Winter Project LS-2 Coils

[XfireZ51]

Originally Posted by carter200

I'm willing and able.

Carter,

Different styles of LS coils. The ones mounted on the car are an earlier version LS-2 coil. I also have a set of the "truck" coils you see in the video. The ones with the heat sinks. =Jeff= and I can talk to you about some different style brackets. PM me if you're interested.

[carter200]

XFIREZ51,
You draw it up and I can machine it. Fax me at 325-625-5795

[tpepmeie]

Originally Posted by XfireZ51

Bob,

Actually spark timing could be affected. There is a "spark latency" associated with our ignition module and the LS coils would add another layer to that. I'll need to put a timing light to it and check how much.
I'd also like to think that the air/fuel combustion is benefitting from hotter spark.

Dom, you must have a really good eye or equipment to see 122 microseconds with a timing light. That's the ECU adjustment for spark latency. Not sure I can understand how the exhaust note is affected either. But, maybe.

Nonetheless, cool project. I'll be watching. Any reason this has to use LS coils? Could it be done with an aftermarket coil on plug (ie, cigar-type coils)?

Todd

[XfireZ51]

Originally Posted by tpepmeie

Dom, you must have a really good eye or equipment to see 122 microseconds with a timing light. That's the ECU adjustment for spark latency. Not sure I can understand how the exhaust note is affected either. But, maybe.

Nonetheless, cool project. I'll be watching. Any reason this has to use LS coils? Could it be done with an aftermarket coil on plug (ie, cigar-type coils)?

Todd

Todd,

Thanks. I dealt with the question of whether timing could be affected and so I responded that spark latency can affect timing if not accounted for. As you point out the Spark Latency in our cal is 122microsec at 800rpm. Just to be clear, I wasn't suggesting that the spark latency was changing the timing to the point of where it made a difference in engine note. As I understand it, the spark latency on the LS coils is in the neighborhood of 22microsec. Not enough to be discernible by me or anybody else. Maybe my dog. And the faster the rpms, the shorter the latency needs to be. The LT-5 cal drops to 91microsec by 4800rpm.

Just for sh*ts and giggles,if we do the math,

1000rpm/60 sec = 16.67rpsec
16.67rps/1,000,000microsec/sec= .00001667rev/msec
.00001667rev/msec * 360degrees/rev = .006deg/msec
.006deg/microsec * 122microsec = .732deg

5000rpm/60sec = 83.35rps
83.35rps/1000000microsec/sec = .00008335rpm/microsec.
.00008335rpm/msec. * 360deg/rev = .03deg/msec
.03deg/microsec * 91microsec = 2.73deg
91microsec (LT-5 latency) + 22microsec (LS coil latency) = 113microsec
113microsec * .03deg/microsec = 3.39.

So something about .6 -.7deg at 5000rpm additional error

At 7000rpm, its pretty close to 1deg of timing error if not compensated for.

What's pretty neat is that the LS coils have a latency that is nearly 4 times shorter than th LT-5 ignition module. That I suspect can be converted into dwell instead. Effectively, GM eliminated the ignition module by distributing its function to the coils with the PCM doing the sequencing using the crank and cam sensors.(Another reason I'd like to see GM saved.)

As to the COP, I don't know enough about those applications to give an opinion. I suspect part of the reason the GM CNP (Coil Near Plug) is popular is because of availability. Plus the COP is usually found on hemi type combustion chamber OHC motors like ours and not OHV motors like the LSx. My Vibe GT is a COP with the Toyota VVTL 1.8L motor.
Since those coils are built to form factor, I am speculating that it could be restrictive as to capacity not to mention interchangeability. In order to use a COP for our motor, we'd need to find a COP that fit in the plug well. Plug cables give you greater flexibility.
Theoretically, shoould be no reason to prohibit a suitable COP setup. From a aesthetic POV, it would be desireable.

[rkreigh]

cool stuff but I don't know why this would be worth it.

the factory coil packs are "enough" for even the bad @$$ cars, so what are you trying to "fix" or just daring to be different?

but I have to admit, it sure is a cool idea!

like to hear more because I have a big block chevy that is just dying for that type of mod.

hold the tupperware plz. every time I pop the hood on my TT C5 I kinda sigh a little. it's one ulgly animal. but at least it has teeth!

[Pete]

Originally Posted by rkreigh

cool stuff but I don't know why this would be worth it.

the factory coil packs are "enough" for even the bad @$$ cars, so what are you trying to "fix" or just daring to be different?

but I have to admit, it sure is a cool idea!

like to hear more because I have a big block chevy that is just dying for that type of mod.

hold the tupperware plz. every time I pop the hood on my TT C5 I kinda sigh a little. it's one ulgly animal. but at least it has teeth!

It would be cool to replace or find a lower cost replacement for the OE IM

Ron hoping the LS coils make more power ove stock.
If so, i'm in. mine will go under the plenum.

Hey Ron any news on the BG drags?

Pete

[XfireZ51]

Originally Posted by Pete

It would be cool to replace or find a lower cost replacement for the OE IM

Ron hoping the LS coils make more power ove stock.
If so, i'm in. mine will go under the plenum.

Hey Ron any news on the BG drags?

Pete

Pete,

I'd like to see how that would work. Of course, one of the advantages of CNP(Coil Near Plug) is the short plug leads it makes possible. Coils are also out from under plenum where its cooler. 8 coils under plenum would just multiply heat issue that IMO.


Ron,

The project wasn't started as a whim. My friend Pete above rants about the cost of the LT-5 IM, especially since its unique. That's why I started looking into LS coils. This is a particularly popular ignition upgrade for
Supras, RX-7s, 240/280Zs etc. Also Gen 1 and 2 SBCs are now upgrading ignition systems. Not sure about your BBC. =Jeff= may want to comment on using the eDist for a BBC. The LS-2 coils are favored particularly in forced induction application because the spark is hot enough to allow wider plug gaps without taxing an ignition module.
In its current state, the LS coil conversion removes the IM as part of the "current path" for the ignition coils. By doing so, we significantly reduce the heat and stress on the IM.
Even though this conversion continues to operate in "waste spark" mode,
we are no longer "splitting the spark" between 2 cylinders. Each one gets the voltage of an ignition coil. LS-2 coils have a secondary peak current of 120 milliamps. I have not been able to find what the peak current for the stock LT-5 coils is, but the LS-1 coils have about 40ma.
We'll be doing some testing to see if any of this translates to an increase in power. My working hypothesis is that these coils should be of help, particularly at the top end, with a hotter and more stable spark than stock coils and wires. Some believe that CNP is responsible at least in part for the power the LSx motors make.

[GOLDCYLON]

I think its a pretty neat proof of concept.

[-=Jeff=-]

Ron,

a F.A.S.T. eDIST and a crank trigger and cam sensor would work for your BBC, it will use the LS(x) series coils I was going to do that to my 89, but bought the Z and sold the 89 instead

[jonszr1]

you to have done some impressive work, wish i knew more about this stuff , but am dummer than a post about it . sure hope it works ,and if so would be first in line to buy the conversion .nice job guys