xplicit7

has anyone ever tried that,if so how did it work out?i know the half bridge/streetport works well with single turbos,but what about the twins?

xplicit7

no one has any info on this?

xplicit7

bump

jspecracer7

yes but Why? The stock twins will run out of breath QUICKLY!...They run out of breath on STOCK ports, so a bridgeport would make it ridiculous to even run anything smaller than a t-04S

rynberg

Unless you're running a pure strip car, a bridgeport is worthless. Say hello to no power until 7000 rpm or more. As Jspec said, the stock twins will run out of breath long before then.

In any case, a bridgeport would be totally non-streetable, with or without the twins.

Flybye

How about a semi-bridge on ball bearing twins?

twint78

not streetable?highly doubt it.bridgeport is basically pushing it to the limits without going full peripheral.and with a pport u get good power starting at 5k rpms and an idle of 2k.with a bridge it is loud as hell.steetability is all on what u consider streetable.with a bridge u probably wouldnt start making power until 4k all the way to 9 or 10k rpms.but these are race engines.so be prepared for water jacket issues.best thing to do is talk to rotary shops.

jspecracer7

Why?

peejay

it's funny when bridge ports come up 'cos then people start spouting the usual "yeah you don't make power till the tach needle twists off and you can't drive it on the street"

when at the same time people who actually HAVE bridge or peripheral ports say "it makes great power at all RPM and it's very driveable".

and the people with the HARD FACTS say "a bridge or peripheral port is more efficient and makes more torque at any RPM under heavy load with poorer efficiency at idle or low load". (meaning MPG goes down in cruising but at full throttle and under boost it's MORE POWERFUL at ANY RPM compared to stock or street port) Dyno plots prove this.

Keep in mind that NSU engines were peripheral port. The engines were small for the chassis weight so that you used heavy throttle more, to get into the RPM/load range where the peripheral port shines. They peak power was at 6000rpm, and they made more power from their 10A-sized engines than Mazda's higher-revving, larger 12A engines. That spells greater torque from a smaller engine!

twint78

exactly my thoughts pj

rynberg

do you have a link where I can see dyno plots from BP vs stock/streetport? Also, I would tend to define engines that typically last 20k or less as non-streetable.

neevosh

You'd be choking the engine if you ran the stock twins.

peejay

plenty of people get more than 20k out of a bridgey or peripheral. that line of BS comes from the fact that people typically install carbon-aluminum apex seals (which you do NOT want to do if you have a turbo) which do not last very long esp. when RPMs are kept high for long periods. that's why Mazda stopped using them in production engines after '73.

twint78 you're one of the people i'm talking about... you're spouting that same crap.

i'll look for the plots. unfortunately no pics, just text, so you probably won't believe it, but then again pics can be faked as well.

94touring

I'd like to see some hard facts on this subject. I've been toying with the idea of doing maybe a partial bridge port on my next motor. Theres always ways to get around the noise problem, maybe its a more restricitve exhaust but even if you only gain 50rwhp from a new port and only lose 20rwhp restricting the exhaust.....thats still a 30rwhp gain. Has anyone tried searching, i'm gona see what I can find.

jspecracer7

I think the debate is about the stock twins with bridgeport. The center section of the stock twins which share the same "exhaust housing" is quite small. Also, the stock turbine wheels are small. The bridge makes good power, especially in the high rpm's which is where you would want a larger turbine wheel and a larger exhaust housing, not the puny stock one.

I know that the bridge makes good power after 3000 rpm~...Most of them that I've seen idle at around 1800 rpms~ so you don't make that much torque for 1200 rpm's(whoopie doo), but you'll have exponentially larger hp increases after 3000 rpms!

As far as the streetable thing, that's a matter of opinion. Bridge's are quite loud...but "streetable" is dependent mainly upon law enforcement.

infinit1

I think if you want to make the power you will give up the gas milage and all the stock BS no matter what. A bridge is the only way to go if you want to make over 500hp and the turbo has a lot to do with it. So twins will not work. if you are looking for streetability then keep it stock. If you want to make power you won't care about noise or gas milage. And to top it all off, who wants to make a lot of power before 3000 rpm. not that you won't make any, you'll still make a lot more than stock but not like you will at full boost on a single with a bridge.

I think it is the only way to go if you want to go fast!

94touring

How would a partial bridge work with a smaller turbo like the apexi rx6? Is it true that depending on the partial bridge that the idle can be lowered below 2k?

twint78

how am i spouting out crap?

i know bport and pport engines can last over 20k

i never said they lack bottom end tq

i just said bports have a better power band from 4k-9 or 10k.i never said it doesnt make good power down low.

and i also said it can be streetable.

but then i also said best thing to do is talk with a rotary shop specialist that does it for a living.

get ur facts straight stud.i never said any of the usual ideas about bports.where it idles at a million rpms and u have to keep it at high high high rpms just to make any power.what i have said has been proven to me by a rotary shop no more than 30 mins from here.and u will see the same with an v8 with radical cams.of course u will see good power downlow,but it just has a better power band starting at a certain rpm.or vice versa,good power downlow and breathless at top.once again u can talk to crane cams about this.how do u think vtec works.its all intake exhuast timing, and a bport is more of a radical timing port.streetport is good for a certain range,a bport is good for a certain range,and same with pport.different applications.

peejay

Depending on how it's done, the bridge should make more torque down there too. Usually with a turbo car people (naturally) size the turbo for max power (let's be honest, people don't do BPs expecting to make just 350rwhp ) and that's where some of it is.

Still looking for the plots, not leaving y'all hanging.

jspecracer7

LOL...350 rwhp with a bridge...might as well stick with the stock twins and a big side port.

All the info I have is from people who have used them on their rotary's, so when I say that they don't have a lot of torque down low, it's from me hearing it from their mouth, not from my own personal experience....and I didn't figure into the equation the big turbo thing...which would account for the loss of torque.

My BAD!

infinit1

I think some of you are just scared of a bridge. If you can handle the power go for it. If you are looking to get good RELIABLE power just street port it. A bridge is my choice of ports but then again I have driven a P Port on the streets with open exhaust in LA.