ok, i have an 87 NA, true dual exhaust, intake, pineapple 5/6 sleeves.. now im going to build a motor. i realize the exhaust will have to be changed, i had planned on an expansion chamber to replace the midpipe.

i want to build a 4 port NA, but im not positive what kind of port i want to use.

my plans are:



-S4 TII short block

-S4 NA rotors

-TII intake manifold (shorter runners, plan on porting what i can)

-mazda 2 piece seals (doing some research on 1 piece seals, but i cant find a retailer..)

-will probably switch to TII tranny (rear end too if i can find one)

-microtech LT8



but i cant decide if i want to do a large/extended street port or if i want to build a full bridge motor. im not sure about driveability of a full bridge, because i do a lot of interstate driving (about 1000 miles a month). i read that at a set RPM the air velocity was low and the car would 'hunt' and make it jumpy. there is also the durability, a full bridge just isnt going to last as long as a proper street port.

part of the reason im building a 4 port is because of the large ports, and simplicity porting them, no 5/6 ports to complicate timing. later on, since ill have a full TII drivetrain and a stand alone anyway, i can put a turbo on it and just run conservatively with the higher compression NA rotors. thats IF i get a big horsepower bug.



ill probably end up bringing up my honda to do all my interstate driving anyway, i dont want to log all my miles up a new motor just cruising on the interstate https://www.nopistons.com/forums/pub...IR#>/smile.png



so lets here some educated opinions on this.

If its staying NA (at least at first), why dont u use S5 rotors and e-shaft for more compression and lighter rotating mass? you may lose a little torque down low with large, open exhaust ports, but up high it should be great. Id personally go with a street-port, just b/c it is less extreme and more streetable, plus, it will last long enough in street driving for you to figure out if you want a turbo.

Go half bridge, more power than a street port, more reliable then a full bridge...

i had planned on S4 NA rotors because theyre available, and they arent too much higher than S5 TII.. (9.4 versus 9.0) and i dont want to crack the engine open again later on to change the rotors and front weight, id basically be rebuilding it again.

and now that i think about it, there are two stock S4 turbos available to me.. if i go standalone anyway, all i ahve to do is put the turbo on. im going to use 550s and a turbo fuel pump anyway...

if any of the turbos are in useable shape i may just build it turbo from the get go.. damn. now i feel like ive wasted time. anyway.

i think i want to try out a 'built' (relatively anyway) NA before i turbo it though.



anymore input?

i like it. id do the street port, and sorta plan on the turbo eventually going on the car. 9.4 turbo should be pretty nice.



if you've got 2 s4 turbos available, build em both, and run both https://www.nopistons.com/forums/pub...DIR#>/wink.png

RB has 1piece seals but there pointless. Use OEM seals!

i meant just the turbo, not the whole engine https://www.nopistons.com/forums/pub...IR#>/smile.png

why are 1 piece pointless? no corner bit to gouge the edge of the housings. i would imagine they would seal QUITE as well, but whatever.

Horrid sealing bad leakdown more chatter. Basicly what is good about them? They dont fall into the port on a full bridge??



OEM only if you ask me. Preferably 3piece

well. i rode the dyno today. horrible let down.

i made only about 10-12hp over stock (well, gutted cats).

i put a cone filter on, pineapple sleeve inserts, and a custome true dual exhaust. it all comes down to tuning really.

im about to buy a microtech LT8 from my roommate, so we'll see. i have to wait another 8 weeks for the class to be in the dyno room again, so maybe ill have my engine built by then.