The finished plate; aaahhhh.




It is sad to hide this inside the engine. I pretend that I am a sculptor when doing porting. My ports are my babies.

 

Im curious as to why youre not going down. Its free area without affecting the port timing.

 

88IntegraLS

You are my personal hero, dude.

 

I'm porting my spare engine that I'm building for senior project

 

I'm assuming when you say down, you mean on the Z axis if it were in 3d? x & y being the rotor face itself, and z being depth of the port?

 

I am trying to keep the primary small. I have a theory behind it.

 

By down, I mean down as youre lookign at the pics. The y axis.

I was just curious if you did it for a reason. I definately respect your goals. Im going the totally opposite way, but when I do anything, I go all out.

 

Im curious on how you are gonna plug those holes in the port?
What are they BTW, do they need to be plugged?

 

EGR maybe?

 

yep those holes are on the s4 motors, egr.

 

Man I can't wait to get some more money so I can begin porting. You guys make me prouder and prouder each day . Keep up the good work, and good luck on hitting those goals!

 

Not much of a theory...More of a fact. The bigger you port the primarys, the more power you loose down low.

If I could go back in time and redo my street port on my 86, I would have never touched my primary ports.

I ported the primarys on my engine so much that I had to re-time the opening of my 6-ports. Instead of 3800 RPM, I now have them opening at 4800 RPM. My dyno numbers showed a 10 HP dip when I opened my ports at 3800 RPM. The dip didn't smooth out until around 4800 RPM.

Just a thought.

 

Very good info wozzoom, I've always wanted to do some research on opening the aux ports later on in the power band. That's pretty much a requirment when you go very large on the primary ports in my book . What kinda power are you putting out now with the work you've done? How does the engine react under normal load and hard load?

 

Good bit of info, wozzoom.

Can anyone tell me about the EGR holes in the port.. where do they lead to?

 

My best dyno to date is 167 RWHP. That was with the cat and an airpump. (IE: Full emissions)

Since that run I've dumped the cat and airpump. Currently running a RB silencer. So I'm somewhere in the 170 RWHP range.

The engine overall is a blast under normal and harsh conditions. The only downside is below 2000 RPM, the car is a dog. I have a hard time launching the car from the line becuase it likes to bog. It's because of this that I wish I would have left the main ports alone when I rebuilt it.

 

It should be really straight forward to find out when the aux ports should open with a chassis dyno.
Make two back to back runs, one with the ports wired closed, the other with them wired open. Have the guys plot both curves on the same graph. Where ever the lines cross, that is the RPM they should open.
Good luck

 

That is a good bit of advice.

Remember that one, guys.

 

That's exaclty what I did. That's why I open my ports at 4800 RPM now.

MY POINT is that I gained nothing by porting the main ports. I did however loose low end "grunt". My advice is to focus on porting the aux ports so that you maintain the low end.

 

I disagree on the gained nothing part. The ports are doing a larger share of the overall work, and are making more power. If you left them untouched, you would not have 167 rwhp.

There is only so much hp in the aux ports. No wonder noone on here has broken 200 rwhp. And you cant expect it to work identically to stock, but that doesnt mean it has to be worse. You need to do the whole package. You cant just port the hell out of your ports and expect to make great power. You need to make sure everything else is optimized for your ports, just like the stock setup is for stock ports.

And do you really expect your car to drive like a V8? You cant drive a car with an 8K rpm redline like one with a 5K redline. And you definately cant expect the former to make the same power below 2000 rpm. If below 2000 rpm matters so much to you, you have the wrong car.

 

I knew that but I had forgotten it.

 

Great discussion going here. The egr ports lead to the egr valve opening and I will not plug them. I don't trust anything but a weld or threaded and tack welded rod to plug that hole. It is in a low pressure outward cuved area in the ramp and what slight intake restriction it may cause is okay with me.

My theory is the same as Jimmi325i who doesn't post anymore. He ported an S4 na engine with a mild / medium primary and secondary and a large sixth port. He never showed me his ports but I got the idea that he did most of the work shaping the bowls of his primary and secondary ports and not much change in their overall timing, other than later closing. I also have a hunch that he didn't go down at all on his primary. I know that he didn't open them more than a touch earlier than the stock secondary opening timing.

He put his car on a chassis dyno and put down 165+ rear wheel torque at 4-5000ish rpm using 14.7:1 air fuel ratio. He didn't get to do a full run because the dyno operator kept shutting it down when the air / fuel mixture went beyond 14:7 (there was some S-afc fine tuning still to be done). He was also running out of air from the manifold and stock computer . . in other words, with his medium ports he was still beyond maxing out the stock air / fuel delivery system. Not to mention breaking rear differential mounts right and left.

This gave me the idea to go a different route for power than big ports and big timing. Of course, the one stock port that already has big timing (sixth port) was the one I went wild on with my own porting, making it close significantly later than before. We'll see how this all works out. My porting philosophy is different from the norm. Fluid dynamics is counter-intuitive.

I want torque because I'll need a very strong midrange out on the autocross course. I want to be worrying about not hitting cones instead of shifting a lot. So I went a different route than traditional peaky-powerband ports.

I don't know when I'll get this car on a dyno but it is a future plan for tuning an S-afc, and I will post my results.

 

Midrange isnt what I was talkign about. My motor has awesome midrange. My cars as happy at 4K as it is at 7K. And it still has PLENTY of power for driving from 2000-4000, and builds strongly in that range. My car pulls decently from 1000 rpm in 1st and 2nd. Youre not going to win any races, but it keeps up with traffic easily shifting at 3K.

What year was Jimmy's car? S4's are easy, you cant max out their AFM(Judge Itos FULL bridge 6 port motor didnt max out a S4 n/a afm). S5's are a different story, and Im definately going to have to work around that. Someone told me about a stock port ITS motor on a S5 they dynoed. It maxed out the afm at 7K rpm. On my current motor, I maxed out the afm by 5K, with my shitty exhaust and ported stock intake manifold.

But good luck anyways. I cant wait to compare dyno graphs with you.

 

message to the guy who started the thread, though I havent read all the posts, i basically skipped from your first post to the end of four pages, you said you based some of your port ideas from pictures you've seen on the net from respectable engine builders (ie racing beat act.) note that these companies are not going to show actual porting templates when they have had to probably build many motors with many hours on the dyno to come up with the final product. just advise i was given before my first s4 port job. I work for mazda as an apprentice and have a rotory guru in the next bay. He has over 25 years of experience and he helped me through my rebuild.

Its always a good idea to have a proven template when porting these motors. I know you want to design your own but your theories in porting have already been tried somewhere by somebody. Some fail some rip, its nice to have a that rotory that for some reason just rips, experience will get you there.

mazdaspeed7, ive read many of your posts, im curious to see you dyno charts if you have them yet. I currently have a 87 n/a, streetport w/ ported t2 rotor housing, racing beat header, my own fabbed exhaust- single 2.5', conical airfilter, 1st gen tranny with miata internals, lightened tilden flywheel and hipo clutch, removed p/s, air pump- acv. I am currently altering a spare s4 intake in which i have eliminated the aux port actuators- rods sleeves ect. i tapped out the sleeves where the actuator rods go through and put 8mm bolt in them, then i ported the intake extensively. MAZDASPEED7, your the only one here who both knows what theyre talking about and are for this type of mod, through your experience, would this mod decrease my driveability to an unexceptable level, i know hp would be way up ( my actuation doesnt fuction- no backpressure) but im apprehensive about installing it because its my daily driver, any suggestions????

 

ps i realize you have s5

 

i also left out the fact that i was going to upgrade to a t2 fuel pump and 680cc injectors.