radius entry

[Dave W]

When installing the radius entry on the intake port what does it do? Do you pick up cfm or loose it? Just got the bench done and have no leeks and all orifices (IN & EX) read what there suppose to. I know what guy's talk about when they say companys inflate there cfm numbers because I got one head that is a good 27 off on the intake and 15 on the exhaust stock.

[Thomas Vaught]

The radiused entry actually picks up the head A LOT. If you had a circular port (Like a Ford Tunnel Port head) and the intake face had been surfaced for manifold fit, it would be just like having a sharp edged orifice at the inlet of the port. The flow would be about 60 percent of what the flow would be through a perfect entry.

The radiused entry is a method of getting closer to that perfect entry number vs the 60 percent number.

A profession flow nozzle can be in the 99 percent range for flow efficiency.

On the exhaust side typically people use a length of exhaust pipe to simulate part of the exhaust system. 10 inches seems to work ok.

Dumping out into the atmosphere right out of the head is not representative of a typical exhaust system.

You will never be exactly the same as the running engine but you can make valid comparisons if everyone used the same typical test accessories. Inlets with a given radius and exhaust pipes with a given length and diameter for a given head.

JMO

Tom V.