The module is located underneath the left headlight away from any major heat source. The wires are all wrapped as you can see and the coils are set up just as on the LS1. Over on CamaroZ28.com , there are several people using this setup, some with as much as 30,000 miles already with no side effects or failures.

I just took the car for a road trip(Carlisle) to show how reliable it is and in hopes that some people from GM would take notice, but I was forced to move my car to the back lot where nobody could see it, so much for showing Dave Hill and Gordon Killebrew.

BTW, Mr Goodwrench did the work(my buddy Tommy), so if for any reason that I need to go to a dealer, the guy who did the work would be the guy fixing it.

Tom, as far as a backup, you are correct. In my situation, we cut some wires and threw away the connectors that were no longer used. But, if someone were smart enough to make a hookup for the module to plug into where we cut, then you would have your backup right there. The original coil and module are still there. Of course you would need to carry a set of plug wires.

Since this car is primarily for the track, I'm not too worried about it breaking down(at least not teh ignition).

 

No, hes not the only C4 thats doing a LTCC :thumbs: Tomdcarguy The LTCC was developed on a turbo'ed Impala (Bob Baileys personal car) And as far as the GM engineers are concerned, Bob is now one of them (he is employed by GM). he also knows the engineer who signed off on the orignal opti design.


[Modified by ASRoff, 10:30 PM 8/24/2003]


[Modified by ASRoff, 10:32 PM 8/24/2003]

 

That concerns me about the longevity of the product -- GM is in a position to put an end to it if they want to.

As far as the engineer that signed off on the original design, I would like to personally talk to him and his supervisors about two levels up. In 1992, there was no excuse for it. The distributorless, multi-coil systems had been out there for some time at that point ... including on GM vehicles. Then there's the keyless hub........

Tom Piper

 

I am not all that concerned about longevity. It is a solid state product... I would hope it is reliable enough to hold up. Besides, it has been road tested on the f-body forum for a while before showing up here.

Ok... questions...

1) It seems like the tach and ASR issue has been resolved, right?

2) plug wires... what became of that problem?

The opti's problem seems to revolve around the high voltage side... the low res side is very reliable - as long as the bearings hold up!!!!!

mine is popping like crazy... time to make a move!!!

 

Yo Andy, the ASR and tach problem have been solved, it was 3:00am when we finished, so we left that for later.

The plug wires are another issue, the Vortec Truck wires are about 1.5 inches tto short, so I'll have to call magnecor and find out what part #'s they have available.

At least I can use these on my new truck.

 

thanks!

I was curious, cause LTCC recommends those wires...

 

Bob just recently went to work for GM he developed the box Before he was employed there. His other products work great The scanmaster and MAF translators are good pieces. He just bought a Dodge Stealth and is working on a scanmaster for it. Ask the Turbo Buick guys how much they like his products. By the way incase you are wondering why I know so much about the guy. We did a LTCC on on a friends camaro We ran into some trouble getting it to work. Bob came over himself to help. after about 20min of trouble shooting he realized that his harness supplyer had crossed two wires. we switched them and boom it fired right up. The car sounds incredible compaired to the old opti set up. The car had a hot cam and Idled rather rough. Now it sounds like it has a stock cam. The car hasent been layed into yet because the Mcleoud clutch still needs a few more miles on it. But, my buddy says its a whole new car.

I'm having driveability issues with my car that I think is opti related ( the engine was stroked and a new opti was installed) Ed wright did the programing. It runs badly at part throttle, especially between 120' and 150' the car has to warm up before it will run correctly. with the voltage that this setup develops it should blow thru my 12:1 compression.


[Modified by ASRoff, 11:31 PM 8/25/2003]


[Modified by ASRoff, 11:34 PM 8/25/2003]

 

When I talk about longevity, I'm talking about being able to buy new replacement electronics when the original one becomes defective -- in other words, will it still be in production 5 years from now.

When it comes to reliability, not all solid state devices can stand up to a hostile environment like heat produced under the hood. Years ago, I worked for a semi-conductor manufacturer, we made silicon devices. The question is: are the components designed and selected for the hostile environment? Most small companies are not equipped, or have the time, to test these devices individually to make sure they can stand up -- as a semiconductor manufacterer, we tested, separated, and sold at a premium the ones that were of higher quality. Then there are cheap, junk diodes/semiconductors that have impurities (not manufactured in a clean environment, or simply didn't make the grade) that will degrade with time and heat (thermal runaway) -- they end up in a lot of alternators.
The after-market CD ignition systems are a perfect example: they are solid state with a high percentage of failures. Although, I think most of these are moisture related.

This in no way is meant to down the LTCC -- I believe in the product. Several years ago, before the C5 or the LS1 coil pack existed, I sat down at my test bench with my test equipment and an Opti-Spark and started to document the number of high-res pulses in each low-res window and determine the timing sequence. I simply didn't have the time to do it the way I wanted to. At the time, I was thinking about using a LT5 coil pack and the "waste spark" method of firing two plugs at a time. Plus, I wanted to have dynamic control of the coil dwell time which is more complicated -- with multiple coils, you can have the coil of the next cylinder in the firing sequence charging (dwell time) while the present active cylinder's coil is still firing -- you can't do this with a single coil. Modifying dwell properly in a multi-coil environment is more difficult. Dwell time that is dependant only on angular position of the cam/crank decreases with engine speed -- so, at higher rpm, you have less dwell, which is not what you want. Plus, at low rpm, you don't want excessive dwell that will heat the primary winding of the coil. This is actually the most complicated part to me.
I would really like to know how the LTCC handles dwell time for each coil -- but, that's probably a trade secret.

Tom Piper




[Modified by Tom Piper, 7:37 AM 8/26/2003]

 

I think we'd all like to know how it works.

 

Tom - I see what you mean... and thanks for explaining dwell.

When I was a kid, dwell was kinda important. but I didn't have a car that depended on tuning it - it had electronic ignition!

so, I never took the time to understand it... thanks!!!! :thumbs:

I am going to order the LTCC this week.... my opti is SO dead...

 

For me, it's not just curiosity, it's really a "need to know" how the dwell time is determined before I buy it.

Tom Piper

 

Some info on Dwell Control:

AFAIK, the LS1 coils are "smart coils" - where each unit contains an individual switching transistor ('ignitor') and a dwell control circuit. Thus the LS1 coils rely on the Bailey LTCC Box only for spark sequencing; timing of the 'spark event' still comes from the PCM; dwell is calculated at the coil.

Dunno myself exactly what's in the GM smart coil circuit, I haven't seen one taken apart - but an example of a single-chip dwell-control unit is the ST L482 Ignition Controller (you can find the spec sheets & example circuits by doing a search for that part # here: http://eu.st.com/stonline ). Note that it controls coil current and voltage independent of the PCM, based only on the trigger pulse and some passive external components. I imagine GM used some version of a circuit like that in the LS1 coils - it's similar to the original HEI coil controllers from back in the '70s. Since the LS1 coils are stock GM pieces I think it's safe to assume GM worked out any reliability issues to its satisfaction. With 8 coils there are acres of time available for full coil saturation.


I haven't personally seen the inside of a Bailey Box; but it seems to be functionally similar to the FAST eDist Box. The FAST sequencer appears to use a PIC to act as a 1-8 binary counter/decoder, with what I presume are 8 bilateral switches to direct the ignition pulse to the proper coil. You would need to open the box to see if the builder used Mil-spec components.

If he did, the reliability should be no worse than the base PCM on which it relies for its spark signal. GM used DIS, multi-coils, and solid-state spark sequencing at least as far back as the '85(?) GN. If the Bailey LTCC is a quality unit, IMHO I don't see where reliability should be a big or novel issue compared to other automotive applications.

Note that is only speculation on my part - I don't own one myself.

HTH

 

DOCTOR J

You are loaded with information. This certainly puts a new light on things, and makes me feel better.

However, now I am curious how the "smart coil" works.

Very interesting.

quote:
----------------------------------------------------------------
I haven't personally seen the inside of a Bailey Box; but it seems to be functionally similar to the FAST eDist Box. The FAST sequencer appears to use a PIC to act as a 1-8 binary counter/decoder, with what I presume are 8 bilateral switches to direct the ignition pulse to the proper coil. You would need to open the box to see if the builder used Mil-spec components.
--------------------------------------------------------------
That's what I had figured; my mythical design was simply a window of time for each coil, determined by the low-res pulse, which allowed the PCM pulse to trigger the coil -- a simple "AND" circuit. But, thinking about dynamically controlling the dwell caused me to sweat.

Thanks


Tom Piper


[Modified by Tom Piper, 2:41 PM 8/26/2003]

 

Tom-

Thanks. It's a hobby. And like any engineer, most of the info I have is useless.

I did use the L482 chip in a high-current ignition box a couple of years ago (before I discovered the ready-made LT4 module does the same thing). I run that box with a low-inductance coil on my crank-trigger L98 now - works fine.

Looked at buying the eDist box for a while, but can't justify the high price for what is really just a sequencer.. but I'd still like to see what a multi-coil would do on a small block. So..

This winter, I think I'm going to try adapting a Northstar coil-pack to the L98. It uses all-GM parts, it's all in one package, and I only have to find a place for 4 coils under the hood instead of 8. There is some supporting design info here: http://www.thirdgen.org/techbb2/show...hreadid=193531

DrJ

 

Maybe this is a dumb question, but doesn't the LTCC module interfere with the headlight operation where it's mounted?

That was the first place I mounted a relay for my water pump and I had a problem when I turned the lights on.


[Modified by John Row, 1:50 PM 8/26/2003]

 

John, at first it did, but I moved it lower and it clears just fine.

Doctor J, I have a pic of the "guts" somewhere, just can't find it right now.

 

This is from Bailey's website

 

I imagine the LT5 coil pack is about the same.

Do these systems provide the tach drive signal or will you have to handle it yourself?

Tom Piper

 

This certainly gets the high voltage out of the Opti-Spark.

Since most of the mass of the Opti-Spark is to provide high voltage separation, I wonder if DynoTech could create a DynaSpark package that is only the optical section without the cap and rotor and make the whole unit smaller in diameter (hopefully, this could cut some cost out of it) -- maybe, even small enough to remove without removing the vibration dampener and possibly the water pump.
DynoTech and LTCC could team up and sell a package unit. And, if a group purchase could be lined up on this and LS1 coils..................

Then.....there are times.....when I just go out to the garage and pull the distributor cap off of my '64 coupe and look at the points and condensor...and think about when things were simple.


Tom Piper


[Modified by Tom Piper, 8:33 AM 8/27/2003]

 

you make a valid suggestion... however... the size, I suspect, is dependant on the front cover dimentions and such.

DynoTech is supposed to be developing an all new high-voltage-less opti with coil packs. I don't know where it is in the scheme of things, tho. it is not on their web site, at least I could not find it.

They are doing stages... I, II & III... III being the coil pack system.

BTW, I ordered my LTCC last nite!!!! :thumbs: