RX7 13B 4 UR AZZ

Im going to do a direct port N2O setup on my 86 NA now I wanted to know if it is better to tap the injectors on the middel intake runners or on the outer? A friend of mine told me if I was going to be using N2O below 4K rpm to put on the middle 2 since the other 2 dont really get working till the 5&6th port actuators com into play. any help would be greatly appreciated.

RX7 13B 4 UR AZZ

??????

FCmaniac

hmm, not positive but your logic sounds right.. you got me thinking, I wonder if anyone has ever used the stock holes in the LIM where the metering oil lines go for direct port (with disabled omp obviously).. I'd think the closer to the engine ports and further down the intake the better

mazdadrifter

i also think that you would want to go with the primary runners, so the nos always makes it to the comustion chamber, no chance of being blocked and backfireing.



also less restriction for the secondary runners which push more air and fuel

RX7 13B 4 UR AZZ

yeah i was thinking that to. Is there any way to port the intake manifolds? mabey polish them up a bit? something to get a little more airflow?

mazdadrifter

you can try to know burrs off and such, but I'm not really sure that it will make that much difference.



a decent difference would be the throttle body mod, remove the second set of butterflies and port that out some. The throttle body does seem to be a bottle neck of sorts.

RX7 13B 4 UR AZZ

Like i said some time before I have a 86 Sport and an 88 SE now im getting ready to put the 88 motor into the 86. I noticed that the 86 TB always has the first set of butterflies open and the second ones closed. now the 88 TB both sets of plates open with the throttel like if they are linked together. I also noticed that on the 88 TB the first set dosent close to make a tight seal like the rear ones do would that effect any thing? for safter pourposes im going to use the 88 TB.



How if I got them mixed together can I tell which are the primary and secondary injectors?

RotaryRocket219

There the same...there both 460cc..

FCmaniac

I have my upper and lower manifolds and dynamic chamber and gasket plate (thing between TB and DC) match ported with a die grinder. It smooths everything out nice and matches it up. To port the entire runners would be best obviously but I'd imagine that couldn't be done without extrude honing.. probably not worth it anyhow on my car.