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Interesting ignition observation

Posted: Wed Aug 06, 2014 4:45 pm
by Noisy Cricket
Granted, it's a rotary, but internal combustion is internal combustion:

http://www.rx7club.com/single-turbo-rx- ... n-1068028/

Relevant quotes:
"I modified my ignition with a Crane Hi-6 and LX-92 coil per leading coil about a decade ago (ed. note: this means one ignition box per spark plug!) when I had misdiagnosed a power cut out as poor ignition. It turned out to be two separate things, fuel pressure dropping out under boost creep and BOV popping open.

However, when I dyno tune my set up I find it is unlike most people rotaries that make power by "leaning" out the air fuel mixtures. I believe leaning out the AFRs to make power is often a bandaid for poor ignition strength on a rotary."

"1) The tuner was amazed that my engine wanted LESS timing to make peak power at many load points compared to the Haltech conservative base map I use. Less timing= more manifold burn= more boost."

"We found the motor made the most power with the AFRs flatlined below the 10:1AFRs that the 02 sensor could accurately register once the wastegate was open.

Lowering the AFRs had the added benifit of eliminating the boost drop at peak torque and so raising overall power."

"These findings were consistent with my earlier dynapack dyno tuning session where the tuner found no power leaning out the mixture from my street tuned 9-10AFRs except in the 7-8,000rpm range where 10.5:1 made slightly more power."

And finally:

"MSD 6AL: 135 millijoules/spark

Crane Hi-6: 1200 millijoules/spark"

Re: Interesting ignition observation

Posted: Wed Aug 06, 2014 5:46 pm
by PRY4SNO
How does this output compare to the LS2 coil conversion units and the 2.0t coils?

Re: Interesting ignition observation

Posted: Wed Aug 06, 2014 6:46 pm
by alxdgr8
Some more good reading: http://rennlist.com/forums/944-turbo-an ... ystem.html
A couple of coils are tested/compared in that thread.

Re: Interesting ignition observation

Posted: Wed Aug 06, 2014 8:17 pm
by Noisy Cricket
PRY4SNO wrote:How does this output compare to the LS2 coil conversion units and the 2.0t coils?


Can't really compare a CDI to normal stuff.

I have always used MSD, a friend of mine put a Hi-6 on his car, and when he was off in Basic he had me go over his car and figure out why it wouldn't run. Okay, we have fuel pump, let's check for spark. Did the old "lay a wire near a ground" thing.

The freakin' coils (multiple coils wired in parallel to ONE box) made big, FAT, white-blue arcs to a chunk of metal four or five inches away.

A rule of thumb with CDI boxes is an amp per thousand RPM. So to put that setup on an Audi, that's five Hi-6 boxes (hey, they're cheap right?) times say 7000rpm = 35 amps average draw.

I don't know what peak current draw is on a Hi-6, but the MSD will pull a hair over 30 amps peak when charging the capacitor for each spark. That is why they want you to connect directly to the battery.

Re: Interesting ignition observation

Posted: Mon Aug 11, 2014 12:13 pm
by Wilford Brimley
Noisy Cricket wrote:And finally:

"MSD 6AL: 135 millijoules/spark

Crane Hi-6: 1200 millijoules/spark"


As posted in the rennlist discussion on page 4:

The Crane rating is a little misleading... It does not produce 1200mJ per spark, rather it does 1200mJ per sequence. From what info I can fine, the energy per spark is around 150mJ. So a little more powerful than the MSD box.