StealthTL

iTrader: (1)

Porting a Renesis will never yield full potential until the apex and corner seals are redesigned. Anyone who has seen a Bridgeported engine can see the problem.

The problem is the seals' design lets them move when they pass over the ports - they are held in place by the wall of the rotor housing. They need to be held in place, so that the sideports can be enlarged to their full potential. No streetports, no bridgeports, just huge gaping sideports, as large as theory allows.

The apex/corner seals could be held with pins or redesigned to stay in place, and the little side seals of spring steel could be made as one-piece triangular assemblies (didn't say it would be easy!), but once the seals are prevented from exiting the motor through the exhaust port, then we can get some serious porting results......

Am I out to lunch, or just drunk again?

S

gh0st

even if the port surface area can be enlarged, the internal passage is still quite limited without puncturing the water jacket. we need someone to do some flow bench testing.

chickenwafer

iTrader: (9)

^ I heard that too. The internal passage of the intake port passes very close to the water jacket for the liquid cooling system. It's the exhaust port that has the most potential, in theory (after looking at GuitarJunkie's thread......)

TeamRX8

iTrader: (25)

put down the bottle and step away from the booze please ...

mike1324a

Its the exhaust ports that need the most help anyway.

Nemesis8

iTrader: (3)

There is plenty of intake area for forced induction. I say redesign the intake manifold and get rid of all the actuators. Who needs them if you have a blower on that sucka

rotarygod

You really need to compare the stock Renesis intake ports to even a large streetported 13B intake port. You'd be quite shocked at how large they are on the Renesis. A 13B only wishes it could get that much intake area without a bridge. I see no reason to make the secondary or auxiliary ports any larger than they already are. The primary port can be closed a little bit later bit that's about it. Mazda gave you just about all that you can get.

The exhaust ports do need the most work. I did not agree with Dave's (RIP) exhaust porting style as there is no excuse to hit water. From looking at his pictures I suspect he didn't actually go into the water jacket but rather confused the edge of the exhaust sleeve for the housing. His pictures seem to show the sleeve being welded to the housings rather than a patch job. Overall I wasn't happy with his exhaust port shapes. They could have been much smoother. There still isn't a whole lot you can do to the exhaust port timing anyways but there is work that can be done that can increase flow.

Unlike previous rotaries, don't expect too much more power from porting. You'll get some but the overall percent gain will be very low compared to previous motors that still had so much potential left in them. Proof of this is in the horsepower numbers between the Renesis and the older engines. You've already got stock what most of theose engines only wish they could get and you can do it far more cleanly.

rotarygod

I both agree and disagree with this. It depends on what type of forced induction you are using. If you have a positive displacement supercharger, it is always moving air towards the engine. You don't need to rely on intake velocity like you do on a naturally aspirated engine. If we are talking about a turbo or a (god-forbid!) centrifugal supercharger, then I'd keep them there. When a turbo isn't under boost, it is the intake manifold that is tuning the engine to run. For a turbo I'd actually run longer intake runners. This would help make more low end power when not under boost. The more low end power you make, the more energy you have going out the exhaust which will help spool the turbo up faster. If you have a short intake runner, you will have less low end power which will hurt spool times. Many don't think about this.

Nemesis8

iTrader: (3)

Yep - twin screw was my thinking, since that is the only sc for sale at the moment -

MadDog

Your wish is my command... sort of. Here are the stockers primary intake ports.

EDIT: removing FUBAR

rotarygod

Stealth's picture is of a 13B bridgeport.

This really does show how much larger the ports are in relation to each other. The Renesis side seals are moved outward slightly on the rotor so they can get more opening. It is possible to open the 13B intake ports earlier than they come stock but still not as far as the Renesis port open. You can clearly see that the Renesis intake port closes later too. On a streetported 13b primary you might only get out to this timing level. Maybe slightly past it depending on your casting thickness. The Renesis primaries could be closed a little bit later still. They are some pretty large ports.

Lasse wankel

I think i have posted here before the intake and exhausts flow of the Renesis engine. But of course i can post some numbers comparing stock to stage 1 once again(only reshaping and smoothing out the ports). What i can remember so was overall gain approx 8-12% more flow after reshaping.

/Lasse

brillo

One of the great things about 7stock was the ability to compare the 13B housings to the Renesis. You can really see the difference in port size and design that pics don't do justice.

Frankly, porting to me for the Renesis would be the last thing I would do, unless I just had a motor sitting around I wasn't using. For the money and time, your better off throwing on a lightweight flywheel and a mid pipe, if you want some power you can feel.

I'd like to see what cleaning up the exahust port design might do at some point, but frankly I'm not expecting much. I wouldn't port the intake side at all, the only thing I would do there would be to polish it.

knonfs

Would love to see a semi PP intake and a semi PP exhaust on a Renesis engine

rotarygod

Strangely enough I'm against that idea. I feel that there is alot more to zero overlap than people think there is and that we haven't fully exploited it yet. It could be a good experiment though.

Ice Cold RX8

Exactly what is the restriction in the exhaust sleeves? Are they simply too small? Also, do we have the restrictive sound diffusers in our exhaust sleeves similar to the older rx7 6 ports? What can be done here to gain more power and why hasn't anyone really tried yet? Any pics of Renesis exhaust ports?

rotarygod

The Renesis exhaust ports just have a terrible transition from port to runner. They go straight in and then quite literally make a 90 degree turn out of the engine. There is no gradual bend. It's a corner with an edge. Not good. The port runner in the sleeve is actually larger in area than the port opening itself. I feel that it's too large and needs to be made smaller. However the main focus should be on the port to runner transition point. This really needs to be addressed in some way. Only after that gets taken care of does the runner volume need to be messed with. This may sound easy and straight forward but when you look at one up close, it's not as easy as it sounds. That probably explains why they are done the way they are.

diabolical1

unfortunately i have not yet had the opportunity to get a Renesis to pull apart and play with, so forgive me if it's not something that can be done, but what if one were to bridgeport the exhausts only? i mean for street applications, might that help get more exhaust out without upsetting drivability and fuel economy too much?

Renesis_8

A thicker intermediate plate would provide some space to mess with. (more weight tho) They could make it semi hollow, think brake rotors.

And about smoothing the edges of intake and exhaust ports, is there anyway Mazda can do it on a production engine?
________
Virgin

rotarygod

Do not bridgeport those motors. The ports open too early to do so and the bridge will be too thin. It'll break or you'll lose a corner seal down a port.

diabolical1

nuff said.

dastallion951

well jus as a thought about portin to make it simple i think that someone, should design an individual throttle body setup......... use a map sensor which coudl be a challenge in it self to get it to work with our pain in the A$$ pcm....... clean up the intake ports a bit....... n then clean up the exhaust ports to flow better, but i only recommend this to someone with a flow bench, n enough time and money to **** with a ITB setup..............im down in my free time to help out if anyone else is.........

neit_jnf

how bout aux port bridge? didn't Ito do this and got a lot of top end?

dastallion951

that is a good point neit although mazda did a good job of tryin to flow as much on the exhaust ports, from what i read that ports r very jagged you have to try n clean up the ports as much as possible but other then that theres not much left on n/a power from this exhaust port design........am i right

rotarygod

People on the 7forum have been finding out for years that this doesn't work all that well and unfortunately haven't learned from past mistakes and still try it only to hate it after the fact. It just doesn't work all that well. Besides, the whole point of a bridge port is to introduce overlap that will help scavenge at higher rpms. Even with a bridge on a Renesis, port overlap will still only be about what a stock 13B has. Pretty close at least. There isn't much flow through those little ports and it's only overlap that helps pull air through them that causes them to flow anything appreciable.