Offenhauser Dual Port 360 Intake manifold

Have any of you ever run an Offy Dual Port 360 intake before? The premise of these manifolds is :

the manifold is split into two separate runner systems Primaries and secondaries. Each runner system feeds all eight cylinders. The primaries feed one group which is small diameter to increase port velocity. When the secondaries open, the second runner system starts to flow increasing the amount of air and fuel available to the heads.

This is basically the same theory that Ford is now using with the 3-valve 4.6 and 5.4 with charge motion control valves. The theory is to increase port speed at low RPM while maintaining port volume at Wide Open Throttle. This "should" increase low RPM fuel economy and torque without hurting upper RPM power too much as compared to a similar designed dual plane manifold. (Height, plenum volume, etc.)

So, anyone have any real world experience with these intakes?

 

I've got one on mine, haven't even cranked the motor yet to see how it's going to do...

 

I have used that intake before and it was a dog compaired with the performer.It had low end torque but no upper.This was back in '87 .
Just my

 

friend of mine tried one. wasnt happy with results. the regular offy 360 was pretty good, tho.

 

I had a duel-port Offy on my 351 for about 4 years. It seemed to work pretty good...until I moved up to a Performer RPM. Idle, Vacuum, torque and top end power was like night and day....picked up almost half a sec and 5mph in the quarter. Turned out the intake wasn't so good! Sounded cool to say I had an Offy Duel-port though...but that was as far as it went.

 

I have used the dual port Offy manifolds and with the right cam they perform well. The problem is that they are not meant for high rpm use and they don't make a lot of hp. They are good for gas milage with a very mild cam but don't have enough flow for a medium range cam much less a real cam. They work best with an offset bore carb. Small primaries and large secondaries. Even then it will never be a true performance manifold.
If you want economy use it, if you want power use something else.

 

Looked at mine again and it's not a dual port. Don't know why I was thinking it was...

 

offy 360 intake

Have any of you ever run an Offy Dual Port 360 intake before? The premise of these manifolds is :

they work great of street cars . especially on a 289. works like a dual plane on the bottom and a single plate on the top end