Race car electrical, what to buy?

[MikeBZ]

Was thinking about oil pressure idiot light, maybe coolant temp too. I had mechanical gauges in the old engine and liked that setup, not sure how to do that with the LS. I did see on LS1tech that you can drill out the oil temp sender and tap it for the mech pressure gauge, maybe it's possible to just run a tee to an idiot light. Not sure if there is room with the carby manifold in place. I have the feeling that the pressure gauge in my truck is less than stellar when it comes to accuracy, and it is the same motor. If it is a problem to run both might just run the mech gauge and skip the idiot light.

 

I would add idiot lights for oil pressure and temp. Autometer sells some that are the size of shift lights and they work well. I think using electric gauges is a good idea especially for racing. I had the feed line to my oil pressure gauge break and spray hot oil on my legs and feet. Now I stick with electric gauges

 

 

I'm on the opposite of the relay spectrum, I like using relays on everything practical, but use the ground to control it. I have burned out too many switches and set to many cars on fire to go back to using switches alone to hold the current. Also be sure to hook up an alternator kill switch on that 4 post battery disconnect and don't forget the ford solenoid.

 

I agree on using relays, I put them as close to the device as possible so the current doesnt travel as far. HD switches can handle the load as well, but then that current is running from the battery to the switch then down to the device creating a lot of heat along the wire.

[JMortensen]

I would add idiot lights for oil pressure and temp. Autometer sells some that are the size of shift lights and they work well. I think using electric gauges is a good idea especially for racing. I had the feed line to my oil pressure gauge break and spray hot oil on my legs and feet. Now I stick with electric gauges

I was looking at some Autometer warning lights that were 1 5/8", didn't see anywhere that they could be mounted inside a dash. Are they made for dash mounting?

 

The one thing I don't like about electrical gauges is the slow response. On my mechanical oil pressure the response was INSTANTANEOUS. Haven't seen such response out of electrical gauges, don't know if that is more a function of the gauge or the sender. Similarly with the temp. I could watch the themostat open and close on my mechanical gauge. Electrical always shows it headed to the middle or in the middle of the gauge. Just doesn't seem as accurate. Is that just a function of stock gauges? Do the aftermarket electrical gauges work better than what I'm used to?

Edited September 30, 2010 by JMortensen

[z-ya]

I have a mechanical oil pressure gauge in my car, and like you meant Jon, it is instantaneous. Use an -3AN braided stainless line instead of the cheap nylon ones that come with some of the gauges if you are worried about leakage. Electric temperature is fine. I also have a oil pressure kill switch on the ignition system. Not a bad idea in case you are sucking air in hard corners. You could also wire up and indicator light that would illuminate when you lost oil pressure.

[JMortensen]

Thanks Pete. Fixed my previous post. I think a light would be sufficient. Wouldn't want to be going into a corner at high rate of speed and have the ignition cut off.

 

I also had problem with the stupid plastic hose. Getting the ferrule to seal was impossible, but I switched to copper and never had even a drop after that. I expect a SS hose would be similarly effective.

[MikeBZ]

I was looking at some Autometer warning lights that were 1 5/8", didn't see anywhere that they could be mounted inside a dash. Are they made for dash mounting?

 

The one thing I don't like about electrical gauges is the slow response. On my mechanical oil pressure the response was INSTANTANEOUS. Haven't seen such response out of electrical gauges, don't know if that is more a function of the gauge or the sender. Similarly with the temp. I could watch the themostat open and close on my mechanical gauge. Electrical always shows it headed to the middle or in the middle of the gauge. Just doesn't seem as accurate. Is that just a function of stock gauges? Do the aftermarket electrical gauges work better than what I'm used to?

 

Yeah the mechanical are quicker for oil pressure, as far as mounting the warning light in the dash you could use an "L" type bracket to recess them, I put one in the clock spot.

[ktm]

It depends on the gauge. I am using Speedhut electric gauges that incorporate a high speed stepper motor. The gauges react instantaneously.

[mario_82_ZXT]

If you don't run relay's and just use switches, should you put a cap between the poles so that high amp drawing things don't damage the switch's contacts (like the fans)?

 

Also, I wouldn't run anything smaller then 0 gauge for the battery negative. I'd even run 0/0 instead. And I'd run it all the way to the engine block. This is probably more important for an EFI motor, but a starter motor uses a LOT of current.

 

On the gauge response, most of the time the gauges are dampened. In the miata world the stock oil pressure gauge sucks. What a lot of people do is put in a real sender (instead of a switch) then clean off as much of the grease on the gauge itself (which dampens the movement) to get the fast response.

 

I wouldn't be surprised if the same thing could be done to aftermarket gauges.

Edited October 1, 2010 by mario_82_ZXT

[bjhines]

You are building a race car. Simple is best.

 

The whole argument about switches over relays can go on and on. The fact is many folks just don't know how to use EITHER. Relays are magnetic devices which can produce considerable bucking voltage from the coil. For the switches and relays; inductive loads must be damped and suppressed or they will foul the contacts. Relays are switches similar to the old points in the ignition system. The contacts build up deposits and will fail to connect. Switches use a scraping motion on the contacts that is self-cleaning. Bad experiences with relays are due to lack of knowledge and improper circuit design.

 

Diodes, Resistors, Capacitors are all used to supress arcing across contacts. Capacitors will not suit the current and votage spikes produced by a large fan. A diode is best for fans.

 

The alternator is a strong consideration with such a small battery. I would use the modern style CS130D. It will produce plenty of current under a wide range of conditions. I would not use a "1-wire" alternator with such a small, rear-mounted battery.

Edited October 1, 2010 by bjhines

[JMortensen]

Got all my gauges, shift and warning lights and all the rest together now. I also have a 1' x 2' sheet of T3 aluminum plate .125" thick. Any suggestions on cutting holes in the thing? I only spent about $20 on the aluminum. Considering buying one of these instead, even though I know it will need some modification to fit in my car:

http://www.hrpworld.com/index.cfm?form_prod_id=764&action=product

 

The thing right now that is bugging me about doing it myself is cutting the gauge holes. Right now I don't have a hole saw big enough for the 2 5/8 or 5" gauges, so I'd have to either drill a smaller hole and open it up with a die grinder or go buy the hole saw. My Harbor Freight drill press sucks pretty bad, so that's making me think that carving up a pre-built unit might be the way to go. Anyone done this before and want to offer advice?

[bjhines]

Aluminum galls and sticks to everything. You need a bottle of cutting/tapping fluid, gear oil, or other high surfectant oil. Wipe the oil on blades with a disposable bristle brush. Drip oil on drills and hole saws(inside and out) several times a minute and before each cut. Make sure to pick the aluminum boogers off the teeth regularly.

 

A good hole saw from Lowes or another home store will do fine. You need to use the drill-press. Clamp the piece in at least 2 places and use plenty of cutting fluid. It will chatter but you will find the right speed and pressure with some experimentation. You will be "wearing away" at the metal, expect to take 90-120 seconds to cut through. I usually cut the holes first and then cut the piece out of the stock. The hole saw will cut slightly oversize but will work out fine once you get the hang of it. Loosen the belt and be ready to hit the kill switch. If the hole saw binds too hard it will bend. Wobbly hole saws are even harder to use. You don't need much torque for this operation so ANY drill press can do it.

 

For the 5" and larger cutouts you need a jigsaw with a "hollow ground" toothed blade. These are blades with no tooth set(kerf) they are thicker than usual and the teeth are ground into the blade. The blades have medium teeth size and are intended for cutting wood. If you attempt to use a metal cutting blade on aluminum it will clog quickly.

 

Ohh BTW,

High-tooth-count, carbide-toothed saws are fantastic for cutting aluminum(circular saws, chop saws, etc). The trick is not to use a lot of pressure on the blade. Any heat buildup will cause the aluminum to stick to the teeth(resulting in even more force/heat on the teeth and galling). Just let the blade walk through and it will cut a neat edge. Wear tight-fitting, protective gear because the saw will throw millions of hot, crescent-shaped needles at you. Galling will also put a lot of force on the blade and it will chuck and kickback. You can clean the teeth with a utility knife by prying the chunks off the teeth. Do not scrape the teeth or you will dull them.

 

Whenever you make a cut be sure to de-burr the edge so it does not hang up the saw(or prevent sliding the piece) on the next cut. I use a handheld deburring tool that uses a swiveling, sharpened hook to carve a curly-cue off the edge.

 

You shoould also do some gunsmithing to your jigsaw and circular saws. The baseplates should be free of burrs or deep scratches. Use a file or sandpaper to grind them down, then use fine grit paper to polish the surface. This will prevent scratches and ensure smooth steady feed rates and manuvering(critical to preventing galling and buildup). I cover the sheet metal surface with wide masking tape(edge joined with no overlap) and layout on that surface. This will protect the piece and make cutting smooth and accurrate. When cutting with the drill-press this is not needed.

Edited October 13, 2010 by bjhines

[ktm]

I've used hole saws before for my smaller gauges, though not with all of the prep work that bjhines rightfully recommends, but for the 5-in. gauges I've also used my Dremel with a thin metal cutoff wheel.

 

I draw the hole on the aluminum with a sharpie and then draw 4 lines across the diameter (45 degrees apart). I use my cutoff wheel to cut the lines across and then I cut the chord between two lines near the circumference. You wind up with an octagon that can be cleaned up with a die grinder.

 

bjhines method though leaves you with a very nice clean, regular circular surface. My method leaves you with a clean, irregular surface (depending on how neat you want it) that is hidden by the gauge.

Edited October 13, 2010 by ktm

[JMortensen]

Thanks for the feedback. I'm going to try a 1.75" hole saw in a corner that will need to come off anyway and see how it goes. If it doesn't go well, I'll probably buy that prefabbed unit and hack it up to fit.

 

The spindle on my HF drill press deflects about 1/4" as soon as you start to put any pressure on it, so that was my main concern with using hole saws. I wish they made a 5" unibit...

[stony]

For the wiring harness, check this place out: http://www.autowiringsolutions.com/

 

I ordered from him and I was very happy, especially because every wire is labeled every 6 inches along with the color code. Couldn't be simpler. Plus it's a hell of a lot cheaper than Painless.

 

Thanks for the link. Just ordered my 14 circuit harness and switch panel!!!. Saved 50% over summit. will do a amateur writeup on my harness install..

Edited October 14, 2010 by stony

[stony]

For the wiring harness, check this place out: http://www.autowiringsolutions.com/

 

I ordered from him and I was very happy, especially because every wire is labeled every 6 inches along with the color code. Couldn't be simpler. Plus it's a hell of a lot cheaper than Painless.

 

Did you order the harness that had circuits for headlight and taillights but not wired?

[z-ya]

I'm rewiring the race car this winter and removing the stock dash board.

 

Here is a schematic I cam up with using the Cranston diagram link I posted earlier.

club-car-schematic.pdf