distributor vs distributorless

[AZGhost623]

With the high end distributor like 123Ignition thats fully tunable, how does it compare to those who have gone the route with a crank fired ignition with no distributor? Is the 123 just as good as someone running without? Has anyone seen any comparable "vs" of these new systems pitted against each other?

[Six_Shooter]

I haven't used that particular dizzy, but when I went from a modified 280Z dizzy to a DIS system with no other changes the difference was night and day. Smoother idle, smoother acceleration, just overall improvement in running with the DIS over the dizzy.

 

I am running a Delco (GM) ECM, that was originally set-up for dizzy (The code I'm running was never used with DIS from the factory), a few changes to the code parameters and a proper mechanical set-up using a custom trigger wheel and a coil pack that would be found on many GM V6 cars, like the Cavalier '96+ Malibu, etc, and the DIS was a vast improvement.

[randy 77zt]

The problem  is mechanical slop between the crank gear and the oil pump drive gear.Usually a home gamer will look at the gears and say they look good enough.But since this is old car stuff(hard to get) you run with the parts you have.You probably will end up with 3-5 degrees slop in the gears + possably some slop with the dizzy/oil pump drive shaft.A race engine builder will replace these parts if running a distributor.If the engine is turbo/supercharged you need a  computor to tune the engine on boost.The only error with a computorized set up would be if you didnt use a dial indicator to find true tdc and set up a hioghly accurate tdc mark for checking ignition timing after your efi install

[Tony D]

Crankfire or COP really only makes a measurable benefit if you have an EMS that integrates it. If you are running carbs, chances are good you wouldn't ever encounter a situation where the plugs need the extra juice a COP system can provide because of all the available charge time. The DIS can fire off some horribly tuned fueling, and so everything seems much better after install...but that was more a function of just being able to get it lit. Big enough single coil or CDI and that can happen with a single as well.

 

You give no specific application, so there's really no way to answer it that "yes, maybe, no" -- for the build on the signature if that XDI is similar to HPV then I wouldn't change if it's working.

[johnc]

I ran a distributor on my race engine as the trigger for a Motec M48 EMS. Mechanical timing was straight up with no mechanical advance, all timing was controlled by the EMS. New bronze gear on the crank, new steel gear on the distributor drive shaft.

 

Getting rid of the mechanical advance mechanism and running a good EMS solves all distributor timing scatter issues below 8,500 rpm based on my experience.

 

I did have a dist shaft breakage issue but I fixed that with some brass shim stock.

[AZGhost623]

You give no specific application, so there's really no way to answer it that "yes, maybe, no" -- for the build on the signature if that XDI is similar to HPV then I wouldn't change if it's working.

 

Yes, just in general...I do run the XDI setup, and it works awesome. However, I got into a debate with someone who thinks the latest technology is now on par with distributorless system setup.  Like you say with a proper EMS setup then the COP system is still the way to go. The 123Ignition system seems to just solve part of the equation or a valid solution for those running carbs.

[Tony D]

As John Says "Below 8500" -- even Electromotive allowed triggering off a distributor driven wheel up to that point. And we were fine with our L28 running that setup.

But when we went L20A and were going....uh... "Above 8,500" we started experiencing misfires using the distributor trigger. It was not from the 'slop' per-se but more of a Pulsweidth/Waveform issue as the resolution was not sufficient for even the superfine diameter Mag Pickup we used. By going off the crank the bigger wheel gave better resolution. By notching the flywheel on it's  outer diameter would would likely have gotten even better!

 

For guys looking for a rebuilt distributor...why buy the 257$ Autozone reman, when for about $500 you can get a totally NEW distributor, proper bearings, and programmable spark if you so desire? Really if $200 is that big a deal in your build that you can't wait to raise that money (ESPECIALLY if you have triples!) you should reconsider the choice of hobbies! A distributor recurve really helps on triples for sure. This is something (the 123) that you can make a run, change, make a run, change.... try THAT with Mechanical Weights! It's the same process, but unless you precut your  weight selection and have a spare dizzy to swap while still strapped down to the dyno...it takes a lot longer!

[winstonusmc]

I know some engines went to COP or DIS to have less dwell issues with a single coil at high RPMs. V8s have to start pulling back dwell at higher rpms so that coil isn't firing into the next plug wire. A single coil needs 3-5ms dwell. At 6000rpm, a V8 fire the coil every 5ms. With coil on plug, its every 20ms. This gives much more time for the coil to recharge. I was also reading a hotter spark will resist fouling as well.

[Tony D]

Yes, that is the key to COP, your coil saturation time...exactly as stated.

 

If you investigate the Z31 ECU Box logic for coil triggering it switches from "off - on - off" around 6200 rpms to a continuous "on" with off pulses. The spark from that box degrades above 6,200 on the single coil. You will notice the NISMO vehicles using single coils ran the Bosch Coil P/N used on the Porsche 930 Turbos. Highest Energy, and an extremely fast saturation time....what you need when running high rpms, single coil.

 

Mind you that the spark demands on Turbo Cars drive the COP decision far more than on N/A engines which have CONSIDERABLY lower flashover voltage requirements than the Turbo Combustion process demands.

 

In fact, even on the Electramotive TEC2 there was sensing circuitry to know discharge voltage/amperage of the previous firing cycle, and active management of coil saturation even on multiple coil setups. This could mean the difference between your ignition system drawing 5-9A as opposed to 15-20A from coil overcharging.

 

I don't want to oversimplify the ignition system....but for the street, a lot of this stuff in the OEM Market was driven by emissions requirements that just happens to have a performance payout as well. To a point the single coil is simple, reliable, and more than robust enough to handle pretty radical N/A builds, and even Turbo Builds if you keep it below 6,500 (930 Turbo as no slouch!)

 

For 85-90% of the guys out there that's really going to be all they really "need"....

 

Get into stuff like TimZ or JeffP cranking out 200HP/Litre+ with forced induction???and JeffP can tell you all about how a single coil falls short. Even in Japan in the 80's, they were running triple conventional coils off a distributor gear driven trigger. The trigger really isn't the issue, if you can get the resolution. The 123 is Optical (as was the ZXCAS 82/83 on) so the trigger resolution may well be sufficient to about 12,000 rpms (6,000 rpm trigger speed) in that environment, with current electronics.

 

Remember the Z32 CAS is camshaft mounted, optical trigger firing COP! Not much different from a distributor trigger firing COP there in terms of slop and jumping about.

 

The coil saturation and wether you need it is the first question to ask... If you're magnetic/hall sensor then likely a crank trigger of large diameter will help if you are going above 8,500. For an optical, a half-speed drive from distributor or camshaft seems to trigger them just fine to 12,000 rpms. Trigger selection seems to bias towards optical since the triggering is more precise to higher rpms with smaller diameters making retrofit easier.

 

I digress, and ramble extensively....

Edited July 8, 2014 by Tony D