Distributor Belt Drive Versus Coil-On-Plug In LS Racing Applications

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There’s one thing you can never have too much of in a racing engine, and that’s spark energy. Without the power to light your air/fuel mixture on fire, you’ll be going nowhere fast, and can in fact encounter many other issues as a result.

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Our 9.5:1-compression LSX small block is motivated by a gear-driven ProCharger F-1X supercharger and a host of other go-fast goodies.

When we built the 388 cubic inch supercharged engine for Project BlownZ, we realized that we had a choice – stick with the factory-style coil-on-plug ignition, or “go backwards” and make use of a distributor to distribute the spark energy.

After discussions with MSD Performance and Jesel Valvetrain Innovation, the decision was made to use an MSD Power Grid ignition system with MSD 8-Plus box, a crank trigger to fire the coil, and a Jesel belt-drive distributor to ensure the spark energy is properly distributed.

Now you’re asking “Why go backwards? That makes no sense when you can have a separate coil for each cylinder!” and we’re here to explain our reasoning, along with the thoughts of MSD’s Erik Brock and Jesel’s Bob McDonald.

We combined the Power Grid timing controller with an MSD-8 Plus ignition box and Advanced RPM Control to ensure that we have enough spark to light the boosted air/fuel mixture from the starting line to the finish line.

We combined the Power Grid timing controller with an MSD-8 Plus ignition box and Advanced RPM Control to ensure that we have enough spark to light the boosted air/fuel mixture from the starting line to the finish line. 

 

With a big coil, you’ve got plenty of spark energy even at 14,000 RPM. – Erik Brock, MSD Performance

“The OE’s went to coil-on-plug ignition for a number of reasons, specifically emissions-related performance – you can do a huge timing swing with the individual coils. They can go from 40 degrees of timing to 5 degrees of timing without running into rotor phasing issues, where with a distributor you just can’t do that. Also, if you have one coil that fires every 180 degrees, that coil can essentially get a full charge, even at higher RPM. But when you’re talking about a race vehicle, you’re not going to run into that problem because you have an ignition that’s capable of firing at higher RPM.  When it comes time to troubleshoot, and you’ve got an issue, you’ve got one coil and ignition source to look at versus multiple sources. This is why I wouldn’t use a coil-on-plug ignition in a race application,” says Brock.

MSD's Multiple Spark Coils

Upgrading the coil-on-plug design can be an advantage over a stock-style coil for a racing application that’s not as extreme as ours.

“We offer our LS coils, which offer a higher output than stock coils and differ from the stock coil pack in that they are a multi-spark design at low RPM as well,” Brock explains.

MSD’s Multiple Spark Plug coils for LS engines are sold under three part numbers [PN 82858, 82868, and 82878, each a set of 8] that replace most LS engine coils found in factory applications since 1999 – check out the MSD website to identify the correct coil for your application. The increased spark energy and multi-spark capabilities of these coils help to improve the combustion process and achieve a more complete burn of the mixture in the cylinder, much like MSD’s traditional ignition boxes.

As MSD is in the business of producing coil-on-plug coil-packs, it’s interesting to note that this is Brock’s preference, but when you are talking about serious racing engines like the one in BlownZ, he has a valid point. There are limitations to the coil-on-plug design. 

“You’re not going to get the same amount of spark energy with a typical coil-on-plug system. You could run an eight-channel capacitive-discharge ignition box and eight large coils, and you’re going to get plenty of spark, but I don’t think you’re going to get any more than you would with a large coil and a good box. The spark energy performance is all about the copper, and there is much more copper in a traditional coil like our HVC-II coil that’s used typically when compared to the COP-style coil,” he says.

There are a number of advantages to using this package in our application. “The Power Grid allows you to make changes and do things downtrack that no other ignition does. Back in the day, our Digital 7 was the hot ticket, and even today, some people swear by it. But there were a few things that the Digital 7 was missing and a few things that it needed to do differently, and the Power Grid system gives you those capabilities,” explains Brock.

Those features have been designed right into the Power Grid timing controller – no matter which of MSD’s ignition boxes you are using, taking advantage of these features is a wise choice. He continued, “It has rev limit features, timing features, and expansion capabilities that nothing else on the market has – you can plug in a boost controller, or traction control if you’re racing in a class where that’s legal – it all integrates into the Power Grid and uses the same software. On top of that, you can pull everything from a single place including Racepak data, which integrates seamlessly with the Power Grid,” says Brock.

By separating the timing computer [PN 7730] from the available ignition controller [PN 7720] with the Power Grid design as opposed to the more-traditional 7-Series programmable ignition, you can use some of MSD’s various components like a Pro Mag, or an 8-Plus ignition box like we have to piggyback with the 7730 and gain the timing control over your engine without having to buy the ignition controller – it all retrofits and permits you the use of the 7720’s 32-bit micro controller to use with your existing ignition box.

MSD's Power Grid controller [PN 7730] offers a wide range of timing controls, individual cylinder timing, and the ability to interface with our Racepak datalogger.

MSD’s Power Grid controller [PN 7730] offers a wide range of timing controls, individual cylinder timing, and the ability to interface with our Racepak datalogger.

MSD’s View software is Windows-based and is designed with tabs, much like an internet browser, to allow the racer to easily select the different programming windows to adjust parameters. The box permits timing adjustment based on engine RPM and gear value, along with advanced individual cylinder timing based on gear or time. Five nitrous retard stages are built in, while there are four RPM step limits for burnout, spool, launch and overrev. MSD has also seen fit to include an output switch that can be set on RPM, pressure, or time, and there are shift light settings for each gear programmable through the software. Basically, the Power Grid timing controller is a do-it-all box that really does do it all. 

Here's an example of how we're using the Launch Retard function through MSD's View software. We're pulling out 2 degrees of ignition timing within .1-second, and ramping it back in starting at .4-second so that it's all back into the program by 2 seconds into the run. This helps to kill a tiny bit of power at the hit to ensure the tires hook up.

Here’s an example of how you could use the Launch Retard function through MSD’s View software. Here we demonstrate pulling out 2 degrees of ignition timing within .1-second, and ramping it back in starting at .4-second so that it’s all back into the program by 2 seconds into the run. This helps to kill power at the hit to ensure the tires hook up.

Our application requires the use of one of MSD’s 8-Plus Ignition Controls for the extreme spark energy it produces. The capacitive-discharge ignition box has 315-345 Millijoules of spark output and draws 36 amps of electricity at 12,000 RPM. Spark series duration is 20-degrees of crankshaft rotation.

The 8-Plus does include a pair of rev limiters, although we’re using the ones in the 7730 box to control our limits. As is the case with all MSD ignitions, there is a tachometer signal output that will trigger a tachometer, shift light, or other RPM add-on devices.

The 7730 timing computer has the ability to datalog via this microSD card.

The 7730 timing computer has the ability to datalog via this microSD card.

The analog circuitry within the 8-Plus is race-proven and has served us well with Blown Z so far, as we’ve been able to run a 7.35 at 189.2 mph with it earlier this year, earning the title of “Quickest Magazine Project Car” in the process.

You can use one of MSD’s crank triggers for this application, which is one of the most accurate way possible to trigger the ignition to fire properly. MSD embeds magnets in the trigger wheel that are combined with the non-magnetic pickup system to prevent the Flying Magnet system from false triggering, enabling you to maintain timing control throughout the run. The Flying Magnet will trigger all MSD 6, 7, 8, and 10-series ignitions and all of MSD’s timing accessories. Though for our application, we used an ATI balancer with the embedded magnets to eliminate the need of an additional trigger wheel.

We've also got one of MSD's HVC-II coils mounted to the motor plate. This coil's U-core winding design and low primary resistance help to produce high voltage output and current.

We’ve also got one of MSD’s HVC-II coils mounted to the motor plate. This coil’s U-core winding design and low primary resistance help to produce high voltage output and current.

“Triggering the ignition at the crank gives you rock-steady measurements and allows the distributor to do one thing and one thing only – distribute the spark, instead of leaving it in control of the triggering as well. When you make a timing adjustment, it’s all done within the Power Grid 7730 and everything stays exactly as you set it since there are no physical adjustments on the engine,” explains Brock.

Belt Drive Distributor

Jesel's belt-driven distributor comes with a mounting plate that seamlessly integrates with our Jesel camshaft belt drive and is actuated through a 3mm cog-style belt.

Jesel’s belt-driven distributor comes with a mounting plate that seamlessly integrates with our Jesel camshaft belt drive and is actuated through a 3mm cog-style belt.

The last piece of our ignition puzzle came from Jesel and is one of their Belt Driven Distributor systems, which bolts on to the camshaft belt drive we have. It’s a direct bolt-on that solves a number of problems, most importantly eliminating timing inaccuracies that can occur due to camshaft deflection – along with providing a distributor for an LS application that never had one from the factory.

By driving the distributor directly from the camshaft pulley, ignition timing stays constant and will not deviate from the initial settings, providing repeatability and accuracy in the place where you most need it.

The Extreme Series Belt Driven Distributor for Blown Z’s LS engine uses one of MSD’s 5-inch Pro Caps to separate the spark posts. This ensures accurate spark delivery to each cylinder regardless of what’s happening.

“This style of belt-driven distributor was originally developed for space reasons for racers who needed to get things out of the way due to large manifolds or superchargers and turbochargers. Going to the belt-drive distributor really cleans up the front of the engine. In the LS especially, there was no factory provision for the distributor to begin with, so this is an excellent solution,” says Jesel’s McDonald.

Our Extreme Series distributor hangs off the front of the engine, for an application that was never designed from the factory to use a distributor. In our case, simplicity rules!

Our Extreme Series distributor hangs off the front of the engine, for an application that was never designed from the factory to use a distributor. In our case, simplicity rules!

“There is a small pulley on the front of the camshaft that uses a 3mm belt to spin the rotor within the distributor. Boosted engines require so much ignition energy that they can arc between posts if you don’t use the larger cap in this application – these are used typically in a blown or turbocharged engine with lots of cylinder pressure and the tendency to have the spark scatter. Using our system integrates nicely with our camshaft belt-drive and provides an all-in-one solution that solves a number of problems,” says McDonald.

This combination of parts in conjunction with our ProCharged LS small-block has us running with the field in the NMCA West, PSCA and WCHRA’s 275 classes, and we’re still learning every single time out with the car. We put the car on a diet and lost nearly 200 pounds from our previous runs, so that alone will help to pick up the elapsed times – and we’ve got a new engine in the works that will have us hopefully running at the top of the field. The learning curve with a combination like this is steep, but we think we’re on the right track.

 

About the author

Jason Reiss

Jason draws on over 15 years of experience in the automotive publishing industry, and collaborates with many of the industry's movers and shakers to create compelling technical articles and high-quality race coverage.
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