Most here would agree and even Jayson at MTI that you can safely go 4.060 overbore on LQ4 if not spraying. For extra safety and confidence, simply have the block sonic tested b/f 4.060 overbore. That's what MTI is doing for me as they build me 427 beautiful cubes on my LQ4 with 4.060 overbore and 4.125 forged crank. WILL BE A TORQUE MONSTER no doubt.

MTI 427 C5 Roadster

 

What are the advantages/disadvantages of each:

LQ4 Block

Bore * Bore * Stroke * 8 * .7854 = Cubes

4 * 4 * 4 * 8 * .7854 = 402.1248

4.03 * 4.03 * 4 * 8 * .7854 = 408.17929152

4.03 * 4.03 * 4.125 * 8 * .7854 = 420.93489438

It is my understanding that 4.03 is the reliable limit with this block. Are the different setups for FI, NO2, NA, street use instead of track use?

TIA

Jason

 

oh yeah, and

4 * 4 * 4.125 * 8 * .7854 = 414.6912