Well, if I had some Smartcard reader software, I'd take some pictures at the shop to better explain this stuff...



B

 

BDC sorry I took so long to post. Taking it look at your great pics. I noticed you increased the port volume, changed port opening and closing, very nice so far. You made the eyebrow larger but still left behind about 3mm thickness of the bridge. Which is excellenct for a streetcar(if that bridge is made any thinner,reliability will be a factor, only a matter of time before it cracks) What crispeed is saying is closing the eyebrow at the same time the streetport is closing to aid in a nicer powerband and torque. You have done a badass job. If you compare a streetport vs a streetport 1/2 bridgeport you will have no problem gaining more power and more torque from mid range and higher rpm then a streetport . I applud the bravery to run a bridgeport in a street car.





Know for a grade in my book you get a 95% you don't get 100% only becasue you could have spend a little more time in detailing the bridgeport opening and closing and angle/flow towards the rotor chamber in the bridgeport side. Remember you want to make that bridgeport opening as efficient as possible. You almost want to forget about the streetport and have all the air/fuel enter the rotor chamber through the bridgeport. Focus and study the opening and closing of the port. In your ports I could see where the streetport plays big brother to the bridgeport. Remember the bridgeport is the earlier opening and demands your undivided attention. Fair?????

 

 

sweet..... great information Ito cant wait to open it up again :P



but we do have a cosmo block that is ready to get rebuilt.



here is some pics



http://rx7.cyberosity.com/87GTR/projects/13b-re/

 

nice pics. I like the blue engine pics where everything is so fresh and so clean..

 

yeah I like the blue one too

 

Hey Ito, thanks for the great compliments. I appreciate that quite a bit.



On the porting specifics... yes, I increased the port volume on the outlet side fairly significantly from what it originally was; his motor was one of the first ones I ported a fairly long time ago so it was an opportunity for me to "update" them with particular attention to the port outlets on both the primaries and secondaries.



On the eyebrow, I did widen it a bit as you've correctly pointed out. The eyebrow is about 7mm in width now from what memory serves (unless I'm wrong about my measurement). I left a couple of millimeter inbetween the short radius edge of the eyebrow and the inner water jacket o-ring land. I also re-shaped the eyebrow and made the cut more of the shape of an eyebrow (whereas the earlier cuts were poorly done w/ lesser skill). The underside of the short radius of the eyebrow (underneath the o-ring land) is tapered up and towards the combustion chamber as best as I could do it w/o sacrificing metal or breaking into the land itself. From peering through the intake port tunnel on the tunnel side, you can see how the charge has an easier time hitting the bridgeport cut than it did prior.



We run this setup on the street without any problem with aftermarket EFI systems (of course) after some tuning. I have a less radical (more conservative) half-BP setup I call the "Spec-C" (C is for 'conservative') that I do for people for T4-sized turbo setups. It works out real well -> still good drive-ability and low-end throttle response, mid-range and high end power, the cool bridgeport idle and decel tones, without sacrificing anything major.



What I'd like to know, however, is why as you say "the bridgeport demands your undivided attention". I've always looked at both of them together (the extend port and the bridgeport) as one large intake port with drastically earlier port opening timing. Why the emphasis on the bridgeport cut?



Thanks again,



B

 

which color blue is that and who is the supplier of the actual powder?

 

Here's a better picture of what the BP looks like before (the conservative version):







The eyebrow cut is shorter and much skinnier yet has the same properties as the larger, more radical one. The bridge is 2 to 3 times thicker and there's more iron inbetween the eyebrow cut and the o-ring land. The rotor housing is not beveled to match because the eyebrow cut is made alongside the iron that the edge of the rotor housing lays down on.



B

 

i know who im having rebuild my new engine



nice work bdc..nice work.