ok my car has 157k miles! previous owner treated it like ****!!!! still has good compression and all but the over fill is full of rust! anyways... no bubbles there. but i know the motor is on its last limbs.... and im saving for a rebuild but if i got the motor apart might as well get a bridge port ( or half) how much would i end up spending for it? i already know im gonna spend about 2k on just the motor alone.... seals, new apex 2mm (hurley race seals) then i gotta worry about engine management and dyno time with sensor so about 1.5k then fuel upgrades about 1k then about 2-3k on a new turbo and manfold..... anything else..... anyone done this from experience???? any input!!?!? i just wanna know so i can start saving now getttin a job soon and i need to make some estimates with my money

THANKS!!!
josh

 

a half bridge port will probably run over a grand (can't bridge port a turbo engine). stick with a street port. it'll give almost the same power, but will be alot cheaper and will give power lower in the rpm so you can use it.

just save all the money you think you need, then save a few more grand, cause you'll need it.

 

i really want a bridge port cuz they sound soooooo cool

 

then go none turbo

 

OH YES YOU CAN........................................

it will SPANK a 'street' port at anything over 4500rpm

 

Yeah, what're you getting towards Scott?
and go with a street port, more streetable, and less costly overall (from what i've seen (well towards stuff you would nee dto make it run nicely moneywise))

 

isn't soul assassin running a bridge port on his car?
now that is one bad *** street car

 

i think its a partial bridge....exit13b also has a partial bridge.
now im a little confused as to why exactly you cant bridgeport a turbo engine, not to be confrontational, id just like to know the reasons for my own information. thanks

 

yeah.. a half bridge..

I think bridge ports are more "effective" on n/a's because of the massive overlap you get between intake and exhaust.. like, the percentage power increase is higher for an n/a. However...since you're starting with a good bit more power on the turbo, you will have higher horsepower than a bridgeported n/a. or a streetported turbo. Drivability will suffer, but who really cares about that!

-Tesla

 

The only problem with full bridge ports on a street car is the complete lack of power below 4500rpms or so...

With the partial bridge port and a turbo, you still keep the idle somewhat low, and don't sacrafice all of your low end, but now the engine has plenty of room to breath in the top end, from 4500-8000+ rpms.

Just remember you need to choose your turbo for this motor, as it will be different from a street-ported motor.

bridge ports generally shorten the life of your apex seals to somewhere around 50k miles.

 

the over lap is so big, that when your exhaust is leaving from one side of the rotor, intake is already going into the same side. this helps in an N/A as the exhaust going out sucks in air. but on a turbo the air is already forced in, so some of it is just going in one end and out the other without even being sparked. so you are wasting this air and just making your turbo spin faster for nothing.

 

thanks scott....it all makes perfect sense now!!!

 

ya i'm starting to look more into alot of people said the stock apex seals are the best you can get??? i read some pretty resonable arguments considering they do last over 200k miles some times!

 

this does happen to a degree at low rpm - ie under 3000rpm, above that it doesn't make a difference, if it actually occured as badly as you make it sound, you would never make any descent HP outta a force fed BP or PP, and thats defintily not the case

 

I know what a bridgeport is but what do you mean by partial or half bridgeport? Which types are suitable for turbo. What do you look for in a turbo differently on bp than street port?

 

if you take X turbo and put it on a bridge port it will spool earlier than X turbo would on a street port, ALso a bridge port flows more CFM at a certain PSI level than a street port does at the same PSI.

this means you can run a larger exhuast housing and still retain reasonable spool up and you need to run a bigger compressor if you were planning on maxing out the compressor on a street ported engine. a 60-1 compressor is ok for upto 20psi on a bridge port, but over that and its running outta puff, if you wanna blow more than 20psi down its throat you'll need a 62-1 or T66 compressor wheel

 

You're forgetting one thing... There is also backpressure in the exhaust. The intake air isn't going to "blow right out" because there is also pressure on the exhaust side too.

 

Would it not work the other way round, Exhaust gasses blowing back into the inlet cycle? I thought there is going to be more presure pushing the Exhaust out than the inlet in?

 

Not necessarily! A well designed turbo setup will actually have less pressure in the exhaust manifold than the intake manifold.

Look at it this way... a BP works great at 14.7psi manifold pressure (atmospheric) - why would it start working like **** once over that?

 

My preach is on...

I don't recommend bridgeports for street cars, because...
1) You lost serious power under 4kRPM.
2) When the bridge breaks (and it will), you're practically trashing the entire motor.

Now, I've heard various numbers on when the a bridgeport fails, but I typically say "50,000 miles".

Sure, all the big, peakl horsepower numbers will make you dizzy, but a solid streetpower 13B will ALWAYS make more power under 4kRPM versus a bridgeport 13B with everything else kept identical (i.e. fuel, turbo, etc.).


-Ted

 

RETed has valid points, the only thing I would add is that if you want to run you're car on the street i.e. at a legalish noise limit....then BP/PP even in partial form will be badly restricted in power output, to the point that it may even make less power than a "street port".

I have seen this happen many times !

But with proper exhaust design and the use of truck mufflers (can fit on 1st gen!) you can get around some of these issues. If you wan't to avoid cracked bridges well do what I do...partial PP

 

Gee, now can we get HWO to admit that too?



-Ted

 

Cmon RETed, who is interested in power below 4K????

I am interested in power above 7.5K !

My idea of a perfect street rotary is one that has low fuel consumption (my car) has good spread of power to match stock gear ratio's (my car 6k to 8.8k) and has max power at near or above 8K so you can do near 200mph and still accel faster than a F40 (oh gee, my car does that too )

But seriously, a good street port will deliver all of these things...It will not have a fat power/torque band as a BP or PP it will not have the upper peak rpm power it will not be as efficient at full power, but IT WILL be more legal (i.e. noise) adn it will be much more economical in low load low rev driving.

I would choose the street port over a bp/pp for a daily driver car based on those criteria.

 

How many guys that are thinking about going partial BP turbo are actually doing it to their daily driver? dont think all that many of them are daily drivers.

I know mine will be a saturday driver to and fromt work, for the rest of the week i'll be using my usual run-about, my gas guzzling 58mpg getting Fiat Uno.

who needs power under 4000rpm? (to use one of peter's favourite lines) - what do you think gears and diffs are for???

Rotary's are ment to rev. like any smallish capacity motor, to make HP you have to rev it to get the volumetric efficency up to inhale over 100% of its swept volume.
It amazes me the number of people who want a rotary to pull like a train from idle to 8500rpm. it doesn't happen, NO motor will pull like a train from idle to 8500+ unless of course you have the thing set to idle at 3000rpm or so. until we have truely variable port timing on a rotary its not going to be possible.

 

just get an automatic with a proper torque converter so that the engine never sees load below 4k... floor it and it comes right up to 4500 and the turbo spools up and you're gone

(ducking, running)

A SP can pull like a train from idle to 8500... you just need to pay attention to port runner sizing... yes you kill off some of the top-end power but for a street car or some forms of racing you do good to build up more low-end grunt.