Dwell angle, electronic ignition

"hls" wrote in news: snipped-for-privacy@giganews.com:

or you could get Dr. Jacobs ign book and put any ign module you want on it. chry is cheep and relighible. done many. KB

Chrysler system works well, but GM HEI is more sophisticated. It is common to use HEI module in place of the "orange box," search online for it, have thought about doing that myself. (have an "orange box" ignition on my Studebaker; it works fine, but if it ever dies I will probably use a HEI module.)

nate

can you not get webers for it? a couple of dcoe40's would pep it up nicely.

ah, that makes more sense!

it's still much much cheaper to go with some other vehicle's module from an appropriate donor in the junkyard than going aftermarket. even some of the new oem styles from napa are crazy cheap. it's certainly not worth trying to build one from scratch unless you really have a hankering for the science project aspect.

Nate Nagel wrote in news: snipped-for-privacy@news4.newsguy.com:

The only problem with the HEI is it is not as relighable KB

I don't know the book! Have you got a full citation?

--scott

not sure if that's true, I've never had any kind of electronic ignition failure. that said I knew there was an explanation somewhere of why the HEI was technically better (although interchangeable) here is one

It's on the list of things to do after I get the E28 fixed up. In the meantime, I drive it to work a couple days a week and it's got 480,000 miles on the odometer and still has the original head gasket.

--scott

I think the original poster has a hankering for the science project part, and I understand that. What I don't understand is using a microcontroller for something you can do with a small handful of discretes. I'll even donate some SCRs from the junkbox.

--scott

I've seen the GM HEI system fail a lot of times......more than anything else it was shorting of the high energy coil inside the distributor.

I owned a 1997 Dodge van and never had a moments problem with it as far as ignition.

As far as your link, the great punch line is how the HEI system gives better (this, that and the other) because you have "a hotter, longer-duration spark (for better ignition and more complete combustion) ".

First, you dont really need a hotter spark than it takes to ignite the charge, and the longer duration spark doesnt necessarily give better ignition nor combustion, according to a number of researchers.

There were some REALLY high energy systems that have been researched over the years. Smokey Yunick worked with one that put relatively huge amounts of energy into the spark....I believe he said it sounded like a pistol shot. It never went anywhere to speak of.

A British researcher published a complete and scholarly report on the subject, and he indicated that there was something to be gained, maybe, but he was taking an elephant gun on a mouse hunt.

HEI is good enough, Kettering was good enough for most things, and CD was also pretty good. You CAN overengineer a mousetrap.

I think the issue is that if you have a carb and don't have good even fuel-air mixture going into the cylinders, the hotter spark can help. However, with modern fuel injection systems it's become a complete non-issue.

Smokey Yunick worked on a lot of craziness that never went anywhere....

--scott

True dat... but just my one completely anecdotal data point, the only time I've ever been left at the side of the road by an ignition failure was by a traditional Kettering system. Granted, it was probably poorly maintained, and knowing what I know now, I probably could have been going again with a nail file/matchbook cover/whatever, but neither the Chrysler "orange box" or the HEI module have ever let me down.

I did have some VW coil packs replaced under warranty, now that I think about it...

nate

microcontrollers offer a world of enhanced controllability. thermal management becomes a breeze. current management becomes a breeze. rev limiting [with multiple methods] becomes a breeze. and if you really want to get into it, security becomes a breeze - rfid tag your ignition!

original head gasket is impressive. if it ever has to come off, don't let this happen:

it's not heat, it's total energy. static electricity can create millions of degrees in a spark on a very local basis. but it's not got the energy to do stuff like weld steel. energy matters more than temperature. a good fat energetic spark is what gets the job done. "weaken" a spark by pulling off a plug lead and dissipating some of the energy to atmosphere with a second spark gap and see for yourself.

cite your "sources" big guy.

yeah, all the top fuel dragsters use high energy ignitions just for giggles - no dyno data ever collected on that theory whatsoever.

yeah? where?

i call bullshit. have you ever flown in an old piston engined plane? [rhetorical]. one with dual plugs? [rhetorical] because if you ever had, and you'd tested the magnetos mid flight, i.e. switched off one at a time, you'd know just how ridiculous your statement was.

bullshit. kettering is abysmal compared to any modern ignition, even cdi.

it's an improvement on kettering, but it's not used by oem's for a reason - it's fundamentally inappropriate for the job. but i can't see you getting into the science of it.

not in this case. unlike people who insist on over-speaking their knowledge level.

snipped-for-privacy@panix.com (Scott Dorsey) wrote in news:jnrffp$hpt$ snipped-for-privacy@panix2.panix.com:

I will go look and get back with the full title. KB

ready, fire, aim! right kev?

it's on amazon - just search for "jacobs ignition". the guy likes the sound of his own voice and simply can't resist glossing over the facts from what i can see in the preview. you're better off with the bosch automotive handbook. pages 379 and 570 of the current edition will start you off.