Ignition interference

[4sfed]

The Electromotive ignition can add 10 amps to the load, but only with the engine running at speed.  If you're doing a static test you should add an extra load, like a cooling fan, to make up the extra current the Electromotive would use.  And run your test for several minutes to see how the voltage drops as you use up the surface charge.

[Richard Thomason]

noticed the post about the 16 volt battery. We used to run no alternator with our MSD ignition. Total loss ignition. We were always afraid of low voltage so constantly had the battery on the charger. We got the bright idea of building a 14 volt battery to ensure the voltage was right. We made our own case, got the plates posts etc. from a local battery builder and was working on making a charger. We thought we had a brilliant idea that could make us rich. Went to SEMA that fall and guess what, a new 16 volt battery and charger system was just being introduced to the industry. Came back home and threw the damned thing away.

[rebelce]

That Murphy dude works overtime!     Back in the 70's I needed a way to mount a Chevy alternator on my '38 Ford pick up,  so I made a "Y" shaped mount and put it right where the stock generator went.  Sold it along with the truck and see them all over the place now.  Apparently someone needed the income more than me.            I'm only going to put in a couple more days on the Studie before heading Westward.    I will do my best to test for a voltage drop.   We've been using an old Jabsco water pump and my initial though was some sort of interference from it upsetting the XDI unit.  Now I am suspect of the ground circuit and the voltage drop.  Both good directions to pursue.

[Dean Los Angeles]

Since you're already in the dark about the solution, being in the dark might help. Fire it up and turn off all the lights. In the dark you can see any high voltage problems.

In the early 70's Bruce McLaren was racing at Le Mans and had a miss fire in the final practice session at high speed. They replaced a bunch of stuff, but couldn't test it before the race. Bruce decided to take it out on a farm road late at night to make sure it was OK. At that time a second seat was mandatory so Bruce invited Leo Mehl, Goodyear's head of racing operations to go along with him. Sure enough, in high gear at full pop the engine was missing. Bruce leaned over to Leo and asked him if he could hear the miss. Leo's thought was "Hell, I could hear angels singing!"

[John Burk]

Called Electromotive the other day to ask again about why my HPX needs a 16 volt battery . After many questions I learned that it's not a matter of ignition voltage , it's that their crank triggers get confused by the irregular cranking speed of big high compression engines on 12 volts . He said they work ok on 9 v and that sprint cars have no trouble running on 12 v without alternators . I think the newer XDI was to help with the starting problem .
John

[Ron Golden]

New guy here. I recently had a 598 inch, 15.5:1 alcohol engine on the dyno and tried to use the engine owner's MSD 7AL-3. (170 milijoules) and the engine sounded ragged and didn't want to RPM smoothly. I replaced the 7Al-3 with an MSD 10 Plus (700 milijoules) system and the engine sounded sweet and picked up 70 HP. Are you sure your ignition system is up to the task of alcohol and boost? Just a thought.

Ron