The_Fox

Have a full shortblock under my bed. Lol. I really want to port them, but I'm not sure exactly how to go about it or how big to go. My final goal is 250+ to the wheels with the n/a 13b. How realistic is this goal for a daily? And what port should i do?

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KNONFS

iTrader: (14)

Get the templates from mazdatrix, pineapple racing, or judge ito, and port them.

250rhwp at the wheel is not an easy task on an na. For starters, you will need a stand alone ecu...

j9fd3s

iTrader: (3)

with a 6 port 250 at the flywheel would be a TON. you're really looking at more like 220-230 at the flywheel, which is 180-200rwhp.

if i was going to do one, i would port the 1-4 intake ports to Rx8 specs, the 5th and 6th ports need the pineapple or atkins sleeves. the exhaust port should be the later MFR, so instead of 71 open/48 close, it goes to 73/58.

the factory intake will hold you back, 10-15hp, so you should ditch it, you're looking for something a little shorter, and better flowing.

you will also need an ecu of some kind. RB headers aren't good enough, either make your own, or buy some from defined autoworks

stronger ignition would be good

and then spend a few days tuning it

RotaryEvolution

iTrader: (30)

it's a 4 port block, no auxiliaries.

but still, good luck getting beyond 200whp even with a standalone and custom exhaust. intake restriction will be your biggest hurdle even with massive internal porting.

peejay

You want 250 at the wheels?

Don't bother porting them, fill the intake ports with JB Weld and make a peripheral port.

peejay

It wasn't specified that it was a Turbo II block.

If THAT is the case, then solid maybe. You're still looking at bridge ports and a lot of screwing around trying to find a streetable exhaust that makes power.

I'm currently making about 230 crank HP with a streetable-exhaust bridge port in a 4 port 13B. The Turbo II housings can make more power, I opened up my ports as large as I dared. The Turbo II center ports can be a lot taller and the end ports are a minimum 4mm taller. So a lot more volume can pass through the Turbo II intake ports. The flip side is that to get the same eyebrow size in a TII block as I have, you'd need to cut into the water seal, which will hurt engine life.

On the other hand, I know I'm making about 230 because my injectors are going static at 8000rpm. There's bound to be some more RPM left in the engine, as the VE curve in my map is almost flat from 4000 on out, never dropping. But... I don't know for sure how much more there is. Another 70 horsepower? Probably not...

No matter what, don't starve the engine of air! I'm extremely pleased so far with the Racing Beat intake manifold.

RotaryEvolution

iTrader: (30)

in that event it would be better to use 6 port irons and save the 4 ports for something else. but yes, PP will be the easiest way to break the 200 mark but will also require a custom intake manifold for the PP.

KNONFS

iTrader: (14)

IMO a 4 port - semi PP is where is at, thats a good compromise bettween a full PP and a street port.

The_Fox

My apologies. I should have been specific. Irons are s4 n/a. I believe those are 6 port. MegaSquirt will be the standalone. I'm deciding if I want to do this or follow through with my turbo plans from my other thread. With the turbo I think I could easily make 250+whp

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j9fd3s

iTrader: (3)

put some 8.5 rotors in there, and go turbo, easy 250rwhp, and there's room for more.

rx7freak13v

turbos can easily make the power, but with a cost of lag. it depends on what you want or need. im building a 4 port street bridge port for autocross and later on road racing if all goes well. im using larger street port on the primary and cutting the eyebrow to the edge of the rotor housing. i've never been a fan of turbochargers. one day when i can comfortably afford to drop 2500 bones on a used whipple supercharger i might try that, but until then na all the way. the power is less. ok, but a flat tq curve is fun! instant response and don't have to wait for boost to have power. my power goal is 220rwhp on a na bridge thats quieted some for street use. if i fall short of that then oh well, it'll still be fun and i'll just change to an even shorter rear end gear but if your okay with boost then that would be the cheaper easier way to reach your 250rwhp goal.

RotaryEvolution

iTrader: (30)

have you ever driven a turbo rotary and a bridged or PP rotary? a highly modified n/a has no nuts at all down low.

joeylyrech

iTrader: (11)

Heheheheeheh.Let me take you for a ride on my turbo bridgey and you will never again look and a NA rotary the same

joeylyrech

iTrader: (11)

C,mon papi keep it quit..down low!LOL

joeylyrech

iTrader: (11)

If you want 250hp do a turbo swap with a 3 inch turbo back,720cc secondarys,fcd,sfac up the boost to 13 psi and have fun.

RotaryEvolution

iTrader: (30)

the way to look at things is if you want more than 200WHP naturally aspirated and aren't into doing it for the challenge aspect, save yourself the headache and switch to turbo.

j9fd3s

iTrader: (3)

i drove my 12A p port back to back with my friends CSP 1st gen (stock 12A, modded carb, full exhaust), and the P port makes more power everywhere, but the p port makes more power under 4k than the stock port does at all.

my friends full bridged Rx3 (you know todd, i'm sure he's used your shop), and with 3 people in it, 2000rpm in the Rx3 felt like 2000rpm in my GSL-SE... with 3 people in the Rx3 weight was about the same, same trans too...

peejay

My full bridge port with the RB manifold feels stronger at any RPM than my half bridge TII did, even with the long-runner manifold. Touch the throttle in the lower gears at any RPM over about 1500 and it yanks your head back.

Going by my Megasquirt's VE tables, peak torque is about 4000rpm. None of my previous engines had a VE number higher than 98 or so. This engine is at 112% VE at 4000rpm and tapers down to 106% at the highest RPM bin. I forget what the numbers are at under 4000 but the map curve doesn't fall off until the idle RPM range.

It's kinda neat to drive. Under cruise, you can't hear anything but transmission and diff. Whack the throttle open and the intake rasp overcomes the gear whine. I'm sure the car has an exhaust note, I just can't hear it...

peejay

If it stops raining early enough for the track to dry off, I plan on hitting grudge night at the dragstrip. I'm going to Science the quarter mile, using 4, 5k, 6, 7k, and 8k shift points.

My guess is that it will be quicker than 17 seconds at the 4k mark, which is what a stock GSL could do. My ultimate guess is 13.8-13.7 at maybe 102mph shifting at 8k, but that will depend heavily on my transmission which does not like shifting at those engine speeds at all.

j9fd3s

iTrader: (3)

yeah doing to the Wednesday night drags is on the bucket list! just based on what peepers hangs with on the straight at thunderhill, i'm mid 14's with the stock 12A air cleaner in place, which limits me to like 6500rpm!

The_Fox

Ok. So turbo swap it is. Time to hunt down some parts. Thanks everyone!

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RotaryEvolution

iTrader: (30)

i'm sure the PP is more streetable, with large bridges though my experience has been that they suck *** to take off from a stop and like to buck and surge below 3k as well as a serious lack of torque compared to a stock port setup.

3k is where most decent turbos will begin to pull, and will outrun an n/a without much effort.

yes the power band is broader than stock ports but compared to the rest of the power band anything below 3k feels like the motor is simply dragging it's *** and it is.

peejay

Carbureted or injected?

I can understand a carb not working well, it's a lot to ask of the device.

The only time mine bucks at all is at neutral throttle. Any load at all on the engine and it smooths right out.

Ports, incidentally, are Group A homologation ports on the "secondaries" (look suspiciously like Racing Beat) which are big by huge and the eyebrows are top to bottom and within 1mm of the water seal. I did fudge a little, my bridges are 5.0-5.5mm wide and not 4.5 as specified in the homologation paperwork. "Primary" ports are as large as can be fit on a GSL-SE center without hitting water, and the rotor housings are not relieved because I don't trust two piece seals to reliefs on the corner piece, even if they are large corner piece seals (Atkins).

Primary and secondary are in quotation marks because my non-carburetor opens all four holes at the same time, so it's like having 42mm ITBs.

Track's open, and I have my GoPro with me. Time to look like a dork wearing a helmet and short-shifting the car

RotaryEvolution

iTrader: (30)

both, but injected setups are a little bit better. problem with most standalones though is your idle map is basically where your low RPM cruising map is. depending on the porting it can be difficult to get it just right. have had better luck with microtech and a full bridge than a PFC with the same template at low speed(initially i was working against it wanting to go into fuel cut and buck like hell, it was awful so i disabled it manually. i never run decel cut with the microtech because it simply works like ****).

more timing gives a better take off but the idle suffers, reduce timing and the takeoff feels like a geo metro but the idle is nice and even.

some of these bridges are only making 6-9"Hg at idle.

i'm sure the light flywheels are a big contributor, both running 11lb flywheels. the more recent carbed 13B bridge is running the stocker 20lb but doesn't respond as well as the injected cars, but it's also running the RB intake with a holley 650DP with mechanical secondaries. worked better with the reworked mechanical hitachi at low speed but better with the holley now while cruising.

compromises are just not very forgiving.

peejay

Sounds about right. I idle at 5btdc and at 1500(ish) it's right on around 60kpa manifold pressure. (Atmospheric is around 93kpa around here)

The perverse thing is, having a heavy flywheel means you can run more ignition advance, since the bucking is damped out by the 26lb mass of weight. I will admit that I have to shift to Neutral to coast down hills now, compared to the heavy-flywheel engines. Oh well, it will finally get me off my butt and go to computer control of ignition timing instead of just using the distributor.

But I'll tell ya. 9lb flywheel and four 42mm blades and a TIGHT compression engine means the thing zings like a dirtbike engine when you touch the throttle. Downshifting is a breeze now.

Oh yeah, I forgot that part - besides all new seals (kind of a first for me) I have some supersecret resurfaced rotor housings. No, they're not from that guy. Or that other guy.