Question on ignition advance for increasing RPM

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DaveEFI
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Re: Question on ignition advance for increasing RPM

Post by DaveEFI »

stevieturbo wrote:
Fri Feb 12, 2021 8:21 pm
MSD stuff isn't the most reliable.

I've had a few of their boxes fail over the years.

Although with modern coils....a lot of that stuff is pretty much defunct although a lot still like to use it. Most decent modern coils will have no problems at all with say 2-300hp per litre.

That said, if it's a single coil and dizzy.....given the reduced time available for charging and between cycles.....using all the tricks you can to add ooomph to the coil can help.

With coil per cylinder, there's a lot of time available.
I must admit to being surprised you could improve the spark quality from EDIS. Never heard of any complaints about that - it's massive. One coil per two cylinders, and that coil custom made for the igniter, and vice versa. There are two basic reasons EDIS is a bit old hat. No user adjustable rev limiter, and the tach signal it sends to the fuel ECU being only one pulse per spark, rather than the greater resolution one you get from the 36-1 trigger wheel.


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DEVONMAN
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Re: Question on ignition advance for increasing RPM

Post by DEVONMAN »

DaveEFI wrote:
Sat Feb 13, 2021 10:49 am
stevieturbo wrote:
Fri Feb 12, 2021 8:21 pm
MSD stuff isn't the most reliable.

I've had a few of their boxes fail over the years.

Although with modern coils....a lot of that stuff is pretty much defunct although a lot still like to use it. Most decent modern coils will have no problems at all with say 2-300hp per litre.

That said, if it's a single coil and dizzy.....given the reduced time available for charging and between cycles.....using all the tricks you can to add ooomph to the coil can help.

With coil per cylinder, there's a lot of time available.
I must admit to being surprised you could improve the spark quality from EDIS. Never heard of any complaints about that - it's massive. One coil per two cylinders, and that coil custom made for the igniter, and vice versa. There are two basic reasons EDIS is a bit old hat. No user adjustable rev limiter, and the tach signal it sends to the fuel ECU being only one pulse per spark, rather than the greater resolution one you get from the 36-1 trigger wheel.
The engine does run better with the MSD in circuit. Maybe it's to do with the multi spark per event. Or I have the gaps too big with the EDIS only in circuit.
1950 A40 Devon Hotrod with 5.0 twin turbo RV8.
EDIS8 wasted spark, Holley Injection.
Been as far as the Moon and back in 57 years of driving. Same Car, 5 engine upgrades !!!


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stevieturbo
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Re: Question on ignition advance for increasing RPM

Post by stevieturbo »

DaveEFI wrote:
Sat Feb 13, 2021 10:49 am

I must admit to being surprised you could improve the spark quality from EDIS.
I'd be very surprised if they couldn't. As you say it is old, it is wasted spark etc etc.

Modern stuff is just far above older stuff. Now whether many will need or benefit from the additional spark energy is another matter. I'm sure all too often it's more about retaining a good spark over say 50,000 miles with long plug change intervals, than any actual performance gain with new plugs.
So would a user ever feel the difference on milder setups ? probably not. If you're running say 30, 40, 50psi boost....probably yes. That said, I have run some OEM coils to close to 40psi without issue. I know all wouldn't do it, but some will.

I'm sure I posted this before, but it is a test of various modern coils, and even with them there is a huge variation in spark power. And that's not getting into OEM vs aftermarket replacements, which will almost always be much lower quality than the OEM version. Even if they claim to be the same manufacturer ( and I've had first hand experience of this )

Can't seem to find any tests of spark energy on the EDIS setups though.


9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0

stevieturbo
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Re: Question on ignition advance for increasing RPM

Post by stevieturbo »

And a comparison between proper coils...and copies.

9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0

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