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.)????

 

Yes, it is true.

The gains from a single plane are really only seen north of 6,000 rpms or more. You will lose some low end, especially under 3k.

This is why cars run such high CR to help return some of the low end lost on a single plane setup. A stock shortblock build would probably run slower with a single plane setup then a stock intake.

 

It depends on alot of variables. The guys who win the engine master challenges use single planes and that is average hp and tq from idle to 6500.

I have seen boosted LTX cars with single planes pick up power everywhere swapping from the LTX intake.