I have a manifold that's been epoxy filled (preped) for carb not using the sleeves/actuators and an unmolseted manifold.

Which should I use?

 

The unmolested one. 6-ports low end torque kick ***.

 

who said don't and why?

 

What kind of carb? What will be the use of this car.. daily driver or track car, both? Is gas mileage a concern?
Im with Directfreak on this, and with Mazda for that matter... theres a reason that they designed and built their N/A engines with 6-ports for the last 20 years.

 

48 del dhla, not for daily driving, like it to be somewhat streetable but have no concern for the mileage.

Thanks for the help guys.

 

Use them, because when the '6'-ports are driven off of exhaust backpressure, your lower intake manifold will function just like it was intended, i.e., opening the ports at 3800rpm (or so) to allow for better airflow and velocity, while still retaining high velocity and air column mass at rpm below, which translates into better low-end torque.

As someone stated above, there's a reason why Mazda continues to use the '6'-port 13b - because it's effective at broadening the torque curve of an otherwise 'peaky' engine.

 

thanks
Think it's worth the time to contour the sleeves similar to pineapples sleeve inserts

 

Even Pineapple claims less than 1% improvement over stock with their modified sleeves.

My answer would be no.

 

The Pineapple Racing 6-port sleeve inserts are designed to install into the stock 6-port sleeves Mazda used in all 84-91 13B non-turbo RX-7s. These are close-tolerance CNC'd aluminum parts that are hand-pressed into the stock sleeves*.
The Pineapple Racing 6-port sleeves flow much better that the stock sleeves, which dead-end severely. The bowl of the insert is radiused for maximum flow, while the lip at the end of the insert is designed to properly locate the bowl within the port aperture.

Price is $49 per pair, plus shipping.

To order, please call
(503) 233-3878.

*Note: we recommend a drop or two of Green (#262) or Red (#271) Loctite to bond the insert in the sleeve and that you 'ding' the edge of the sleeve to mechanically secure it, as insurance. For instructions, please click HERE. We will install your inserts for free if you mail us clean 6-port sleeves, but we cannot do a core exchange as we have had problems getting cores returned.


Guess they wouldn't want to mention that in their ad.
Wonder why they even bother, glad I didn't buy them.
Thanks
Joe