example if lets say your engines total volume is two ltrs then the volume of your intake manifold should be 2ltrs so when u snap open the throttle 2ltrs of air is available strait away after the butterflys.so by adding the spacer between the butterflys and the intake manifold i have effectively increased the total volume of the intake manifold,which has given me a dyno proven 7 kw of extra power.manufacturers delibretlty make the intake manifolds smaller to spend less money even though they do a good job of designing the manifolds.its like why do we upgrade the diameter of exhaust systems or add extractors(headers)?.i hope i could answer that for you even though its hard to in a few words ill try to find some info to help you more.
the intake maNIFOLD SPECS ARE EXACTLY THE SAME.MY ONE IS A ONE OFF I GOT MADE FOR 50 AUS DOLLARS AT MY LOCAL ALUMINIUM FABRICATING SHOP YOU KNEED TO DRAW A SCETCH OF IT WHICH IS PRETTY EASY I CAN SUPPLY DIMENSIONS ON MY ONE
well when i measured the two intakes the diameter was exactly the same as the f2t the only difference in manifolds is the bottom half with the fe3 has additional butterflys inside the bottom half of the manifold for better top end.my other suggestion is to adapt an fe3 dohc intake to your f2t engines it should not be too hard as with the secondry intake runners your engine will breath a lot better on the top rpm range.in the mazda manual it showes that the engine torque drops off dramaticly after 5200rpm so that means the long runners in your f2t is restricting the engine on top end.the butterflys on the fe3dohc are operated by a simple vacuum operated solenoid so getting that to work would be simple.im doing a lot of work on the intake area for pics visit my mazda site were im building a turbo fe3dohc. http://www.members.optushome.com.au/mazdas626
click on the pic with me in front of the black 626 to go to pics of fe3dohc.or clik below www.members.optushome.com.au/mazdas626/page7.html
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