Jeff20B

iTrader: (13)

Yeah! I want to go from a nice smooth FC-like idle to nothing but brap brap brap brap brap brap brap! I can't wait!

chookcooker_1

I had an '80 model with a ported 13b 6port making 140 wheel hp according to the G-tech. I ported it myself and it had bridge ports cut into the auxillary ports only. It used an adaptor to bolt on a 13b standard carb & manifold. The carb had its venturies bored out. The exhaust comprised of 1 7/8" primary headers feeding a 24" resonator just prior the diff. It then goes 2.5" over the diff into an offset straight through muffler. It was loud but VERY fast. I had a race with a 2nd gen with the usual mods (exhaust, boost, intercooler) and pulled away from him until my engine starved for fuel. The fuel bowl would be empty by the time I'd get into third gear during hard driving!

Jeff20B

iTrader: (13)

That currently happens in my REPU. By third, it's starved pretty well on its RX-4 carb and Cosmo reversed runner manifold.

So when you say auxiliary ports were bridged, do you mean the 5th and 6th ports only? Did you remove the tubes in them? What about the lower ports on the end plates? Did you grind them at all?

Oh, and welcome to the forum!

Ah, I've got some time to go inspect my side plates for wear. If they're good, BP here I come!

Hyper4mance2k

iTrader: (40)

ohhh i wanna build a 12a bridgy sooo bac but my daily is a 13b and if i was to build a race car i'd love to do it 12a bridgy. oh well one day i'll have the funds

12abridgeport

Hey, sorry guys it took so long to respond, i work with computers so on weekends i try to stay as far away from it as possible. Friday night at the track wasn't too bad but could be better, it turns out that besides traction problem i was also having high rpm power fading. My secondaries were not opening up all the way and also i found out they were hiting the intake manifold. I still ended up smoking two hondas and came even with a turbo beetle (that had slicks), my best pass was 15.5 at 90mph. I know nothing too excited but i fixed the high rpm power fading now and still playing around with the jets. Also Orlando Speedworld dragway it far not the fastest track, so 15s here is actually pretty decent for a street car. Defenetly to be continued....

Sorrow, yeah as Jeff20B said the bridge is shorter than the main port on the RB template, but as far as i heard it is possible to mach them up to the same length.
I didn't use any template on the exhaust port, just matched it up with the sleeve but i still wouldn't mind using one for the next porting project.
Oh yeah, also if you have just a 2 bridge the car would rumble more than a 4 bridge, not exactly sure why that happens.

SoRRoW

Man...Im cring tears for you ..
15.5 on bridge?
I ran that and better on stock ports,

You knwo what will hep your carb problems?
Use an adaptor plate from discount or pep boys as a spacer.It give more low end torque,helps the fuel anotomize...and will help your butterfliy problem..

I used the spread bore one..

Do you want the exhast port on that posterd board I got or on metal?

It might take me a couple of days to get to HomeDepot and get some sheets to make the template for you,unless I can send it as is,but thats basically what yoru going is opening it up to be big as the sleeve,

Did you knotch the houisings?

Maybe when I get my car done,we can either meet at Lakeland for some braket racing or Bradenton 1/4 for time times,and Honda kills..

BTW I got yoru info somewhere in boxes around my house,so you can either PM me your info or contact me by AIM or ICQ..

Thanks man..

Post some pics!

12abridgeport

That was one of the things i did this weekend is install one of those 1in spacers, defenetly made a big difference. I can spool up so much higher now without any hesitation in the engine, i wish i had that done before the race. The next time i go, it would be after i get some new tires.

Yeah man, i wouldn't mind actually going to the Lakeland track. I hear people say they pick up like .3 or .4 just from going to a different track, Orlando Speedworld really is very slippery.

SoRRoW

Never been to Orlando..

I will meet with you soon,What rear end and tranny you running?

You got pics of the engine?

BTW ill find out next event at Lakeland and let you know,if your car is ready..Ill go up there and met with you..most likly my friend will have hs FB out there..

12abridgeport

I'm running stock tranny and rear, with all the luxuries of a '84gsl except for the a/c. I do have pictures of the bridge underneath the rotor housing, but i have to dig for them.
Yeah, let me know when is the next event. Hopefully i'll have everything set up by that time.

Jeff20B

iTrader: (13)

That's odd. I may go with a half bridge where only the secondary ports are bridged because the engine is going into a REPU. I need some low end power because it's a truck. I'm also going to find a set of '86-'88 NA rotors and use the stock flywheel. It's a lot lighter than a stock REPU flywheel, that's for sure, but still has more inertia than a light steel flywheel from RB. Would this stock '86 flywheel hurt bridgeport performance if I were to go full bridge (all 4)? Or do you think it'll be ok with just a half bridge? Oh, I'm also going to notch the rotor housings, but not all the way into the water seals.

12abridgeport

I'm using stock flywheel, so i wouldn't know about performance differences, it supposed to make it spool up a lot faster. But defenetly don't go into the water seals, your engine temperature is going to go up as it is. I went pretty close but not over water seals and sometimes during real hot Floriday days my temperature goes just over the half way mark, most of the time though it is below.

12abridgeport

BTW REPU's are cool as hell, especially if it's with a bridgey

Jeff20B

iTrader: (13)

Oh, ok. I've got a big radiator and oil cooler and the temp so far has been pretty low here. I'll keep an eye on it before and after the engine swap.

So, do you know anything else about half bridge vs full bridge? I've got what looks like an RB modded double pumper Holley. I think it is supposed to run on a seperate runner manifold. You're full bridge, right? That spacer plate you got made a big difference, but it's an open plenum. I think mine needs to stay seperated, which would be ok with only the front and rear plates bridged (I think).

12abridgeport

Half bridge would also idle lower and eat less gass, defenetly better for street.
The spacer was needed mainly to make the secondaries not hit the intake manifold when they are open all the way, you don't have to put it if you slightly port the top of the intake. Would still make the same effects on a half or a full bridge. I did notice a slight power loss in lower rpms but way before the power band kicks in, so i do not lose any power with it whatsoever.

Jeff20B

iTrader: (13)

Oh, ok. This carb I've got has larger butterflies so I'd have to port both primaries and secondaries of the manifold anyway. Yeah, I'm thinking a half bridge would be the best since it'll be for the street. I did want lots of lope at idle, but maybe next time. Besides, this 13B 4 port has seen better days; I cleaned some of the parts today, and while usable, the previous owner didn't change the oil as aften as he should've. Oh well, I'll just measure everything and go from there.

680RWHP12A

bridgeports= fun
bridgeport turbo = too much fun!
3 rotor bridgeport= i will never know, i dont have enough money! but im sure it the s*****

karism

i just love no emissions.brap-brap-brap..waaaaaaaaaaaaaaaaaa....flame..2nd..waaaaaaaa a....flame..3rd...Gives me a smile everytime i hear it !
:-))))))))))

pillage6

I don't think a 3 rotor bridge will sound good.

I heard a 3 rotor dragster that was ported and supercharged and it sounded funny.

karism

I have heard a 3 rotor peripheral,and it sounded terrible!!!!
My moto...2,4 rotors sound the best!

Pillage6,which Rx7 do you drive? Turbo or NA ?

813KR$

Bridge port is the sht!
But you dont get high miles on those bridges, I have heard
they crack easily. No 100,000 mile Bridge Ports out there!
Also, turbo on bridge port not possible, you need little to no
back pressure. No one said you cant use a super charger though,
or Nitrous! Atkins rotary, $2500 super charger. Screw type too!

12abridgeport

I have heard the Kilo Racing 20B N/A car in a 1st gen and i thought it sounded a little bit funny also, it's got like that sharp sound to it.

It's true BP's don't get as high of a mileage, but the whole beauty of it is that it will last the same if you take it easy on it, or race the **** out of it, actually i think it would last less if you don't push it too much.

I think that 680rwhp12a proves that turbo's go well with BP's, i'm not sure about superchargers though. Personally i think that you can only use a supercharger on a rotary if it's a stock port. I would probably end up going with NOS cause it's so much cheaper.

Jeff20B

iTrader: (13)

Supechargers and streetports work very well together. Lots better than stock ports. I'd imagine SC and bridgeports would work ok too. All you're doing is forcing more in and more out. It's wasteful with the overlap, but more in = more power.

I think the best sounding 20Bs are the ones with turbos (either stock twins or a single large turbo). NA exhaust will always sound funny because the three ports exit at 120º apart, and if the header collector doesn't allow the pipes to be the same length, which is very difficult in the limited space down there, then the pipes will be out of balance and sound even worse. The pulses will hit each other (beat) out of time and cause a funny sounding heterodyne. The coolest sounding 20Bs I've ever heard are Lance Warren's HB Cosmo, and Pac Performance's RX-3 (both have turbos).

Well, I'm still a go for a half bridge port for my REPU. I'll just bump the oil pressure to 85-90PSI to take care of any clearanced bearing issues if you know what I mean (PO sort of neglected his oil changing duties so the bearings are a little worn).

DriveFast7

iTrader: (1)

FYI

I talked to *many* racers and shops that build/use bridgeports including 2 top USA shops. *None* said they've seen a bridge crack. Failure in bridgeports are usually carbon apex seal going, or any of the usual items like bearings, clearancing, low oil pressure, over-revving....etc....

Fennix_sr

man same here everytime .

pillage6

I have a turbo FB, it is my first turbo car and boy what a learning experience this has turned out to be.