Best porting for consistent 3:3 cyclic misfire on N/A Renesis
 

OK so like the title says, I'm looking for either an educated opinion or an opinion based on personal experience about which kind of Porting will achieve the most stable and consistent 3:3 cyclic misfire on an N/A Renesis 6 port engine...
So yeah I'm going for that sweet sweet Brap Brap Brap! It's the main goal, performance gains are just the bonus in this case...


For anyone who cares or incase it makes a huge difference I'll list my mods:

-Exoticspeed 3" High Flow Catalytic Converter
-Borla Exhaust
-AEM Cold Air Intake
-Act Xact Prolight Flywheel and Counterweight
-Agency Underdrive Crank Pulley
-Cobb AP w/ Race Tuner
-Stainless Steel Clutch Line and Brake Lines

And I will be working on initial engine run in as I'm currently getting a new engine and transmission under warranty from Mazda.

Thanks for your input and time guys! Always lots of great info to be had from this group! :P

Have only ever heard a bridgeported renesis do the brap brap thing once and it was not nearly as marked as what you are probably wanting to achieve .

with that coming from you, I would be fairly confident with that knowledge.
so this brings up another question, I've heard of 1/3rd, 1/2 and full bridgeports, which one(s) would best achieve this :P I'm getting a port done either way, just trying to see if I can gain a better understanding of what to ask for exactly. Of course I have to wait for the spring, and for Mazda to give me my damn car back... (*grumbles*) and if I do get a bridge of some sort perhaps I can ask for a specific angle for the intake and exhaust ports instead of leaving the guess work up to the last minute.

So I guess I need to figure out the optimal amount of degrees of overlap and just how much earlier I want the intake to open and the exhaust to close :P
By the end of this I would like to have a nice thread giving newer or veteran (*which I am not*) 8 owners some info on what an ideal setup for this is ^_^ cause lets face it, its a sweet sound and I'm sure lots of people love it... (*but I bet most people are more worried about the gains then the sound :S*)

FTFY

:boring:

^_^ well, I happen to be the dumb one who likes to do dumb things, so on with the topic!

And thx for the fix! :P I'm not sure which complications to expect but meh... I'll live, I can tune the ecu at least instead of trying to make it run on a stock map... :S And I'll get any of the supporting mods before I consider the porting :P No point in getting ahead of myself and F***ing up my car...

Dude whats up with all the little characters ^_^ :P :S *)
Your post looks like it was written by a 12 year old girl! =/

"brap-brap-brap" is not "3:3 cyclic misfire", or whatever you meant by that.
There is no "misfire" involved.
It is just idle instability, cause by low air velocity.
If that is all you are looking for, just gouge a small trough in both housings directly opposite the spark plug holes.

You just need a cam with a low LSA :D:


Man, I've spent the last hour searching for a vid someone posted here of an old Rx7 with ported engine. That car sounded wicked! I will find it!!!

-edit found it!

http://www.youtube.com/bdc196#p/u/76/5sAHlRGHj5Y

the novelty wears off, I promise

http://foxed.ca/rx7manual/manuals/RE...amoto-1971.pdf

somewhere in there is the explanation of the 3:3 cyclic misfire where the intake has enough vacuum pressure to pull some of the exhaust back through its port (*during overlap*) to mix with the intake just before it closes, this happens on all three faces of the rotor, which causes the intake to be too diluted by the exhaust to ignite, so all three faces misfire (*or rather the sparkplugs spark but can't ignite the mixture*) now with the mix of fresh fuel/air and exhaust being pushed out the exhaust ports the same thing happens, it pulls some of it back in and mixes it with fresh air/fuel which does fire, causing the unstable idle... Thats the best way to explain it I've found so far, and really this is my summer car, and I plan to keep it as my hobby car, so messing with it is kinda the point

And I like my smiley faces :P I'm an infanteer in the Canadian Armed Forces with combat experience so if you wanna call me a little girl by all means, just don't say it to my face >: ] (*but seriously I don't give a c**p *)

Mawnee! You win, thats the EXACT kinda idle I'm going for...

I wish I could have made my rx8 sound like that. I ended up with this:

http://www.youtube.com/watch?v=0NuSJmiRxLU

and then i gave up and went back to this :D:

http://www.youtube.com/watch?v=Wpp3xkDpMYM

what did you do to your renesis exactly

This :)

https://www.rx8club.com/showthread.p...ghlight=Mawnee

ahhhh interesting indeed.... well I'm chatting with 2 of three shops in Ontario that specialize in porting rotaries and they are all confident they can get it to do what I want, but they are all so skeptical about it and keep trying to convince me to streetport instead... saying it will rev like a race car and have poor idle and such, but um, THATS THE POINT! I really hate not having the resources to do this stuff myself, I would seriously rather destroy a few engines myself and get a sweet template out of it and start porting for people in canada myself, but that will never happen, so back to arguing with the shops I go

PS: is it SERIOUSLY as bad as they make it out to be driving a bridgeported renesis...

Go for it! And keep us updated with the process and results :)

There have already been attempts to bridgeport the Renesis which have been documented on this website. I would research them and note the outcomes before spending your hard earned cash.

After that, I would follow your shops' advice.

Remember that a race car is not a street car. The two exist in very very different worlds.

Have they actually attempted porting a Renesis, as opposed to being only familiar with older 13B's? The Renesis/RX-8 has presented many different challenges to those who have only dealt with FD's and older.

Besides, a shitty idle (a "lopey" idle, although attractive to some, is not desireable) says nothing about the potential horsepower generated by any engine. Even with piston engines, modern technologies involving airflow allow them to develop all the power they used to with a much smoother idle and a smoother/wider torque curve than previously attainable.

Several years ago when I first rebuilt my own Renesis I analogized the Renesis as being the "LS engine of the rotary world" and I still believe that to be the case.

Here is a street port idle

http://www.youtube.com/watch?v=IDzon...er_profilepage

turn up the volume at 47 sec and back down at 1:38 :p:
bump it up to 720p also...

hmmmm well now I'm starting to see some familiar names! :P ok, so I'm not overly concerned about the drivability of my 8, I've driven in a stupid modified Tiburon with a stage 5 clutch and crazy lightweight flywheel.... While interesting, it doesn't bug me... I just drove my car for over a year on one rotor, FINALLY got mazda to fix the damn thing, so poor drivability is a nonissue I'm just concerned about the reliability of a bridge build (*although the street port is starting to look like a fair option :< *) and I have a COBB AP so changing idle, timings, and fuel maps is also a nonissue (*the shop said they would help with that anyways*) besides I'm sure a nice bridgeport will help when I do get a supercharger for this engine (*probably gonna wait a fair while on that mod :P*) I would also be getting the 3mm seals while I get it ported

unless anyone has SERIOUS beef or can bring up a persistent issue of reliability in a bridgeport then I'm getting one this summer (*going down to the shop on my march break to see some of their cars and how they run, sound, feel, operate, the likes. Get to meet the mechanics and what not too*)

PS very nice video, great quality for what it's showing
worst case scenario I will have a lovely under 5K bridgeported engine for sale! >: }

and please tell me I was right to call it 3:3 cyclic misfire... I'm 90% sure I got that part right...

I've also read almost all the threads on this site and quite a few others about porting now and I know I'm a little excessive, I like solid facts

A bridgeport will potentially cause a lot of reliablity issues. There isn't much space to do it right and your engine life is going to suffer from that anyway.
We have got plenty of intake surface but little exhaust ports, why would you want them even larger with any form of FI if you can't exhaust the gasses properly?
Trading velocity for volume isn't always as smart as it seems. It's easy to destroy our relatively flat powerband to gain maybe 10 peak hp,while possibly losing twice as much everywhere else!
Also keep in mind that a good port job doesn't focus on just removing material, you also have to add some to smoothen up the curves.
Of course if you're happy with a car that underperforms and drives like crap all that we have just said is plainly useless.

Streetport it dude, bridgeport will kill it. My car sounds like brap, brap when the plugs were fouled, that's all, and I have a custom streetport on my renesis. If you want a real brap, brap, bridgeport a 20b. :)

*sigh* it's starting to look like streetport is the way to go, I will however ask lots of questions about it at the shop in march and make my final decision then... however even without the bridge port, if you scalloped the other side of the rotor and did a fair size street port and cleaned up the exhaust well enough, would you not get enough overlap to achieve this effect?

Are you aware of the fact that Mazda spent a lot of money and time to create a 0 overlap engine to increase performance?
A little porting works fine but you'll never achieve what you're looking for.

I would be very concerned with side seal failure on a bridgeport. The exhaust ports put a lot off stress on them already...

With all the increased port volume of both the intake and exhaust on the Renesis when compared to older rotaries... There is just no comparison.

http://www.rotarydevelopment.net/Rot...790_Rotary.pdf


Not really trying to dissuade you, but it just seems silly to do all that just for some noise.

Your trying to reinvent the wheel. A street port is good, however you are limited on how much you can do on the renesis. The rotors are already scalloped from the factory, and the more you do this the more you will lower the CR.

You need to find a good engine builder in your area and work w/ them on your goals. Just posting random ideas will not get you very far.

I don't think you will get the "noise" you are looking for.
I am including a (amateur) sound clip I took with my phone when I got home, car is warmed up, properly tuned. I only sampled the idle, cause my leg isn't long enough to reach the pedal from the back of the car. Keep in mind it did make my car a bit louder.
click on the pic.
http://vid848.photobucket.com/albums...h_MOV00081.jpg

A guy named Joe in Toronto ported my msp. He also nitrided? and installed NRS apex seals.
I'm getting a newer 8 very soon though. I will probably get it done again.

I'd like that cool Crip walk thingy I've seen, it seems very stylish.

How can I get someone to shoot me in the leg? I am not concerned with bleeding out or any long term damage since I don't walk very far, I just want that cool cool Crip walk....

:suspect:

Kane, I can help you...and when your leg is dead, I'll replace your leg with a reman, and we can do it over, and over, and over, until you run out of money, then you join the bloods.

^^^ Good one....

...O_O crip walks? not fun.. :P either way, I'm going to the shop during my march break to start figuring this out, I assume the shop your talking about is RPM Fine Auto in Pickering?

RPM. Look into any other mods you would like done while everything is out and apart to save some dollars.

seals for sure... if youve dealt with them before whatelse can you suggest

:dunno: It's a preference thing. I'd get it done in Detroit next time because it's local for me. When I do it again on my new car I will install ceramic seals again + a sohn adapter with nicely run braided lines and paint the block while it's out. I'd install a race header when reinstalling the msp.

Just try to avoid those "I shoulda" moments. Try to save money spending money, you know?

:P thats the point of asking all this first!

:bubbrubb:I thought you wanted the loud brap brap to wake the neighbours.

btw, if your car looks stock it'll just sound broken.

Hmmm are you guys talking about me? I'm Joe Ferguson, I used to run RPM Motorsports in Kitchener.
I'm a full time Porsche/BMW mechanic now but I still have a small shop on the side where I build/port Rotaries.

I'm going to be working with Dave Pratt from Modified Mag on a Renny build for his RX-8, he's documenting it and will be a tech article in the mag for a few issues.

I also have full bridge ported a race engine for a customer out in Halifax using RX-8 rotors, I had to design and develop my own RX-8 bridge porting template because no one else does it.

there is your answer for a bridgeported rx8.

Hey Chad, did I work on your car before? I cant remember lol.

Hahaha I'm still pretty reasonable, my shop is small and I do this sort of stuff only in my spare time. Most everything I'm doing at my shop is project stuff, so the owners dont mind it taking a while to get their engines or cars finished.

Here is a build thread about the race engine bridge ported and using Renny rotors

http://www.rx7club.com/showthread.ph...ht=bridge+port

Here is a video of it running:

http://www.youtube.com/watch?v=IMev7...layer_embedded


Other pics of porting:
http://www.rx7club.com/showthread.ph...ht=bridge+port

The internetz are slow and I think I deleted a post instead of editing.
That car sounds mean. The build looks great/
I will have to contact you when I'm ready to put a 13b in my Austin 1100. I really like the weber's used. That'll be in a year or two.
I've submitted as much as I can in this thread. I'm out.
I'll hit you up someday on the 7club Joe, I have the same name there.

How long have you had the bridge ported running? What sort of power did you make with it? Did you keep it NA? I'm pretty curious what sort of power the MSP can make NA with a bridgeport. I haven't seen any dynos yet.

He said bridgeported race engine running rx8 rotors, not a 13b msp with a bridgeport... :)

well if I can't get it to run reliably then a streetport makes more sense, but yeah the noise would be a bonus...

Yeah sorry, the bridge ported engine I built used FC turbo 4 port irons and peripheral exhaust ports.
The internals were Renny parts.

But because of the location of the Renny sideseals, a normal bridge port template wont work, so I had to make my own.

Brandonien - pickup a cheap used Renny engine, I've seen a few running engines for less then $1000. Lets tear it apart and bridge it. I have the porting template for it.

:P I'll get the streetport and seals done first then I will get my hands on an extra engine! (*so I'll take you up on that offer in say a year, being realistic*) It's something I will definitly be trying to pull off at some point, although the next engine I want is that damn 16x when she comes out... and I'm saving for it already... hehehe I WANT

There's a couple shops that bridge port them... There's just not a lot of demand because it's unproven just how beneficial it is... if at all.
http://tnhangout.com/images/DSCN1443.JPG

Maybe I'll have my motor together soon, and I can do some dyno testing.