HEI vs MSD comparison

Electrical and Ignition

  1. kc0r8y

    kc0r8y Well-Known Member

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    Before I pull the trigger on a HEI setup for my SB Dart I wanted to make sure I'm not overlooking something.

    What am I losing and/or gaining by going HEI over MSD.

    Thank you.
     
  2. Hellrats

    Hellrats Just another dumbass FABO Gold Member

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    I run HEI on everything now. MSD works great but it's pricey. I have a GM HEI module hidden under the distributor. Check this link out Mopar HEI Conversion I'm sure the purest will jump on me because it's not a MOPAR part but believe me after you make the switch you'll never go back to the old Chrysler box :) I left the old module on the firewall for looks and no one knows the difference. I just cut the back of the ballast resistor out and put a piece of wire in there instead. Nice thing is you can go to any parts store an get everything you need. I used this same setup on Fords too. Works great. Just make sure you get a HEI coil.
     
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    • kc0r8y

      kc0r8y Well-Known Member

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      I have no worries about that, I'm looking for performance, cost and minimal hassle.
       
      Last edited: Jan 28, 2018
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      • BillGrissom

        BillGrissom Well-Known Member

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        Many youtubes showing the spark from various ignition controllers. That is in air (not high cylinder pressure) and doesn't always account for dwell vs rpm (less coil charge-up time. Still, the most powerful spark is surely from a single coil per plug which most/all current engines have (even 2 plugs per cyl like new Hemi). Among those, retro guys mostly retrofit GM LS coils (see megasquirt site). But, a single coil and distributor is certainly fine, and Mopar used that thru ~2002 (Magnum engines).

        The coil is probably more important, so use an e-core type as did the big-three by the late 1980's. You can't do much more than fully charge-up the coil between sparks, which the GM HEI did (auto-dwell control) as did Ford (TFI) and Mopar (inside PCM) so not sure how MSD could do better. But, their namesake is "multi-spark" and perhaps there is value in that (Pertronix Ignitor III also has), but the big-three didn't think so or perhaps wouldn't pay royalties. Other advantages of MSD and Ignitor III are rev control.

        If you go GM HEI, their 8-pin module is best (85-95 "small cap" distributor). Grab their cable & coil for easy plug n play. Also snip off the pickup connector. TrailBeast sells as a kit if scared of junkyards. Try both polarities for the pickup connection to your Mopar distributor since only way works correctly.
         
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        • Mopar92

          Mopar92 Well-Known Member

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          What does HEI do for a rev limiter ?
           
        • Abodybomber

          Abodybomber Breaking street machines , since 1983.....:) Legendary Member

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          Doesnt happen.. Unless you check out MSD , Accel's adjustable 4 pin HEI modules(100 -125 U.S. Dollars ,IIRC..).
           
        • Mopar92

          Mopar92 Well-Known Member

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          That’s exactly why I went with MSD and not an HEI. I personally like a rev limiter. To me the 6AL was the simplest route.
           
        • kc0r8y

          kc0r8y Well-Known Member

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          So at the end of the day most go with MSD because of the rev limiter?

          Also does the MSD setup allow me to get rid of the ballast resistor? I know the 6AL replaces the orange box.
           
        • Mopar92

          Mopar92 Well-Known Member

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          Yes it does. No more Ballast with MSD.
           
        • 67Dart273

          67Dart273 FABO Gold Member FABO Gold Member

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          I believe someone else is marketing an HEI module with rev limiter.

          The OP does not seem to understand?? that MSD is completely different. There are two general (well there is more) types of ignition on these girls

          1...A form of Kettering.........derives from breaker points.......this is where power is supplied to the coil from the battery, and the points / electronic box switches the ground side of the coil on and off. Regardless of performance level, this type includes (by memory)

          breaker points.........Mopar breakerless, Ford breakerless, GM HEI, Pertronix, Skip White and MSD 'ready to run' setups which hook in with no "box." There are other brands

          2.....Some type of high energy discharge, IE CDI (Capacitive Discharge Ignition) of which MSD is one. MSD is "Multiple Spark Discharge). CDI works like an electronic camera photoflash, when triggered, it discharges a large charged capacitor into the coil, a "pulse." MSD does this multiple times at some RPM


          BALLAST...........Not all switched/ Kettering systems need a ballast. Tractors, generaly are an example.........the coil operates direct off the battery, they were designed for this.

          "My take" on why US car makers universally used a ballast is COLD WEATHER starting.......because during cranking, the ballast gets bypassed, and this generates a stronger spark during cranking.
          =======================================

          OP.......you need to ask yourself, "what are" my ultimate HP goals? Example, my mild 360, later 318 Dart didn't need anything like MSD. I used a GM 4 pin module, triggered by the Mopar dist. firing a factory Mopar coil with no ballast. This combination STILL makes stronger spark than the factory ECU did
           
        • sireland67

          sireland67 FABO Gold Member FABO Gold Member

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          Pentronx makes a hei module with an adjustable rev limiter for around $70
           
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          • 67Dart273

            67Dart273 FABO Gold Member FABO Gold Member

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            ^^That may be the one I saw^^
             
          • 67 gt

            67 gt A Wog boy who loves his Mopars ! FABO Gold Member

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            Apparently with the Pertronix 3 Ready to run has the multiple spark through out the rev range and rev limiter is adjustable via module . Factory set at 5500rpm.
             
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            • rumblefish360

              rumblefish360 So close, yet so far away FABO Gold Member

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              The only thing I really like about the (basic) MSD is the multi spark that helps a good bit on low speed idle/cruise conditions as it helps clean up idle and helps the car to run smoother with increased mileage. This also shows itself on well hopped up engines.

              On the race end, everything else about the ignition is a grey area for me as I haven’t found a margin of improvements that would have me do a MSD everything over any other well sorted out and strong spark ignition system. And that is the key. Strong spark! All the way up the rpm scale your driving.

              I’m not trashing, faulting or claiming anything about or over the MSD. As a lot of what is used is also choice in what I’m doing.
               
            • Mopar92

              Mopar92 Well-Known Member

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              I still can’t belive how long it took MSD to finally come out with a dial in rev limiter. Those resistor chips are more expensive than they should be. My new 6AL is dial chip instead of a resistor chip.
               
            • AJ/FormS

              AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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              I run an 11/1 367 with a 230* cam, and a 750DP, on the big yellow Accel Super Coil. I used to use a circa 1998 Orange box. That combo went 7200 for years. I'm a streeter and only use a rev-limiter as a safety for if I miss a shift in my A833.Accuracy is not called for. So I bought a Jacob's dial-back ignition timing module. This eventually replaced my Orange box. It's a great tool for zeroing in on creating a timing curve, and also has a dial back rev limiter in it. But I haven't missed a shift now since 2004. And it really doesn't matter much, cuz my lifter preload is only .020 and adjustable.
              So, since I thought a tach might be a good idea, I finally bought a cheap one with a dial-type shift light.I set it to 7000, but I rarely get to see it, cuz, with 3.55s, 65 = 6900, in first-over,heehee.
              That light is often set to 2300,(65 =2250 in overdrive) to indicate I'm speeding, kindof like a poor-mans cruise-control. It doesn't work in the US, on the Interstate, tho; Man people fly down there. On time,I was keeping up in traffic at 85, and some people kept flying by me. Since it was a 10 hour drive, I decided to follow this shiny red Corvette, giving him some lead. Man he was boogieing! I gave the old overdrive a workout that day at 2400/2500,lol. So I had to turn the little red light off, it was kindof bothering me.
               
              Last edited: Jan 30, 2018
            • rumblefish360

              rumblefish360 So close, yet so far away FABO Gold Member

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              AJ, make a move to the Chrome box for those rpms.
               
            • cuda66273

              cuda66273 Well-Known Member

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              Here's the concerns I'm reading on this thread.....
              Voltage output.... The ignition system will only develop the amount of voltage it takes to find a ground. Ideally this will be from the electrode to the ground strap. If resistance is too high for example, it may find ground to some other location, it may jump to ground at the boot (If plug gap is too wide) arch to the block etc. A naturally aspirated 4 stroke engine will only require 12-18KV at idle with low cylinder pressure and maybe as high as 34-36KV at WOT at 6-7,000 RPM. My Small block with 14:1 compression under full load at 6800 RPM showed a draw of 34KV through the traps. So having a 60,000V coil doesn't mean much unless your building huge cylinder pressures in 3000-10,000 PSI range (naturally aspirated street engines are in the 2200-2800 range) . The HRR688 ECU can easily maintain a load of 44KV for 4 hours at 6800 RPM as tested.

              Dependability.... Even a PTX 3 Module which is probably the best one available carry's a 30 Months (2.5 years) warranty, most carry 30-90 days, the HRR688 ECU has a 5 Year Warranty. We use probably 8-10 of the PTX modules a month in our shop. We experience about a 2% failure rate within the warranty period. The HRR688 ECU has a .0005% failure rate after 6 years of production. The new Chinese made MSD boxes warranty rate is not known for sure as won't tell you but from our experience I can only guess that it's one of the highest in this industry.

              Wiring Issues.... None, the HRR688 is a plug and play 20 minute installation with the stock wiring harness. No wire cutting and splicing and mounts in the factory holes, direct replacement for a stock ECU.

              Technology.... REV limiters are obviously important to protect your investment from catastrophic failures, the HRR688 ECU has an externally adjustable, algorithm, dead stop, dial type REV Limiter 5200 to 7000 in 200 RPM increments.
              The HRR688 uses two microprocessors to insure absolute accurate timing events from crank to 7000 RPM with a minimal .8 Nanosecond slew rate. Transistorized ECU's have on average a 1.5 Millisecond slew rate which causes the timing to retard as the RPM and load builds. Most HEI modules have a slew rate of about 1 Millisecond which is better than any stock type transistorized Mopar ECU no matter what color it might be, what they claim or what they try and lead you to believe.

              Multi-Spark.... If your engine combination is good and the motor is built correctly for the application a multi spark unit is probably not going to make any difference in how your engine performs. Race engines are obviously a different animal and will benefit from a multi spark controller. Inductive ignition systems have a longer burn time but are limited to about 7,000 rpm. Time is required to allow the coil to soak to give that one hit, longer burn time. This why we always state after 7000rpm you need to use a CD ignition, but CD Ignitions on a street car are really overkill and not needed.

              Cost.... The HEI conversion, mounting plate, module, wiring adapters, coil and rev limiter will push you close to the $300 range, warranty? Tech support?. MSD 6al with coil will reduce your bank balance by about $350 with a 1 year warranty, and of course their super tech support? The HRR688 will set you back $219.00 with a 5 year warranty, includes the Advance limiter plate to set your distributor up correctly, and tech support that many here will tell you is unsurpassed.

              You can spend thousands on some awesome ignition system with features that you will probably never use and it won't make you car run much better. The ignition system is a system and is made up several components, each one must be balanced and designed to work together as a System. The distributor is one of those major components, as much or more attention needs to be directed at it as the ignition controller itself for perfect results. A $2000 ignition box will never be able to overcome incorrect timing events. Don't just do 1/2 the job.
               
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