I want something a bit more unique, but I'm not sure what I should do. I'm going for 400+ to the rear wheels, and it would be nice to hit 450...

Just not sure how streetable the half-briege would be... but right now, thats what I'm leaning towards.

What are your opinons on this?

 

Since not everyone knows what a half-bridge is, its when the secondaries are bridge ported.. and the primaries are street ported. some people may call it a partial bridge, or something else that I haven't heard before...

anyways, its WICKED for top end power, and its a lot better for low end power than a full bridge port.

Most people know what a street port is...

 

I am sure you know this but if you bridgeport it it wont be that reliable and wont really be a street driven car. Although i noticed you say half a bridgeport...would that really make a difference just being half? because i am not sure. If i were you i would street port it. good luck
just my .02 cents
later

 

well all be damned i asked a question then i noticed before my reply was posted you answered..now that is a quick response.
well now that i know what a half bridgeport is...and sense you want something different then i would do that half bridgeport.
later

 

Why do people think a brideport is so unstreetable. Sure it will make your idle sound like an oversized cam on a V8, and sure it will hurt your low-end, and sure it won't last as long as regular street-port, but there are definently streetable. I know a guy with an RX-2 who drives around on the streets of Portland all the time. He also auto-x's it. And thats a FULL bridge-port.

 

You can make 400-450 with a "good" street port, but remember: No 2 enngine builders' street ports are the same.

 

Well, when you bridge port you do lose bottom end power-if you put it in a 1800lb car (r100, rx2) even the reduced bottom end is enough to get it going easily. With 1000 extra pounds, the reduced bottom end may not be fun. I guess I am just saying, don't compare a bridgeported RX-2, 3 w/ TII.
What if you half bridged it and put in a forced induction system (super charger, SC and turbo) that could achieve FULL desired boost by say 1 or 2k rpm- would that help low end?

 

Hey guys,

I to have been thinking about porting my TII, where is a good place to have it done? What is the cost? I live in Kansas City (center of the US) so nothing is close, but nothing is really far. Is it good to rebuild an engine at the same as porting it?

Thanks,
Kris

 

Half bridge ports are wicked. You should do it. I just remember to put the rear apex seals in backwards so you dont drop the small corner piece into the port. That would not be good for your engine.

 

i went with an aggressive street port on my FD engine...... seems like less issues and still a nice power gain. half bridge sounds interesting give it a try, i'm sure you will love power increase up top

 

The street port will make the power he wants, but if he wants something badass then he should go with the half bridge. Have you guys seen Exit13B's movie or heard the mp3 of his car? HIs car is pretty cool. If anyone wants them you can e-mail me at jfrederi@juno.com . I'm sure he would be ok with me sending them to you since he posted them a while back.

 

Exit13b's mp3 is the SOLE reason that I even considered the partial bridge approach

His car, IS BADASS!

Now, I just need thelp deciding on the exhaust trim for my turbo... right now, I have a to4e with a .96 undivided housing on my HKS cast manifold. I'm going with a custom tubular manifold and want to change the exhaust A/R at the same time... but I don't know what to get for a partial bridge port...

One camp says to get a very large A/R because that is a top end turbo, and the bridge port is a top end engine... and the other camp says to go with a smaller .81 or so because that will help with low end.

Blarg! I love conflicting view points

 

P-Port Turbo!! DO that


or do a 20B halfbridge then you won't have to worry about low end. You will just have to worry about keeping the front end on the ground.



BTW just keep your turbo for now.. If it doesnt work well (.96) we can change it from there..

If it does work well, just get a divided tubular manifold & devided housing.

 

If you're going with a divided manifold then you can go to a higher A/R. What are you going to do with the HKS manifold?

 

are there really any real reliability problems with a half bridge, compared to a streetport or just in general.

 

I'll prolly keep the manifold for now, I want a turbo'd RX3 Otherwise, it'll go on parts trader or something...

 

 

My $0.02 on bridgeporting a turbo....

Bridgeports effectively open the intake far earlier than a normal port, creating a significant overlap with the exhaust port. Obviously, you must also port the exhuast, so even more overlap is created there. What's good about overlap? In a non-turbo car, if you have a fairly squared-off exhaust port and a well-tuned exhaust length, then the negative pulse of the exhaust will (1) actually suck the intake mixture into the chamber and, (2) in the process, all the unspent exhaust gasses will be purged from the chamber. This is great for performance over a certain RPM but kills the low-end. In a turbocharged appication, you have two things different: (1) The intake charge is already under pressure (no sucking required) and (2) there is a big obstruction in the exhuast system (the turbo). Basically, you lose the negative exhaust pulse and the associated intake sucking/chamber clearing effect. So, the benefits of overlap are not the same as with a non-turbo. Now, you're asking the turbo to provide extra boost that will get blown through the chamber and into the exhaust during the overlap period. This gives you the chamber cleaning effect, but no real head start on filling the chamber over what you'd normally get with a turbo on a stock port. And, you need a larger turbo that has boost to spare, since your giving some of it away to the exhaust. This isn't all bad, but you are losing a lot of the benefits seen in the non-turbo application. Doing a so-called "half-bridge" on the secondary side is a means of limiting the boost lost, as only so much can get through the small aperture of the bridge. This should help clear out the chamber and give you a bit of a gain, provided you have an adequate turbo and are willing to sacrifice quite a bit of off-boost power and idle quality. However, I'd recommend a different approach....

Any streetport that opens the intake earlier will create more overlap. You can actually go so far as to only support slightly more than half of the corner seal, which means the main port area is larger than it could possibly be on a bridgeport (the bridge would go right in the middle of the corner seal). If you went this route, you get plenty of overlap to ensure good chamber clearing by "leaking" some boost, but you don't open the intake so soon that your off-boost driving is shot to hell. Also, remember that you will be porting the exhaust (if you're smart), so more overlap is introduced on that end. And, finally, you can go the other way and extend the port opening significantly, which is a good proposition on a turbo application as the boost will continue to fill the chamber well into the compression stroke. Ports that just extend the timing are called "extend ports", which are very popular in turbo applications. Ports that truely maximize timing in both directions are called "rally ports". I'm suggesting that, if you really are thinking of a "half-bridge", that you consider a rally port as an alternative with similar advantages but fewer tradeoffs. Again, just my $0.02....

 

Keep in mind that a divided housing will spool quicker due to the turbine "seeing" stronger exhaust pulses. If what you have works well now, I would go up to the next size in a divided housing. Only run a divided housing turbo with a divided manifold of course.

I'd go with a 1.0x divided housing turbo... 60-1 (NOT HI-FI) on the compressor side. I don't know what you are running now though. BDC is making 425 at the wheels with a similar setup and a street port.

Brad

 

I have a 60-1 (not hifi) and I'm keeping it. Right now, it has a .96 undivided... going 1.15 or maybe 1.0 divided with tubular manifold this winter.

I know about BDC's accomplishments, his car is pretty amazing. He was maxing out his fuel on those runs... prolly could have made more power.

I think I'm going to keep a street port for now... I'm going to pull my engine and fix the oil leak on the dowel... hopefully my engine will stay together a bit longer next time. If this doesn't work, I'm going to have Don Marvel at Marvelspeed build me a magical motor out of go faster goodies

 

So no 20B