the air does in fact flow through the condenser and not around it.

D.

No disrespect intended, but another way I might look at this is to say that your condenser needs modification.
If you are touting high-efficiency, custom made condensers, aim to make it fit. The heat transfer area you are losing by making it fit the stock location is negligible anyway with the anemic Bosch blower fan that sits over the top if it.

Yes, and even WORSE at the rear with NO fan and the engine idling.

Just to add...I had originally told Reid I have a front condenser on my factory AC equipped '71, but after a further look it appears I don't have one.. Any other early car users have only a rear condenser??

"..suspect...temperature...engine compartment (and the condensor) is pretty close to outside ambient temperature..."

No on your life...!!

"..suspect..." " pretty close"

It should be really easy to come by actual measurements rather that speculate..."suspect"

But don't forget you need to take 2 measurements, air temperature and radiant temperature.

NEVER have I encountered a time, after the engine has been running for some period, including at roadspeed conditions, that I did not "feel" a blast of hot air, "HOTNESS" (***) upon opening the engine lid.

*** possibly radiant HOTNESS, but that has just as much impact, or even maybe moreso, on the efficiency of the engine lid mounted condensor as does the lack of sufficient cooling airflow.

"..that fan moves a lot of air..."

Have you taken note of the fact that absolutely no effort has been made to prevent the fan's "draw", suction, from bypassing the condensor, at least partially..??

No engine lid seals, sealing.

Clearly for his application he is happy, and the airflow bypass of the condenser is not making an appreciable difference in his operating temps. Could it be more efficient? Yes, probably, but he has functioning air and is happy with minimal fuss from the Retroair kit.

If the cabin is adequately cooled to his liking, with marginal or no effect on engine oil operating temp, I call that a win.

As has been noted, so far I am happy with the install and also the gap looks far bigger than it is as there is a depression to fit the grille which makes the space between the condenser and the opening quite small (like 1 cm or less). It does block off part of the condenser though, which makes the one being discussed here interesting.

I guess the question would be, how much air flow does the condenser need to work at an optimal level? I do know that airspeed that is too fast can impair heat transfer, so what does it really need?

I have a seal on the back of my engine compartment, plus the fits are reasonably tight around the lid, so my bet is that the vast majority of air comes through the grille anyway and most of that goes through the condenser.

I have never experienced the heat flash you mentioned, in my case at idle, it is cool enough and close enough to ambient that I have not felt any major heat off of the engine unless I was close enough to hug the metal parts of course..

D,

"..how much airflow does the condensor need to work at an optimal level.."

Difficult question that..!

Obviously the need for increased airflow rises as OAT and radiant heating effects rise. A secondary factor is the pressure/temperature of the refrigerant inside the condensors, the high that pressure(temperature) gets the more effecient will be the heat exchange functionality of the condensors.

The easy answer would be, enough to condense the refrigerant gas into liquid form/state and it reaches the recvr/dryer. In the Porsche the airflow control is pretty much totally open loop, a result of engine RPM.

"..in my case at idle.."

Yes, but I wasn't speaking of idle. My original point was the HEAT soaking of the condensor post engine shutdown.

"..how much airflow.."

You can build a control to modulate the fan speed as a function of the temperature at the condensor outlet. Tape a thermistor (A) at the condensor outlet, and have another thermistor (B) to measure OAT. Now control the condensor airflow level, fan speed, to keep the "A" temperature to within a defined/selected temperature difference above ambient (B).

wwest...What is the defined perfect "A" temp...I guess I am missing the point you are trying to make...why not come out and tell us what you are trying to accomplish on this thread because I, for one, don't get it. All of us with A/C cars want better and the exploration of new tech - low tech - any tech is better than what we got now..Love to hear your theory on what to do to make it better..

BGCarrera32; No disrespect back to you too!

First you have made comments about a picture you know nothing about and furthermore you have completely taken your comments out of context for what this picture represents or why it was posted!!!

Did you not read what I wrote and said about these 2 pictures before making your negative comment???

Picture Subject caption “THE ROCK GUARD NEEDS MODIFICATION”

*The description words posted with it to explain*
“I just uploaded these pictures and do not have time at the moment to write the discription and what will be needed”

“I will re-edit this to explain so you understand better about this subject”

Lets clue you in;

These 2 pictures have to do only with the “MODIFICATION of the OEM 911 ROCK-GUARD” and adapting the OEM 911 ROCK-GUARD to fit my Patent Pending Front Condenser<<<NOTHING MORE!!!

My Patent Pending condensers need no modification they were specifically designed to be exactly what they are and appear to be for good engineering reasons; furthermore I am not going to discuss with you or anyone here the technology or specifics because they are Patent Pending,

MY test result prove they work as designed or better.

FYI: I have no intention of making perfect replacement exact fit of the original dimensions of the 911 OEM extremely old technology Porsche/Behr condensers, and have never claimed this!!! Furthermore; if you had read my whole tread here I stared and all of my posts, you would have read of my almost complete refusal to do this when someone asked me here almost a month or so ago, and why I told them I did not intend too!

Where did you get your degree in thermal dynamics and/or also mechanical engineering?

What professional experience do you have in these fields?

How Many A/C heat exchanger condensers have you invented, or made, and what was the technology you used?

What is your scientific experience, background, and knowledge with Parallel Flow heat exchangers & BAM coils?


Give me good answers to this questions and maybe I will take some time with you, as long as your intent is not only negativity.

No disrespect intended

Perhaps the next time you start making comments about something someone started to post here, “said it was not finished yet and would be finished later”; you will wait until they FINNISHED what the started writing that was not finished, so you know what it is before you make a comment about something so far off topic it has nothing to do with what the person was writing about!

P.S I never said anything in any of my posts about the anemic Bosch blower fan except I DO NOT USE IT!!!

Now I can go back and finish what I started writing this morning

Problem really is that this car was originaly designed in a cold environment .

Yes you can and its done all the time (smile)

There are a ton if really cool things you can do with current technology

hint go read about what major appliance A/C companies have done to get their SEER numbers up so high, and all the different things they now have also micro processer controlled with actuators and sensers <grin>

with ready you will gain lots of knowledge

Yes you did <grin?

ratpiper71T got a surprise for you comeing in a few days SmileWavy:

Stop what you are doing on your toy or at least slow down until you read it, as it will extremly help you to say the least. (Speaking of saying I cant say much at this time)

I am doing something with RennAire (wink) related to a 1971 911; you will read about I think maybe next week .

I have edited THE ROCK GUARD NEEDS MODIFICATION
 

In case you missed it because it was not finished this morning I had posted some pictures about THE ROCK GUARD NEEDS MODIFICATION but without saying anything except its not finished and I would edit it later when I had more time.

so go back a few messages and you will see it now what I have to say about THE ROCK GUARD NEEDS MODIFICATION

if you get one of my front condensers you are going to want to read this

Reid

Heat soak is an issue, that 250kg of hot metal, when parked, only has one way to get out and that is through the same condenser that was cooling you a few minutes ago. I think it would labour for a while until you got some real airflow through it.

Just checked with Bruce Anderson's book, my fan pulls 1380 litres per second at 6000 rpm, so if one assume linear flow (likely not true, it almost for certain tails off at higher rpm) then at idle one is drawing about 200 litres per second (about 7 cu. ft. per second or 420 cfm) so a decent flow even at idle. Certainly I notice that at dead idle, my AC is not quite as cool ( I have left the thermometer in the vent while I check out the system), I see about 40-45 F in traffic idle, and about 36 F best case while cruising (all temps at 28 c outside temperature).

I started on the math for the heat extraction capacity of this airflow, but ended up needing to know such esoteric things as the temperature of the condenser under load....but it is .569 watts per cfm for a 1 degree C change. So very simplistic calculation ought to show that if the condenser is 10 c over ambient, at idle I came up with about 2300 watts of heat extraction capacity in the air with the air leaving the condenser of course 10 degrees higher than it went in. And then I got lazy....get into transfer efficiencies ...

Empirically it works and the practical side says leave it at that...

D.

Cool.. Now I'm intrigued. I'll hold off on ordering until I see the surprise, then. Glad I haven't pulled the trigger on purchasing the rennaire kit from pelican, yet. And glad you're teamed up with them as maybe I'll be able to get this part of the resto planning locked up.

"...Now I can go back and finish.."

Why bother, By your standards, high-lighted above, your requirements for our understanding most of what you write is beyond our comprehension.

RetroAire system condenser
 

I have one of these same exact condensers and have completely thoroughly tested it on my 911, Then removed it because I was not satisfied with its efficiency or its vey old Parallel Flow condenser technology, after I tried and tested several other newer designed technology condensers , but I will say it works better than anything Porsche and/or Behr has for a 911 which is not saying much, except to say RetroAire’s claims are overblown

THE ONE I BOUGHT DID NOT COME FROM RetroAire <grin>; the condenser is American Made and I bought it strictly for testing purposes, and I was disappointed in it after I tried and tested several others newer ones to say the least before building my own.


This is a “Generic Universal Parallel Flow condenser”, is using rather very old technology called “Multi-Flow technology” compared to today’s much newer Parallel Flow condenser technologies!!!


FYI Parallel Flow “Multi-Flow technology” Condensers is obsolete technology and I DO NOT USE IT!
If you want to save a few dollars you can use it I guess, it definitely works better then what you have but that is not saying much because I have been there and done that and if you want to spend your money on old technologies instead of new technology I leave this up to you

As a courtesy and respect to RetroAire I am not going to rain on their parade and post the link to where this same condenser can be found much cheaper

Reid

...Reid, just a small note of caution. I realize you are passionate about your work and are more than likely correct about the efficiency, but you just want to be careful not to diss people who are otherwise happy. Leave it as being that you are working on a better mouse trap and take care not to cast too many aspersions on other companies or people who knowingly bought from them.

I do hope you are able to get your product well into market and it gets picked up by some of the vendors that you refer to, or perhaps you become a worthy competitor for them.

D.

"..made several of my own..."

If "you" were in charge of making these than why are they not fully form and fit compatible with your target market....?

Isn't it rather ARROGANT to ask ALL your buyers to modify their cars in order to fit something you "made", something that in the end that will prove to be less effective, efficient, and a LOT more expensive, that simply installing 2 12 volt fans at $34...?

Something you found on the Russian internet...?

KelogGes, is your tubing from Brazeway?

looks like it. Brazeway Automotive micro-multiport tubing Â

Just curious... I have designed machines that help them produce the stuff along with other types of aluminum tubing they make.

That's Patent Pending

no

Subscribed, ..........do you ship to Europe?

1975 Carrera

Hello André,

Thank you for asking

Answer unfortunately at least for now I must say NO

I am just starting up what I have invented which is Patent Pending and my patent attorney has advised me not to export outside the USA at this time

For your information;
I have worked on FEADSHIP's on and off for 30 years related to Marine engineering; I have great repect for people in the the Netherlands ( believe you know about FEADSHIP ?)

I like this idea... but the only way I would buy a new front condensor at hundreds of dollars is if it fit the stock location.
There is no point with the crappy fan that is pushing air through it. The limiting factor between yours and the Rennaire Dessert Duty I have already is not the condensor its the amount of air generated by the Bosch Fan.

I would be game on the rear deck condensor. I already have a fender mounted supplemental condensor with a fan.

I disagree. I have a supplemental condensor with a hight output fan... it helps, but the deck lid condensor performance absolutely was NOT mitigated by adding a $34 fan...

".....but the deck lid condensor (poor) performance absolutly was NOT mitigated by adding a $34 fan....

First, $34 gets you TWO fans.

You imply that you TRIED the deck lid fan(s) technique and it did not work to your satisfaction...

How so...?

i am not saying that fan(s) dont help. i am saying that if you want 35 degree vent temps in 96 degree 80% humidity texas weather (it was 106 today)... adding 34 dollars worth of fans isnt going to get you there... been there done that... you need a wholistic approach to AC in the 911 anytime its over 88 degrees.. changing the evap to more efficient type, adding high output evap fan, changing condensors to more efficient models, adding supplemental condensors with fans.. will get you there. What this guy is selling is in fact one peice of the puzzle. Griffiths and Rennaire have proven that. I was merely pointing out that saying that an upgraded superior condensor is a waste of money and all you need is 34 dollars worth of fans... is really oversimplifying the problem for anyone in the southern half of the US.. Wouldnt you agree?

Perhaps in the Paciffic NW that is all you need... I assure you that you would be VERY unhappy in Houston TX if that is all you did...

"..I assure you..."

I hope you don't mind if I don't take your word for that.

IMMHO the proof is in the pudding.

To late to plan for this year but maybe next year, August, we can bring our '88 to "planet" Houston. You do know, do you not, that the Porsche 911 A/C sysetm is ALWAYS in recirculate. If you can deliver a continous flow of liquid refrigerant to the evaporator expansion valve, you're home free.

Oh, looking down into the "cubby" today I couldn't help but think discharging a full can of "Good Stuff" to fill in, isulate, the exterior of the evaporator/blower plenum might be of help.

No disrepect, you made some comments,

My reply is not ment just for you, many people are reading here that do not post post messages in the channel, and there are somethings going on in the background

As such this is my reply
Please note: I will do a long post about condenser blowers/fans soon when i have more time

FYI or anyone who missed this; My patent pending front condenser was specifically designed to fit within the 911 930 stock location!!!

I guess some people don’t bother to read everything I have taken the time to already address and written here, then make comments

I GUESS YOU NEVER READ WHAT I SAID/WROTE HERE A MONTH AGO WHEN SOMEONE SAID BASICALLY THE SAME THING YOU SAID TO ME TODAY? THAT I ANSWERED ALREADY ABOUT A MONTH AGO

However my front condenser ON PURPOSE does not use the original OEM screw holes because MY SPECIFIALLY INTENDED DESIGN IS slightly larger in length and width, but it also mounts far more securely to the front pan underside body then the OEM condenser does. THERFORE if a rock guard is going to be used, the rock guard will need to be modified or be replaced with a new fabrication

When I read some of the posts here by others; You guys just don’t seem to get it sometimes, SOME OF YOU ARE LOCKED INSIDE A BOX OF OLD TECHNOLOGY and attitudes that never worked VERY G-O-O-D ON 911s!

Porsche 911 930 A/C history lesson 101 GENERAL KNOLEDGE
Never forget THIS SIMPLE FACT; Porsche never designed the 1963 to 1989 911/912 930 body to accommodate air conditioning to be used PERIOD!!!

A/C WAS AN AFTER THOUGHT ONLY, caused from Porsche 930 USA American sales demand!!!
AFTER the body HAD BEEN SET IN STONE, and Porsche never changed it, until about the END of 1989; The 930 body was completely redesign for a completely new model, and that for the very first time EVER; the replacement model FINALLY had an air-conditioning system included IN THE NEW MODEL BODY COMPLETELY RE=DESIGNED AS AN INTEGRAL PART OF THE NEW BODY!!!


I am not like most people!
I think outside the box, I have new technology never before used on a 911 and I have used every possible millimeter available that can be found in the body, if I needed too, to enhance its design to the extreme that I can and still allow it to fit if it enhances it, that Porsche engineers overlooked when they gave BEHR original parameters for design their OEM models Condensers, and furthermore I have done things they either never dreamed of or decided to use for whatever reason, and they both made a lot of mistakes what they dumped on their multitude of buyers to give the world a Porsche car with a bad joke for an a/c system.

You would have thought that Porsche with some of the best engineers in the world would have re-engineered the 911 somehow in the early 70s to have a decent A/C but I guess corporate greed just did not care enough to fix it!

Well I HAVE DECIDED TO PERSONALLY DO SOMETHING ABOUT IT TO FIX IT FINALLY THEN JUST TALK;
IN MY OPIONION WITH WHAT I HAVE DONE WITH MY LITTLE CONTRIBUTION FOR THIS FINE CAR;
IT NOW WORKS!

I AM USING R-134A and After I DESIGNED, CUSTOM MADE AND INSTALLED 2 HIGH TECH STATE OF THE ART CONDENSERS’ borrowed a RennAire Serpentine Evaporator from Cab after he read about what I am doing here and messaged me to inquire about my condensers;

MY VENT TEMPS HIT MY TARGET of 41; sometimes I get in the mid 30s F, and I know without a doubt when I make further tweaking of the car and the A/C SYSTEM it will only get far colder’ ( except I have been just too dam busy so far making more condensers to tweak it,)

To the Nay Sayers if there are any my question is;

SO HOW COLD IS YOUR 911 AND WHAT ARE YOUR VENT TEMPS NOW IT’S AUGUST WITH RECORD HIGH TEMP???

""I am not like most people..."

GRANTED..., in spades.

"...I think outside the BOX.."

And therein lies the problem...

A little more thinking inside the box (rock guard box:cool:), common sense, non-degreed shade-tree mechanic thinking, would be of tremendous aid.

"...WHAT ARE YOUR VENT TEMPS..."?

And the price of tea in china is....

As long as the compressor system can deliver a continous stream of liquid refrigerant to the evaporator expansion valve NOTHING else matters on the HIGH side.

Your upgrade is not only useless in that scenerio and therefore extraordinarily costly.

You have a good idea, but why not stop with the rear condensor, properly sized, and fit 2 inexpensive fans....?

TRY IT, you might LIKE IT.

Since you're running trials anyway.

Why do you talk about air-to-air condensors on shipboat when there are so MANY BTUs to be much more easily had in that water...?