my point exactly......wonder why the guy advertises a TII Aux. Bridge?

 

i actually love the way the BP sounds so i guess i can deal with that!!! so far Im thinking to do as pfsantos said. i might do some kind of combination of both. Have any of you tried this before?

 

semi P-port puertorican style -BRA,BRA,BRA

 

It's called the half-bridge.

Look up BDC.

 

That's what i'm doing a F/B & S/P just have the housings drilled out and add runners to your intake for the air & fuel...

 

that's what im running............. if u guys don't know the proper names for porting then you shouldn't even post here.

 

So much tension in here!

 

Definitly go with a bridge! I imagin all the people that say bridgy's aren't streetable havn't had one before. . .

 

The one downside that most have not mentioned is getting around 8 MPG in city driving.

Also, don't bother with a half bridge. A bridge is a bridge is a bridge. If you are going to bridgeport, then you might as well go all the way and build it full bridge.

 

So when will you be full bridging yours?

 

I don't have 8MPG around town. I haven't for a really long time. I'm not sure where this figure came from, Aaron. Is it an embellishment of the fact that yes there is a drop in gas mileage for around town when running low RPM (stuff like 2500rpm and under)?

A bridge isn't a bridge, either. I don't agree here with the assessment that's been made. There's decided differences between partial and full bridges of all sizes and I think it equates to the differences in the degree of overlap. I've seen videos of your high-compression, half-bridge 6-port setup. It looks nice, btw. It looks like it's turned out well. However, if you were to go full bridge and make the cuts on the centre plate as well, you'd notice a few things: Your turbocharger would hit harder and even more aggressively, the engine wouldn't idle at 1200-1300rpm like it normally does and would require something else, it would get even worse mileage around town at anything in lower RPM operation, and it would be massively louder.

B

 

^ Win ^

 

my buddy is running a half bridge for his RX7 track / street car.. probably uses it simular to how often you plan on using it.. its fine on gas as long as you drive in the powerband (by fine in mean nothing too horrible) and it makes 500hp @ the wheels. very fun car! i also know of sombody else running a full bridge for a daily driver, still kicking around town. both with upgraded turbos and running microtech ECUS good luck and post some pics and vids once your all done!

 

Half bridge is bridgeporting the secondaries

Aux bridge is bridgeporting the auxillaries on a 6-port engine.

These are the commonly accepted definitions. Just because you call it aux bridging doesn't mean it's right.

4-ports have two sets of ports, primaries and secondaries.

6-ports have three sets of ports, primaries, secondaries and auxillaries.

On your 4-PORT ENGINE, where are you bridging the auxillaries?

Don't call people out when you don't know what most people think of when you say aux bridge and/or half bridge.

Search aux bridge and tell me how many threads you find on bridging the secondaries and how many MORE threads you find on bridging the 5th and 6th ports on an NA.

Aaron, did you change your NA aux bridge turbo to an NA half bridge turbo? (On NA's, I still prefer calling it the 2/3rd's bridge as an NA half bridge bridges 4 out of the 6 ports)

 

I'm not. When this engine bites it, the next engine going into the car will be a 4 rotor NA peripheral port.

What's your secret? I've tried several different timing curves (from very mild to very aggressive, as well as different split tables) and several different A/F ratios at light load the result is basically the same; 8-10MPG around town. Timing doesn't seem to make much of a difference, but interestingly I get a LOT better mileage at 13-14:1 then I do at 15:1. This spring I'm going to richen the low load and bump the timing a bit past 35 degrees and see what the result is. It would seem reasonable that running around 20 degrees of split would help pick it up as well?

Eh, it does the job. If I had to do it again, full bridge. This spring I'll get an LSD in there so I can bring the boost up. With the open diff it's just plain dangerous even at 13 PSI.

I'm running the image in my head of a rotor passing over an eyebrow in the center plates and the end plates and can't see much more overlap vs. a half bridge. Obviously I don't have a degree wheel in my brain so that may not be accurate.

Yes, that's basically what would be expected and those are the reasons (well, not the mileage hit) I would go for a full bridge. Bigger turbo spooling faster is worth a little mileage issue, and a 1500 RPM idle is not the end of the world in a large port car.

That said, I have never built a full bridge car. Half bridges for sure. I also don't bring my exhaust ports up at all. I widen a little and move down. That could explain the differences.

 

I drove a half bridge car for a good while.

I didn't even finish tuning it before regretting not full bridging it. If you're going to do it, you're going to introduce the negative traits of it idle wise whether you go all in or just dip your feet. You're doing with the expectations of benefits so do a nice one

 

i was taught to call it an aux bridge by some older time builders. to each their own..... i have a half bridge.

 

Hey Aaron,

I get over 25mpg @ 80mph with my HBP REW, Around that speed the timing is 38 degrees advanced and about 18.2-18.8AFR

Here is a Log to prove this timing and AFR

 

I think highway has always been fine, but city mileage is where the HBP hits the crapper.

Who tuned your car?

 

25mpg? I'm shocked. I'm surprised a stock rotary would get 25mpg, let alone a half bridge ported 13B-REW.

Maybe he turbo'd a 6 port N/A ? The only person I have heard that has done this is one of the mods, and I can't remember who. Maybe Aaron Cake?

 

yea, Aaron Cake has an aux bridge turbo to the best of my memory.

 

You need a new wideband sensor/controller or there's something screwed up somewhere, Chuck. The engine won't run at 18's:1. It barely runs at low 15's as it's starving for fuel. There's hardly enough to light it at even 15's:1.

B

 

Dear God, man! So are you doing the Kiwi-re 4-rotor?

Also, for the record, I got 29 MPG in my car with the previous engine on highway cruising. It had a ported intake and exhaust, and a dead stock fuel system.

 

15:1 is barely enough to keep the engine running. May be able to get away with it realistically while cruising on the highway with some aggressive O2 loop but it won't work when under any load other than that. The engine will buck and stumble.

I think I've got some of my maps up on my website. Let me link what I have. They're for Haltech E6K/E6X and PowerFC. I'd bet you'd do better with the Haltech stuff. I made some different ignition curves I've pretty much stuck with. Been goofing with that for about 4-5 years now for the partial bridge. This is however for the 4-port turbo block. Download the JPBP1 map and load it up in the Haltech E6X software:

http://bdc.cyberosity.com/v/Technica...h/HaltechMaps/

You can see the Lead and Trail-split I do. Give it a try! I've replicated it on alot of HBP cars. Hopefully it'll help the car run smoother and be less of a gasaholic. May want to take a degree out across the board for the higher comp rotors you run, though.


There is. I'm not sure what's dictating it or know all of the physics behind it but there is a significant difference between part and full bridge by the external indications.

I like the HBP myself for a street car and a conservative HBP at that. In my experience, there seems to be a fairly significant change in all of those above factors when there's even the slightest change of bridgeport cut width and size.

B

 

I've passed cars through emissions running at 16.2:1, at a 1500 rpm idle and at cruise. O2 sensor was placed ahead of the air pump feed, so exhaust dilution is not a possibility. Most engines were done on an FJO using the NTK sensor, one on an AEM unit. Swapping in a Motec wideband unit in one car at another date showed identical readings to my FJO. It yakes some fiddling with the timing, but it will run.

It is amazing how low the emissions will get running the engines like these. Every time I have to laugh at the readings of 0.00% for Carbon Monoxide.

For regular highway cruising, the engine will run stabily around 15.5:1 AFR's without misfiring.