Wiring Question

Britain Smith · 12-03-2004, 09:32 AM

I need to run a bunch of wires from the engine bay to the front of the car through the tunnel for various EFI sensors, switches, lights, relays, etc. How long do you think that this path is? I am trying to decide how much wire that I need as they are cut in 10, 15, 20 and 25 ft lenghts and sold at a set price. I would get bulk wiring, but I want each wire to be a different color combination to ease the wiring pain later we I try to figure what goes to what. Does anyone know approximately how long a wire would need to be to snake in and out the body following the wiring harness?

-Britain

Grady Clay · 12-03-2004, 10:03 AM

Get the shortest wire you can. I have a wire stretcher I can sell you.

No offense; measure twice, cut once.

Every custom wiring harness project I have done left 20% or more excess wire. The best procedure is to leave the excess at one end and then install the harness. When in place, then trim the excess to fit. I am a proponent of making Factory appearing harnesses using proper heat-shrink and wires. Study the Factory wiring diagrams and try and use similar color-codes where possible. Worth sells wire identical or close to Factory colors. Of course there are much higher quality products available from the aerospace industry.

Carefully document everything you make, including wire length. You never know when you might need to replace the harness.

Best,
Grady

Britain Smith · 12-03-2004, 10:20 AM

I guess that I wasn't exactly clear. I have already completely rewired the car with the orginal harness and it is all working just fine. I now need to run some additional wires for the Electromotive TEC-3 controls from the back of the car to the front. This includes some of the relays, switches, indicator lights, CHT, EGT, etc. I am trying to figure out the lenght of wire that I need to get. I am sure that it is between 15 - 20 feet, I was trying to get an closer approximation so that I can add a bit for the fudge factor and order the wire today.

-Britain

randywebb · 12-03-2004, 11:06 AM

I would just measure from the exterior (as in a cross-section) and add a generous amt. extra - wiring isn't that spendy.

Mike Bonkalski · 12-03-2004, 01:00 PM

I bought my EFI ECU harness here: http://www.rs-autosport.com

Plenty of length - 10', color-coded and labeled.

Groesbeck Hurricane · 12-03-2004, 01:04 PM

wire is cheap, get more than you need.

Britain Smith · 12-03-2004, 01:32 PM

Ok, I think that 15' should be plenty to run from the engine bay to the front of the car...at least to the gauge area where I need the wire the most.

Now, would you all recommend 16 AWG or 18 AWG wire for sensors, small indicator lights, etc.?

-Britain

Britain Smith · 12-03-2004, 01:36 PM

Another question. Does anyone have any recommendations for an in-line type connector for 20 or so wires? I want to wiring in my electromotive TEC-3 harness to the car but I do not want it to be permenantly attached to the engine. I need some sort of weatherproof, heat resistance type plug that I can plug the engine wiring harness into and mount the TEC-3 inside the car. That way I can tune the motor on an engine dyno or take it out of the car without having to disconnect several little sensors everywhere.

-Britain

randywebb · 12-03-2004, 01:44 PM

You could use two of the stock 14 pin connectors - then it would look factory. I'm sure there are also some top-notch marine grade connectors out there nowdays.

Grady Clay · 12-03-2004, 02:41 PM

I agree with Randy, a standard 14-pin connector would serve your purpose and look correct. The only issue I can see is to prevent improper connection with the engine-to-chassis 14-pin connector.

If you have thermocouple wires to deal with, they take special contacts or connectors.

Best,
Grady

Britain Smith · 12-03-2004, 03:05 PM

This is a very old picture of my engine bay, it is all nice and painted now, but it shows the connectors that are on my car. I do not have any of these 14-pin connectors that you are talking about, do you know where I can get a picture of them or where I can purchase a pair?

-Britain

Grady Clay · 12-03-2004, 03:31 PM

Britain,

So, you have a ’69T.

The 14-pin connectors came into service in ’70 so there isn’t any concern about improper connections if you use them. The 14-pin connectors are available an new Porsche spare parts of from salvage.

How many wires do you need to connect? Are any thermocouple wires? You have a spare 9-pin connecter available in the engine compartment.

Best,
Grady

Britain Smith · 12-03-2004, 04:04 PM

It is actually a '69 912 getting a turbo engine. The engine bay looks much cleaner than that now...I will post a picture this evening.

I have about 30 or so wires total that need to be connected to the engine from the EFI system. Would you recommend 16 or 18 guage wire to run through the tunnel?

-Britain

randywebb · 12-03-2004, 04:21 PM

Pelican carries these (and other connectors).

Scale the wire size to the current demand for each circuit.

Grady Clay · 12-03-2004, 04:33 PM

Britain,

Aah, dumb o’l me should have spotted that.

If I were doing this, I would use the original wiring for a ’69 911 for all the normal functions. I would then use a Mil-spec connector for all the EFI, sensors, and other wiring, positioning it in the left-most opening behind the engine. Most instrumentation wiring can be 22-24 gauge wires from the aerospace industry. If you need thermocouple connections, there are appropriate pins available in those connectors. With automotive 12V, you can get 50+ wires in that space.

At 2.3 liters I assume it is a six-cylinder turbo engine. Give us some details.

Cool project!

Best,
Grady

randywebb · 12-03-2004, 05:56 PM

For T'cles - Omega Instruments is the main place to go.

BTW, you realize that the fuel lines run thru the tunnel....

Britain Smith · 12-03-2004, 08:20 PM

Quote:

Originally posted by Grady Clay
Britain,

Aah, dumb o’l me should have spotted that.

If I were doing this, I would use the original wiring for a ’69 911 for all the normal functions. I would then use a Mil-spec connector for all the EFI, sensors, and other wiring, positioning it in the left-most opening behind the engine. Most instrumentation wiring can be 22-24 gauge wires from the aerospace industry. If you need thermocouple connections, there are appropriate pins available in those connectors. With automotive 12V, you can get 50+ wires in that space.

At 2.3 liters I assume it is a six-cylinder turbo engine. Give us some details.

Cool project!

Best,
Grady

I am using all the orginal wiring for all the normal functions, I want to run additional wires seperately for everything that I am adding on.

What is a Mil-spec connector that you mention?

It is acutally a 2.3L type-4 engine with all the goodies that you can think of.

-Britain

Britain Smith · 12-03-2004, 08:21 PM

Quote:

Originally posted by randywebb
For T'cles - Omega Instruments is the main place to go.

BTW, you realize that the fuel lines run thru the tunnel....

Why should I be concerned about the fuel lines running through the tunnel? The OEM wiring run through here also and I plan of using a jacket for all the additional wiring. I am also using stainless steel fuel lines.

-Britain

RoninLB · 12-03-2004, 10:00 PM

I use Deutsch connectors for my CHT & EGT wiring. They are a bit expensive. They're silver plated. Although not marine they are somewhat water protected, not water proof. Nice marine connectors can be huge. These pins can be crimped & soldered. I use silver solder and dielectric.
fwiw, each of my probes have 2 wires inside a single sheath.

raceman · 12-04-2004, 01:45 AM

this kind of attention to detail is what allows the bar to be raised and awesome cars to come together the right way for others to see.l bought an old 64 lnternational 1500 flatbed with a wiring harness remade by wookies.One of the fuses was a 22 cal.long,unfired.l`m all about the milspec amigos and it`s in those details that many builders fail,you can`t make the harness too perfect.lt`s an art form