Hi, I was just curious if anyone has built a NA engine using 13bt block? Is the port timing not good for NA? What if I got it ported , would I be able ot change the timing to benefit NA?
I was on mazdatrix's website and I noticed instead of using NA alluminum housings, they use the 13bt housings since they dont have that baffle in the way already. They never mentioned anything about building a NA engine starting with a s4 or s5 t2 irons.

 

With the stock NA manifold, the 6 port NA block is the best choice.

Old school methods dictate that for radical porting you would start with a 4 port engine (TII irons), but every NA Mazda rotary since '84 has been 6 port for a reason.

 

you are correct Aaron, but alas, a t2 running in na setup can make some power as well.

but at this point, your going to have to run a stand alone, or go with a simple carb setup.

 

Has anyone ever tried putting a header on a stock TII engine and ECU? How would it run?

 

You know I was thinking of that myself. So building like the basic T2 block but not putting the turbo on it.

 

mine is a TII engine without all turbo accesories and i guess its quick, i havent driven/raced any S5's before.

 

What if I were to build an engine with high compression and big street ports? Would it still b more worth it to start with a 6 port? I'm asking because I have spare s4 t2 engine sitting.

Also, if I had a 6 port engine with a stand alone, would the 2ndary intake ports still work?


A friend had told me the older fb engines with 4 ports are better than the newer 6 ports when you build them. ZIm kinda wondering how a t2 4 port in NA high comp application would b. Thanks guys

 

heres an na with the 5th and 6th port together with the 3rd and 4th they use a webber though to feed it, they also have a flow bench to there disposal. I always wanted to try this in a na

heres a link to the build http://www.yawpower.com/dec2004.html

 

Yeah, so if you are fed up and just strap a header on a 100% stock TII setup would it work? The pressure sensor wouldnt see pressure so it would just be in vacuum I guess, has anyone done this? I guess this is a threadjack, sorry....

 

I know one guy with a N/A Turbo Block. Uses S5 Intake, and 9:0 rotors. Makes 187 whp on a dynapak dyno.

 

Please read the previous posts more carefully. First off this would not be on a stock ecu, 2nd I would not try to build a Low compression NA engine, no matter the price of fuel.

 

That is a crazy setup, but without the 2ndary intake port working like stock, wouldnt that make almost no power in low end? It looks like its going to idle like an aggresive port, but how is the mid and high end power? Is this setup proven? The timing is insane to not have 2 stages, no?

 

a lot of people have done it. mostly for engine break-in. you'll have a stand alone so fuel and timing can be adjusted for peak horsepower. due to the turbo intake manifold there will be a lack of torque, but not too much.

i currently have a s4 turbo block, but built with a street port and n/a 9.4:1 rotors. depending on how my financial situation for the moment turns out, I might just be running this n/a on the stock computer and a safc.

 

You will have more port area and a better torque curve using the 6 port plates and intake manifold. While both the 4 port and 6 port engines would make similar power numbers at redline, the 6 port would have a better midrange.

[quote]
Also, if I had a 6 port engine with a stand alone, would the 2ndary intake ports still work?[/qute]

You mean the aux ports? Yes.

"Better" must be defined. Mazda many years ago went away from 4 port NA engines because they could not make ports with aggressive enough timing for high operation while keeping the torque for low RPM operation.

Doing something like that is just plain crazy. The engine won't make power until after 6K and will have virtually no low end. If you are at the point where you think you need to make such huge ports, then you should cut the foreplay, lose the side ports and bring your housings to the machine shop to have them peripheral ported.

 

I had always thought that an aggressively streetported 4-port with custom manifolds would have a better midrange than a 6-port of the same configuration.

 

Going back to the mazdatrix comment, note that they use TII *rotor* housings in an NA, only when they know they'll be porting the exhaust, since the TII rotor housings don't have the sleeves. They still use the NA irons for the rest of the NA block though.

 

Thanks Aaon Cake, makes perfect sense.

I just mentioned Mazdatrix using the exhaust housings off the turbo engine because I was not sure if the port timing on the NA and Turbo versions being different. I guess if there is a differnence, its not by much and they are porting it anyways.

Great info guys, I guess that engine will b a turbo application if I ever build it

 

https://www.rx7club.com/defined-autoworks-176/customer-dyno-charts-679163/

And here is a n/a 13B

13B-RE converted to n/a crappy header, small street port

206 rwhp, 151 rwtq



Looks good to me