For most of us at least, when it comes to ignition systems, as long as we are getting spark in all eight cylinders and the engine isn't popping and missing, we're usually pretty happy. Maybe we'll hook up a timing light every now and then just to make sure the engine timing is still at least close where the engine builder said to put it, but that is probably about it.
Honestly, the problem with ignition systems is it can be tough to tell what effect any changes you make will have on your engine's performance. And as a result, most racers feel that their time is better served dialing in the perfect suspension set up or experimenting with spring pressures. As long as the engine is still running when the checkered flag flies, that's probably good enough as far as the ignition system goes.
Of course, we're not saying that you need to be changing the ignition advance between the hot laps and the feature. Once the ignition is operating at peak efficiency, it should be left alone. But there are some interesting things going on with the leading race engine builders when it comes to optimizing ignition systems that you can benefit from.
Recently, we had the opportunity to sit in on an R&D session at race engine builder Keith Dorton's Automotive Specialists facilities. Dorton is so serious about maximizing ignition system efficiency that he has invested in equipment that allows him to track the ignition timing in all eight cylinders individually during the course of a kind of pull. This allows him to see how the timing varies by as little as a tenth of one degree both as the rpm changes and from one cylinder to the next.
After the racetrack, few things are as much fun as a day spent testing on the dyno. Engine
1 During the tests Keith Dorton manned the controls at the dyno while his son, Jeff, logg
2 Data is collected thanks to a system that matches up date from a crank trigger (shown)
So, for example, if one cylinder is firing earlier than the rest, that cylinder can go into detonation. As a result, the engine builder may pull back on the ignition timing of the engine as a whole instead of looking at that particular cylinder. As a result, the racer misses out on potential horsepower because of a Band-Aid fix.
Another scenario happens when ignition timing fluctuates across the rpm range. When this happens, you may set your timing correctly for a particular rpm and think that you are good to go, but the timing can actually vary all throughout much of the rest of the rpm range.
Dorton's ignition timing equipment is still fairly new, and there is lots that we want to dig into and test in the future. But for now, we just wanted to take a look at how the consistency of ignition timing can vary with different types of technologies. For his own testing, Dorton had gathered a wide range of distributors from Crane as well as two different ignition boxes. The longtime engine builder has done some very extensive testing and the results should show up in his engines in the very near future, but he did allow us to share some of his most basic findings--which were still pretty advanced by our standards.
Dorton began by choosing three Crane ignitions for testing. On the high end were two of Crane's Oval Track Pro Race distributors. These units are the ones Dorton normally uses in his Pro Cup and NASCAR touring engines. They feature optical triggers which Crane says is the most accurate method currently available for routing the spark to the correct cylinders at the appropriate time. One distributor used a standard electrical wiring system while the second was fitted up with a high-end fiber-optic trigger interface which is supposed to be more accurate in a high-heat environment like a race car.
The Pro Race distributors utilize the latest in ignition technology and are proven as capable performers on the racetrack, but as such, they are also priced accordingly. Crane's Pro Race units can vary anywhere from $850 to $1,500 depending on the application and how you have one tricked out. So, for a more appropriate option for Saturday night racers we also grabbed a Pro Curve Billet unit as well. The Pro Curve Billet also features an optical trigger, but it can be purchased for less than $400.
In addition, we tested a Crane analog ignition box versus a newer digital box to see if digital technology has a real advantage or if it's all just marketing hype. And finally, Dorton also went to the trouble to test oversized distributor gears versus the standard units to see if removing some of the backlash can help improve the ignition timing pattern.
The test engine is Dorton's Circle Track Spec engine that is currently racing in a few different series. At 383 cubic inches, the engine is capable of 600 horsepower and except for a hydraulic roller cam, uses many of the same components found in most upper level Saturday night racing engines. The tests all took place over the course of a single day, and no changes were made to the engine during the tests except to swap out distributors and confirm proper timing.
Low vs. High End Distributors
It's a lie to call Crane's Pro Curve Billet distributor "low end. This is a high-quality distributor that Dorton says he has no qualms racing in many different classes. But for the purpose of our tests, this is the lower end, or more affordable distributor.
Then, of course, we paired it against Crane's top-of-the-line distributors. Interestingly, it did quite well, as you can see in the chart titled Distributor Comparison below. The timing was set at 36 degrees BTDC with the engine at 5,000 rpm, and the dyno pulls were from 4,000 to 8,000 rpm. Compared to either of the Pro Race distributors, the Pro Curve Billet had the most variation of timing. The lowest mark we had was 30.4 degrees and the highest was 37.4, so the timing varied across the pull by as much as 7 degrees from the highest to the lowest, but the average timing was 34.288 degrees. So, overall, this distributor lost a little timing.
In comparison, the Pro Race distributors performed almost identically. The standard electrical wiring unit had an average of 35.85 while the fiber-optic Pro Race showed an average timing mark of 36.217. We also charted the percentage each distributor was off from the 36-degree target, and while the standard Pro Race shows up a little better in that regard, we suggest you don't put too much into it. The difference is tenths of one percent, which is negligible.
So while the Pro Curve Billet expectedly didn't hold the ignition timing across all eight cylinders as precisely as the Pro Race units, we don't think this shows the Pro Curve unit isn't a quality race piece. On the dyno, the power curves were practically identical. But Dorton cautioned us to remember that these are identical conditions with brand-new distributors. Racing doesn't take place in a dyno room. And Dorton says that for professional racers he trusts the ultra-high construction quality of the Pro Race distributors to hold their high tolerances despite heat, vibration, shocks, and general abuse that they will see in a race car over a season or more of racing.
3 Timing was set at 36 degrees BTDC with the engine running at 5,000 rpm. Dorton recomme
4 To minimize variables for the test, Jeff and Keith Dorton worked with Crane to have a
5 Although Crane’s Pro Curve Billet distributor was the least expensive in our tests, it