LF4 Spark Plug Information
Stock LF4 spark plugs are AC Delco 41-147, 12662396, iridium, gapped between .030 and .035″.
Most people tuned for higher boost are running one or two heat ranges colder than stock, gapped a little tighter.
We recommend Denso ITV24 gapped at .027″.
LF4 Boost Information
13 to 15 psi is stock for lower altitudes. Those at higher elevations will likely see less.
17 to 20 psi is what you can expect with most aftermarket tunes.
18 to 23 psi may be run with methanol injection or ethanol fuel blends. That’s the practical limit for stock LF4 turbochargers.
Generally speaking, it’s realistic with proper tuning to add approximately 15 to 20 whp for each additional pound of boost on these engines.
ATS-V ECM Information
2016 ATS-V uses E92 controller. 2017 through 2019 use E92A. E92 was used in many 2014 through 2017 SIDI engines. E92A is GM’s premium direct injection controller.
ATS-V Turbocharger information
The OEM LF4 turbochargers are Mitsubishi TD04L6 models with 20TK3S compressor wheel. These units can effectively support 275 to 340 crankshaft horsepower per turbo, which works out to approximately 600 whp on the dyno. They just can’t move more air than that, so realistically there’s no more power to be made.
Torque Based Controller information from HP Tuners
The E78 controller was introduced in 2011 and used a new torque based control structure. To get an idea how this system functions, take a look at the following report from HP Tuners.
HP Tuners How to tune the E78 and E39 ECM
How to Calculate Quarter Mile Time from Eighth Mile Time
If you have run your car in the eighth mile and want to know how it will do in the quarter mile, simply multiply your time by 1.555. Approximately 80% of ATS-V time slips we have data for show a ratio between 1.550 and 1.560. Ratios lower than that imply a back half problem such as knock retard, boost drop-off or a missed 3-4 shift in the case on an M6 car. Ratios higher than that normally indicate a front half problem such as starting line traction or a missed 1-2 or 2-3 shift in the case of a manual transmission.