Brandonien

iTrader: (2)

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

Brettus

iTrader: (2)

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 .

Brandonien

iTrader: (2)

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*)

paulmasoner

iTrader: (1)

FTFY

Brandonien

iTrader: (2)

^_^ 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...

terch1

iTrader: (2)

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

MazdaManiac

iTrader: (3)

"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.

Mawnee

You just need a cam with a low LSA


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

arghx7

the novelty wears off, I promise

Brandonien

iTrader: (2)

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 *)

Brandonien

iTrader: (2)

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

Mawnee

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

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

Brandonien

iTrader: (2)

what did you do to your renesis exactly

Mawnee

This

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

Brandonien

iTrader: (2)

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...

Mawnee

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

Flashwing

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.

Charles R. Hill

iTrader: (7)

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.

Nemesis8

iTrader: (3)

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
bump it up to 720p also...

Brandonien

iTrader: (2)

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! >: }

Brandonien

iTrader: (2)

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

Brandonien

iTrader: (2)

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

Flashwing

https://www.rx8club.com/showthread.p...bridge+porting

bse50

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.

Chad D.

iTrader: (19)

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.