79fb

has anyone ever thought about smoothing out the defects in the stock intake on a 12a?..i was thinking about it..

Rx-7Doctor

iTrader: (13)

On a intake you do not want to smooth out but enlarge openings for better air flow
There needs to be a tumbling effect when the air goes into the intake. You can enlarge the openings with attachment sanding discs that attach to drills, they are round and will still create a rough swirl opening at the same time. I have done this with my injected se but can't give any results at this time. Carburetion tends to do much better when porting than on injection systems. rx7doctor

lovintha7

RX7Carl just finished his prototype 12a ported intake, and he said it's flowing much better. Keep in mind Carl and Sterling have a flowbench.

Remember about porting an intake, a huge hole is not always good, velocity and flow is what you're looking for.

Rx-7Doctor

iTrader: (13)

did carl do this on a stock intake or other type? rx7doctor

lovintha7

Stock mazda intake.

I think he's intending it for use with the Sterling carb (which i have ordered) and a SP motor.

Rx-7Doctor

iTrader: (13)

Cool, cant wait to see the results. rx7doctor

79fb

thanks ya i cjecked out sterling's site just waiting for results as well

coldy13

I thought about porting my stock manifold, but I just made this instead:

813KR$

coldy13 :

Nice, really nice ! ! !

Where is the e fan, direct fire ignition and air to oil, oil cooler?

What is that? A blowthrough dellorto? Wassup with your set up? I would like to hear what it is and how it runs, I like the way it looks. Looks like it will flow fast . . .

813KR$

Oh and yes people do port stock intake manifolds, I have never done it, because I have a RB intake and have ported that, but not a stock one. I hear people do for racing in certain classes where you have to use the stock components? The port and fill holes and what not with JB weld keep it as smooth(not shiny) as possible and even.

coldy13

E fans cost money, and don't help that much. Direct fire isn't much better than just a normal setup MSD. Air to oil cooler would be good, but again it costs $, and I don't have any overheating problems or leaks as it is. I'll do that stuff eventually, but I did all the upgrades that would help me the most first. It ran mid 13's like that, then I bew the motor. Still looking for a new one right now so it's just sitting for a while. It's a Weber 48dco-sp, I think a dell would work about the same though.

Rx7carl

Well the development has stalled for many reasons. The hurricaines, my daughter running away, bought a new house, moving, getting old house ready for sale, setting up shop here.....................

Anyway heres the quick and dirty. Working with Rx-3, SA and FB manifolds in different configurations both on the flowbench and on my daily driver I have come to some understanding as to what at least a stock port 12A needs ( it will be tweaked for SP engines as necessary). The final product will be an enlarged dual plenum design that wont kill the low end but will greatly enhance the mid range and top end, whether with a stock carb or a modded one. The closest thing to what we will offer would be an Rx-3 manifold with plenums cut in it. The preferred manifold for those who wish to roll their own would be an SA manifold. Less material to remove.


Oh and lovin is right, its about flow without losing velocity.

Rx7carl

Sorry, to answer your question, yes smoothing the bumps will help the flow. You have to be careful not to break thru the casting into another chamber depending on the year manifold your messing with. BTDT. Fixed with JB weld and my engine ate it Didnt seem to hurt it though. Man I got lucky........................