2 setups...

4port 13BT turned N/A. Early-Open Streetport, S5 N/A rotating assembly, high-RPM mods. Stock TII Intake, ported/polished until I can afford an IDA setup.

6port S5 13B. Large Streetport (w/ still-functioning 5/6thport setup) same rotating assembly, same mods. Stock N/A intake (S4? S5?) P&P until IDA.

Engine will have a 2.5" exhaust with a cutout after the header. 3.5" CAI to the fender. Running a MegaSquirt for fuel, and a 12A Dizzy w/ Direct-Fire for spark.

The goal for this engine is lasting a while (not asking 120K there, but more than 25K) while running 13's N/A; and being a good base for an FI setup later (Turbo or Nitrous for the 4port, Nitrous for the 6).

Which of these setups would be better? I've emailed hitman, mazdatrix, guru, pineapple, atkins, asked some shops, talked to Mazdaspeed7 & Pengaru, PMed Judge Ito; noone can give me a decent answer. Someone help me out! ~CE

 

I would go for the 4 port, if nothing else it would be simpler

and to FI it wouldnt be a big deal at all

 

Anyone else have an opinion on this?

 

4 port for sure. I like them better too.

Oh, before I forget, what type of direct-fire will you be using?

 

Most likely a stock 2nd Gen Leading coil; then likely upgrading it down the road.

 

A well setup IDA based EFI should give 230HP (flywheel) in either 4 port or 6 port setup with still acceptable road manners and life expectancy .

Now theory would indicate that the 6-port should be able to give more HP, but there are very few documented cases of it.

Bill

 

Thanks for the post Bill; I'll be talking to you about the MS later, I'm sure.

That's 3 for 4port; anyone else have any input? I know Mazdaspeed7 says 6port es' numbah 1. Other than that, a whole lot of nothing. None of the "big names" have any input on this? ReTed? Icemark? Banzai? Dez?

Edit: Also note that it has been brought to my attention; for the price of the IDA manifold and TB setup, I could do something a little more custom. So the IDA setup could be substituted for an ITB setup or something other than just 2 butterflys.

 

Off list me if you want to find out how to build the ultimate in 4 or 6-port setups.

 

I say four port. You can get a bigger port with the four port and make more power. The six port will give you more torque down low the way you have it set up though. The four port will make all it's power up top.


The main reason I say four port is because you will want to turbo it later when you realise that nothing you do to an N/A will get the power you want. I've owned 10 RX-7's and Will never Own an N/A again.

Our EP car Runs a 6 port with a 48 IDA (the biggest we are allowed to run) and a full 3" exhaust. We dynoed 213RWHP and ~130ftlbs torque.

Just curious, Why would you want to run a IDA over Fuel injection?
What would be cool is a webber style throttle body with 4 injectors. That would make it easy to turbo later and give you the great tunability of FI.

Mike

 

I believe 6 ports flow more in N/A form. But you should talk to Rob at pineapple racing, he car steer you in the right direction. I talked with him a long time ago about doing a 4 port N/A, he told me to stay with 6 port.

 

IDA-Style Manifold. It'll be FI. But I'm thinking more along the lines of ITB right now...

 

Mike,

'you get a bigger port with a 4-port' Care to back that up with some numbers, as I do not think this is correct.

Bill

 

I actually believe him.

If you look; a big SP that keeps the 5/6ports working as-designed will be smaller by surface area than an early-open 4port. Timing on the other hand... the 6port kicks the 4's ***.

 

Ah. UK 6-ports have a butterfly so no sleeve and can therefore be made huge.

ven so inspection of the mazdatrix pictures show that the total port area is much larger. As is the runner area (which I have measured)

Bill

 

Too bad UK Endplates and LIM's are so hard to get.

Correction; so expensive to get.

 

I sold my LIM for $40 to an australian as I thought it had no place in a performance app.

Sure I can get more cheaply. The butterflies are still horribly restrictive

Bill

 

Yeah... I was still leaning towards 4port anyway :-P

 

^happy to entertain more answers^