vj226966

I forgot that i have some real nice 12a irons laying around and i want to bridge port them. If i have the templates, can a machine shop grind them for me? I found some sites that show where the grinding takes place, but i am still wondering what to go with. Some say the bridge port has to cut into the water jackets and some say no. Is it the half bridge that clears it and the full that dose not. These 12a irons are in great shape. Oh, by the way i have a 13b 4 port with a fresh rebuild and street port.

Man_in_black49464

iTrader: (1)

http://www.rebuildingrotaryengines.c...ting_templates

This will help, you CAN do it yourself!
its real easy just start on a bad housing then when you think you got it do your good housing!

Man_in_black49464

iTrader: (1)

sorry forgot to mention that all the actual "cutting" is done with a dremal!
You can buy all the bits needed from racing beat or your local industrial supply store.
I cant state enough how really easy it is but just remeber your first one may not be right so dont put new parts in it i suggest buying a used motor that runs and buy the gasket kit once you get the first motor done and your comfident in your work you can then do a "good" motor with new apex seals and all.

Your takeing the next step in engine building so tread lightly do your research and be prepared to fail.

if you dont feel like this is right just send your parts to a shop to be done and rest easy.

Man_in_black49464

iTrader: (1)

http://www.mazdatrix.com/videos.htm
another great resource

trochoid

iTrader: (6)

Machine shops aren't set up to port rotaries unless you find one that has someone with rotary porting experience. Porting is hand work using a die grinder and possibly a drill press for the pilot holes at the start of cutting the eyebrow for a bridgeport. A 1/2 bridge is when only the primary or secondary ports are bridged, usually the secondary ports. A full bridge is both primary and secondary ports, a J-bridge or monster port is the one that gets into the water jacket.

My first question is why a bridgeport, what do you plan on using the car for? Some say a 1/2-full bridgeport is streetable, I have to strongly disagree with that. I have a 1/2sp-1/2bp 12A in the widebody and it was a major pita to drive on the street until I installed the dual Weber DCD carbs. A full bridge I wouldn't even consider trying to drive on the street with any regularity. If you go with a 1/2 bridge or more, you should port the exhaust too.

NoPistons . com has excellent info on porting in the Engine Building and Porting section.

Jibaro 12A

iTrader: (8)

Just port it yourself.

vj226966

My plans for the car is just to drive it around once in a while. Take it out on weekends. I only live 4 miles from work, so 50 miles a week or so. I want a fast,fun car to drive. I may take it to the track to see what it will run, thats about it.I see alot of videos of people with bridge ports and it dose not seem all that hard to drive. If i lived in the city, maybe.

Man_in_black49464

iTrader: (1)

maybe a nice big streetport?

rxtasy3

iTrader: (2)

yeah go streetport for dd.

vj226966

I went over to Nopistons and they have great info on porting. I am still confused about bridge porting. Some people say that you have to cut into the housings, and some say you do not. I am able to use the tools needed to port, but they say you have to worry about the angles so you dont have seals hitting the port. Also they say the size of the port changes the timing. So how do you know what to do?

vj226966

After more searching and a few phone calls, i should go with a Half-bridge. I really like that brap. With the hp gains that should work right?

trochoid

iTrader: (6)

Notching the housings is optional in some cases. The notch improves air flow by opening up a larger cross section. I notch my housings and it's very effective. What should you do, keep reading, learning, then buy a template from a reputable shop. There are different sizes of templates, the Racing Beat one for example is supposedly a small bp. If you want a good street port template, find the one Judge Ito sells.

I personally would like to find a set irons or the templates used by Rotary Engineering back when they were still in business. Their 'Turbo Alternative' and 'Super Off-Roadary' 13B engines produced 225 and 240 hp respectively. Their catalog doesn't say if their engines are street or bridge ported.

Directfreak

iTrader: (2)

To do a REAL bridgeport, the RIGHT WAY, as GOD HIMSELF intended -
you do notch the housings.

Personally, my belief is that you should notch the housings on a naturally aspirated engine, and not on a turbo setup.

vj226966

In what cases would you have to notch the housings? Does it deapend on the condition of the plates? Really to be honest, i want the brap. I cant get over how great that sounds. From a Street Port to a Bridge or half bridge port is there really that much of a H/P difference? 20-25 h/p is what it is.

Dcashdollar

iTrader: (8)

Bevel the rotors while your at it too.

Man_in_black49464

iTrader: (1)

this will mean new fuel delivery and your going to need to beef up your drivetrain or you will be replacing things every time you drive it.
$$$$$$$$$$$$

trochoid

iTrader: (6)

You just want the brap, then just port the exhaust ports up a 1/2 inch and forget the rest of this crap.

vj226966

I am still new to all of this Rotary tech so i dont understand the whole porting thing. I know its like putting a mild to hot cam in a v8.If i knew how to share links i would. There was one diagram i was looking at that should the timing degrees, i guess when porting.If it is that finicky than i can understand being hard to drive at low rpms. When i lived in NJ, there was a couple of 7s and one was ported. The only hard thing about driving that was the "bronze clutch" I dont want to waste your guys time with this but ithought you had to port the irons to get that lope and not the exhaust. The Wankle is a simple engine in one hand but hard to understand on the other.

DivinDriver

iTrader: (15)

Porting is similar to exchanging cams... except there's no going back if you take it too far.

Just like swapping cams, you're changing the opening/closing timing, and the "lift" of the "valves" that controls F/A mix entry and exit from the working chamber, for purposes of increasing flow.

zaridar

iTrader: (3)

the brap is due to more overlap from exhaust to intake. so correct me if im wrong but if you move the exhaust port up you will increase overlap with the intake and get the brap brap brap.... however it will probably have less low end, and if nothing is done to the intake ports it will have less power than a nice streetport...

trochoid

iTrader: (6)

Exactly. You win a cookie.

DriveFast7

iTrader: (1)

The condition of the plates does not determine if a notch is necessary. The condition of the plates determines if they are usable at all, and how much they need to be lapped straight/smooth in order to be used.

The wider the bridgeport is, the earlier your bridgeport opens, the more it necessitates notching the rotor housing. Most people here just bevel the rotor housing and do not cut deeply into it.

You're on the right track, keep learning. If it were me I'd send the block out to get ported professionally as I don't have the time to practice to get it right. Plus all of your drill, grinding, sanding bits, and practice motors are consumables and cost you $$$...........

zaridar

iTrader: (3)

can i have my cookie now im getting hungry

BlackWorksInc

No cookie for you!

Question, when you say bevel the rotors you mean only one side our both sides of the rotor. Also wouldn't that make the corner seal seat a little weaker and does it affect the balance of the rotors drastically if at all?

trochoid

iTrader: (6)

Generally the housings are notched to match the eyebrow on the bp. Notching rotors is a whole 'nother game best left to the real pros that can also balance the rotors after notching. Rotor notching is getting into the extreme finer details of porting.