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 Post subject: MSD GROUNDING
 Post Posted: Wed Oct 12, 2011 1:02 pm 
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How many of you use the ground diagram that msd suggest,the one where you run #10 wire from head to head to block to frame.from msd box to frame and 0 or 00 from block to the battery and a wire from negative side of coil to frame.

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 Post subject: Re: MSD GROUNDING
 Post Posted: Wed Oct 12, 2011 1:18 pm 
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Not me on any car I've ever had? Only problems I've encountered lately was the box mounted too close to the coil and last weekend the MSD provided connector at the box had a problem where I lost crank trigger.

I think some of this might be because of a bunch of custom built race cars chassis being power coated. On my car with power coating I took a file and got to bare metal for the ground connections.

Are you having problems with yours or what? :-k

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 Post subject: Re: MSD GROUNDING
 Post Posted: Wed Oct 12, 2011 2:01 pm 
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I did it on my Camaro and I'll do the same on my Nova. I became a ground freak when I started data logging! =;

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 Post subject: Re: MSD GROUNDING
 Post Posted: Wed Oct 12, 2011 3:15 pm 
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They don't tell you to do that on the Innovate logger manual? The manual specifically states that you ground to the engine, which is what I did with my Camaro and what I'm doing on this dragster. :-k

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 Post subject: Re: MSD GROUNDING
 Post Posted: Wed Oct 12, 2011 3:35 pm 
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I do and I had to learn the hard way too. I posted about it here a couple of months ago.
viewtopic.php?f=7&t=8316

gearhead1011 wrote:
When I built the car I just used the chassis for grounds and pulled the power off of the heavy battery cable at the solenoid. That was good for 5 years. I guess there is a certain amount of "noise" that can be eliminated by using dedicated circuits. I always doubted the need for dedicated grounds and power sources but not now, seeing is believing.


You can skip to the last 3 post in that thread to get my opinion on it. My chassis is painted not powder coated and the ground tabs were sanded off.

By the way that running problem cost me at least 2 rounds (possible more) of racing this past year. I missed the UMTR championship by 9 points. We get 5 points per round so I would have REALLY liked to have won those rounds.

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 Post subject: Re: MSD GROUNDING
 Post Posted: Wed Oct 12, 2011 4:12 pm 
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Yeh Chuck, I remember your problem but I didn't remember how you fixed it? I see my post there ? it horking up after 5 years of running?

On this dragster the power for the MSD Digital 7 comes directly from the battery and the negative is also connected directly to the battery ground on the car chassis, ie, the copper end of that negative battery cable is connected to the negative cable of the MSD. The Camaro was like yours was in the beginning and I never had a problem traceable to that but I did have multiple 10ga grounds connected to the chassis ground on the roll cage.

I guess since others have had a problem with this then it wouldn't hurt to do it now before problems cost you rounds or a race.

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 Post subject: Re: MSD GROUNDING
 Post Posted: Sat Oct 29, 2011 8:26 am 
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This is kind of late for a reply, and maybe part of this could be wrong and I will get into a little bit of detail about it. Does MSD NOT recommend any grounds or 12v+ connections to come off of any components and useage of frames, but to ONLY RUN A POWER AND NEGATIVE SEPERATE WIRES TO THE BATTERY ONLY!!!!!!!!!!

I have a short story to tell on here that has changed my elect. system for ever and it should not have problems for a loong time to come.

The late great Michael Brown from the now closed up Wires n Pliars company once told me this ("John, with all the stock bodied cars and chassis's being used, and all the full tube chassis cars being made now a days, the racer can NOT afford to use any of these chassis's to help run an electrical system period!, and that they all need to have a seperate connection system to not have any problems in the future") ("All these chassis's flex, and this creates many problems for many racers") and this I will remember forever ;-)

With that statement, and that statement alone, Michael has changed my racing program for ever and if you don't believe me, go as Mike Janis of the Pro Mod fame or Billy Glidden and abunch of others, and ask them who else's cars Michael wired, and they will tell you , or show you how it's done the most effective way!!!!

I talked to him on the phone on a Monday, and I was attending a NMCA race at Milan Dragway on the weekend and we were going to meet on the following Monday and talk things over and do some show & tell, well, on the way to the track on Sat. morning, Michael's truck went off the road at the final curve before the exit and was killed instantly by a tree smashing his truck very badly and took his life away.

The key info to this whole post was this, Michael told me, that if you don't want to have any problems with an electrical system when all hooked up correctly, to ANY chassis, new or old, to only run (2) large enough wires to supply enough current to the driver area where all the controls and swtiches are useually mounted and connected from the BATTERY ONLY!!!! Did everyone read that part?(this was his key point on the whole elec. system) and anything else will creat problems as the elect. system needs to be isolated from bad chassis grounds, cyl heads, blocks and other power sources as they have been calculated per the companies that built them and not to have power drawn from them to creat other problems that WILL happen.

As mentioned, Michael said to just run 2 wires, 1 hot, 1 gnd. from the batt. to the inside of the car and make 2 seperate pickup points there, to ground and power up everything in the chassis, then and only then will you have an electrical system built perfectly for racing. So, according to MSD, they want battery power only to supply there systems and they have a reason for this in there instructions too, so install the system this way and many of your problems just go away instantly. Once the wires from the battery are in the driver area, or where ever you hook up your components, that you need (two) connecting points, 1 for power, and 1 for grnds. and pull everything from these two locations, and multiple connection points can be added if needed for multiple wired chassis's with a ton of electronics in them, like nitrous, data loggers and so on an dif in dought with wire size, go up one size, but to investigate wiring as well vs. your component amperage draws and wire accordingly.

I am not bragging on here by any means, but people look at my elect. system on the floor and we get to talking and the next thing you know, they say they use there frame, engine, body and what ever they think is a good power source or ground and still have problems!, then I tell them Michael's story and POOP! the light goes on in there head \:D/ BINGO, MISSION ACCOMPLISHED =; and all of the guys that I have told this story to have come back to me and said, (Thanks for the info on the wiring system, I did what Michael told you to do and I don't have any problems now and that there car is going faster and better then ever). =D>

So, what Michael told me, and what I pass on is truely something that works, keeps your hotrod running electrically, and then you can concentrate on other issue's then.

I used to have problems, and was slowely finding them and repairing them the best way I knew how, and then I met Michael and it all changed to the good. :-$ R.I.P. Michael, you are missed by many people in this industry...

I hope this info helps someone out on here, and although we all have different ideas about elecr. systems and we don't always agree with each other, I am willing to bet, that many of the fastest and quickest cars in this country have a system like Michael's in there cars, and they may not have been wired by him, but many have followed his examples. Have a question?, just ask me and I will do my best to help out.

John

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 Post subject: Re: MSD GROUNDING
 Post Posted: Sat Oct 29, 2011 9:12 am 
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Each and every connection in your cars system can add to the total resistance and has the potential to increase the voltage drop. The fewer connections the better. K.I.S.S. - Keep It Simple Stupid.

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 Post subject: Re: MSD GROUNDING
 Post Posted: Sat Oct 29, 2011 6:17 pm 
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This is how it goes, if your using a battery total loss system then you wire everything direct to the battery positve and negative just like John described from this guy Michael. If you use an alternator then the alternator is in fact the highest voltage point on the car. So you have to wire everything to and from the alternator. The alternator negative is its housing. You have to connect the housing of the alternator with large enough wires to a negative post or something similar with all your grounds going to it.

If you connect your grounds to the battery terminal or the chassis and you run an alternator you will get a voltage offset and data logging will be inaccurate. Data logging is extremely small voltages and you have to be fussy.


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 Post subject: Re: MSD GROUNDING
 Post Posted: Sun Oct 30, 2011 12:38 pm 
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shrinker wrote:
If you connect your grounds to the battery terminal or the chassis and you run an alternator you will get a voltage offset and data logging will be inaccurate. Data logging is extremely small voltages and you have to be fussy.


How does this make the data logging inaccurate?

Rick


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 Post subject: Re: MSD GROUNDING
 Post Posted: Sun Oct 30, 2011 3:45 pm 
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Because things like pressure sensors have their grounds internal to the casing and when their attached to the engine block you then get a ground offset. The sensor ground is on the thread of the sensor and the alternator is on the outside casing of the alternator. Because both of these grounds are then on the engine block but the data logger and other electronics of the car are on the battery there is a ground voltage differential between the circuits. Ground offsets are simply this, you have 2 sources of voltage, one is a battery the other is the alternator, any resistance in the negative between those sources causes a change in voltage if you read from the positive of either source to the negative of the other.


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 Post subject: Re: MSD GROUNDING
 Post Posted: Thu Nov 03, 2011 5:41 pm 
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shrinker wrote:
This is how it goes, if your using a battery total loss system then you wire everything direct to the battery positve and negative just like John described from this guy Michael. If you use an alternator then the alternator is in fact the highest voltage point on the car. So you have to wire everything to and from the alternator. The alternator negative is its housing. You have to connect the housing of the alternator with large enough wires to a negative post or something similar with all your grounds going to it.

If you connect your grounds to the battery terminal or the chassis and you run an alternator you will get a voltage offset and data logging will be inaccurate. Data logging is extremely small voltages and you have to be fussy.



Bruce, if one uses a 1 wire alt., and that one wire goes to the positive post of the battery for charging( or the pos. side of the main kill switch as per NHRA rules( correct me if I am wrong on this), does it still supply anything connected to the battery pos. termainal with the alt. supposidly higher voltage provided the alt. is doing it's job? I really sucked in elect. class, but I figured a lot of things out wiring my race car, but, this is something I need to dig into. NHRA requires that all power be cut off at the back of a chassis, ie; the main kill switch, but when a alt. is connected to the batteries( or the kill switch pos. term.), isn't the alt. supplying the power to what ever needs power when the engine is spinning the alt.?

I have everything on my car on a circuit board with breakers and, fuses, so I am covered in that area, but I noticed my tach just doesn't do what I think it is supposed to do like give the correct data!!!! I may have a problem from what you are saying then :-k

And this ground wire from the alt. deal, so, what your saying is, that even if the alt. case is the grounding point, that everything should be coming off of the alt. grounding point like the bolt running thru the alt. case itself to a bracket??? that that bolt should be long enough to hook up a large eyelet with a pretty large gage wire to support all the grounds in the chassis??? is this right??? :-k

I have a hugh ground strap from my engine to my frame to ground the engine(and now the alt. too!!!) and the frame is also grounded to the body, but I run all my grounds from all my components to that one ground terminal inside my chassis driver compartment, so will this cause my Tach to give me these funny readings then? I am pretty sure I understand how you are explaining it, but I want to make sure...

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 Post subject: Re: MSD GROUNDING
 Post Posted: Thu Nov 03, 2011 8:27 pm 
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gearhead1011 wrote:
I do and I had to learn the hard way too. I posted about it here a couple of months ago.
viewtopic.php?f=7&t=8316

gearhead1011 wrote:
When I built the car I just used the chassis for grounds and pulled the power off of the heavy battery cable at the solenoid. That was good for 5 years. I guess there is a certain amount of "noise" that can be eliminated by using dedicated circuits. I always doubted the need for dedicated grounds and power sources but not now, seeing is believing.


You can skip to the last 3 post in that thread to get my opinion on it. My chassis is painted not powder coated and the ground tabs were sanded off.

By the way that running problem cost me at least 2 rounds (possible more) of racing this past year. I missed the UMTR championship by 9 points. We get 5 points per round so I would have REALLY liked to have won those rounds.


I have seen this and trouble shot this exact problem on many Cars in the past.

If your ignition doesn't have a good ground then it will not work properly. Heads have to have a good ground for them to jump an good strong spark. Grounding is the, bar none, the most over looked part of an electrical system. That loose electron needs to make it's way around the complete loop.

First time I saw this to be a problem was on a Dodge prostocker.

Don

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 Post subject: Re: MSD GROUNDING
 Post Posted: Fri Nov 04, 2011 7:18 am 
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NHRA requires you wire the car so the battery and the alternator are both disconnected when you turn the isolator switch. that is what you have described. You have to wire the alternator output of the one wire alternators to the positive terminal of the battery and connect nothing else to the alternator output. In other words there has to be one one wire connected to the alternator output and it has to be on the battery terminal. Then when you turn off the switch everything is disconnected and the engine will stop no matter what.
When its wired like that you have to ground everything to a cable from the battery negative. Run a cable from there around the car and connect to all components and the engine block and the chassis. Sensors have their grounds on the body of the sensors so they ground through the object their screwed into. The tacho is grounded to the casing or maybe it has a negative wire so its connected to the chassis mount its on or the black wireetc. All these things have to be connected to the battery negative correctly with effective connections .
Elkyman wrote:
does it still supply anything connected to the battery pos. termainal with the alt. supposidly higher voltage provided the alt. is doing it's job?
Yes it does, everything connected to the positive terminal will run at alternator voltage. Voltage goes in all direction in a wire its not a one way thing.


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 Post subject: Re: MSD GROUNDING
 Post Posted: Fri Nov 04, 2011 5:17 pm 
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shrinker wrote:
Because things like pressure sensors have their grounds internal to the casing and when their attached to the engine block you then get a ground offset. The sensor ground is on the thread of the sensor and the alternator is on the outside casing of the alternator. Because both of these grounds are then on the engine block but the data logger and other electronics of the car are on the battery there is a ground voltage differential between the circuits. Ground offsets are simply this, you have 2 sources of voltage, one is a battery the other is the alternator, any resistance in the negative between those sources causes a change in voltage if you read from the positive of either source to the negative of the other.


I see where sensors grounded as you describe (factory sensors are this way) would cause an error based on the voltage difference between the ground locations. In this case the data logger should also be grounded to the engine block. I don't know how other data loggers are made but sensor loops where the power and return for each sensor comes from the logger and have no other connections and are isolated from their case is how I'd do it and probably how racepak etc do it.

As far as connecting things to the alternator (+), there are a lot of reasons not to do that even though it would provide for a lower total resitive loss circuit. The electrical noise (spikes and fluctutations) from the alternator is bad and would cause problems with some things. The alternator must be separated from the ignition when the disconnect switch is opened or the engine stays running. When the engine is off the resistive losses would be more which is when your voltage is lowest (think cooling fan).

Rick


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