Drag racing with turbochargers presents its own set of problems. In order to have boost in time for launch, you foot brake WOT on a 3 step limiter coming into the staging beam, then transbrake WOT on the 2 step limiter, then launch. The problem with the typical ignition box limiter is it usually picks the same 2 or 3 cylinders to misfire and those cylinders go cold before launch and have to play catch-up during the run. EFI systems like Bigstuff3 now come with a 2 step that insures even cylinder control to eliminate the problem. The following run is a 7.03@ 198 mph twin 88 @ 25 lbs of boost, Accel EFI triggering a MSD 7530T. single plane manifold. Yellow line is engine RPM Note how the cylinder temps are affected during the 2 step rev limit. By the end of the run the grouping is finally coming together I added the boost curve so you see how nicely it is controlled by simply regulating the wastegate pressure without using the manifold MAP sensor as feedback for the boost controller. Here is a 375 hp shot nitrous run ( No turbos) where we used a Mega 450 delay box with the "Starting Line Enhancer". You come into the staging beam with the gas pedal to the floor with a preset rpm using an air cylinder on the throttle linkage. Then 1/2 second before launch, the system goes WOT so you are only on the limiter for 1/4 of a second. Now the cylinder temps stay grouped at launch. As you can see cylinder #2 was running lean. At the end of the run EGT temps where only 81 degrees apart or 55 degrees apart without #2..
That is great instrumentation. I don't see how turbochargers could be used properly before we had the electronics. Bruce Roe
