So I want to build a n/a race engine. It's gotta be n/a and a 13b bridgy. I'm not sure what to go with. I've been planing to just rebuilt a gsl-se with some bridges in it. I was thinking a 4 port 13b with s5 rotors. What would I need to make that work. Who's done this I want 250whp...

I have a GSL-SE block that is going to use the rotor housings from and the iorns from 12a to get a 4 port bridgeport. It'll be with a 48 DCO weber... I'm quite good tuning carbs so I'll figure that out my self. The issue is exactly what Ill need engine wise to acomplish everything. Gslse block w/ 12a iorns, and using a S4 t2 intake manifold. I think that'll fit. Then I plan in using s5 rotors, but I'm not sure If I'll need the whole rotating assembly. To include rotors e-shaft, bearings, and counter weights. This will be a bracket drag car. No rules. And money is not an object. i dont think the lower intake manifoold will fit on the 12A end plates. I might keep the GSL-SE eccentric with modified oil jets. So i find any s4 or s5 block with some turbo housings and s5 rotors and my t2 mani with a 48 dcoe and I'm set. I'm a pretty good webertuner so I hope this should put me in the 250whp range. If I go cheap and use the gsl-se block and old 12a housings w/ s5 rotors does anyone know what intake manifold I should use for a side draft weber? I'm thinking that the s1 13b RB manifold should work right?!?! This is random thoughs joined into a thread anyone with info on a bridgy 13b let me know I want all the info I can get!

 

If the rotors come from a differently weighted rotating assembly, then you need the entire rotating assembly (rotors, eshaft, counterweights). Buy a proper DCOE manifold, I use the lake cities one as the motor revvs much better and more hp. If money no object and no rules on porting then go peripheral with a jerico air shift tranny. More power, narrower powerband than bridge but the close ratio jerico will make for that and more.

That said, a 48 will not allow either motor to breathe to full effeciency and make most hp. Gene Berg 56IDA with 48mm chokes will and is what some friends use on their 13B periphs. Search in the race section, there is info on race porting and carbs. Good luck, you'll love it at 7000rpms when the porting really starts to work. Brad.

 

E-shafts are interchangeable so you can retain the SE shaft if using S5 rotors. You just need the counterweights. The good thing about that is you don't have to worry about the oil thermostat like in the later model shafts.

I'd forget about using the TII manifold. It won't fit the SE engine (if you decide to go that way) without an adapter plate and from what I've heard it doesn't work very well for n/a applications anyway.

 

From what I have read the older intakes form earlier 13B's have the best flow characteristics...and they are 4 port no less

 

That Gene Berg will set you back a pretty penny.

Who sells that lake cities manifold?

 

If money is no object go with peripheral port. If you are set on using a bridge-port, use TII rotor housings with S5 NA rotors. I don't recommend 86 and up rotors in 85 and older rotor housings because the shape is slightly different. There are, however quite a few people who do it anyway including Mazdatrix.


Go with an IDA-style intake and use an IDA-style throttle body of 50mm or bigger. Run it with a Megasquirt.

 

Gene berg is too much $$$. If you have a stock 48 IDA, it only takes $150 roughly to make it a 51. Besdies, its only a bridgeport. 46 venturies?? I only have a big 13-B streetport and I my venturies are almost paper thin. It runs good. You should have seen it when I was running the carb without venturies.

 

Gene Berg ain't cheap but he said $ is no object. Atkins Rotary makes the LC mani now.

 

well if you are going with a standard setup, ie not pp, then look for a 76 13b intake...

 

http://rotaryracing.com/ff_Turn_key_bridge_port.htm

That bridgey makes a claimed 275-300 flywheel horsepower N/A, but it costs a pretty penny. I show you this to let you know that it is definately possible.

I have one of Nick's motors, and it is fantastic. I have an older street ported 4 port which Nick built to about 215 flywheel hp. His work is definately top notch, which may describe the price. Hehe.

 

if you want the ultimate 13b then go with RX8 rotors. Theres a few IPRA guys over here running 13B BP with rx8 rotors, seems the be the best way to do it coz there higher comp than s5's

-James

 

FIrst things first I DON'T want a PP. I want a bridgy... Please keep this bridgport specific thanks for all the info. Let's make this the ultimate 13b bridge port info thread. I searched for hours and only found stuff for 12a's.

 

they're lighter too. I forgot about those.

 

Check AusRotary.com Tech section

 

I had a 4 port 13b in my race RX3 in Australia, guesstimate around 240 at the flywheel, it was a street bridgeport by Warrick Massey, that engine was awesome, came on tap like a turbo at 5000 rpm and pulled like crazy to 8500 and beyond. Warrick was self employed asWJM Rotaries then he went to port engines for Maztech, he has a lot of experience with bridgeporting 13b 4 ports, and raced a 13b bridgeported FB to several state Club Car titles. If money is no problem have him do you porting. I raced it for 5 years without any problems except tuning updates, I took two state titles with that engine. His engine was considerably more powerful than mine at least 280 flywheel.

 

Keep in mind the intake as well like I said the 76 intake is the most free flowing

 

see the thing is I don't believe in other people building your car for you. I feel that if you have o buy an engine it's not your car. I never let any one work on my car at all. It's my car and I've got to build my own engine! That's why I want to build the ultimate info thread so other's later will be able to find info on bridgy 13b's

 

i know that 2" long primary exhaust is best for a BP, but this is what I'm thinking about doing. from my understanding the megaphone allows the pipe diameter to increase without causing any turbulance and therefore mimicing shorter exhaust. It's almost as of the exhaust is oen to the air at the point of the megaphone. Thats what I've been told anywayz. Plus I allready have these parts available so it wouldn't hurt to use 'em.

 

There's no point talking about standard intakes when it comes to bridgeports.

 

That exhaust will burst your eardrums! I run the same header, same presilencer, plus and additional presilencer and a larger dual tip magnaflow with 2 1/2" pipe throughout. Loud at cruise, almost hurts the eardrums, but nice on full acceleration.

 

Where you merge your exhaust is related to port timing, in order to make the most of the power/torque-band you are building the motor for.

 

Does anyone else see the obvious problem?

 

i would say if you wanna get the best bridge port. you're gonna have to use some mid 70's irons. i've heard they have more meat on them at the water jacket so you can port bigger and deeper.

 

ha ha ha ha haaa you're so funny! i was a little drunk when i typed that. Everyone else knew that I ment i was going to use 12a endplates to make it a 4 port...

 

NO it won't... First off this is going to be primarly a race car. second i drove areund with just the header and presilencer on the car for about a week and it din't bother me at all I loved it!