Corvette Performance Distributor's "Hi-Voltage" Coil Kit, 1985-1991
09-25-2018, 04:14 PM
#1
Melting Slicks
Thread Starter
Corvette Performance Distributor's "Hi-Voltage" Coil Kit, 1985-1991
I saw this at Ecklers today and wondered if anyone else has installed this and what kind of performance improvements if any one can expect:
Corvette Performance Distributor's "Hi-Voltage" Coil Kit, 1985-1991
Would you also need to upgrade the ICM?
Corvette Performance Distributor's "Hi-Voltage" Coil Kit, 1985-1991
Would you also need to upgrade the ICM?
09-26-2018, 11:21 AM
#2
Safety Car
I have that same Ignition setup on my 1988 C4 and after testing it "before and after" with a GTECH PRO I saw NO significant difference in horsepower or torque after the installation of the "Davis Unified Ignition" coil setup.
The ad claims to be able to make incredible voltages at much higher RPM's than the factory unit could, but does a L98 really need that much spark? What I thought was interesting was that they do not replace the Distributor Ignition Module in the distributor. It is simply a cap, rotor and new coil. On my car I did not replace the "Distributor Ignition Module" inside the distributor or the ICM on my 1988 C4 with a stock engine. I suspect that a hotter aftermarket Distributor Ignition Module might help in making extra horsepower that people expect from an expensive coil setup.
A hotter spark is really necessary when you have high compression or a forced induction system. In the past I have installed Higher Voltage Coils from MSD on another Chevrolet and I ended up getting Carbon tracking inside the distributor cap which makes the engine miss until you replace the cap again.
I hope that this helps you a bit. This has been my personal experience, I like verifying results from upgrades and the GTECH is very accurate way of doing this for us.
The ad claims to be able to make incredible voltages at much higher RPM's than the factory unit could, but does a L98 really need that much spark? What I thought was interesting was that they do not replace the Distributor Ignition Module in the distributor. It is simply a cap, rotor and new coil. On my car I did not replace the "Distributor Ignition Module" inside the distributor or the ICM on my 1988 C4 with a stock engine. I suspect that a hotter aftermarket Distributor Ignition Module might help in making extra horsepower that people expect from an expensive coil setup.
A hotter spark is really necessary when you have high compression or a forced induction system. In the past I have installed Higher Voltage Coils from MSD on another Chevrolet and I ended up getting Carbon tracking inside the distributor cap which makes the engine miss until you replace the cap again.
I hope that this helps you a bit. This has been my personal experience, I like verifying results from upgrades and the GTECH is very accurate way of doing this for us.
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09-26-2018, 11:52 AM
#3
Team Owner
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C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
You're not going to get any gains from that stuff.
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BlowerWorks (09-26-2018)
09-26-2018, 02:54 PM
#4
Melting Slicks
Thread Starter
Thanks for the great post
I have that same Ignition setup on my 1988 C4 and after testing it "before and after" with a GTECH PRO I saw NO significant difference in horsepower or torque after the installation of the "Davis Unified Ignition" coil setup.
The ad claims to be able to make incredible voltages at much higher RPM's than the factory unit could, but does a L98 really need that much spark? What I thought was interesting was that they do not replace the Distributor Ignition Module in the distributor. It is simply a cap, rotor and new coil. On my car I did not replace the "Distributor Ignition Module" inside the distributor or the ICM on my 1988 C4 with a stock engine. I suspect that a hotter aftermarket Distributor Ignition Module might help in making extra horsepower that people expect from an expensive coil setup.
A hotter spark is really necessary when you have high compression or a forced induction system. In the past I have installed Higher Voltage Coils from MSD on another Chevrolet and I ended up getting Carbon tracking inside the distributor cap which makes the engine miss until you replace the cap again.
I hope that this helps you a bit. This has been my personal experience, I like verifying results from upgrades and the GTECH is very accurate way of doing this for us.
The ad claims to be able to make incredible voltages at much higher RPM's than the factory unit could, but does a L98 really need that much spark? What I thought was interesting was that they do not replace the Distributor Ignition Module in the distributor. It is simply a cap, rotor and new coil. On my car I did not replace the "Distributor Ignition Module" inside the distributor or the ICM on my 1988 C4 with a stock engine. I suspect that a hotter aftermarket Distributor Ignition Module might help in making extra horsepower that people expect from an expensive coil setup.
A hotter spark is really necessary when you have high compression or a forced induction system. In the past I have installed Higher Voltage Coils from MSD on another Chevrolet and I ended up getting Carbon tracking inside the distributor cap which makes the engine miss until you replace the cap again.
I hope that this helps you a bit. This has been my personal experience, I like verifying results from upgrades and the GTECH is very accurate way of doing this for us.
09-27-2018, 01:47 PM
#7
with Vader86 !!!Voltage will rise only as high as required to jump plug gap - stock engine with stock gap the stock coil etc. is plenty !
Last edited by BlowerWorks; 09-27-2018 at 01:49 PM. Reason: add to whom
09-27-2018, 07:12 PM
#8
Tech Contributor
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Correct! And as the RPM climbs to the higher regions, the cylinder volumetric efficiency keeps dropping, reducing cylinder pressure and the required coil voltage necessary to jump the spark plug gap.
09-27-2018, 09:42 PM
#9
Team Owner
Depends. If I am selling that item, you bet I will paint a rosy scenario where you gain 20HP. OTOH, I'm not selling it so I agree with you with the stipulation that I will disagree as and when my company decides we are selling it and I am on duty.
09-28-2018, 06:24 AM
#10
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St. Jude Donor '05
Most bolt ons dont do anything except make you poor. Dig into the engine...intake, exhaust, cam/heads as usuall theres your power.
It only takes x amount of spark to light that fuel mixture off, more isnt better. HEI is a good ignition setup.
It only takes x amount of spark to light that fuel mixture off, more isnt better. HEI is a good ignition setup.
09-28-2018, 07:05 AM
#11
Team Owner
What they did is sell you some hope that you can do something good for little money. The placebo effect goes the rest of the way
09-28-2018, 11:06 AM
#12
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I had a similar setup from Hyper-Tech on my prior '88. Also I opened up the cut-back electrodes to a wider gap. Then came the low resistance wire set.
This "mod" won't do much at low-medium RPM but matters if you work the intake and up the shift points to the 6k RPM range, which I had done. Our OEM distributors drop off in the 4,500-5k RPM range since the engine is designed to be a low-mid range mule.
Since you're having "issues" with the OEM setup, you might install a new OEM wire set next time you replace the cap.
This "mod" won't do much at low-medium RPM but matters if you work the intake and up the shift points to the 6k RPM range, which I had done. Our OEM distributors drop off in the 4,500-5k RPM range since the engine is designed to be a low-mid range mule.
Since you're having "issues" with the OEM setup, you might install a new OEM wire set next time you replace the cap.
09-28-2018, 11:25 AM
#13
On a stock HEI ignition the coil is fired with battery voltage. As the engine RPM goes up there is less and less time to 'charge' the coil which is why the spark falls off at high RPM. The solution is to raise the voltage used to fire/charge the coil. CDI systems like the MSD, Crane, Mallory etc. fix this by using a power inverter that raises the 12vdc to maybe 400 or more vdc. Stereo power amps do the same thing which is how you get a 100 watts or more from 12 vdc. With 400 vdc the coil has no problem charging up at 6K or more engine RPM.
09-28-2018, 03:02 PM
#14
Le Mans Master
Its also a good idea to shim your distributor for racing.. Shim it to around .012 to .015 to stop spark scatter..WW
09-28-2018, 10:47 PM
#15
Le Mans Master
I'm going to be honest, I'd bet even at 7k on a 10:1 engine you wouldn't even be able to measure a difference between points and the best aftermarket system. Theres merit on some really insane systems sure, but anything you'd even think about putting on the street it isn't even necessary imo. Prove me wrong but I've seen some crazy setups on points and HEI... just stock units bolted on. Just my opinion.