This is not for a daily driver. Plan is to go with a large single and PFC. It needs to have some reliability however. That is why we went with a street instead of half bridge. I just wanted to get opinions on how this approximation looks before I start cutting. The blue is of where the RB street port would be, red is about a 65ish degree port. Should I go bigger? (more toward where the corner seal rides?)


Secondly, Should I go the same size on the intermediate housing. On my last 13bt I did, but this rew housing seems to have even smaller factory primary ports. (or maybe I just dont remember) Im worried about cutting into the water jacket on the lower side of the port.


All comments are welcome. So please feel free...

 

Porting is somewhat counterintuitive. Be sure to check any of your personal port inventions over an open rotor / housing / eshaft to determine the scissor angle of the closing side seal relative to the port closing edge. Parallel interaction = busted side seal!

I'd take the primary closing edge higher and wouldn't take its tail down at all, though RB style is pretty established and seems to work. Big closing duration on the primary won't necessarily hurt low end or midrange torque if you keep the bowl and runner relatively small.

 

Periphreal it, you're not in California, and don't have to worry about smog, so perophreal it, and you won't have to worry about cutting into the water jacket !

My 2 Cents

 

1/2 bridge is reliable... if you want alot of power go with a 1/2 bridge, i LOVED mine befor i sold the car, the current FD im building is going to be a FULL bridge port..

the 1/2 bridge port was my daily driver for over 6k miles, only problem i had was i flooded it 2 times

 

I wouldn't take the primary down really at all. I might not even go out and up that much for a primary, but I like a little low-end. It's all preference really. Other than that, looks good.

I am doing a 1/2 bridge as well. I guess I'll find out how reliable and streetable it is...

 

Its very reiable and streetable!!!!

 

Well Im trying to convince him to go half bridge. Mostly b/c i want practice because Ive never done one. Which is pry why he doesnt want me to do it... Here is a pic of a junk housing I started to bp.

The other pic is of the intermediate housing. The blue is of a RB template again, and the green is of what I am proposing to try. Hows it look?


Last one is of a proposed exhaust port. Do they even need porting on the rew, they look pretty big as is. Anyways just let me know how they all look.

 

Your start of a bridge looks great, we ported the crap out of the exhaust port when we did my motor.

 

looks nice.

here's something i found on the exhaust porting:
http://www.yawpower.com/Flow%20Testing.html

with a bridgeport, i wouldn't make the port close a whole lot later, just give the closing edge a nice radius (which you're well on your way to doing). the size of your original markings for the streetport look pretty similar in size to mine.

http://www.rotaryheads.com/porting/i...et-overlay.jpg

i polished the ports on the website to a mirror finish--that was just for the bling factor, but a nice 80 grit finish with the sanding wheels will be better for atomisation. you can polish the very closing edge to a mirror shine without any negative effects, though.

you can see the port slightly taper towards the top. i wanted maximum port timing, while still having the leading edge of the side seal supported on the port closing edge. but i guess you don't even have to worry about that with a bridge.

 

That was an excellent read! Thanks. I think I will play around w/ the bp a bit more but go ahead and get rolling on the exhaust port. I dont think that Im going to mod it very much, just a bit more arch.

 

Almost forgot, I know there is alot of debate on the exhaust sleeves, but what is the general concensus? Leave them close to stock, take them out, buy new ones? I guess im not buying new ones and propably will just leave them as is, w/ some minor work maybe.

 

The exhaust sleeves is really subject to opinion. Everyone likes doing it differently. I personally use new ones that keep the area of the port the same out of the engine so exhaust velocity stays high. I've used these for several years and would never go back to stock sleeves. You can't buy these however. I have them specially machined. If I were to ever not build an engine with these, it would depend on the situation whether or not I would use the stock sleeves or not. For street use I would but for a race engine I wouldn't. I am not a fan of huge porting for the street nor am I a fan of any bridgeport for the street. This again is just personal opinion. I like some semblence of gas mileage and I have emissions testing. I'd do a bridge for track use though. Some people say a bridgeport is streetable. Others say it isn't. Yet others claim a peripheral port is a streetable engine. It's all subject to opinion and you'll get lots of different ones. If you aren't sure which is best for you, I say stay a little conservative. You can still get tons of horsepower without going to the more extreme porting styles. If you like taking risks by venturing into an area you've never been before, go for it. Either way you'll end up with a very fun very fast car.

 

The only problem with that type of exhaust sleeve would be that you need a special manifold to make it work properly, and I read somewhere the you need a special type of turbine wheel that will withstand the extra heat that your exhaust would have w/ that setup. Also Im sure you spend a pretty penny on those sleeves huh. Since it will be a street car I think ill take your advice and use the stockers. Good info tho, thanks!

 

chris, is this your first port job?

 

Have a peek, folks. Tell me what you think.

http://bdc.genxracing.com/videos/Bri...BP_GasMileage/

I forgot to add one thing: This is an HBP with Series 5 housings and Series 4 rotors. I had a car full of junk including about 300lbs of crap in the back hatch (an engine torn down). This trip was from Dallas, to New Orleans, and back. I also had two manifold gasket leaks and a leak out of my throttle body that I fixed later.

B

 

Nope, this would have been my first bp though, but we decided to just keep with the streetport. Ill try to get some finished pics up.