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You can modify the Start-up Airflow table, but you can also just pedal the throttle to start the engine up and modify the Start-up Airflow table once you've sorted out the table above. An easy trick is to get the above table sorted first and fully (do this at proper engine operating temperature, with normal operating oil temperature as well) and then go back to the Start-up Airflow table and increase the values in the table at normal operating temperature to match what you have in the above table for Neutral values plus 2 gms/sec. Scale the colder start-up airflow table values from there, but don't exceed 32 gms/sec as some operating systems won't jive with this.
Next up is the Idle Spark Advance - Base table...
So let's get on with it, then. This 2008 Z06 project started out with the usual goodies, including a Halltech Super Bee intake and a set of 1 7/8" headers. When we first tuned this setup on the dyno, it put out 456 hp and 448 lbs/ft at the rear wheels. Considering that the driveline losses in a stock Corvette Z06 are approximately 17%, this translates to about 550 hp at the crankshaft. A gain of 45 hp is nothing to sneeze at, so we were quite pleased with this result. The tuning was conservative with a 12.6:1 AFR at peak torque, a 12.8:1 AFR at peak hp and a maximum of 25 degrees of ignition advance at the upper end of the rev-range. The LS7 will run all day, every day with conservative settings like this. But, for track days, we need more. So on went a F.A.S.T LSX intake manifold and the power got bumped up to 484 HP @ 6,085 RPM and 475 lbs/ft @ 4,885 RPM. If you haven't read that article, you can find it here. This is awesome performance for a relatively stock engine, but we want more for the track lest we run into a turbo-something-or-other. So in goes the cam, and since we would have the heads off, well, you may as well send those off, too. These heads went off to Texas Speed and Performance for some porting, new exhaust valves and new springs as well as a rocker arm trunion/bearing upgrade. The folks at Vengeance were called for a cam. On our doorstep in no time at all was a big, long box from Vengeance that had "Sumbich" printed on it. In that box was a big Sumbich, indeed. This cam has 247 degrees of intake duration (at 0.050") and 258 degrees of exhaust duration with a 112 +4 LSA and 0.661" / 0.652" lift on intake and exhaust, respectively. We also called up Comp Cams (who also make the trunion/bearing upgrade kit and supply the valve springs for the heads as well as grind the cam for Vengeance) to send us a set of their Hi-Tech 3/8" pushrods for the LS7. With a few new gaskets and a 6-pack, we were ready to go. Work happened, drink was drunk, and onto the dyno went the mighty Z06!
We have a process here that we swear by before tuning any modified engine and that is our own little Pre-startup Procedure. Before firing up any engine, run this little Pre-startup Procedure to ensure success when tuning:
1. Check the engine oil! If the engine is fresh out of the machine shop, use a break-in oil. If it has a few hours on it but has been run and broken-in properly, use a good quality oil and make sure the engine oil level is correct.
2. Always use fresh fuel. We drain the fuel tank, clean the fuel system and injectors (if not new) and then fill the fuel tank with whatever fuel the owner of the car intends on using regularly. For those of you tuning for paying customers, ask them to bring you fuel from where they purchase it most often. Tune with what you'll use!
3. Use new spark plugs that are properly gapped.
4. Before going on the dyno, check tire pressures, lug nuts for proper torque and suspension control arm bolts for proper torque.
5. Make sure the battery is fully charged and that the electrical system is tip-top.
These few steps above will go a long way toward ensuring that your tuning session goes well. There's no point in fighting potentially bad fuel or fouled plugs when these problems are so easy to preempt. Once we've gone through the Pre-startup Procedure and gone over the nuts and bolts on last time, we turn to the EFI calibration. Before starting the cammed engine, we modify the following tables and parameters:
1. Target Idle Speed
2. Start-up Idle RPM
3. Idle RPM Limits
4. Base Running Airflow - Airflow Final Minimum
5. Idle Spark Advance - Base
6. Engine Diagnostics
The target idle speed can be set to 900 RPM initially. You can lower this value later, but for initial start-up and tuning, it's nice to prevent the engine from stalling and keep idle slightly higher to ensure adequate oil pressure for the new components you've installed. Increase the Idle RPM Limits to allow the Target Idle Speed and Start-up Idle RPM functions to work properly.
Next you can adjust the Airflow Final Minimum table. We started with the table values as shown below:
This is it. "The next step." Research tells us that "the average auto enthusiast buys and installs a cold-air-intake system first, followed by some form of exhaust modification and then either wheels and tires or an intake manifold for those more adventurous and who consider "chipping" to be next on their list." Well, GOOD NEWS, everybody! We consider "chipping" pretty important around here as that's what makes performance possible. Anybody can throw parts at an engine, but making it work properly and efficiently, that's a whole other beast. And we're glad you're with us on this, because all of that other stuff, the cold-air intake, the headers, exhaust and intake manifold are all installed to get our rides ready for the new cam that's going in, right? After all, you're not the "average" auto enthusiast; you're a Tuner! A Master Engine Tuner! Everything before the cam is just foreplay!