One Slick--One P-Mag

[SHORTRV7]

Thought I would ask if it made any difference which side, left or right, I put the slick mag with the Impulse Coupler or with one P-Mag if it made any difference if it was on the left or right??? I have 2 P-Mags just not 110% convinenced to put both on or not??????? Old subject,,,any thoughts.
Don Hanging Engine

 

[Radomir]

I can't think of anything that would force you to go one way or the other... except for maybe wanting to stick with the "usual" (IC mag on left.. the other on the right).. If your engine has appropriate studs installed that way already, not sure it's worth the effort of swapping them around

 

[RV7AV8R]

I have an impulse SLick on the Left and P-mag on the right and it works fine. Be sure to change the grounding contacts on the ignition switch per the P-mag instructions so both mags will give you starting sparks. Normally the ignition switch has the right mag P lead grounded during starting and it only starts on the left impulse mag. Starting on the Pmag is real quick!
John Adams

 

[videobobk]

Since you have two, your best bet would be to sell me one of them (deeply discounted, of course.) That way I could replace my left mag, as I have an E-mag in the right hole. I would say do which ever is more convenient as to location. Shouldn't make any difference IMHO.

Bob Kelly

 

[az_gila]

Stud length

Since you have two, your best bet would be to sell me one of them (deeply discounted, of course.) That way I could replace my left mag, as I have an E-mag in the right hole. I would say do which ever is more convenient as to location. Shouldn't make any difference IMHO.

Bob Kelly

The difference may be defined by the length of the studs on the accessory case...

The Impulse mag needs a spacer and hence longer studs... and, if the engine came with only one impulse mag (which is typical), then the longer studs are on the left side...

gil A

 

[SHORTRV7]

Top or Bottom spark plugs

Hey, thanks to all of you for your answers. I replaced the longer studs last week with the shorter on for both P-Mags so I will have to change back on the Slick. I am still a little confused on the Mag Switch. My switch is Off-Left-Right-Both no Start. My start will be on a push button. When I want to start this beast, the P-Mag delays the spark and I think the Slick Impulse fires immediately, so----start on one or both?? Also, should I run the Slick on the bottom plugs and the P-mag on the Top, any and all responses would be greatly appriciated.
Don

 

[SHORTRV7]

I Still Have Questions about Slick and P-Mag Timing

I need some help here understanding timing a Slick at 25 degrees and timing the P-Mag to what ever. QUESTION--- When setting the timing on the Slick at 25 degrees means it will be firing at 25 degrees BTC at sea level or at 20,000 ft. The P-Mag I am assuming will adjust via Manifold Pressure so at sea level it might be firing at 25 degrees BTC and adjust for economy at 20,000 feet and fire at 32 degrees. Is the Slick still firing and defeating the purpuse for a P-Mag? Am I missing something here? Help!

 

[Ted Johns]

"Is the Slick still firing..." Yes.
"...and defeating the purpose for a P-Mag?" No.
"Am I missing something here?" Probably.
"Help!" Ok.

With any engine (somewhat less so with an injected engine), the mixture at the spark plug continuously varies at ignition time. This is due to swirl and stratification in the combustion chamber, as well as swirl in the intake manifold. This variable mixture is not always conducive to ignition by a short, weak spark. The result is that some percentage of the firing strokes are poor quality, due to late or even missing ignition.

Ignition manufacturers understand this, and have come up with things like multi spark and high energy ignitions to combat this. Some automotive aftermarket ignition systems advertise up to 20 crankshaft degrees of spark duration!

Just consider the pmag firing at 32deg. BTDC, and the slick firing at 25deg. BTDC, as a multispark ignition.

Given the pmag's hotter spark, 99.99% of the ignition events will happen at it's timing.

 

[SHORTRV7]

Starting to understand

Ted, I realize the Slick will still fire even after the P-Mag has fired but, ordinaraly one would set both mags (Slick) to fire at the same time say 25 degrees BTD. My concern is this: When checking mags at run up and switching to one you get a drop of say 50 to 100 rpm's so both firing in this set up is helpfull and I am assuming that in cruse condition if both are firing and both plugs in each hole are firing at the same time then power is there. Now inject a P-Mag firing at when it feels is the best for preformance, what happens to power when the slick is firing at a different time???? I am trying to get the picture here.
Thanks for any help here,
Don Hanging engine

 

[Ted Johns]

Yeah, the mags have a weak enough spark that turning one off results in a 50 - 100 rpm drop at idle. This is an example of the difference in spark timing vs. effective timing. What I mean by effective timing is the time when maximum cylinder pressure occurs. For best performance, this should occur about 15 to 25deg. ATDC, if I recall correctly.

This timing of peak cylinder pressure is dependent upon good, consistent ignition. A single, weak mag spark is kind of like lighting a brush pile with a match. A electronic ignition system is more like a blowtorch. Which one will light the brush pile faster?

People that have an E.I. replacing a mag usually report very little rpm drop when the mag is turned off, by the way. The much hotter spark from the E.I. doesn't benefit much from the addition of the mag.

Bottom line, most of the gain is from the first E.I. There might be a fraction of a percent gain to be had by adding a second.

Here's a really good description of the combustion event, from wiki, of course. http://en.wikipedia.org/wiki/Engine_knocking

 

[SHORTRV7]

Thanks

Thanks Ted, it is my asumption from all of this is that because of the intensity of the P-Mag spark and if at altitude the P-Mag fires at 32 degrees it will not cause the engine to loose any power with the Slick mag firing later at 25 degrees. Thanks again.
Don