High-Tech Nitrous

What I have seen in general with the LSx platform is they like a little leaner than motors of past days. Why? This has to do with BSFC and overall VE from the get go. These cylinder heads flow so well and are so efficient that a stockish n/a LSx motor is seeing BSFC's in the .450 range, un-heard of out-side of race motors not that long ago. Do the math for injectors sizing for the C5 Z06 with the BSFC of .450 and we can easily see that GM knew how good these motors breathed. Then a performance, purpose-built, motor will even have better BSFC numbers and skew the old guard even more. This brings up the second issue, timing.

Again due to the great efficiency of our heads, we need to pull more timing than motors of the past. The LSx platform likes a lot of timing pull. If we don't get aggressive with timing removal on the spray, and get the firing of the cylinder back to the retreating piston, rather than fighting an up-wards traveling piston, we will get pre-ignition that can lead to the dreaded detonation. This early or quick firing is more pronounced on the LSx than motors of old. We need to properly time the pressure spike to the retreating piston. Some of the heavy hitters running the LSx are in the single digit arena for max timing on the spray, and this is still the street/strip realm.

So in conclusion, the standard low/mid 11.x:1 a/f ratio is to rich, and the recommended 2° for every 50 shot is not always enough. Many do not realize that rich can do more damage than lean. This is where the problems arise, we have vendors/companies still recommending tunes that are not correct for the modern EFI motors. They like to use the general blanket statements that worked well in the past, but not absolutely correct for our new-tech motors. Knowledge is power, in more ways than one.

This all brings up running a 200hp or larger shot in multi stage. Given the tuner really knows how to tune the 427 with spray, there is no reason at all why we can not survive a long life by splitting up the torque curve. It is this low RPM torque that does the real damage, compared to the high RPM max HP. The cylinder pressure increase and staying there longer can be the factor that hurts the motor. I contend that a dual staged 200rwhp shot can be safer and easier on the 427 than a 150rwhp all in one off the line shot.

We have set-up dual staged dry hits that mimic the turbo curves for power and torque almost point for point. What does this mean? It means that the sprayed torque can indeed be applied in a nice progressive linear manor, with no massive low RPM spikes. Ultimately this leads to longer life before rebuilds. (see the dyno overlay in prior blog)

I think we will see more and more high HP 427ci motors coming down the pike as more tuners understand exactly what these motors like. Yes, there are those tuners out there already, but there are also those that were left in the early 90's. Technology is our friend, LOL. These are just my opinions, and everyone may not agree, but that is fine. We would love to hear any constructive critisisim.

Robert