Ignition Upgrade

[MudderChuck]

1054256

http://store.summitracing.com/partdetail.asp?part=10291
http://store.summitracing.com/partdetail.asp?part=11014
http://store.summitracing.com/partdetail.asp?part=12411
http://www.off-road.com/jeep/258ignition.htm

Mentioned on the board awhile back, ought to pull all that junk out and install a MoPar ICM. Looks like someone has beaten me to it. Only done it better, by piggy backing on the existing system and make changing back real easy (you don´t have to cut anything). I´ve made serous horsepower over the years, with a comparable Module (the old blue box). The big duraspark cap (Duraspark ignition upgrade) would be a good addition, the small cap has a tendancy to arch.
A stock ICM should cost five bucks at any junk yard (good to 4500 RPM or so) to throw in the glove box for a spare. These boxes are plentiful, cheap, durable and work well. Though they can be voltage spiked and damaged. The 1 ohm ballast resistor in the primary circuit, protects the coil from overheating, at idle.
The ballast resistor can be jumped if it fails.

But I do have a question or two, maybe I could get some help. I believe the YJ has an in-line resistor someplace (if I remember correctly 6 ohms). Don´t really know what a resistor of this size will affect the ICM. I don´t have a good wiring schematic of the YJ, just bits and pieces.

Still researching a bit. Would appreciate any imput.


edited by: MudderChuck, Feb 09, 2003 - 07:14 AM[addsig]

 

[Tug-n-pull]

1054384

Hey Mudderchuck is there any kind of up grade for my little 4 banger? tug :-? [addsig]

 

[MudderChuck]

1054403

For the TBI motor can´t help you much, for the carburated motor same rules apply.
4 bangers are another beast, they have less overlapping combustion stroke. So they kind of start from ground zero at every cylinders igniition. The flywheel is alot more important. So they always seem to work better at higher RPM´s (above 2,000-sweet spot around 2600-2800). Anything that helps them to rev faster usually helps, low restriction intake, low restriction exhaust, removing the mechanical fan (electric) a good head job. On the pratical side, keeping the vehicle as light as possible, using 9.00 31´s instead of 10.50 31´s. Put the tires on a scale, before you buy them, the lighter the better.
I don´t know squat about the TBI in the four banger, but on alot of other motors, the computer doesn´t give a darn how big the TBI is.

edited by: MudderChuck, Feb 10, 2003 - 07:13 AM[addsig]

 

[chinard]

1054406

hmm... this may be getting a little off topic, chuck but you've perked my curiosity about this overlapping combustion stroke.

Do you have anywhere i can look at on this?
(Mostly just academic curiosity about how things work) :-D[addsig]

 

[MudderChuck]

1054454

The first time I wrote the post, I said my experience in four bangers is limited (VW dune buggies) but when I went to post it, it was sent to outerspace, and I forgot to add the disclaimer, the second time. Your right I´m gonna edit no to less, but what I was thinking (was what I was taught, a long time ago), was the power curve on a typical combustion stroke (per cylinder), during (4 cylinders of combustion stroke) of rotation. If you take the curve (bell curve,peak thrust) of the power stroke, per cylinder, for four cylinders and lay them on a base line, there is little (at significant thrust) overlap. A typical 6 cylinder, will make more torque per cubic inch at lower RPM than the four, the reason is overlap of the combustion stroke.

I was taught, that it took at least 5 cylinders to achieve significant overlap, and 3, 6, 8 for much of any overlap of thrust.

If I was taught wrong it´s not to late to change.

www.howstuffworks.com is interesting

This is a good graphic.

http://auto.howstuffworks.com/framed.htm?parent=engine.htm&url=http://www.e31.net/engines_e.html




edited by: MudderChuck, Feb 11, 2003 - 01:38 AM[addsig]

 

[Tug-n-pull]

1054461

Thank you sir! tug ;-) [addsig]