Liquid Anarchy

iTrader: (2)

Simple question, why can't you?



Ok, what are the issues with bridgeports? No low-end power. Reliability. Big power gains are at high RPM.

Why can't you BP an N/A and fix a lot of these problems?

No low-end power comes because the fuel can't atomize until the air moves faster. Solution: Keep the 5/6th port actuation. Less space for the air to move, the faster it will move.

Reliability is because the bridge is only supported by it's ends. With the 5/6th "bridge" in place, it's being supported at one more spot.

For the power gains; an N/A is a better candidate for a BP than a TII. They have higher redlines, and overlap is GOOD (as opposed to a turbo application, where overlap is just a waste of boost).

So, why can't you BP an N/A? I'm considering doing this as a project engine once my CF business gets going.

BTW I got the $$ to start it yesterday. After doing a little talking with my laborer, we'll get the ball rolling.

Liquid Anarchy

iTrader: (2)

...

OC_

you know what, now that i think about it, i think bridge porting and 6 port engine has been done. I read about it somewhere. I think they have 2 "eye brows" over the normal ports. I dont think they make one large one like you have drawn. They leave that "divider" in there., though, i dont see any problem making one large hole would cause, you could also trim the port sleeve. I wonder what kind of power this could make.

Liquid Anarchy

iTrader: (2)

Oh, if I can get a motor for cheap, we'll find out.

As per the bridge, I'm needing to see the sleeve w/ the parkings to see if I'll need the eyebrows.

The "cut" in the sleeves could be exposed while the ports are closed. if that's the case, then that bridge would need to stay.

Anyone have a spare S4 intake manifold I can have for the cost of shipping??

annuerysm

I'm interested if anyone knows anything about only bridge porting the 5/6 ports?

joep

call me dumb. Can anyone describe what bridgeporting is? Is it just porting you intake and exhaust ports to make them larger??

OC_

well, our engines have somthing called a side seal. And unfortunately, the side seal goes right by the intake ports. When we make the ports bigger on an engine, if we make them too big, it goes into the area where the side seals ride, and we cant do that cuz oil can come into the engine. So we cut around that area thats needed for the side seals to seal. the end result is a larger port with a line going down the "center" so the side seals can still do their job. so that line acts like a bridge for the seal to ride on. thats how it got its name.

OC_

btw, when they bridge port a 4-port engine for NA use, they add overlap... thats what gives that "brap" sound.

it just seems that the 4 port engines have more material to work with. but im still interested in this.

mazdaspeed7

You obviously havent done much research into into this, but Ill forgive you if you can actually listen to someone who does(unlike so many of the stupid kids here who cant be wrong).

The 2 ports on the end housing combine to make a port with nearly as much timing as a PP motor, but it opens a good bit later. If you bridged it like in the pic, you would have an unusable powerband. Period. That port would put your power peak somewhere around 12K on a n/a motor. Also, good luck getting it to idle below 2500 rpm. That motor wouldnt really get into its powerband until 7K or so.

If you have the money for a 2 piece ecc shaft with a center bearing, then it would make a good race motor. But its not somehting you would want on a street car. Simply WAY too many compromises.

Aside from the block, youll need a custom intake manifold that can flow enough air to support the motor at 12K rpm, a set or the lightest rotors you can get, carbon apex seals, and a very expensive EMS. Controlling a motor at 12K rpm is no easy task. Also expect to need very large injectors. The pulsewidths will be limited to how long they can be from the port not being open long at high rpm. But theyll still need to flow a lot of fuel.

If you dont have $10K to throw in to a n/a motor, youre wasting your time even thinking about it.

mazdaspeed7

Forgot a few things. At those kinds of rpm's, stationary gear integrity will be questionable for any amount of time, same goes for the flywheel/clutch.

Considering that, you would need $15K to do it right.

Suds7

Man, I wish I had a 'tude like this dude!

Racing beat says in their catalog/perf. manual that there haven't been significant gains in bridgeporting a 6 port motor, or any sort of porting for that matter.

annuerysm

what if you only bridge ported the 5/6 ports and left the sleeves in place then it shouldnt affect idle.

mazdaspeed7

Jim Langer of Racing Beat also says 6 port motors are very mild and not worth modifying. His attitude(like a few too many rotary tuners) is that if it isnt boosted, its not worth working on.

Suds7

In reference to 6 port porting.

Suds7

I guess I am beganning to think like that as well
It's kind of hard to make good power from a 1.3 liter non turbo. On the rx7.com site they have world record times for rotarys and the factory-port fastest n/a in the world was 14.1 sec in the quater. Which is SAD.

OC_

Thanks for sounding so arrogant mazdaspeed7. Did you think that maybe we didn’t know? And have you tried searching around on the web for bridge ported 6-port engines? The amount of info you will find is none! The only thing I ever saw on the subject was a reference saying that there’s a shop that has done this… and that’s all!

so you tried this and know for a fact that it wont idle below 2500 (i have read PP engines can ******* idle lower) and it will peak at about 12k?

what i would like to know though, is wheres the bottle neck in the 6 port NA engine? and can you make a 6 port engine flow as much as a bridged 4 port engine? if so, can you make the same power?

Jimmy325i

The side seal isn't in question with the bridge port, its the corner seals that want to fall out in that region.

I looked into this quite a bit when deciding what to do with my rebuild. I ended up using the intermediate housing from a S5 TII because of the thicker casting and larger initial port. I ported the hell out of that and then ported the hell out of the side housings including maximizing the flow capacity of the 6 ports. There's not a lot you can do with them without moving the power band well beyond the usable range of the rest of the motor.

As mazdaspeed7 said, the power peak would be well beyond the capacity of the rotating assembly. An engine with that much overlap wouldn't idle for ****. And if you cut the sleaves to allow the bridge to breathe when the engine was at low revs it would most likely choke from so little intake velocity due to the extremely early timing of such a port. He's right, you'd be lucky if it made power before 7K.

Bridging the 6 ports was another option I looked at, and subsequently decided against. The port would cause so much turbulence you'd likely decrease flow from the original port and actually narrow your powerband to the rev band where the flow in the bridge section caused the least turbulence.

If you had an extra engine with nothing better to do than **** around with, it would be more advantagous to experiment with a combination PP/ side port motor that myself and another member concocted in another thread. Make the PP actuated much like the 6 ports are and do the fortifying needed to sustain 15K. If you could get it to work, you'd see power from 3-15K. Not too shabby for an N/A. (keep in mind I was on percocet when I thought of it)

Liquid Anarchy

iTrader: (2)

Ok adam, let's try a few other questions (you seem to know)

How do you tell where the powerband of an engine is from the surface area of a port?

I've heard of people in SCCA competition porting their 5/6th ports as a bridge (like the upper bridges above) in order to sneak a bigger port onto the track; (as it would sound the exact same at Idle and low RPM) if what you say is true, why would they do this?

If what you saw is the case, is the "Ito Spec Streetport" engine even going to run, or idle under 6,000 RPM? It seems to have more area on it's port (especially since ½ of the area of this would be closed off below 3800RPM {which would improve idle}) which is reminicent of a 4-port on the Ito-Spec vs. the one propositioned.

Where does a NORMAL (TII) Bridgeport idle at? Why would this idle higher?

Lastly, where did you get your information? If not by heresay then I'd love to give it a read.

Liquid Anarchy

iTrader: (2)

Jimmy, the PP/Sideport thing has been done. I remember someone on the forum doing it; there's also a japanese company (can't think of the name right now) that makes PP/Sideport LIM's that bolt to the FD intake manifold. You might try and track an owner down, I'll look into the companys name.

I bring this up because I'm about to get a good portion of money, starting a business, and have a friend w/ a S5 6port lying in his garage. For a little $$ it could be mine.

MaTT_FoULk

Factory ports..... bah!

mazdaspeed7

I havent seen anyone show me theyre smarter then me in this thread, so until then, I have no need to pretend there are people smarter then me here.

Ill bite. Ive never heard that about SCCA motors. Correct me if Im wrong, but arent BP's of any kind prohibited in the class youre referring to? Then wouldnt that be cheating?

The ito spec Sp is still a street port. It opens only a few degrees earlier than the stock ports, and closes a few degrees later. It does move the powerband up, but not by nearly as much as a bridge port. And Ito's port isnt really that radical. I would really like to see how it idles, but I can already tell you it wont be below 1000 rpm. The area of Itos port is enough to give extra HP, but not enough to really compomise flow at low rpm's. No matter what, its still a street port. The whole idea behind street ports is to not make many compromises on drivability or streetability.

I dont know exactly where a BP TII motor idles at. Ive never asked anyone, because it wasnt a big thing to me. But I can tell you that a PP, which is moe extreme than most bridge ports cant idle below 1500 rpm with fuel injection, and around 2000 rpm with a carb. Now take a look at a bridge ported 6 port. The port will open at the same time as a PP motor, but closes later. And the area is larger. Larger area and longer timing both slow down the intake velocity for a given rpm. So therefore, the bottom end and idle would be worse than a PP(read above on the idle of a PP). Ive never seen a motor built like that, and never seen a dyno graph of one, so my numbers were just guesses, but my point still stands. Its NOT usable without LOTS of money to make the motor be able to rev past the 10500 rpm limit of the stock ecc shaft.

Most of my information is from reading posts by or talking to people with first hand experience. Ill see if I can find anything useful for you though.

Liquid Anarchy

iTrader: (2)

*note the FACTORY PORT comment*

mazdaspeed7

Scoot made that car. Cant find a page in english, but heres a video of that car making 710 hp.

Liquid Anarchy, if you have the funds to do it, go for it. I would love to do something like that, but cant afford it right now. I can help you out with some of it, Ive done research into that kind of thing before, and have a bit of a background in aviation rotaries, where custom PP motors are the norm.

Liquid Anarchy

iTrader: (2)

This port was made by combining a bridgeport, and a stock 5/6th port. The ports would both open a bit earlier, but close at the same point as stock (both opened, and closed)

The surface area OPEN is still under the ito-spec. Nevertheless with the 5/6th closed, which would bring the area down to less than a streetported 4port.

Time to talk to soul.

Liquid Anarchy

iTrader: (2)

Oh, and I'll probably make the motor reguardless. I was just making sure there were no TERRIBLY obvious reasons not to. Just the powerband being HUGE isn't going to stop me.