BDC

Finally finished nyt's front secondaries today. I also bridgeported them and matched both the BP cuts and the port outlets to the already done rear ports. Link to the folder of all pictures:



http://bdc.cyberosity.com/pictures/RobertMosher



Here's a few pictures:























B

SPEED_NYC

very nice brian. i cant wait to see the car running

rfreeman27

I love thoes backlit pics. Really shows the port well.



Your ports look killer man! Great work!

toddp31

NICE JOB

BDC

Thank you.



You and me both -> First time to do a half-BP on a 13BREW motor. I'm interested to see its torque and horsepower curves.



B

IGY

Come on chicken. Ok, just go out 2mm more. Next time try angling your port at about 30 degrees through the plate. You can also try leaving some material on the backside of the bridge so that the bridge port actually catches more air. If you look from the intake manifold side it looks like a flap hanging out. leaving this extra material also makes the bridge stronger, so you don't have to worry about it breaking out. That's alot nicer finishing work than what is in my motor. Of course I'm not doing it for anyone else but me anyway.

BDC

Thank you. Glad to hear that from someone in Japan who is around this all the time with the best of them.



B

BDC

Chicken? Nah, it's not about being scared; it's about applying certain theory and ideology to this stuff. I very well could have angled the port outlets on the secondaries to be at a considerably more obtuse angle but I chose not to. The port opening timing has been extended but not a great deal. Considering the use of the vehicle (still being comfortably street driven), I felt this as well as leaving the primary port outlets small comparably speaking was a good compromise for gaining benefits of the bridgeport style of intake port along with retaining a fair level of streetability and low-end torque. You guys in Japan may have more experience with that, but over here in the states there's not many folks who run turbocharged, half-bridgeported or full-bridgeported 13B's on the street.



On the bridgeport cut comments, I left 9/64" of bridge iron in the shape of a wedge instead of that of a rectangle (which is difficult to see). I don't believe there will be a strength issue with this thickness and shape. I've seen bridgeports done with substantially thinner iron bridges left over after hogging everything out that still withstood boost up to about 26psi on a fairly large turbocharger (Turbonetics T70).



As far as scooping more air in, I also ramped the underside of the port tunnel behind the bridgeport cut just for that very reason you eluded to -> make the bridgeport cut less turbulent and more efficient at 'scooping' air in. You're right on that, by the way. The way some people do BP cuts is by going down and leaving a port that's exactly 90 degrees adjacent to the port tunnel just below it and I feel that that doesn't make much sense.



The finish of the port outlet and tunnel is left somewhat rough on purpose (as you can see in the pictures). Having a slight boundary layer in the intake ports has been proven to better distribute and mix and air/fuel mixture as well as produce higher power, everything else remaining constant.



Thanks for the vote of confidence.



B

BDC

Correction, I meant to say port closing timing on the secondary port outlet; not port opening timing. I kept that almost the same minus matching the nitride facing to the cast iron port.



B

IGY

Actually the I was not refering to port closing, I was referring to cutting the bridge port down through the plate towards the port inlet at a slight angle. Your bridge iron is actually thicker than most I've seen. I just added that by leaving it thicker and shaping it you can benefit. It also seems to me that most bridge's I have seen are cut at a 90 to the runner and it doesn't seem right.



Basically I just put the info out there for everyone. I can't stand when people don't share info. I run across this alot in Japan.



The chicken comment was all in fun. Whenever I port something I always have someone calling me a chicken(Dragon and a couple of others not on the forum).



As a side note, all these people that say the secondary bridge is not going to drive as nice, you are way wrong. My car actually made more low to midrange torque with the bridge than with the side. The only reason I don't have one now is because they are to damn loud for the cops and my neighbors.