Bridgeport For Street?
06-01-2003, 07:12 PM
#22
Senior Member
Join Date: Jan 2003
Posts: 237
Originally Posted by rotary fury' date='May 20 2003, 04:09 PM
any one got stoped for driving a bridge port on the street before?
06-09-2003, 04:49 AM
#24
Member
Join Date: Mar 2003
Posts: 32
Well, there are some things that can help you pass...set your idle very high, like 1200 RPM, place your factory computer in and drive it for a week slowly, use good gas, make sure your air pump and main cat are in....you might make it. I passed with a raceport.
06-09-2003, 05:59 AM
#25
Senior Member
Join Date: May 2002
Location: Okinawa, Japan
Posts: 4,928
Originally Posted by richierich' date='Jun 9 2003, 06:49 PM
Well, there are some things that can help you pass...set your idle very high, like 1200 RPM, place your factory computer in and drive it for a week slowly, use good gas, make sure your air pump and main cat are in....you might make it. I passed with a raceport.
either way, because of the overlap that bridgeports have, it's difficult to pass emissions. Even if you could pass emissions, passing noise pollution may be a bit difficult as well.
06-19-2003, 09:23 PM
#26
Junior Member
Join Date: Jun 2003
Posts: 5
Im getting a street-bridge or sometimes called half bridge. Ill just find a ghetto service center and pay them off for a sticker. I also think the standalone ems im getting well help smoothen the idle. hopefully more than 10k miles guess well see in about a week or so 
06-27-2003, 12:21 PM
#27
Senior Member
Join Date: Jun 2003
Location: Grand Prairie, TX
Posts: 917
Hold on a sec here, guys. Let me give you everything I know about bridgeporting up to this point: I've built three streeted bridgeport motors as of the time of this post. All of them are half-bridgeports in that they have the standard, "eyebrow" bridgeport cut on only the front and rear end plates.
If you notice where the eyebrow BP cut is made, the space of iron the rotor housing has to sit on (marked in the blackish colour) is left virtually untouched. With respect to the world of bridgeporting, this is the smaller type (but still effective). With substantial metal left for the inner water jacket o-ring to land, there should be no reason why it would only last 10k to 30k miles as another poster suggested. The iron bridge is left fairly thick, albeit wedge-shaped below, and there's no other reason why it would break otherwise. There's plenty of metal leftover for the corner seal and (side of the) apex seal to ride across. This type of assembly requires that the rotors be assembled with the triangular-shaped, corner piece of the apex seal riding on the centre iron plate as opposed to the front/rear iron plates. I also recommend use of the Atkins 2-piece apex seal (or other vendor) so larger, wider eyebrow cuts can be made.
The other types of bridgeporting combinations include cutting chunks out of the side of the rotor just prior to the side seal, cutting into the water jacket area (J-port, monster port, etc.) and sealing the jacket up, cutting into the rotor housing, etc., all of which I shy away from. Once you step into the water jacket, you reduce the life expectancy of the engine. For a turbocharged 13B, I don't think it's honestly necessary at all.
The engine from the two pictures above I modified and built about 2 weeks ago. The centre primary intake ports were modified to my large spec. The motor is an old late 80's HB Cosmo 13B w/ 8.5:1 rotors and Series 5-style plates minus the ability to use the teflon/o-ring front cover assembly. The eyebrow bridgeport cuts on it are 1 7/16" long. It's a street car in the most liberal sense of the word in that it is driven on the street, idles at 1200rpm, and drives decently. This particular one is a bit more aggressive than the first one I've done and it requires a higher idle and is more difficult to get running with closed O2 loop. Even though there is substantial overlap, it is still perfectly driveable on the street and still has decent low-end torque and throttle response to warrant it 'street worthy', in my opinion. It's about as extreme as I would personally go for porting in regards to a "street car". The results from such a setup (bit more conservative than the pictures shown above) have netted almost 400rwhp and 330ft/lbs of torque, at 12psi of boost, under 8000rpm, using a TO4E 57trim compressor and P-Trim 0.96 A/R tangential undivided turbine.
For anyone endeavouring to do this, an aftermarket EFI system is *required* unless you're a carburetor freak and know your way around that stuff. Roughly, from a standard or extend ported motor, idle injector timing is reduced by nearly 25% and standard fuel injector timing maps are increased by atleast 15 to 20%. The curves are also different. Fuel cut decel is not used and not recommended.
As far as emissions goes, I honestly don't know if one would pass but I suspect it wouldn't per the dramatic increase in port overlap and scavenging of charge air/fuel, especially at lower RPMs where the emissions testers tend to check.
I hope this answers some questions.
B
If you notice where the eyebrow BP cut is made, the space of iron the rotor housing has to sit on (marked in the blackish colour) is left virtually untouched. With respect to the world of bridgeporting, this is the smaller type (but still effective). With substantial metal left for the inner water jacket o-ring to land, there should be no reason why it would only last 10k to 30k miles as another poster suggested. The iron bridge is left fairly thick, albeit wedge-shaped below, and there's no other reason why it would break otherwise. There's plenty of metal leftover for the corner seal and (side of the) apex seal to ride across. This type of assembly requires that the rotors be assembled with the triangular-shaped, corner piece of the apex seal riding on the centre iron plate as opposed to the front/rear iron plates. I also recommend use of the Atkins 2-piece apex seal (or other vendor) so larger, wider eyebrow cuts can be made.
The other types of bridgeporting combinations include cutting chunks out of the side of the rotor just prior to the side seal, cutting into the water jacket area (J-port, monster port, etc.) and sealing the jacket up, cutting into the rotor housing, etc., all of which I shy away from. Once you step into the water jacket, you reduce the life expectancy of the engine. For a turbocharged 13B, I don't think it's honestly necessary at all.
The engine from the two pictures above I modified and built about 2 weeks ago. The centre primary intake ports were modified to my large spec. The motor is an old late 80's HB Cosmo 13B w/ 8.5:1 rotors and Series 5-style plates minus the ability to use the teflon/o-ring front cover assembly. The eyebrow bridgeport cuts on it are 1 7/16" long. It's a street car in the most liberal sense of the word in that it is driven on the street, idles at 1200rpm, and drives decently. This particular one is a bit more aggressive than the first one I've done and it requires a higher idle and is more difficult to get running with closed O2 loop. Even though there is substantial overlap, it is still perfectly driveable on the street and still has decent low-end torque and throttle response to warrant it 'street worthy', in my opinion. It's about as extreme as I would personally go for porting in regards to a "street car". The results from such a setup (bit more conservative than the pictures shown above) have netted almost 400rwhp and 330ft/lbs of torque, at 12psi of boost, under 8000rpm, using a TO4E 57trim compressor and P-Trim 0.96 A/R tangential undivided turbine.
For anyone endeavouring to do this, an aftermarket EFI system is *required* unless you're a carburetor freak and know your way around that stuff. Roughly, from a standard or extend ported motor, idle injector timing is reduced by nearly 25% and standard fuel injector timing maps are increased by atleast 15 to 20%. The curves are also different. Fuel cut decel is not used and not recommended.
As far as emissions goes, I honestly don't know if one would pass but I suspect it wouldn't per the dramatic increase in port overlap and scavenging of charge air/fuel, especially at lower RPMs where the emissions testers tend to check.
I hope this answers some questions.
B
06-27-2003, 12:36 PM
#29
Senior Member
Join Date: Jun 2003
Location: Grand Prairie, TX
Posts: 917
Here's two links to some videos of one of the half-bridgeported street cars I've built. You can hear how they sound, how they act, and the power they can make.
http://rx7.cyberosity.com/87GTR/pics/2003/03242003/
http://rx7.cyberosity.com/87GTR/pics/2003/04122003/
Feedback welcome. Enjoy.
B
http://rx7.cyberosity.com/87GTR/pics/2003/03242003/
http://rx7.cyberosity.com/87GTR/pics/2003/04122003/
Feedback welcome. Enjoy.
B
