311unity13B

Well, its currently at Kevin's getting a rebuild and:



Nonturbo 6 port engines, auxiliaries (5/6 ports) only:


I have recently developed a special version of SP unique to the 6 port nonturbo engines (84-91 13B). This port allows for a nice top end power increase with absolutely NO decrease in low end pull, driveability, or even emissions testing. This is accomplished by only porting the 5th and 6th intake ports, and a very light exhaust port. The “lower” 4 intake ports, responsible for idle and low rpm driving remain untouched, and so do the normal driving characteristics of the engine. Only at/above 3800rpm,when the auxiliary ports open, does the porting take effect and move more air through. No emissions test that I am aware of, even the dyno/roll test, pushes the engine to the point where the auxiliary ports open, therefore this is a good way to “hide” your performance gains from the emissions test. For those who don’t care about this, I can/do still port all the ports of a 6 port engine, though there isn't much performance gain for the 4 smaller ports, and there isn't much room to port into them anyway.

For exhaust ports, I cut out the nonturbo exhaust diffusers with a torch on all streetported engines. This leaves a port sleeve basically the same as a turbo sleeve. Noise is slightly increased, as well as flow. The port shape itself is not altered.

classicauto

iTrader: (3)

this method has been applied to TII's as well, I have seen a number of people running 1/2 bridges on the secondairies only....

good idea for those in emission compliant areas

311unity13B

this was taken from www.rotaryresurrection.com i didnt develop any of this

FirstRotaryExp

iTrader: (3)

Ahhh, what all is Kevin doing for ya? Ive been up there a few times over the past few months for lil things, live close by haha to all those who ship to him.

311unity13B

i trailer the car up last thursday, he is doing a R&R and rebuild since i didnt have time to take the engine out and strip it down. plus i will get the extra 6 months warranty

he is also doing that version of a street port, so i am interested in how it will turn out

he seems like a really nice and legit guy, i feel very comfortable leaving my car with him to get it done right

FirstRotaryExp

iTrader: (3)

Yeah its a pretty safe place round his business, and hes got the knowhow, I trusted him to fix my front stack on a whim when I was up there time before last. Hes a great guy too. I hope it turns out to yoru liking, and let us know how it goes, id be interested in how the ports turn out since my na wants more uumph

rotarygod

iTrader: (1)

Two things: (flame suit zipped up as I've been through this before)

There is no way in hell that "unique" porting style was "developed" by anyone here as Mazda tried just about everything out there at some point or another. No one here has ever come up with an idea that Mazda didn't already try at some point in time. They even ran semi p-ports in the early 70's so even that isn't a new thing.

Second, that porting style doesn't work as claimed anyways. It's completely bogus. It's not even based on theory. It's based on a guess using some flawed logic. The port itself isn't the limiting factor in airflow and power in that engine. It's the flow of the runners. They suck with the auxiliary port rods in the way. Those rods affect the flow so bad that adding a radius to the port such as with the radiused sleeves does nothing to improve airflow to a usable degree. It's only with the actuator rod removal that any gain would be seen from that. Even if the sleeves weren't used with this "unique" style of porting, the port timing is way too long and the port is so large in comparison to the intake runner, velocity actually slows down as it gets to the port opening and you ultimately flow less than a smaller port would due to a lack of velocity. If you aren't testing, you are guessing. Ask for the proof to verify the claims. Any shop that is trying to make money off of their claims had better be able to prove it works as advertised.

Take a look at the dyno's below and look at who built them. Pay special attention to that. You may be surprised.

Here's a street ported engine using RB templates. These are mild compared to what you are having done:
https://www.rx7club.com/time-slips-dyno-128/s4-n-6-port-puts-down-172rwhp-488387/

Here's another streetported engine that isn't as wild as what you are getting:
https://www.rx7club.com/time-slips-dyno-128/na-streetport-6-port-dynoed-182whp-details-inside-416012/

Here's an update to it:
https://www.rx7club.com/time-slips-dyno-128/na-6port-streetport-dynoed-195whp-update-418805/

You might want to pay special attention to this one. It's got a large port that was extreme compared to the above and check out it's power:

https://www.rx7club.com/time-slips-dyno-128/dynod-streetport-today-393588/

Just for the fun of it, let's compare a stock ported Mazda rebuild with a few bolt-ons tuned with a limited S-AFC just for comparison. Interesting isn't it?

https://www.rx7club.com/time-slips-dyno-128/na-6-port-dynoed-152whp-details-inside-461424/

Dom_C

The second to last one. . ht eone with the extremly large port was my old car. . Let me remind you that that dyno was done with no form of fuel control, on the completly stock ecu. I'm sure that that engine is cabable of much more but just not sutable for what it was intended to be used for. . I'm sure with some fuel control, and a switch from the s5 manifold back to the s4 that car would hit about 180rwhp or so. . although I doubt that that engine would make peak power below 8500 after being tuned. . the ports were f-ing huge. In the end I wouldn't get an engine ported like that again . .there are much smaller, more drivable, more efficient ports, that will make more power. But the porting style you chose is not what I had so I have no input on that. Oh but yea Kevin is a great guy and I recomend him for your rebuild, just don't know which port to recomend.
Dom

SirCygnus

iTrader: (1)

ill build you a ms for it man dont worry!

classicauto

iTrader: (3)

there is alot to be said for what the stock ports are capable of though.....

it says these numbers were on a mild port on INTAKE ONLY, stock exhaust (granted its a 3rd gen with a 30psi capable turbo, but still)

https://www.rx7club.com/single-turbo-rx-7s-23/new-dyno-numbers-%2A%2A%2A603-whp-%4027psi-uncorrected%2A%2A%2A-506468/