theboy

sorry i am a tech noob, please help.

does changing your exhaust manifold to a 3 pipe outlet means 1 extra port for 4AT? cause i found that all 13B msp engine is the same, only port diffrent. does this means a 4at manifold cover the middle hole in the engine so it become 2 port exhaust?

please enlighten me and correct me if i am wrong.

theboy

are these 4at exhaust manifold?

zaglo6204

covering holes?? not such a good idea...

theboy

u got me wrong bro. i just wanna know is the holes for 6MT and 4AT in both engine is the same. did madza cover up the 1 port. or its different in the engine housing.

SmokeyTheBalrog

I believe I read a post (in the axial flow Super charger thread) that the holes are the same just that the lower power AT engines have one port sealed. Aside from that everything is in the same place.

theboy

thanks for this precious information. do u know whether its sealed with the manifold exhaust mounted plate or its welded?

RoXanneBlack8

the exhaust ports are the same, the 4 port/6 port names are for the INTAKE side.

04-05 ATs got 4 intake ports, everyone else gets 6

theboy

i opened my 4AT hood and my friend's 6MT hood found that there is one more intake port made of plastic that look like a flexible plugin part for the 6MT. i am not sure whether it will fit the 4AT if we got the part.

i remember reading from the forum that the 6port in 6MT come from 1 extra intake port and 1 extra exhaust port. i think 4AT '03 is with only 2 intake port.

QBallz

All exhaust ports are the same. It looks like those headers are for the RX7.

TeamRX8

iTrader: (25)

RX7 headers

rotarygod

^correct. The pictures posted above are of RX-7 headers. ALL Renesis engines, regardless of if they are 4 or 6 port engines, have 3 exhaust ports. The difference in name (4 or 6 port) comes from the total number of intake ports per engine. The number of exhaust ports is the same.

theboy

now i get it! thanks guys, for double confirming it.

another question. so does the 6MT extra intake ports available in 4AT engine housing too? thats mean different in piping? or it actually have different holes in the engine housing?

86rx7

Differnt holes, the 4 port is missing the top two holes on the side plates. there is no way to turn a 4 port motor into a 6-port unless you rebuild with 6 port side plates.

theboy

Thanks! thats what i need to know. you guys are really great!

i was thinking of Rebuild it with 6MT Side plates and intake pipes. with a bit tuning 4AT will gain abit of horse.

with a second hand 6mt engine parts and tuning less than 250HP. it still cost less than a turbo kit. NA rocks.

SmokeyTheBalrog

Keep in mind they removed the last port for a reason. The 3rd intake port only opens after you hit 7,500 rpm. and the auto trans cannot handle such high rpm.

AdRoCK3217

It's not like Mazda couldn't have had a 6-port on the AT from the beginning. Notice, the new AT is 6-port, with 7500 RPM redline.

On the 2nd gen NA RX7's, the aux. ports opened (by vacuum, so not always reliably) at around 3000rpm.

cajunrx8

And don't forget the 84-85 GSL-SE RX-7 had 6port intake also if memory is correct.

AdRoCK3217

Yeah, I think so...O.o