Mid-winter update

You guys are probably wondering where I've gone.  No posts since September on this project.  Had to spend some time doing other things in the fall, and now it's just too damn cold out in the shop to do much.  Nonetheless, some things are moving forward.

• The cylinder heads are installed on the shortblock, torqued to 120 lbs-ft (ARP studs).  Cams and lifters are in place, temporarily.

• Degree wheel is installed, ready to time the camshafts.

On the advice of my camshaft supplier, I will slightly modify the cam timing to suit the new intake flows and higher compression (14.5:1 from 12:1).  New timing will be ICL: 109 ATDC / ECL: 111 BTDC.  This compares to 107/109 on the first build.  Perhaps idle quality will be a touch better with the less valve overlap.

• Fuel system design continues.  This includes new rails with larger ID, and a new regulator to bump fuel rail pressure to 75 psi.  The Bosch series III injectors handle that pressure just fine, and the better atomization should help combustion efficiency.  We will feed the rail with -8 supply lines (1/2" ID).

• Crankcase evacuation strategy continues to develop.  I am convinced the main issue with the previous build causing oil in the combustion chambers, was due to the flow through the stock PCV system.  At idle the manifold vacuum was sufficiently low (~60-65 kpa) to prevent the valves from closing, thus allowing significant oil and vapor back into the intake manifold.  This time around, I plan to vent the crankcase directly to a catch can.  I'd appreciate feedback from anyone who's done this.  I know it was done successfully on a recent LT5 for racing application.  At 14.5:1 compression, the combustion chambers have to be oil-free.

• The calibration and datalogging setup continues to mature.  I will initially use Tunerpro RT with a custom dash, including a new ALDL stream to monitor exactly the variables I want (such as commanded Lambda).  A NTK wideband output, and a dedicated fuel pressure sensor will be fed into the stock ECM for monitoring.

• And lastly, in a few weeks the top end pieces (plenum, airhorn, cam covers) will be going out for powdercoating.  Not real urgent on that one.

Until next time.