Bridgeport Pics
 

let me know what you guys think


1st. Partial bridge 4 port
2nd . Full bridge 6-port
3rd. 6-port primary. i know its dirty but i will clean it up also will rework the bottom bowl

Not bad, but i thought the bridge ports extended the length of the main runner?

nicely done

Its done that way so its a little more streetable.

http://www.teamfc3s.org/forum/showth...threadid=34458

:rlaugh:

Nice. We like bridgeports. :D

i know this thread is old, but i just wanted to bump it to see what people think about the 6-port pics shown.

just wondering how having a bridgeport on both the aux and secondary ports behaves?
do you need a custom intake manifold (or something like a IDA setup) to really make it work properly?
and what type of powerband are we talking about?

No, you don't need custom manifiolds, but I'm sure that there are gains to be had there. Also with a bridge on the primary, secondary, and aux... it is actually driveable. I used Devcon Steel Putty to smooth the end of the aux port inward so the air would not be hitting a wall and threw the sleeves in the parts bin. There is virtually no get up an go below 3000, but it's still a very drivable street car IMO.

I've never seen a primary port extended in like that, interesting.

thanks for the comments. i guess everyone has their opinions on what is "drivable", so it is hard to judge...but i guess you are saying if you keep the stock intake manifold, then the runner length is quite long so decent mid range should be kept. i'm basically trying to gauge if it is worth it to spend the money on a custom/IDA type manifold, which can get expensive with aftermarket ITBs.

also, what is the effect of bridging the primary like that? i know you can go pretty agressive with a streetport alone, so i'm trying to see if it would be worth it to bridge the primary...

i don't know if the original poster actually used those irons in an engine. it would be interesting to see what the actual results were (who knows if the porting is entirely reliable even)...

My opinion is that the stock NA manifold is totally unsuitable for a bridgeport. Bridgeporting RADICALLY changes intake port timing, which basically blows up all the tuning that Mazda did on the stock intake. When you have a port that never closes, you have a really hard time generating the pressure waves that the Mazda intake relies on to make it's power. :)

The effect of bridging the primary is simply a more radical port. The bridge on the primary opens even earlier then one on the secondaries, so idle and low end suffers much more then with a half bridge. The powerband moves up.

nice sig, good ole group 'x'

i was waiting for your opinion actually :)

yeah, i don't think i'm going to decide to do a bridge on the primary...i think the powerband might be slighty unreasonable for the street...i'd rather go PP at that point probably (my car will be seeing more track time next season).

now, what is the specific problem with the stock NA manifold? is the runner length out of whack? what i was thinking with the S5 manifold, is that when the VDI valve is open, the runner length is decently short. i could do TWO dyno runs, one with the valve closed and one with it open, to determine a new optimal opening point..

or is it a flow issue?

really the stock manifold would keep a decently broad powerband with a radical port on the secondary and aux, since the runner length is long AND the stock TB has progressive secondary plates...

maybe this discussion is for another thread, but i still haven't found a specific answer as to why the stock manifold just wouldn't work on a early opening, high overlap engine. is it worth the $1000+ for a custom/IDA setup?

:)

edit: btw, i am planning to build and put in a MegaSquirt (and spark)

ahahaha. someone please make a rx7 rendition of that song.

If the car was turbo, I would bridge the primary if you can handle the higher idle. Turbo bridgeports have no lack of low end.

The specific problem with the stock intake and bridgeports is that all of Mazda's NA intake are designed to rely on opposing pressure waves to force air into the currently open port (really simplified explanation). With bridges, the ports are basically never closed, hence these waves don't exist. The runners are also very long, desinged to maximize velocity at low RPMs for greater torque. For a bridgeport where it's powerband is much higher, this is a problem.

No, it is absolutely not worth the $1000 for the IDA intake. You can make it for MUCH less (my custom intake is nearly done, and not counting the throttle body, I have about $100 into it).

ok, the pressure wave explanation does make sense, although i think maybe with different porting you are just shifting or changing the effect of those waves, not completely screwing up the air flow. the stock manifold is after all just 4 intake runners still.
so you are saying that because of this, the stock manifold just doesn't provide enough air? you are implying lack of velocity to the ports?

i will however have to talk to you about that custom manifold :)
although i think in an NA application, it may be a little more complicated...

Bridgeports act much differently then any other type of porting. An unbridged port still closes fully and thus generates a pressure wave off the side of the closed rotor. This bounces through the intake to the opposing rotor and forces in more air. Because of the eyebrow port, bridgeports never really close so those waves are minimal.

Now, whether this is going to really matter is a good question. The S4 intake would be better suited since it lacks VDI. I'm assuming that the NA intake CAN flow the required air (after all, turbo-NAs with the stock intake make some good power :) ), but that the runner length and tuning are unsuitable for bridgeports. You generally find much shorter runners on bridged engines (the NA manifold runners are LONG). You could always use a TII manifold. Or make something custom.

My custom manifold is nearly done. It's not really more complicated making a manifold for NA vs. turbo, because both systems act exactly the same. What works for NA generally works for turbo. It's just that tuning the manifold can be more critical in NA since it's harder to get the power. With turbo it's easy since you just turn up the boost until you make the power you want. :)

I can vouch for the s4 na manifold being better than the s5 na for a na bridgeport. I had the s5 hooked up for a couple of months, car felt good, made power nicely, then i went to s4 manifolds for shits and giggles. So I did a quick port to the manifolds, slapped them on and WOW the car pulls much much harder then it used to and just screams to redline now! I'm having some hesitation though but I just think those are lean spikes from the damn intake flowing in so much more air! I'll be doing a redyno soon of this setup then in a month or so of my itb setup to see a before/after

ok, thanks for the info everyone.
i think i will stick with the stock manifolds when i first get this engine built and going. i have both S4 and S5 manifolds, so i can try using either one and see what works best.

what i am going to try first is to use the S4 lower, and the S5 upper, and put an adjustable RPM signal from the MS going to the VDI...i'll try out different RPMs and see if i can get something decent to work...

am i right in assuming that the stock manifold though might sacrifice some of the top end power gains of the bridgeport for a broader power band in the low and mid range?
or could a custom manifold be made to improve power in all areas compared to the stock manifold?

I would say that a stock manifold will sacrifice power at the high end for sure. It's just not desinged for the purpose.

Are you planning a full bridge or half bridge? Are you building the engine or using another builder.

A full custom manifold is nice because it can be built to suite the engine. Generally for bridgeports this means short, fat runners that flow well at high RPM. A nice free exhaust is also critical. But of course, making a custom manifold adds a large amount of work to the project. When I post my next Tina thread, you'll see. :)

well originally i was planning on starting with a streetport template, and then just doing a bridge on the auxilary ports.
but now i've been thinking of doing a bridge on the secondaries also...

i'll be building the engine myself...i was considering sending the irons away for porting, but i have a few junk irons. i'm going to start practicing on them and hopefully get enough confidence to do all the porting myself...the engine probably isn't going to start coming together until next summer. i'm not going to touch the engine that is currently in my car, this is a seperate project.

i guess i have nothing loose trying to do a custom manifold other than time. anticipating your next thread :)

edit: oh, to answer the question i don't want to do a full bridge

Doing a "full" half bridge is the best idea. Just bridging the aux ports certainly works, but you will gain much more timing (and thus flow) by extending the port down to the secondaries as well.

As far as the manifold...yes, time is the major issue. Though mine is at this point 95% done, and has come out spectacularly.

aaron, I was wondering if any of the factory manifolds, (BT, REW or RE) would be suited to a bridgeport
what about with a secondary bridge? I like the stock throttlebodies setup.

-Ben Martin

OK, I have lots of questions.

Aaron says " Full half-bribge". Sounds like an oxymoron to me. So, here's Q1.

Is the difference between a "Half" and a "Full" bridge the fact that the extra port does or does not cut through the water o-ring regardless of weather it runs the full length of the port or not?. A "full" needing notching of the housing.

There was reference to bridge-porting turbos and less problems. True?

I love what ShureShot did with his rotors, but, I'm leaning towards a "Half-Bridge" (don't cut water seal, four port), no intake bevel, but using a simalar exaust bevel.

Opinions?

The factory turbo manifolds have been used the past for plenty of bridgeported engines with success.

Full bridge = both primary and secondary ports bridged
Half bridge = only secondary ports bridged
Aux bridge = only 5th and 6th (aux) ports bridged

A small half bridge is one that will only cover the top half of the secondary ports (or only the aux ports on 6 port engines). A "full half" bridge would be where the eyebrow port extends along the entire port.

Edit...When you are beginning to cut into the water jacket, it becomes a J-bridge. Probably the most unreliable port ever invented to get around anti-peripheral rules in some racing classes. Never for a street car.

BT and RE would probably be the best choices because they are plenum manifolds, not DEI like the s4/s5 NA and REW. However, its still going to be hit or miss depending on the timming of your bridge ports as to whether they will be the right length or not.