I made my first attempt at porting my engine tonight. I started on the primary port. I followed a few basic rules of porting that I have found from a few sources:

Short duration makes torque and gas mileage,

Gradual opening and closing makes a broad power band,

Shape inside the bowl is VERY important, must be smooth.

So here is my interpretation of the rules, a primary port with slightly earlier opening and later closing timing, very smooth curves defining these events, and of course, the "free" port area found by grinding down the tail and inside of the port, which do not affect timing. Of course, my secondaries and sixth ports will be more radical. I don't need the gas mileage or torque above 3800 rpm as much as i need air/fuel CFM. Hopefully my RB collected header is timed for around 4000 rpm.

Before:






After 1 hour of grinding with a die grinder and dremel:






What do you think?

 

did you use a template? What works better, a die grinder or dremel? I'm considering doing the same to my engine.

 

Both have their advantages...

I use a die grinder for the bigger work and then the dremel for the edging of the port opening.

There's commonly availible (white in color) ball shaped fine grit stones for die grinders, which work beautifully on the port runners. Smaller bullet shaped stones work good for the opening.


One thing that bothers me about your porting on that housing is the inner shape of the eyebrow. It looks like you cut into the oil contol ring travel surface. Got any close-up pics?

 

Yeah that does look pretty close.

 

sorry to sound retarded but... is that a hole in your port?

 

hahahaha Colby, your eyes are not working right or something...

Actually, that is a hole in the port. Thanks to the good old federal govt! Thats the EGR port.

 

Ahh, that would be the reason. My S5 has nothing that even resembles that

 

`Cause they moved it into the intake manifold.

 

Yes, I cut into the oil control ring track. This housing is not going into the engine (that was a mistake). I was testing my aptitude to use the die grinder and dremel, and was looking to find the water jacket (but didn't) that I hear so much about with NA center housings. I came to the conclusion that with the stock NA housing, I have enough iron to do the mild porting that I want.

And no, I did not use a template. I freestyled it. I used the die grinder for rough shaping and the dremel for final bowl / roof work. And I didn't find myself wanting any carbide burrs. Basic stones did fine. I did outline the desired port before going for it with the tools, however.

 

I'd probably use a better template, and something better to mark the port... like an awl or something that will give a HARD line

 

Close-up of the after one is what I wanted

I did mine total freestyle. Made a couple alignment marks to keep them even but pretty much just sat down and made them happen.

I have the original broken intermediate housing that I'm going to try playing with for future reference as to what can be done with them. I intend on grinding a port into it and then if I havent broken through the wall yet, drilling to see how much material is left. I'll be posting pics of that when the time comes.

 

Here you go:




Neither pics show the oil wear track too well but I am sure you get the idea. I cut in too far about one MM. I also let the die grinder get away and take a walk over my one layer of duct tape protecting the housing, and it left a mark. Mental note: use 3+ layers of duct tape to protect the immediate area around the port!

So . . . you would use a "better" template? Like the actual port shaping and size or just the means of marking the line? I don't get what you are saying (ie. how would you improve this port aside from the oil seal track issue?).

 

Just a couple pieces of advice.

The air going through the runner should be like a ski jump going into the chamber. The rounded edge does nothing for flow and occupies space which could be better used for flowing air.

the oil ring line is just for reference.

 

Thanks. I was thinking the same thing about the inside bowl where it was too rounded. I appreciate your help because I have no mentor in this and don't trust the RB templates because there is no one right way to port an NA . . . RB seems more into the four port engines anyhow.

The Racing Beat template does match your port timing better than mine, though, and closes about 10* later than stock. I was shooting for about 2* earlier and later with very gradual opening / closing. But if that timing gave you the torque you wanted then I may as well go for it.

I owe you a beer.

 

Beer is gross. Jimmy + =

That's also a pretty rough scetch and those lines are primarily for educational effect. I actually layed out the ports with the rotor mocked up on the housing and measured everything out (put little scribe lines like colby said) where the begining and ending went. Side housings are much easier as you can only go up to the aux ports before you have to stop. lol Then the aux ports are pretty free style on mine. I did all I could to enhance the escape route of the charge from the port runner and still make the sleeves function properly.

Somewhere they have the port timing degrees all layed out. I used that to increase the primary durration to 2 fingers wide. (hey this is still a secret port design here)

 

S5's actually don't have any EGR.

 

Im pretty sure the US S5 has a egr

 

I'm pretty sure you're wrong...

The place in the intermediate housing where the EGR is supposed to be is solid metal.

 

Didn't anyone see this

 

EGR is also accomplished through the ACV plumbing. Just because there isn't a dedicated EGR valve doesn't mean the system is not employed. Some cars didn't come with them. This was debated by some of the same people here in this thread something like, oh, 7 months ago... C'mon guys lets keep some of this info in the long term memory shall we?

 

Well... my S5 doesn't have any form of EGR.... :P

Doesn't mean others don't use the ACV to do the same function as the EGR; reguardless S5's don't have an EGR, and my S5 doesn't have an EGR/ACV hybrid either.

 

The rotary engine, with stock ports, is so naturally high in exhaust gas recirculation anyways that it makes you wonder if EGR was more of a concession to the USA's emissions politics than actually there to reduce NOx emissions. The new renesis, on the other hand, which has no overlap at all, may need EGR . . .

 

well, with you extending the port down so far that statement is probably true at low revs.

In all honesty, the mark I made for the bottom of that port is nearly dead on for my motor. Mine is aligned with the top of that bolt hole and another mysterious point on the other side of the engine. Low rev overlap isn't significant but does effect the power below 3K.

 

I extended the top of my primary port and worked on the bowl's problem areas. I went a little bigger with the closing timing than I had originally planned but still have some metal between the bowl and water jacket:



Checking this port with a rotor on the plate, I found that the port opens abruptly but closes very gradually. Blowing into the runner with compressed air showed that the port directs airflow up and toward the combustion chamber, which would be moving away from the port, around the inside of the housing.

Looking at my end housing, I surveyed the situation with the secondaries and sketched my plan:



There is much less material to remove for the secondary / sixth ports. Porting these appears to be more of just cleaning up the sleeves / bowls and opening the ports a tad. I am planning on grinding down (to a ski jump shape) the pineapple sleeve "wedges" when I get around to sending away to get them.

Musing at the end housing brought thoughts of forum member Von and his self-titled "godzilla port". Judging by his reports of having no power at 5-6000rpm, I surmise that he removed his sleeves, removed the barrier between the primary and secondary port, ported the primaries to the limit of the corner seal and water jacket, and did the same with what was left of the secondaries / sixth ports. This would produce an extremely radical closing timing for any kind of idling below 3000rpm and negate any low end torque the engine could potentially make. In an engine configured like that, the main restriction would then be the intake manifold and throttle body / afm. Imagining how low the intake velocity would be at the port openings makes me almost laugh out loud.

 

Grasshopper, You are learning.

Most of the work in the end housings (per my design) is done in the runner of the secondaries. The aux opening needs to be ported with consideration to the sleeve which will effect how the air moves through the port. You can extend its timing a little as well.