A few days ago I was in discussion with a reputable engine builder in Illinois RE: a 383 LT1 build. When I expressed my desire to ditch the stock LT1 intake manifold in favor of a carb style single plane intake the tech said to me that I will experience a big decrease in low and midrange torque in going to the single plane. I thought this was counterintuitive I was lead to believe that the shorter the intake runner the lower the low and midrange torque and the longer the runner are the greater the torque like the famous or infamous Tuned Port Intake on the L98.

He went on to say that though the runners on the LT1 intake are indeed extremely short (3") but the intake has a small plenum volume and this enables the engine to have very port velocities at low and midrange RPM's which aids in cylinder filling at such low RPM's hence the high torque even with short runners

1. Is this true??.

2. What is yours or anybody else who know's experiences with changes in low and midrange torque in switching out the stock LT1 intake for a carb style single plane or anything else(holley Stealthram, Accel Superram, etc.)????

 

he is correct. IF you were to increase the plenum size you would loose low end torque, but actually pick up on the top end. You would have to start looking into the fluid dynamics of the intake to fully understand what is happening.

 

to over simplitfy it, the single plane will pick up top end and lose on the low end.

on a stock or mostly stock engine, the stock intake will suffice. on a larger more radical engine like your 383, the engine could make use or the extra flow offered by a single plane intake, especially at high rpms.

im converting a victor junior to use on my lt1, looking to make about 550hp through a 355.

 

does this apply to a fuel injection setup? being the injector is sitting so close to the valve..