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  #561  
Old 11-17-2015, 07:23 PM
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JaysinSpaceman JaysinSpaceman is offline
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For some reason the cops don't like seeing a parachute on a street car either. A friend of mine has a fast street car and when he had a chute on it he would get pulled over by just about every cop he passed on the road. Surprisingly they never gave him a ticket for the chute but they always wanted to make sure that the license plate matched the registration, I think they figured he just swapped a plate on it from another car.

Bandit, you're getting closer with every nut, bolt and fitting.

Jaysin
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  #562  
Old 11-19-2015, 05:46 PM
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As luck would have it, a snug fitting grommet resulted in a lot of binding, so I ended up opening the tailpanel hole to use the 5/8" ID grommet already supplied with the Jeg's push-pull assembly. The resulting mechanism works well, but is definitely not water tight. Below is a photo of it mounted; the light coming through the hole makes it look like a bigger gap that it is; there is 1/8" difference between the grommet ID and rod OD.



I've been wanting to get my son involved in the build and shortening the actuation rod was a perfect opportunity. We cut it down on the band saw then we put it into a little 3-jaw chuck to keep it reasonably square on the drill press. He helped me drill the hole and tap it for 1/4-20.



Then I had him assemble the rod into the switch and test it out. Mission accomplished!





I'm happy with how it turned out. Now I need to get the bumper back on and order the wiring components.
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  #563  
Old 11-21-2015, 07:16 PM
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Today I cut a piece of copper pipe



Then I hammered it flat



Next I bent it in a vice, drilled a couple holes, and rounded the corners.



Finally I installed it - buss bar for the master disconnect switch.

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Last edited by TheBandit; 11-21-2015 at 08:29 PM.
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  #564  
Old 11-21-2015, 09:08 PM
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Good thinking.
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  #565  
Old 11-22-2015, 01:43 AM
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I would have to guess that I was your son's age when I started working on cars and projects with dad and grandpa, I was just tall enough to see over a fender. I haven't stopped working on them since. And if it wasn't for cars and other mechanical things I never would have gotten through maths and whatnot in school. I grew up in a strange family though, I think I was about 8 years old the first time I ran a skill saw. And the only thing I remember my folks hiring someone to do was concrete work. If something needed fixing or building the family did it, kids, dads, granddads, even great granddads. Many a family vacation was spent building a deck, or moving a barn, or fencing, whatever needed doing. It is something that this country lacks today, I have students that come from home where parents literally hire a handyman to change light bulbs. These kids come into my class with nothing, zero skills. To be honest I am not sure how some of them will make it through life. Enough about that, I am happy to see you initiate your son into our world of fixing and building. I like the safety glasses, SAFETY FIRST.

Jaysin

Last edited by JaysinSpaceman; 11-22-2015 at 01:46 AM.
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  #566  
Old 12-03-2015, 05:06 PM
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Jaysin - I read your post the day you replied, but after a few reply attempts, I kind of gave up. I just couldn't quite put into words how that resonated with me and my hopes for my two kids. I had a lot of great influencers early in life that set me on my path toward engineering and hobbies like this. While I over think a lot of things and I'm not as practical/street smart as most of the folks on this forum, I am able to make things from time to time and think very practically compared to other engineers. It's made me successful in my career and helped me at home too, so I want similar experiences for my kids.

Continuing on the overthinking theme, I am gathering wiring components to accomplish my next goal of wiring from the battery to the fuse center so I can move on to more signal-level engine wiring. Before the work starts, I'd like to share my electrical design and see if anyone has feedback one way or another.

Here are the basic requirements:
(1) Reliably supply current to all required components with minimal voltage loss
(2) Meet NHRA requirements for master disconnect ("This cutoff switch must be connected to the positive side of the electrical system and must stop all electrical functions, including magneto ignition.")
(4) Be tidy and serviceable

Master disconnect wiring was a topic of interest for me. There are three conventional ways of accomplishing this:
  • Method 1: Run a STSP (single throw, single pole) disconnect switch and run on dedicated, heavy gauge charge wire from battery positive terminal to the alternator and a separate heavy gauge wire from the disconnect switch to the rest of the vehicle. When the switch is opened, the alternator can charge the battery, but can't keep the engine running so everything shuts down. There are two disadvantages to this method: (1) the heavy gauge alternator cable is kept hot by the battery even with the switch is open and (2) it requires two heavy gauge wires to the back of the car.
  • Method 2: Run a STDP (single throw, double pole) disconnect switch. For one pole, run a heavy gauge wire to the starter and rest of the vehicle. For the other pole, run a heavy gauge wire to the alternator charge wire. Compared to method 1, this has the advantage of eliminating a hot wire to the front of the vehicle, but still requires two heavy gauge wires and violates the current limitations for most STDP disconnect switches where the second pole is typically only rated to around 20amps.
  • Method 3: My favorite of the conventional wiring methods is this method. You run a STDP disconnect switch. For one pole, you run heavy gauge wire to the starte, alternator charge line and the rest of the vehicle. You run the other pole in series with the alternator field wire. This allow use of a light gauge wire because the field line for the alternator is relatively low current. When the switch is open, no wires are hot forward of the battery/disconnect area.

Unfortunately for me, method 3 only works if you have access to the field wire for the alternator. On Gen IV LSxs, the alternator has an internal voltage regulator and PWM-commanded voltage. The PWM functionality relies on a couple of things I am not implementing for my swap (specifically a body control module and a battery current sensing module); without those components the alternator defaults to an output of 13.8v and behaves like a 1-wire alternator. There is no way to separate the field input from the charge wire. The 13.8v is not ideal for supplying the car, but that's what the alternator puts out as default when it's not supplied with a PWM signal.

I am not very keen on running a bunch of heavy gauge wire front to back of my car and I want to make sure the full regulated voltage is available from the alternator to supply the vehicle, so I've come up with an alternate method which I've diagrammed below (note I have omitted fuses from the diagram). This method uses the power turn on relay that supplies dedicated power to the ignition coils, injectors and other engine components as a means of stopping the engine (therefore alternator charging) when the disconnect is opened.



Starting at the bottom of the diagram, the battery will be grounded locally to the formed frame-rail area using a bumper attachment bolt. I know some people run dedicated, heavy gauge grounds to the front of the vehicle subframe or engine, but I will rely on strapping and the body as a conductor (as many OEMs do).

The positive battery terminal will go to the disconnect switch and will be bussed to supply power to both poles of the switch. The high current side of the switch will run via 1/0 welding cable to the front, passenger side of the car where I will install a jump-start terminal. From there, 1/0 welding cable will supply the starter and 4awg welding cable will supply the main power junction at the horn relay on the driver's side of the car. The alternator charge line will be connected to the main power junction, which should keep this point regulated very close to 13.8v. This is very similar to how a 2010+ Camaro is wired from the factory, except they use the jump start terminal as the main junction and it is located on the driver's side.

The interesting part is on the low current side of the disconnect switch. This will be used to supply isolated power to the fuel pump (via a relay) and signal level power for the power turn on relay at the front of the car. Most "5-wire" harnesses for these engines eliminate the power turn on relay and simply power these components directly from the ignition swiitch, key-on position. By keeping this relay and supplying it with isolated power from the disconnect switch, I am able to use the disconnect switch to kill ignition and fuel supply to the engine, independently of the alternator charge line. This should stop engine function and result in dead wires everywhere except the battery itself and a short length of cable leading to the disconnect switch.

End result will be 2 small gauge (probably 18awg) wires running to the front of the car to run relays and one heavy gauge wire to the front of the car to run vehicle including the starter and to charge the battery during normal use.

At this point I think everything will work as diagrammed, but I am open to input. The only change I am seriously considering at the moment is putting the fuel pump on the heavy gauge output side of the disconnect rather than the same side as the power turn on relay. This would give something to sink alternator current in the brief period that the engine turns without ignition.
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Last edited by TheBandit; 12-03-2015 at 05:36 PM.
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  #567  
Old 12-04-2015, 08:40 AM
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Nice! Automotive wiring isn't something I've dug real deeply into, but I admire the effort you're putting into this to make a clean, functional system. I don't have enough experience to comment on how you're doing this, other than it looks like it should work and meet all the goals you've identified. The diagram is a nice touch and should save WTF moments in the future.

I agree 100% with Jaysin's post, and I'm trying to at least expose my boys to DIY stuff...I don't want them to have to depend on anyone for simple stuff they could do themselves.
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  #568  
Old 12-04-2015, 03:19 PM
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A DNF, for something that could have easily been prevented, is one of the most frustrating things!!!
When it counts, and it always counts I'll never use the body/chassis for a ground again.
There will be a fat cable directly between the battery negative and the engine block.

E
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  #569  
Old 12-04-2015, 04:57 PM
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I ain't skeered. The alternator is grounded to the block and the block will be grounded to the chassis and the body. The battery ground only matters for charging the battery and starting ;P
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  #570  
Old 12-04-2015, 06:42 PM
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Quote:
Originally Posted by TheBandit View Post
I ain't skeered. The alternator is grounded to the block and the block will be grounded to the chassis and the body. The battery ground only matters for charging the battery and starting ;P
OH! CRAP!
I forgot you are running a Carburetor...

Ummmm.... nevermind


E
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  #571  
Old 12-04-2015, 06:49 PM
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ECM is ground to the block also :P C'mon e, what's the worse that could go wrong??? HA!
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  #572  
Old 12-04-2015, 06:55 PM
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Quote:
Originally Posted by TheBandit View Post
ECM is ground to the block also :P C'mon e, what's the worse that could go wrong??? HA!
Oh, ya got me
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  #573  
Old 12-04-2015, 07:24 PM
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Next thing you're gonna ask me to put one of those f*rd starter relays in my trunk
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  #574  
Old 12-05-2015, 02:04 AM
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Quote:
Originally Posted by TheBandit View Post
Next thing you're gonna ask me to put one of those f*rd starter relays in my trunk
Nope, not at all, not even close!
There are better ways to do it, much better ways. . .

And at that, I wish you a Good Evening.

E
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  #575  
Old 12-07-2015, 10:38 AM
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Finally got a chance to look over your wiring diagram. It looks good to me.

You probably dont really need to run 4awg to the alternator as its a short run but if you have plenty of 4awg, why not. Likely 8 would be plenty.

A nice 4awg ground to the chassis from the motor and maybe an 8 from the motor to the body should be more than sufficient.

The only thing that would be nice, but Im not sure how you could implement it with how you are wiring it and with your switch, is to have a resistor to allow the alternator a place to discharge between the time you disconnect the switch and when the motor stops spinning. Likely (and hopefully) you will never be turning the car off with the switch so it probably wont matter anyway, but just food for thought.

This is the switch that I used and most or less the way in which I wired it.

https://www.pegasusautoracing.com/do...ocID=TECH00109



Dan
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  #576  
Old 12-09-2015, 08:21 AM
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Dan - Thanks for the checkover and feedback! I am thinking about running the fuel pump off the same feed going from the disconnect switch to the alternator/starter so it will act as a current sink when the power is cut from the injectors and coils. That would give a reasonably high load to dissipate anything produced by the alternator and I think it would prevent any voltage spikes that might otherwise damage the ECU. I don't think the pump would run for more than a couple seconds while the engine dies so probably not a high risk for fuel spill.
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  #577  
Old 12-09-2015, 10:02 AM
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Its too bad there isnt an easy way to force the alternator to output 14.4v. Its only a 4.5% decrease in voltage, but that means a 4.5% increase in current to everything. The ECU corrects for this down to even lower voltages (for injector on times etc) so it shouldnt be a huge deal, itd just be "nice".

Now get wiring!

Dan
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  #578  
Old 12-09-2015, 10:40 AM
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I may breadboard a PWM generator to accomplish that.
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Old 12-09-2015, 11:06 AM
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There ya go. Put it on the (as we say here in upstate NY) "list for next winter"

Dan
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  #580  
Old 12-09-2015, 11:11 AM
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Next winter could be a long ways out haha!

Regarding wiring, I'd love to get started, but I had to do some last minute traveling for business this week to London / Oxford. Having to travel last minute was very disruptive, but an experience I'm grateful for. This is my first trip to the UK and I was able to bring my wife along on mileage for a "vacation" away from the kids (thanks grandparents!). We spent a couple amazing days in London walking our feet off and now my wife is exploring Oxford while I work. I'll get back to crimping, shrink tube, and wire clamps next week - can't wait to get things "cheeky" in the "boot" and under the "bonnet"
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