Howdy all, as some of you may know my motor just **** a seal (side seal) so i'm obviously about to start rebuilding it and of course will be porting it while it is out.



So i'm here looking for some ideas about what porting I should do to it. Keeping in mind that I circuit race this car every month(when its running that is https://www.nopistons.com/forums/pub...IR ) and this motor will probably end up being turbocharged again in the near future, but we'll leave what turbo i'll be using out of the equation for now. I've heard that big streetports can tend to be rather peaky even on a turbo motor, so I was thinking about bridgeporting the 6-port housings, having just had a very quick look at some(and being a porting newbie) i can't see any reason I couldn't do this?



I was thinking about running the bridge on the secondary port (not the aux port like everyone seems to do) now i know this will create some more overlap, that doesn't phase me to badly, i'm after mid range and a good (not peaky) power delivery.



So guys, I need some ideas, what would YOU all do?

I wouldnt do it. Tuning is a pain in the ass, and you will need an intake manifold with individual runners for each port, and a standalone to get power from it. I wasnt very happy with how my aux bridge motor turned out, and am now running a big SP.

Yes, You are definately going to need a standalone along with some other mods if you ever want to see the maximum output of that engine. There is no way that the stock ecu could ever handle it.

unless u are gonan modify your EFI and get new intake manifolds bridgeportign shoudl really be left alone on your otherwise "stock" car. if u want to do anythgin just bbridge the aux since that wont affect your idle if the 6 port sleeves are still in place, i have yet to dyno teh resulsts from such a ported motor. this car will be on the dyno shortly and i will post results asap.



anything bigger then street port would rreally suck for teh street to have a civilized car, unless like mazdaspeed said u get the standaloen and the mani.

I just pulled my aux bridge motor out. I wasnt happy with how it turned out. I NEVER got it to run right with the 6 ports open. The past 15K miles were spent with my 6 ports wired shut. You will need individual runners to get good power out of an aux bridge motor. The HUGE difference in port timing between the 2 ports on the end housing will cause interference since they share the same runner with the stock manifold. That will severly limit the power of an aux bridge motor. Youll need a seperate runner for each port, and the runners for the 6 ports need to be considerably longer to be tuned for the same RPM.



Kahren, tell me about your setup, and how you plan to address these issues. I could help you out, if you like. Ive thought through whats necessary to make it work, it just wasnt worth it to me to go through with it. Im much happier with my SP engine I put in on thursday anyways.

Adam; you're saying you don't think it's worth the time/effort to Aux-Bridge an engine when running the stock manifold?



Even w/ a standalone, the stock manifold is enough of a restriction to not warrant the BP?

Thats EXACTLY what Im saying. First, the manifold sucks. The runners are too long and narrow. Second, the pulses from the bridged port and the non-bridged port will interfere with each other since they share the same runner. That makes an already poor flowing intake manifold even worse.

Thank you all for your replies..



I already am running a microtech in my car and I will be using a different inlet manifold (quad throttle body setup actually) with short runners.



Now I was more interested in if there is enough 'room' to actually run a bridge along the secondary inlet port (and possibly the auxillary one aswell).



If I did it I would do the center plate aswell.



So, has any bridge ported not just the AUX port but the normal secondary port?

Judge Ito built a motor like that. From what I heard, it was making good power, around 250 or so. That car ran with a modded TII, and I think it was wrecked before it was dynoed or taken to the track.

you are CORRECT! https://www.nopistons.com/forums/pub...DIR#>/ohmy.png https://www.nopistons.com/forums/pub...O_DIR#>/11.gif

Don't suppose that Judge Ito would have anything else to add to this then?



I'm very seriously considering doing a BP, I have a few spare irons I can practice on, i'm just after some info on wether the side seals will survive, and how big I can make the extra bridge port.



250hp at the wheels i assume? was this with S4 or 5 rotors? and at what rpm more importantly?

what intake was he using? quad throttle setup with short runners?

If you bridge both of the ports on the end housings, you wont run into the interference problems I mentioned earlier. Thet was pertaining to an aux bridge motor. If you bridge both ports, you will have *more* port timing than a PP. The powerband will be VERY high.

I think I recall you saying something about the bridged-aux. problem having to do with the VDI. Any idea if this would work at all for an S4, or would there still be major problems?

The VDI makes it worse, but ANY manifold that doesnt have seperate runners for the bridged and non-bridged ports will have problems.

ok, thanks https://www.nopistons.com/forums/pub...IR#>/bigok.gif

wasnt that ito built engine running on stock ecu and stock manifolds and making good power?



It sounds to me that mazdaspeed7's statements about the need for seperate runners for every port and it not working well with the stock intake is speculation. It seems like there is proof of it working well enough to make good power. (some people have reported the AFM being a limitation, so perhaps just a standalone or some clever electronics is all you need).





Vosko, if I remember correctly, you knew the person with that car ito built the engine for. Can you provide any details about the setup or estimated power output? Mazdaspeed7's engine was probably capable of great power, I thought he just had issues with the S5 ecu being a limiting factor. This guy has a standalone.

i think that the s4 intake works better once you port, while the s5 is more tuned to the stock ports. itos car was s4



mike

Wellll........



I won't be using either the S4 or 5 inlet manifold, so that doesn't matter to me and the bridged/non-bridged inlet runners 'interfereing' with each other doesn't sound quite right to me.



I can't see the porting timing being too far off of a radical 4 port style bridgeport? as I wont be changing the closing timming of the port, just the opening. So it'll be like a 'normal' bridgeport + ~20deg. longer duration? which is no where near aslong as a PP? no?



Either way I might try this combo out, just looking more about side seal wear, as there doesn't seem to be much iron to be able to take away in that area, so i'm just looking for some tips about bridgeporting basically.

It is speculation, but not a shot in the dark. Everything I know about fluid dynamics tells me there will be problems. It may make decent to good power, but the potential of the port will NEVER be realized with is sharing a runner with a non-bridged port. I know the ECU was a major limiting factor in my motor, as well as the intake manifold, and the exhaust. Also, I think you can get as much hp out of a good SP, and have less issues to deal with. The bridge is very small, so the gains wont be very large.



My aux bridge motor is getting a weber and being dropped in a SA. I cant wait to see that run.

the car judge ito built was running stock EVERYTHING, full stock exhaust, ECU, AFM, EVEN AIR BOX and it kept up with a S5 T2 with dp,hiflow cat, catback and intake and rebuilt engine....the T2 is a low 14second car..... that car was FAST... i saw it in action a few times and i have driven the T2. i was supposed to drive the N/A but never got a chance

thanks https://www.nopistons.com/forums/pub...IR#>/smile.png

an engine is only as good as it is put together and all its supporting hardware

That car also had all 6 ports bridged. So the runner problems I mentioned time and time again were not an issue.

the man is a genious what can i say https://www.nopistons.com/forums/pub...#>/biggrin.png

correct, if you watch the video the car braps away at idle. I have seen just aux-bridged motors that do not idle like that car did in the video

i couldnt edit my post from above because my mind to so damn slow.



I dont believe that the white FC that ito built had stock exhaust, considering that the thing idled so damn loud. Possibly a straight pipe/cat bypass setup.



I really like this thread, it has answered quite a few questions about the intake harmonics and flow dynamics of the FC that i have had in the back of my mind.

With a stock port motor, my true duals were barely louder than stock. Fast forward to my aux bridge motor. Same exhaust. My car was as loud at redline as my friends stock port S4 with RB headers, custom collector, and straight pipes. NO mufflers at all. Porting makes a huge difference in sound level.

i saw the car with my OWN EYES. it had two precats and a main cat!

gutted?

Well, personally I don't think these questions are answered yet... https://www.nopistons.com/forums/pub...IR#>/smile.png





Obviously, if you have individual runners for each intake port into the engine that shared a different port timing you would see gains, however my 6-port motor does not have the sleves or any other associated 6-port crap on it, these two runners combine a few inches from the engine, effectivly making them completly combined (WRT reversion anyway).



Now my car with these sleves gone did not loose much (IF ANY!) low end torque at all, however picked up alot in the mid/high RPMS compared to what it was like stock.



and the port timing is radically different between the Secondary and the aux ports. reversion(assuming there is some) does NOT seem to have an adverse effect on the motor at all.



ANYWAY, this is all a mute point to what i was getting at since, everyone with a sane mind will agree that if you made each inlet runner tunned length to the port timing of its respective port you will net more power.

However! what I was talking about was doing a bridge port on the scondary 'runner' if you will and not cutting into the aux port 'runner'. and possibly doing another small bridge on the aux port 'runner' but not interfering with the secondary one, after doing a little bit of measuring I think I could get this to work. Of course the aux port bridge if I did it would not extend far up since I don't want much, if any longer port duration.



Since it will be a turbo motor intake runner velocity is not as important either, smooth flow obviously is still though.

However, my fluid dynamics knowledge because rather hazey when it comes to fully turbulant gas flow so i'm probably wrong. https://www.nopistons.com/forums/pub...IR#>/smile.png

I'd really like to see this thread progress further. Especially from someone (other than Adam) with first-hand experience. I'm really wanting to do the standard aux-bridge, but as the time gets closer to start cutting away metal, I keep wanting to go back to the standard big-assed SP... https://www.nopistons.com/forums/pub..._DIR#>/sad.png

Mazdaspeed, what kind of custom intake do you envision would work well for a bridged aux port motor that still uses the aux. port actuators? I was thinking of a tubular manifold design with longer runners for the 4 main ports and shorter runners for the bridged aux ports. So six runners total running to a common plenum. Hopefully I could design the runner lengths to be appropriate for the port timing and redline.

Thats exactly what I had in mind, except you have the runner lengths backwards. The bridged aux ports will need longer runners to be tuned for the same rpm, because the port is open much longer. The bridged aux port will be the first to open, and the last to close, and has more duration than a PP motor.



Liquid, give me a 2 weeks to break in my SP, so I can give a full review, but even after 290 miles, I couldnt be any happier with my SP motor. No regrets about the aux bridge at all.



I have an Excel spreadsheet someone on RX7club did a little while ago, with my formula for calculating runner length, BUT, it wont let me attach it. The port timing for the aux bridge was from my motor. I measured it with a degree wheel before I assembled the engine.

Why would I want to tune both sets of runners for the same torque peek? It seems like with the 6th port actuators in tact we have an opportunity to have ram effects at two different RPM's, resulting in a flatter torque curve.

I saw your runner length calc. on the other forum. I love that thread. https://www.nopistons.com/forums/pub...IR#>/smile.png

I never said you had to tune for the same torque peak, but even tuned for different rpm's, the lengths of the runners will be considerably different. There is a very large difference in port timing between the bridged aux port, and the other non-bridged port.

What about something like this?

Here's a slightly modified version of my Uber-crappy pic in case there was any confusion about the runner layout.

Enjoy! https://www.nopistons.com/forums/pub...R#>/tongue.png

aren't the upper tubes for the aux's? shouldn't those be longer, according to mazdaspeed7?

aren't the upper tubes for the aux's? shouldn't those be longer, according to mazdaspeed7? [/quote]

Yep. He did exactly the opposite of what I told him to...

Ha ha! Who are you my dad? https://www.nopistons.com/forums/pub...DIR#>/wink.png

If I want the aux port runner to be tuned for higher RPM wouldn't I want it to be short?

I think I understand that they will be open the longest, but how does that relate to the time it takes for the wave to get to the plenum and back?