Brideport 6-port Ideas
#41
Originally Posted by Travis R' date='Oct 7 2003, 07:07 PM
Ha ha! Who are you my dad?
If I want the aux port runner to be tuned for higher RPM wouldn't I want it to be short?
I think I understand that they will be open the longest, but how does that relate to the time it takes for the wave to get to the plenum and back?
If I want the aux port runner to be tuned for higher RPM wouldn't I want it to be short?
I think I understand that they will be open the longest, but how does that relate to the time it takes for the wave to get to the plenum and back?
#43
Originally Posted by Travis R' date='Oct 7 2003, 03:07 PM
Ha ha! Who are you my dad?
If I want the aux port runner to be tuned for higher RPM wouldn't I want it to be short?
I think I understand that they will be open the longest, but how does that relate to the time it takes for the wave to get to the plenum and back?
If I want the aux port runner to be tuned for higher RPM wouldn't I want it to be short?
I think I understand that they will be open the longest, but how does that relate to the time it takes for the wave to get to the plenum and back?
Shorter runners are needed for higher rpm, BUT, the runners for a bridged port need to be considerably longer than the other ports in a n/a motor, EVEN if its tuned for a higher RPM range.
#44
Originally Posted by mazdaspeed7' date='Oct 7 2003, 11:45 AM
Shorter runners are needed for higher rpm, BUT, the runners for a bridged port need to be considerably longer than the other ports in a n/a motor, EVEN if its tuned for a higher RPM range.
#45
This is a great topic - mazdaspeed thanks for your insights. I have been sitting around pondering this route - [bridge on the aux. port] - as well, thinking it would a 'cake and eat it' scenario. Retain low rpm torque, emissions, but above ~4000 rpm the breathing would improve with earlier opening and later closing of the aux. Seems it is not the case?
The only 'documented' instance I have seen of this kind of approach is the Grassroots Motorsports magazine folks. They built a S4 13B powered Spitfire (car, not WWII fighter!). The motor was built by Tri-Point Engineering with both a bridge on the aux, and slightly extended timing of the aux. However, the sleeves were removed and it runs on a standalone with a pair of TWM throttlebodies on a Weber type manifold. Apparently makes around 220 hp (which is plenty in a 1400 lb car!).
Having working aux. actutators is means there's a lot of obstruction in the airflow path, with the lumpy boss in the runner, and the actutator shaft, cross pin in the sleeve.......not to mention the sharper turn the air must make in the runner to get to the upper sleeve port.
If it's not worth it, what is the best 'mild' approach to porting a 6-port motor?
Curtis
'86 GXL autox'r
The only 'documented' instance I have seen of this kind of approach is the Grassroots Motorsports magazine folks. They built a S4 13B powered Spitfire (car, not WWII fighter!). The motor was built by Tri-Point Engineering with both a bridge on the aux, and slightly extended timing of the aux. However, the sleeves were removed and it runs on a standalone with a pair of TWM throttlebodies on a Weber type manifold. Apparently makes around 220 hp (which is plenty in a 1400 lb car!).
Having working aux. actutators is means there's a lot of obstruction in the airflow path, with the lumpy boss in the runner, and the actutator shaft, cross pin in the sleeve.......not to mention the sharper turn the air must make in the runner to get to the upper sleeve port.
If it's not worth it, what is the best 'mild' approach to porting a 6-port motor?
Curtis
'86 GXL autox'r
#46
Originally Posted by Travis R' date='Oct 7 2003, 03:47 PM
Explain more please. Don't be afraid to use big words... I'm an Inguhneer.
#47
Well I guess the guys here in Oz that race in improved production and are just cracking 300rwhp on their bridgeports have their inlet runner length all *** about then aswell hey?
I can't see how having a longer runner would benefit a bridgeport to make more power, I don't care what a excel spreadsheet says, it doesn't happen like that...
I can't see how having a longer runner would benefit a bridgeport to make more power, I don't care what a excel spreadsheet says, it doesn't happen like that...
#48
While we're sort of on the subject, how does everyone here prefer to start the new port on their side plates?
Just use a center punch and then drill some pilot holes along the way?
Or just start grinding straight away instead of drilling some guiding holes first?
My engine will be out and pulled appart tomorrow, so c'mon guys, anyone here that can actually back up the claims of a longer inlet runner making more power (per RPM of course..) than a short one on a BP motor? I just can't see how it is possible... but I am willing to accept it if I see some real proof before I make up my inlet manifold....
and mazdaspeed7, you mentioned somewhere back it was because of the earlier opening was it? I can't remember..
Mazda's tech paper on the lemans R26B would tend to agree that a shorter runnger = more high end torque... that was a PP but the basic principal is the same.
Just use a center punch and then drill some pilot holes along the way?
Or just start grinding straight away instead of drilling some guiding holes first?
My engine will be out and pulled appart tomorrow, so c'mon guys, anyone here that can actually back up the claims of a longer inlet runner making more power (per RPM of course..) than a short one on a BP motor? I just can't see how it is possible... but I am willing to accept it if I see some real proof before I make up my inlet manifold....
and mazdaspeed7, you mentioned somewhere back it was because of the earlier opening was it? I can't remember..
Mazda's tech paper on the lemans R26B would tend to agree that a shorter runnger = more high end torque... that was a PP but the basic principal is the same.
#49
Sorry, but that doesn't tell me why a longer runner is needed for a longer duration. Reverse engineering your formulas is a little difficult. I don't know what all of your constants mean.
I just want to make sure we're talking about the same thing too... In your spreadsheet you have "primary" and "secondary" ports listed. The primaries are the four ports that are always open and the secondaries are the two actuated by the rotary sleeves?
Thanks
I just want to make sure we're talking about the same thing too... In your spreadsheet you have "primary" and "secondary" ports listed. The primaries are the four ports that are always open and the secondaries are the two actuated by the rotary sleeves?
Thanks
#50
Originally Posted by White_FC' date='Oct 8 2003, 02:24 AM
While we're sort of on the subject, how does everyone here prefer to start the new port on their side plates?
Just use a center punch and then drill some pilot holes along the way?
Or just start grinding straight away instead of drilling some guiding holes first?
My engine will be out and pulled appart tomorrow, so c'mon guys, anyone here that can actually back up the claims of a longer inlet runner making more power (per RPM of course..) than a short one on a BP motor? I just can't see how it is possible... but I am willing to accept it if I see some real proof before I make up my inlet manifold....
and mazdaspeed7, you mentioned somewhere back it was because of the earlier opening was it? I can't remember..
Mazda's tech paper on the lemans R26B would tend to agree that a shorter runnger = more high end torque... that was a PP but the basic principal is the same.
Just use a center punch and then drill some pilot holes along the way?
Or just start grinding straight away instead of drilling some guiding holes first?
My engine will be out and pulled appart tomorrow, so c'mon guys, anyone here that can actually back up the claims of a longer inlet runner making more power (per RPM of course..) than a short one on a BP motor? I just can't see how it is possible... but I am willing to accept it if I see some real proof before I make up my inlet manifold....
and mazdaspeed7, you mentioned somewhere back it was because of the earlier opening was it? I can't remember..
Mazda's tech paper on the lemans R26B would tend to agree that a shorter runnger = more high end torque... that was a PP but the basic principal is the same.
i'm thinking that after a point it might be better just to loose the 6 ports altogether and go for a bp 4 port, you can get similar port size with less crazy port timing, but thats just conjecture
mike