BangShift.com is proud to announce that we have partnered with Westech Performance Group to bring you killer engine tech in 2011! From the complicated to the just plain fun, we’ll have it all right here at BangShift.com, so stay tuned for more. We started off with two solid days on the Superflow Dyno, along with our pal Steve “Lightning Lash” Brule, and were able to knock out 7 tests your are going to want to see. This particular tech story is about using programmable timing systems to tune your car on the drag strip. This applies to street strip guys all the way up to Pro Stock. The turbo guys have been doing it with boost control for years, but the naturally aspirated guys have always seemed to struggle with actually pulling out the laptop. You will struggle no more my friends.
Our test engine is a Dart 372 SHP short block topped with AFR CNC 195cc L98 heads. The little stroker motor has 10.5:1 compression, a Comp Cams Extreme Energy XR294 Hydraulic Roller and valvetrain, 1 3/4 inch Hooker dyno headers, TCI Rattler balancer, a Milodon Oil Pan, and MSD Digital 7 Ignition. For this test it was outfitted with a Holley Strip Dominator intake and an 850 Street HP Holley Carb. In this configuration the little bastard makes 535 horsepower and 481lb. ft. of torque. In two days of testing we made almost 50 pulls and this combo never skipped a beat. It would make a typical 3500 lb muscle car a riot to drive. Oh, and did I mention we sprayed a 200 shot through it too. You’ll have to wait for that test.
Our goal in this first test was to show how ignition timing affects the power curve and how you can use this information to make your car quicker and more consistent on the drag strip. For you street car guys, don’t think this is a race only story. It is in fact aimed directly at you. With just a few mouse clicks you can have more fun and be quicker at your local track thanks to a programmable ignition like the Digital 7 we used from MSD. No more smoking the street tires at the hit of the throttle. No more pedaling and looking like a rookie. A programmable ignition system can make you look like a hero. The cool guys are doing it, why aren’t you?
We all know that connecting your laptop to your programmable ignition system can be an intimidating task. It shouldn’t be. With MSD’s line of programmable ignitions, you can be the next Austin Coil in no time. Well, almost. Once you have your software installed and your laptop is connected to the ignition system, a few mouse clicks will allow you to change your timing curve as you like. In fact, you can download the software FREE at MSDIgnition.com and play with it before you even get connected to your car. You can even make and save multiple curves to test and then just upload them to your ignition system before you make your run. It really is simple, and the truth is, you will have a hard time hurting anything. You don’t have to build some beautiful curve in order to make your power and torque controllable. Simple, and even aggressive, changes to the curve will not make abrupt changes to the way your engine behaves. You can significantly alter the power levels and shape of your power curves however. The photo below is what you can expect to see on your computer screen if you are using an MSD programmable 6AL-2. The Digital 7 that we used for our test has more bells and whistles, including separate timing curves in up to 6 gears, but operates basically the same. For more information on the Digital 7, check it out at MSDIgnition.com.
To illustrate how timing adjustments affect the curve, we have a Superflow Dyno graph below that shows horsepower and torque with a total of 36 degrees of timing that is all in by 2500 rpm. This is a fairly typical timing curve for a healthy small block in a 3500 lb car with a performance torque converter and 3.73 or lower rear gears. On a heavier car or one that has less rear gear, you might not have all your timing in until 3000 rpm. With a non programmable ignition system this is controlled by the weights and springs in your distributor. For our tests, and when using any programmable ignition, we locked out our distributor and set the total timing. In our case we knew that best peak power was made with 36 degrees. The programmable MSD will take timing away, not add it. This is why it would be hard to hurt parts. It isn’t like you can add 50 degrees of timing on accident.
The next two curves show us pulling 6 degrees of timing out of the entire curve, and and the resulting loss in power. This represents our engine only having 30 degrees of timing. Clearly it wants more than that as we have seen a decrease in power across the board, but the drop in power isn’t as dramatic as you might have expected. At slow engine speeds, ignition timing doesn’t need to be as high in order to make the best power. But as engine speed increases, you see that the power starts to drop off more dramatically due to 6 degrees less ignition timing. At 6500 rpm, the engine is down almost 16 horsepower and 12 pound feet of torque.
Now it was time to start really tuning. The graphs below show horsepower and torque after creating a timing curve that pulls 14 degrees of timing out of our original 36 degrees. This left us with 22 degrees of timing from 2500 to 5000 rpm and then let it have all 36 degrees we knew it liked for peak power. This curve represents the kind of changes you can make to help your street strip car leave the starting line without spinning the tires. Small tire drag racers running turbos have been doing this with boost control for years. Roots blown combos have been doing this with timing for years. Naturally aspirated hot rodders, who race their cars a few times a year, and have programmable MSD ignitions are typically not taking advantage of the easy tuning they can do on their cars. By playing with their timing curves they can make them quicker and more fun to drive at their local track. The power curves below show the comparison between our initial pull with 36 degrees of timing and the pull with only 22 degrees up to 5000 rpm. It is very likely that a hot street car will be able to apply all the power to the ground as they leave the starting line and then feed the timing and power in around 5000 rpm. Shifting at 6700 with a 4.10 gear and 27 inch tall tires makes our ignition curve just about right. On each shift, the engine will drop just below the peak power curve, and shift without spinning the tires and make a clean smooth run. Note that our timing curve below is not some fancy 10 step curve. Simple, easy, and it works. But also not that the power curve is still smooth as it takes them engine some time to react to the increas or decrease in timing. This all happens much slower on a dyno than in your car. Play with the rate at which the timing comes in and out. You’ll like the results.
With a few passes down the track, paying attention to your shift points and the rpm after each gear change, you can really dial this in so that your car is fast and fun to drive. Variations in transmissions, rear gear ratios, and tire size will affect the rpm level that you want all your timing in, but it shouldn’t take more than one night at the drags to get damn close.
For fun, we decided we wanted to see how to make an ignition curve that would represent killing power when we were at a slick spot on the track in a particular gear. The curve below is UGLY simple. And yet look at the smooth drop in power it makes to get us through that slick spot. Think of the fun you can have playing with this.
Remember, downloading the software, installing it on your system, and being ready to adjust your timing curve with any one of MSD’s Programmable ignition systems will take less time than it takes you to eat a pizza. Seriously, you can be ready to go in 10 minutes. With a little reading, great tech support from MSD, and a little bit of time you can make changes that can dramatically affect your cars performance and your level of fun at the track. No more kicking and screaming about not being able to get your car to hook. In fact, go to MSDIgnition.com and you can download the software right now and start playing with it. Getting familiar with the software doesn’t require you to be connected to your ignition system. Changes can be made on your couch, and then transferred to the computer later. You can even save multiple curves ahead of time and try them out in a hurry at the track. So get off your ass and go have fun with your timing. Your car just might be even quicker than you think.
