GrossPolluter

iTrader: (1)

I was curious on how an engine would be if the center irons were a big street port, and the front and rear were a normal or mild ported? I may buy someones spare engine and its a big street port. I don't know the details on the build, I guess I'll have to pull it apart and see.

Generally what is the powerband of a big street port vs a basic? I would consider reporting my irons to match, but I will be driving on the street and occasional weekend track use.

Oh, I have a 13bt, I want to throw my s5 t2 rear iron on. Also possibley s4 na rotors. I have a bnr stage 3 turbo with a megasquirt.

djseven

iTrader: (56)

Rougher idle, less low end torque. Power curve is moved to the right.

It will run fine, all depends on your goals.

stevensimon

iTrader: (11)

wouldnt you want your primary ports or center ports to be smaller than your secondary ports to help with low end? seems like that setup will run bit it will ha a wonky powerband having small secondaries and huge primaries.

GrossPolluter

iTrader: (1)

Well, it's not like there are valves opening and closing the ports.

Anyone have a good link to primary vs 2nd ports c timing, porting etc?

bumpstart

with FC turbo and FD middle plates,, best you may manage with the port is a late close approx equiv to secondary ports .. and it is very difficult to port down and get the same port area as a secondary port

overall.. it is possible to make the port earlier open than the secondaries by moving the outside edge

.. but it is doubtful the port could be cut so much as to have larger area and worse airspeed than the stock secondaries

at worst you will end up all 4 ports almost the same . a strategy mazda used in the 74-76 years in the lighter cars ,, less bottom end,, more top end

GrossPolluter

iTrader: (1)

so what is the powerband on most big street ports? I know everyone does it diferent. I may just consider porting out my rear s5 iron to match everything else

diabolical1

iTrader: (3)

Djseven and Bumpstart pretty much spoke on the what to expect from the big streetports. however, you also have to add to that the intake manifold and turbo that you plan to use as well. you also mentioned possibly using 9.4:1 rotors and that will be a factor to some extent, too.

BLUE TII

iTrader: (9)

I actually port my primary ports with a tiny bit later closing than my (conservative) secondary ports.

My reasoning is I have disabled the double throttle and the primary ports will have slightly higher velocity due to inline tb intake path (FD UIM), smalled dia runners and smaller volume ports- thus they will suffer less from intake reversion from later closing.