50truck Posted March 21, 2012 Report Share Posted March 21, 2012 What is the amount of volts being pushed out of a stock GM 602 crate HEI Coil? Also what is the most effective way to boost it up? Link to comment Share on other sites More sharing options...
50truck Posted March 21, 2012 Author Report Share Posted March 21, 2012 Also whats the best MSD ignition system to help the situation? Link to comment Share on other sites More sharing options...
JamesHigdon Posted March 21, 2012 Report Share Posted March 21, 2012 If it's a stock ACDelco in cap HEI coil they typically produce in the low 20K volt range at normal operating temp and drop off as distributor temps get higher. There are two “problems” with HEI ignitions when you start using them in high-performance applications and making the best system addresses both of those issues. Heat is any high-output electrical systems enemy. As the coil and module heat up less of the systems total available amperage and voltage make it to the spark plugs. The first thing to start causing problems in an HEI system is almost always the module. A factory GM module uses the distributor body as a heat sync and the higher oil temps of a high-output motor along with a high performance in cap coil will quickly put a stock module out of its operating range. The two solutions to the problem are a circuit board style in-cap module (MSD 83647 as an example) or an external MSD box such as the 6AL. Any heat you can draw out of the distributor is good and if rules allow the best external box you can afford is the best choice. The second problem is the in-cap coil. Again, as an electrical system gains heat it loses potential to produce electrical energy. Most aftermarket coils rated around 50K volts only actually produce 25 to 30K volts at normal in-distributor operating temps. MSD offers an HEI cap (8401) to relocate the coil to an external location where you can allow outside air to move over it and keep it cool and producing maximum output. The MSD 85001 kit offers all the parts you need to do both conversions as well as a good coil and a 6al box at right around $315, I’ve been using one (with a blaster 2 canister coil) on my high performance daily-driver/tow vehicle/drag racer/auto-crosser for close to a decade now and have never had a single complaint save for the need to replace caps and rotors roughly every 10 to 15K miles (at $45 for both). Link to comment Share on other sites More sharing options...
1-Crew Posted March 22, 2012 Report Share Posted March 22, 2012 The quickest, most effective "bang for the buck" in increasing coil output is to run an alternator. The coil is functioning as a step up transformer with a fixed turns ratio that determines the final output potential. Assume the typical output is in 25kV for a 12V input, if you increase the system voltage to 13.8 (nominal regulator setting), the increase in output is proportional - 13% or ~3 kV. This will be true for aftermarket systems as well, and maybe even more important for MSD style systems as they tend to draw much more current than the stock HEI. Link to comment Share on other sites More sharing options...
50truck Posted March 22, 2012 Author Report Share Posted March 22, 2012 Right now im running a regular alternator putting out that voltage. I was wondering what the easiest way to put more volts out of the coil keeping the HEI system. Run a MSD ignition system or run a different coil? Link to comment Share on other sites More sharing options...
50truck Posted March 22, 2012 Author Report Share Posted March 22, 2012 Also the HEI im running is the STOCK 602 crate. Whats the best way to boost it up? Link to comment Share on other sites More sharing options...
jwmbishop Posted March 22, 2012 Report Share Posted March 22, 2012 Mr Higdon explained it well... His approach was direct answer to the OUT question. There are only three aspects. Volts in, volts thru and volts out. Increasing volts in and making sure you are not losing volts through (he explained that part) will guarantee higher volts out! Link to comment Share on other sites More sharing options...
50truck Posted March 23, 2012 Author Report Share Posted March 23, 2012 Alright, Thanks! Link to comment Share on other sites More sharing options...
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