what are your guys opinions on Bridgeporting? When I have my engine apart I would at least like a mild street port, but might throw out the cash for a bridgeport if it doesn't make the car too undriveable. To make it work right I'm thinking you would need bigger injectors, fuel pump,.... what else? Just thinking about it, testing out my options. Thanks.

Just a question, since I've never had to tear down my engine or thought to upgrade a lil my rx7, I don't know much about that. I know what porting is but what about bridgeporting? ???

It is the addition of an extra port. Check out the Mazdatrix faq, they have some good pictures. bridgeport

Thanks.. that's a good explanation, a picture's worth a thousand words. But on those photos, they almost remove the water seal groove, wouldn't that cause a failure of the water seal before long?

It probably could, but I don't know all that much about it either. Hopefully someone can enlighten us. I just know it will cost around 800.00 to have it done.

You mean the whole job done, intake and exhaust porting plus the bridgeporting. But I'd probably go for standard street intake and exhaust porting.

Do we have to upgrade the exhaust system for taking advantage of porting? How much without the bridgeporting?

bridgeporting adds gobs of power, but they are more prone to break because the apex seals have more distance to travel on the ports. Sometimes they can fall in, thats the most common problem i have heard with them, and the idle is a little rough. You would most likely need a bigger fuel system. why not just get a mega streetport? its just a huge version of a streetport. thats what id do. I don't think bridgeported engines last long than 30k. and hell if your going bridgeport go full bridgeport. https://www.nopistons.com/forums/pub...IR#>/devil.gif

It means I'd need to have higher flow injectors and fuel pump. It has 460cc secondary injectors (NA) supposedly so if I'd put higher flow injectors in, would I need to upgrade the ECU then? ???

And what about the exhaust system afterwards?

When you cut across the water seal groove you should fill the surrounding water passages with a high temperature epoxy to keep water from flowing through that area.



You would really need a standalone ECU for a bridgeported motor. You'll gain your power up high, but unless you build the motor to handle revs consistently above 9K you won't be able to enjoy all of the benefits.

But for just a mild street porting (without bridgeport), it isn't necessary to change anything in fuel and exhaust systems but it is advised, right?

But for just a mild street porting (without bridgeport), it isn't necessary to change anything in fuel and exhaust systems but it is advised, right?[/quote]

With a normal streetport you should be ok with the stock ECU. I had a mild port with a stock ECU, and it worked ok.

But for just a mild street porting (without bridgeport), it isn't necessary to change anything in fuel and exhaust systems but it is advised, right?[/quote]

With a normal streetport you should be ok with the stock ECU. I had a mild port with a stock ECU, and it worked ok.[/quote]

So I could start by doing a normal streetport, and a further improvement would be the exhaust system and so on? Could I do it myself or it's too complicated, because I've always been doing my mechanic things by myself, even engine rebuildings.



By the way, have you seen some benefits from you MSD 6A since you installed it?

Correct me if im wrong, but on a N/A motor, isnt a porting job almost a waste?

By the way, isnt Bridgeporting just a name that they use from the machine its done on? A Bridgeport machine?

umm n/a porting you can gain alot ! check this 6port out courtesy of judge ito



http://www.vosko.net/photos/sixports...reetport-1.JPG

No, it's called a bridgeport because you need to leave a bridge between the stock port and new port for the corner seal to go across. If you didn't have the "bridge" then the corner seal would pop out.

That's why I'm asking questions. But I think if you make a porting on the engine, intake manifold, you could get some useful HPs.

And bridgeporting is the name for the kind of porting. See for yourself there Bridgeporting

But for just a mild street porting (without bridgeport), it isn't necessary to change anything in fuel and exhaust systems but it is advised, right?[/quote]

With a normal streetport you should be ok with the stock ECU. I had a mild port with a stock ECU, and it worked ok.[/quote]

So I could start by doing a normal streetport, and a further improvement would be the exhaust system and so on? Could I do it myself or it's too complicated, because I've always been doing my mechanic things by myself, even engine rebuildings.



By the way, have you seen some benefits from you MSD 6A since you installed it?[/quote]

The street port with exhaust and intake mods would be a good choice. I'm still working out somne tuning issues, but the 6A definitely gives a stronger spark.

vosko, that's a pretty good one. How much HPs can you get this porting? Do you need to upgrade the fuel system to get good results?

MazdaTrix claims that porting isnt a big power gain to do to a engine, but if its out and being rebuilt, then it doesnt hurt, for N/A, has anyone done any dyno tuning to see what power gains can be had by porting alone versus no porting on a N/A? Ive always been curious to find out? They do Bridgeporting to outboard boat engines, and its called that because of the machine its done on, a Bridgeport machine can pretty much do any machine work when set-up properly, especially porting and milling and what not.

Yeah...that's exactly what I'd do if ever I had the engine out for rebuilding, why not as you say! :sigh:

So the stock computer would not work so well with the Bridgeport? I had heard that it caused a rough idle and remember reading somewhere that it was for "track only" cars. Do you think the n/a drivetrain would be up to it? Mine has 102,000 so I'm betting that my engine will be in decent shape when I open it up. Hoping anyways. If the Bridgeport is just too much, I will pay the 300 for the streetport and polish and put the rest into the exhaust. Thanks

Yeah...with stock computer it would work but without having all the benefits of the difference in price so I think the best choice is a street porting. I would keep my ECU and fuel system as it is, like you said maybe put some extra money in the exhaust system. My car has also about 100,000, but the drivetrain is in pretty good shape. My engine is not bad either but has power lacking problem but the compressions, fuel pressure and all the systems seem to work as needed...Mystery! I'm waiting for my performance meter, I hope I'll get it on monday.

I'll see then if I'm very far from what it is supposed to give.

You won't be able to utilize the full potential of a bridgeport with a stock ECU. Just go with the street port, and you should be happy.

Does anyone have ever seen what is the power gain with a street port alone on a NA, without any other mod and with exhaust mods, etc...

In other words, what power can you get from a NA. ???

I've read both NA and turbo, on MazdaTrix site and they claim exactly the same thing for both engine.

And I quote : "By the same token, do not expect substantial gains in power from "street porting" these engines - it's a worthwhile addition IF the engine is going to be apart anyway, but definitely not worth taking a running engine apart just to street port it."

This comes from 86-95 Turbo Street Porting at MazdaTrix.

So what's the truth? ???

I can not remember where, but the figure I saw for street porting was around a 22% gain on stock horsepower. So I suppose you would gain about 30hp on a 146hp engine.

When you say 22% gain it's for porting alone, without any other mods? Hard to believe, but if I'd gain 10 hp I would be happy anyway.



What year is your car, is it a '86 like mine?

When you say 22% gain it's for porting alone, without any other mods? Hard to believe, but if I'd gain 10 hp I would be happy anyway.



What year is your car, is it a '86 like mine?[/quote]

:newlaugh: :newlaugh: :newlaugh:

U'd be willing to spend $ 800 and remove your engine and put it back in for 10hp. thats some funny stuff.

with porting like that about 200hp. gsl-se secondaries are recommended 680cc

First of all, as a moderator you're a good one. :newlaugh: :newlaugh: :newlaugh:

Secondly, I've never said that I'll be spending $800 just for porting. I would do it if I had to rebuild the engine for any reason.

And thirdly, it's not $800, it's $350 for a 6-port and $280 for the 6 intakes only. :madgo:

with porting like that about 200hp. gsl-se secondaries are recommended 680cc[/quote]

You're talking about a NA here, but with some upgrades in the exhaust system at least, right?



Thanks a lot Vosko.



Hopefully, not everyboby laugh at guys who wants to learn, I bet he doesn't know everything.

You can probably get close to 10 HP by changing your air cleaner. A few more by adding a header and free flowing exhaust.



I wouldn't recommend a BridgePorted engine for the street. I had one years back in a R100 that I drove on the street and it.... Well sure it was fast (13 sec 1/4 miler), but it was like a really radical cam. No idle, very lopy at best. Botton end was pretty shallow, it was rev monster. It was fun at first, but got old quick.



I don't know of anyone doing bridgeports on 6 port motors. So to truly get a Bridgeport you would need to replace the housings.

with porting like that about 200hp. gsl-se secondaries are recommended 680cc[/quote]

You're talking about a NA here, but with some upgrades in the exhaust system at least, right?

Thanks a lot Vosko.



Hopefully, not everyboby laugh at guys who wants to learn, I bet he doesn't know everything.[/quote]

to take advantage of that porting you would need rb headers,presilencer, and catback, intake, etc. the car that has THAT engine is about as fast as a stock TII. you can make power N/A just not as much.

I just want do some changes here and there as you say, not big things but good things. The free flowing exhaust, is it just like a exhaust porting or is it a polishing? My idea is a street porting when I'll have to tear it down and maybe an RB exhaust system in near future.



When you only change the secondaries for 680cc, the stock ECU switchover correction factor will not match anymore (0.4 instead of 0.5), does this have some importance?



Thanks to both of you. :sigh:

You would want to get atleast a piggy back fuel computer, i bet those injectors would make u run rich real quick and most likely stumble when they came on. U probably could even keep the stock injectors, just either bump up the fuel pressure or get a performace fuel pump. I know ur not supposed to run the injectors past an 85% duty cycly but the n/a injectors can handle 200hp. U could also get some TII injectors, which would still probably be an overkill, unless u did some HUGE porting. But if u did get TII injectors u would have to change the impedance, u could wire in a 10 omh resistor, to change the pulse length. Whats the impedance on the 680ccs? Whats ur question on free flowing exhaust? All they mean is open it up so there are no restrictions ( no restrictions as soon as it leaves the engine). If u can't push the air out, there is no point of trying to cram more air in.

I'm a technician in automated control system and electrician, and I can tell you that adding a resistor will not change the pulse length in any manner (it's the ECU's task). At most, it will help to keep the waveform more square but slower response. The resistor is for impedance adaptation with the ECU and to limit the current through the injector and ECU when the impedance is too low for operating directly on 12 volts (it would burn itself up). I already have low impedance injectors anyway. I would say that changing my low impedance for high impedance and removing the resistor pack could help. In my opinion, they should have a better response above 50% duty since it'd have the same current but all the voltage is going to the injector (12 watts instead of 2 watts with low impedance).



As for free flowing, I know it's not really as free as you say but I've been thinking about the cat replacement pipe w/presilencer system and the Cat Back system w/mufflers. I've thought about headers but it would probably be too loud. Is this a good choice? They say we can get about 13% of power increase from a RX7-146hp.



Thanks, sorry for being so harsh with you but you asked for it!

I thank everyone for their replies on this, it has been very informing.

Powerpack: the cars an 88.

Is the '88 and later model supposed to have more power, like 10 hp. Or were you talking about my 146hp car?

Hey...what about your rear rotor, have you checked to see if everything was in there? Is the apex missing? ???

I'm a technician in automated control system and electrician, and I can tell you that adding a resistor will not change the pulse length in any manner (it's the ECU's task). At most, it will help to keep the waveform more square but slower response. The resistor is for impedance adaptation with the ECU and to limit the current through the injector and ECU when the impedance is too low for operating directly on 12 volts (it would burn itself up). I already have low impedance injectors anyway. I would say that changing my low impedance for high impedance and removing the resistor pack could help. In my opinion, they should have a better response above 50% duty since it'd have the same current but all the voltage is going to the injector (12 watts instead of 2 watts with low impedance).



As for free flowing, I know it's not really as free as you say but I've been thinking about the cat replacement pipe w/presilencer system and the Cat Back system w/mufflers. I've thought about headers but it would probably be too loud. Is this a good choice? They say we can get about 13% of power increase from a RX7-146hp.



Thanks, sorry for being so harsh with you but you asked for it![/quote]

damn u showed me up there :sigh: I have that same setup as ur talking about. I have Rotary Perforance's midpipe and some high flow mufflers. I would have got the header/presilencer combo but it was $250 more, and since i can't tune my fuel, i didn't want to mess around with a header. I think u will like it, its a good setup. ps yes i did ask for https://www.nopistons.com/forums/pub...#>/biggrin.png no hard feelings