Empty shell to finished car
01-19-2014, 01:10 PM
#271
Rennlist Member
Thread Starter
Voltage drop in wiring
As part of this project, I am redoing the electrical system. I will be utilizing the ISIS multiplex system, and while preparing for that, I made up a simple spreadsheet that calculates the voltage drop over a length of wire to figure out what wire size I would need. It seems many of the factory wires are of marginal size to begin with, so this spreadsheet is set to show in green any wire that has less than 0.5V drop based on user defined wire length and amperage of the driven device. Bare in mind it is very simple and I am sure there are other things that affect voltage loss (connector size, corrosion, loose connections etc).
Also the numbers shown are fairly arbitrary at the moment but can be adjusted to correctly reflect the actual amperage draws and wire lengths. Might come in handy for someone redoing their electrical system. I have included the metric cross section of wires (as Porsche wiring diagrams show) next to the AWG value. To use, just change the length and device amperage fields to whatever you want and the conditional highlighting will show what wire has less than 0.5 volts of drop. Red fields have a larger than 0.5V drop. Hopefully I got close enough...
EDIT: Oops, it seems the XLS spreadsheet does not attach...until I figure out why, if anyone wants a copy, I can email it.
Cheers!
Carl
Also the numbers shown are fairly arbitrary at the moment but can be adjusted to correctly reflect the actual amperage draws and wire lengths. Might come in handy for someone redoing their electrical system. I have included the metric cross section of wires (as Porsche wiring diagrams show) next to the AWG value. To use, just change the length and device amperage fields to whatever you want and the conditional highlighting will show what wire has less than 0.5 volts of drop. Red fields have a larger than 0.5V drop. Hopefully I got close enough...
EDIT: Oops, it seems the XLS spreadsheet does not attach...until I figure out why, if anyone wants a copy, I can email it.
Cheers!
Carl
01-31-2014, 01:19 PM
#272
Rennlist Member
Thread Starter
Insulation and HVAC disassembly
Current project update is that the stage 2 of the insulation installation (VB2) is almost complete, and after cutting myself on those pesky metal wire holders that the factory welded in place, I decided to insulate them with some heat shrink. Picked up a roll of heat shrink tubing (3/8" or 10mm works too) at Harbor Freight and covered all the metal tabs that hold wire bundles in place. Stops the bleeding knuckles and will protect wires from chafing. Those things are sharp!!
The HVAC box is disassembled, cleaned and painted (Fusion Plastic paint), and the old evaporator and heater cores are out. Test fitted the new evaporator and it fits perfectly. Seems it has a few less loops that the factory evaporator, but I think it will do the trick. The outer HVAC box is currently being dissected for the cabin filter retrofit. It is very doable, but it does take some time. Will post pictures of that once it is complete. Denso online is a good source for the filter, and very reasonable at $16.00.
The heater core looks very clean apart from some discoloration of the plastic end tanks. Does anyone have any experience with these as far as leakage, or do they hold up well? Perhaps the end tanks are replaceable?
The old evaporator was dirty, it doesn't look too bad in the picture, but it stunk of old and dead....something. Picked up a brand new evaporator online for $99. from a Rock Auto clearance sale...hope I won't regret it. Will have it pressure tested before I put it in to be sure.
Cheers!
Carl
The HVAC box is disassembled, cleaned and painted (Fusion Plastic paint), and the old evaporator and heater cores are out. Test fitted the new evaporator and it fits perfectly. Seems it has a few less loops that the factory evaporator, but I think it will do the trick. The outer HVAC box is currently being dissected for the cabin filter retrofit. It is very doable, but it does take some time. Will post pictures of that once it is complete. Denso online is a good source for the filter, and very reasonable at $16.00.
The heater core looks very clean apart from some discoloration of the plastic end tanks. Does anyone have any experience with these as far as leakage, or do they hold up well? Perhaps the end tanks are replaceable?
The old evaporator was dirty, it doesn't look too bad in the picture, but it stunk of old and dead....something. Picked up a brand new evaporator online for $99. from a Rock Auto clearance sale...hope I won't regret it. Will have it pressure tested before I put it in to be sure.
Cheers!
Carl
01-31-2014, 04:33 PM
#273
Did you look at the ends of that Evaporator? The pipe ends.
Last edited by BC; 01-31-2014 at 05:15 PM.
01-31-2014, 04:34 PM
#274
When I rebuild my HVAC, I took weather strip and rebuilt the pads on all the ends of the metal flap box.
01-31-2014, 04:39 PM
#275
Archive Gatekeeper
Rennlist Member
Rennlist Member
Are you replacing all the foam sealing strips and insulation on the flapper doors in the HVAC box? Certianly a worthwhile WYAIT if any of the original foam is crumbly or missing.
I dunno on the A/C evaporator, I think I'd spend some effort cleaning the snot out of the old one before tossing a Rock Auto especiale in there. I'd bet a radiator shop would have a big enough ultrasonic cleaner to kill the residual evaporator smell.
Normally the heater core would be a WYAIT replacement on most 24 year old cars, but I think the 928 heater core track record is pretty good, based on my unscientific, off-the-cuff, gestalt. Maybe Mark or Roger can comment on their sales volumes of replacements?
I dunno on the A/C evaporator, I think I'd spend some effort cleaning the snot out of the old one before tossing a Rock Auto especiale in there. I'd bet a radiator shop would have a big enough ultrasonic cleaner to kill the residual evaporator smell.
Normally the heater core would be a WYAIT replacement on most 24 year old cars, but I think the 928 heater core track record is pretty good, based on my unscientific, off-the-cuff, gestalt. Maybe Mark or Roger can comment on their sales volumes of replacements?
01-31-2014, 05:15 PM
#276
Sounds like you guys got a killer deal on the new evaporator http://www.ebay.com/itm/Original-Por...2d6d1e&vxp=mtr
01-31-2014, 06:58 PM
#278
Rennlist Member
Thread Starter
Which one? They both look good, although the new one seems to have copper bends instead of aluminum. I found a repair shop that will test both of them and will clean out the old one as well.
The foam on all the doors and flappers are being replaced, although I am working on a possible modification that will make the heater doors obsolete. Figured while I was in there and putting in a pollen filter I might as well attack those doors as well.
Cheers!
Carl
The foam on all the doors and flappers are being replaced, although I am working on a possible modification that will make the heater doors obsolete. Figured while I was in there and putting in a pollen filter I might as well attack those doors as well.
Cheers!
Carl
01-31-2014, 07:03 PM
#279
Rennlist Member
Thread Starter
Are you replacing all the foam sealing strips and insulation on the flapper doors in the HVAC box? Certianly a worthwhile WYAIT if any of the original foam is crumbly or missing.
I dunno on the A/C evaporator, I think I'd spend some effort cleaning the snot out of the old one before tossing a Rock Auto especiale in there. I'd bet a radiator shop would have a big enough ultrasonic cleaner to kill the residual evaporator smell.
Normally the heater core would be a WYAIT replacement on most 24 year old cars, but I think the 928 heater core track record is pretty good, based on my unscientific, off-the-cuff, gestalt. Maybe Mark or Roger can comment on their sales volumes of replacements?
I dunno on the A/C evaporator, I think I'd spend some effort cleaning the snot out of the old one before tossing a Rock Auto especiale in there. I'd bet a radiator shop would have a big enough ultrasonic cleaner to kill the residual evaporator smell.
Normally the heater core would be a WYAIT replacement on most 24 year old cars, but I think the 928 heater core track record is pretty good, based on my unscientific, off-the-cuff, gestalt. Maybe Mark or Roger can comment on their sales volumes of replacements?
Rob,
I agree, I won't put the new one in there unless it passes a full physical, cough test and all. I'll have the shop test the heater core and clean it as well. My track record for the evaporators have been a mix, 2 leaking ones out of three units. So far, no bad luck with the heater core.
The foam on the doors was gone, the recirculation flap in the foot well is the worst. Luckily I have a spare to cut open and play with...maybe some modifications there are in order as well. I have replaced most of the foam so far, but still have some more to replace.
Cheers!
Carl
01-31-2014, 07:07 PM
#280
Rennlist Member
Thread Starter
02-01-2014, 04:48 PM
#282
Rennlist Member
Thread Starter
It is fun therapy for sure, but very time consuming. For me it is enjoyable to look at a "thing" and come up with an improvement that suits my needs, while at the same time keeping the pure essence of this car. And I learn new skills while I'm at it...a win-win situation.
Cheers!
Carl
02-01-2014, 06:34 PM
#283
If you don't mind me asking, where did you find your non-sunroof headliner? I'm in the process of sunroof delete and the only part I need to complete is the headliner. Any thoughts would be greatly appreciated. Thanks, Brian
02-01-2014, 07:38 PM
#284
Rennlist Member
Thread Starter
I got it from another Rennlist member who had a spare from a wrecked non-sunroof car. Last time I checked they were NLA from Porsche but it is possible that they are available again. If not (and much, much cheaper) would be to get one from a wrecked 928. I think they are more common in Europe so perhaps a wrecker there has one in case none are available here. Probably a better chance of it NOT being warped too if you get it from Europe. Downside is shipping cost of course.
Cheers!
Carl
