Drago86

Porting my primarys and i origonally planned on not touching the opening side of the port, but its getting tempting. I was just wondering how many people with NA's open there primarys earlier? I'm planning on porting the exhaust up a little so i dont want to get to much overlap, only because i dont want a really lumpy idle when i have to get her smoged. But that opening edge is just screaming port me,..

GMON

I was thinking the same thing on my turbo engine. Then I made a paper template and saw how close the stock seals are to falling in. I highly suggest giving this a try before you do that.



Gregory

Drago86

allready have, you can go out a couple MM with no trouble, But i think ive decided to keep the opening stock.

Fluid Dynamics

I opened my primaries about 1 mm outward toward the corner seal track and have no regrets. The engine has more low end and off-idle torque than before I rebuilt / ported it.

Fluid Dynamics

2 hours of dremeling later:

kahren

you can port the primary up a LOT, i dont like to go give any more overlap to the primary then what it already has. if you are looking for teh biggest street port then its a diffrent story, esp one u dont really care about low end much. i like to port the primary up a lot since that doesn loose much of the low end at all, if not give it more off idle power. i dont have a dyno comparison just yet but i will soon. it deffinately feels better then stock primary port. porting out without proper intake manifold mods and exhaust mods is not as effective.

dont forget to port the exhaust. like mazdaspeed7 said elsewhere "north american tunners dont concentrate on the exhaust portign enouf" i tend to agree with that.

rx7_re

I'm with Kahren.



I really didn't give it any more overlap than stock on mine, all i did was clean up the area a little bit. I did however go up a lot. I still have all the low end if not quite a bit more.

Drago86

I've allready ported up a ton. I think im gonna leave the opeing stock, and use my "free" overlap on the exhaust ports going up a little.

kahren

portign teh exhaust up is the same thing as portign the tntake out, but it dpends where u want to add the area, portign exhaust up dramaticly increases overlap then if u port intake, so watch what u are doing.

83turbo

No, there is a difference. Opening the intake earlier vs closing the exhaust later both increase overlap, but not in the same way.

Overlap due to early intake opening is not equivalent to overlap due to late exhaust closing. Excessively late exhaust closing does stupid things to the powerband.