choosing wire gauge/size for engine looms?

Wiring best practices and loom building technique
welshpug
Posts: 130
Joined: Tue Sep 06, 2011 4:53 am
ECU Model: S40 Pro

choosing wire gauge/size for engine looms?

Post by welshpug »

As per title, wondering if anyone can point me in the right direction for what gauge/size wire I need to use for each particular application when building my own loom, I have an S40 loom and plug, a set of crimper wire cutters and a fair understanding of engine wiring.

It would be to run an XU10J4RS engine in a Citroen ZX, aka the 306 gti6/Xsara VTS engine.

I know the injectors and coils would need larger wire from relays before splitting to each individual component, then a smaller wire from thereon, which guess would be sufficient for most sensors as well, bar the crank sensor that uses a 3 wire shielded cable.

The engine does have a camshaft sensor and a knock sensor, I know the S40 is only capable of semi sequential injection+wasted spark, so the cam sensor doesnt need to be added, but what about the knock?

Further on what do people use to cover and protect the wiring? heat shrink all the way or only on the joins and something else on the longer runs?

Any input and links much appreciated, I have used SimtekUk before for a few multiplugs doing wiring conversions and repairs, but never a full loom, also know of VWP Polevolt, RS and maplin etc.
Gadgetman
Posts: 34
Joined: Sat Sep 03, 2011 9:29 am
ECU Model: S80 Pro

Re: choosing wire gauge/size for engine looms?

Post by Gadgetman »

I normally heat shrink all the runs, with a short length of adhesive lined heat shrink used at the end of the regular heat shrink to seal it, especially where you have a number of separate cable runs branching out from the main trunk. I then use a label gun to mark up the various connections, and slip some clear heat shrink over the labels
to stop them coming off or getting damaged.

DTA quote for the wiring:
Different parts of the installation have different requirements regarding the type of wire used. Wire grades for a quality wire such as Raychem Spec 44 are given. With the exception of the wire used for the rotational sensors these are minimum requirements to handle the currents generated.

ALL SENSOR CONNECTIONS 250 milli Amp (24 AWG)
ALL POWER CONNECTIONS 10 Amp (22 AWG)
BATTERY NEGATIVE CONNECTIONS 30 Amp (2 x 20 AWG)
CRANK & CAM SENSORS SCREENED TWISTED PAIR
WHEEL SPEED SENSORS SCREENED MULTI CONDUCTOR
Forgot to add, last time I used an S40, I didn't think there was any knock sensor facility?
welshpug
Posts: 130
Joined: Tue Sep 06, 2011 4:53 am
ECU Model: S40 Pro

Re: choosing wire gauge/size for engine looms?

Post by welshpug »

:lol: should have thought to start there!
stevieturbo
Posts: 3578
Joined: Tue Aug 02, 2011 12:08 pm
ECU Model: No ECU
Location: Norn Iron

Re: choosing wire gauge/size for engine looms?

Post by stevieturbo »

Or get someone else to do it lol

mef makes looms for dta
welshpug
Posts: 130
Joined: Tue Sep 06, 2011 4:53 am
ECU Model: S40 Pro

Re: choosing wire gauge/size for engine looms?

Post by welshpug »

there is that, problem is its my daily driver and I live 4 hours from Martin ! not sure how much he'd charge either.

quick calcs project that I'd need to spend about £30 odd of wire and £30 on connectors as the engine loom is fairly compact and I plan on siting the ecu in the original ecu box which is on the back of the battry box, and the relays can sit in a box next to that.
welshpug
Posts: 130
Joined: Tue Sep 06, 2011 4:53 am
ECU Model: S40 Pro

Re: choosing wire gauge/size for engine looms?

Post by welshpug »

excuse the shoddy night time phone pic and photobucket editing skillz, but this pic illustrates the routing of the loom.

Image
VR6Turbo
Posts: 329
Joined: Wed Mar 17, 2010 9:24 am
ECU Model: S80 Pro
Firmware Version: 62

Re: choosing wire gauge/size for engine looms?

Post by VR6Turbo »

No DTA ECU supports knock control unfortunately, but that's not to say you can't connect an aftermarket system to one of it's Aux inputs though 8-)

I think JS Knock guard or some such is a popular one.

Regarding the overall sleeving, I over-engineer mine with the best abrasion resistant stuff I could find. I've been victim to abrasion wear in the past (despite careful cable routing and support) so I take no chances these days!.

This stuff is amazing - http://uk.farnell.com/te-connectivity-r ... dp/4967239
welshpug
Posts: 130
Joined: Tue Sep 06, 2011 4:53 am
ECU Model: S40 Pro

Re: choosing wire gauge/size for engine looms?

Post by welshpug »

I understood that most DTA ecu's didnt use knock, just wondered if having it in the loom would be desirable or now, much the same story with the cam sensor, though TBH I dont think I'll ever run it on onything more sophisticated than an S40.

well.. the original Magnetti Marelli MM1AP ecu is pretty damn sophisticated to tell the truth, but there's not many thatr map it!

Have dropped martin (MEF) an email to see if he could supply what i'd need to build it up myself, may be easier that way as I imagine he'd know what to use and save me buing lots and finding I need something different or having too much of something :D
VR6Turbo
Posts: 329
Joined: Wed Mar 17, 2010 9:24 am
ECU Model: S80 Pro
Firmware Version: 62

Re: choosing wire gauge/size for engine looms?

Post by VR6Turbo »

My view on that is it's better to cater for knock and cam position in the loom now, rather than having to pick it apart at a later date to re-add them in :D

I'm doing an engine conversion at the moment I'm just using the original loom that came with the engine. It has a lot more functions on it that I will use, but I'm leaving them in... just in case!! The quality of the loom is waaaaay better than anything I could make myself, plus everything is cut to the right length and has all the right suppor brackets, plugs etc etc.... can't beat OE quality for this sort of thing imo. Then all you need to do is chop off the Peugeot ECU plug and reterminate the wires onto a DTA plug. Did you not get a GTi-6 loom with your engine?
welshpug
Posts: 130
Joined: Tue Sep 06, 2011 4:53 am
ECU Model: S40 Pro

Re: choosing wire gauge/size for engine looms?

Post by welshpug »

yeah it is running on the gti6 loom and ecu, wanted to make up something tidier as its pretty bulky really.
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