J-bridging
01-09-2004, 12:35 PM
#1
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Thread Starter
Join Date: Jun 2003
Location: Columbus, Ga
Posts: 233
What is involved in J-Bridging? I talked to a guy a mazdatrix and he said that its just a bigbridge port but you cut in the coolant seal groove and just cut the seal at each end and put hylomar down around the rest.Wouldent this cause a big coolant leak? could some of you give me some help, maybe a pic?
David
David
01-09-2004, 12:43 PM
#2
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Join Date: Sep 2002
Location: Tallahassee, FL
Posts: 5,425
J or Monster Port
The J ported engine (also known as monster port) is as big as conventional side-plate porting can go. It is the same as the bridge port in design, but the bridged port is now fatter and extends past the face of the rotor and into the housing’s water seal / O-ring requiring the need for the seal to be cut back and filled with a metal type sealant such as "Devcon", plus, depending on the side plate used, the water gallery requires blocking off and filling on the side plate and the rotor matching.
Cutting into the rotor housing is also needed for port matching. The main problem with this design of port is a short life-span as water does and will seep through the seals. The main field where a J-port is likely to be seen is on the track where restrictions don't allow peripheral porting, or a slightly wider power band is desired. Typically around 300hp can be expected.
PRO'S: Slightly better power than a bridge port (5 to 10%) without the expense of a PP
CON'S: Short life-span, 6-12 months / 5,000-10,000km, narrow power band, need for free-flowing/loud exhaust system, poor drivability
The J ported engine (also known as monster port) is as big as conventional side-plate porting can go. It is the same as the bridge port in design, but the bridged port is now fatter and extends past the face of the rotor and into the housing’s water seal / O-ring requiring the need for the seal to be cut back and filled with a metal type sealant such as "Devcon", plus, depending on the side plate used, the water gallery requires blocking off and filling on the side plate and the rotor matching.
Cutting into the rotor housing is also needed for port matching. The main problem with this design of port is a short life-span as water does and will seep through the seals. The main field where a J-port is likely to be seen is on the track where restrictions don't allow peripheral porting, or a slightly wider power band is desired. Typically around 300hp can be expected.
PRO'S: Slightly better power than a bridge port (5 to 10%) without the expense of a PP
CON'S: Short life-span, 6-12 months / 5,000-10,000km, narrow power band, need for free-flowing/loud exhaust system, poor drivability
01-09-2004, 03:01 PM
#5
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Join Date: May 2002
Location: California
Posts: 22,465
Originally Posted by FrostRacing' date='Jan 9 2004, 11:08 AM
im not sure that it does, but i cant see how it wont
01-26-2004, 08:26 AM
#6
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Join Date: Jan 2004
Location: Central Ohio (Hebron) Zephyrhills Fla.
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The "monster" port and the "J" bridge port are not the same thing.
The "J" bridge port is cut through the iron to the front wall of the water "O" ring groove. So if the rotor housing is not filled with Devcon Plastic Aluminum, there will be only the width of the front wall of the "O" ring groove to seal out any coolant. Just a bead of silicone or whatever to hold back the water. It generally lasts a racing season and even when it does leak, so little water can get through the mechanical joint that it is just not a factor.
No power below 6,000 RPM. Max power above 9,000 RPM
This is used where the rules do not permit the addition of any material to the engines.
The monster port involves cutting the port runner well passed the the "O" ring groove. The only way this can work is to fill the adjoining section of the rotor housing with Plastic Aluminum. Otherwise the coolant would just run into the engine. So where there is no coolant, there is no leakage. The Epoxy material forms one wall of the runner, and the opening into the chamber is extended into the face of the rotor housing.
It will have similar port timing as a periphery port. Useless on the street. Very high idle speeds. No power below 6,500 RPM. Max power above 9,000 RPM.
Both require a very free flowing muffler. Very loud, just under 103 DB.
Lynn E. Hanover
The "J" bridge port is cut through the iron to the front wall of the water "O" ring groove. So if the rotor housing is not filled with Devcon Plastic Aluminum, there will be only the width of the front wall of the "O" ring groove to seal out any coolant. Just a bead of silicone or whatever to hold back the water. It generally lasts a racing season and even when it does leak, so little water can get through the mechanical joint that it is just not a factor.
No power below 6,000 RPM. Max power above 9,000 RPM
This is used where the rules do not permit the addition of any material to the engines.
The monster port involves cutting the port runner well passed the the "O" ring groove. The only way this can work is to fill the adjoining section of the rotor housing with Plastic Aluminum. Otherwise the coolant would just run into the engine. So where there is no coolant, there is no leakage. The Epoxy material forms one wall of the runner, and the opening into the chamber is extended into the face of the rotor housing.
It will have similar port timing as a periphery port. Useless on the street. Very high idle speeds. No power below 6,500 RPM. Max power above 9,000 RPM.
Both require a very free flowing muffler. Very loud, just under 103 DB.
Lynn E. Hanover
01-26-2004, 10:08 AM
#7
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Join Date: May 2002
Location: California
Posts: 22,465
Originally Posted by Lynn E. Hanover' date='Jan 26 2004, 06:26 AM
It generally lasts a racing season and even when it does leak, so little water can get through the mechanical joint that it is just not a factor.
Both require a very free flowing muffler. Very loud, just under 103 DB.
Lynn E. Hanover
Both require a very free flowing muffler. Very loud, just under 103 DB.
Lynn E. Hanover
103 is quiet! our its car is 122, its insanely loud, we need a new exhaust
02-25-2004, 10:57 AM
#8
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Join Date: Jan 2004
Location: Central Ohio (Hebron) Zephyrhills Fla.
Posts: 1,322
Originally Posted by Lynn E. Hanover' date='Jan 26 2004, 06:26 AM
The "monster" port and the "J" bridge port are not the same thing.
The "J" bridge port is cut through the iron to the front wall of the water "O" ring groove. So if the rotor housing is not filled with Devcon Plastic Aluminum, there will be only the width of the front wall of the "O" ring groove to seal out any coolant. Just a bead of silicone or whatever to hold back the water. It generally lasts a racing season and even when it does leak, so little water can get through the mechanical joint that it is just not a factor.
No power below 6,000 RPM. Max power above 9,000 RPM
This is used where the rules do not permit the addition of any material to the engines.
The monster port involves cutting the port runner well passed the the "O" ring groove. The only way this can work is to fill the adjoining section of the rotor housing with Plastic Aluminum. Otherwise the coolant would just run into the engine. So where there is no coolant, there is no leakage. The Epoxy material forms one wall of the runner, and the opening into the chamber is extended into the face of the rotor housing.
It will have similar port timing as a periphery port. Useless on the street. Very high idle speeds. No power below 6,500 RPM. Max power above 9,000 RPM.
Both require a very free flowing muffler. Very loud, just under 103 DB.
Lynn E. Hanover
The "J" bridge port is cut through the iron to the front wall of the water "O" ring groove. So if the rotor housing is not filled with Devcon Plastic Aluminum, there will be only the width of the front wall of the "O" ring groove to seal out any coolant. Just a bead of silicone or whatever to hold back the water. It generally lasts a racing season and even when it does leak, so little water can get through the mechanical joint that it is just not a factor.
No power below 6,000 RPM. Max power above 9,000 RPM
This is used where the rules do not permit the addition of any material to the engines.
The monster port involves cutting the port runner well passed the the "O" ring groove. The only way this can work is to fill the adjoining section of the rotor housing with Plastic Aluminum. Otherwise the coolant would just run into the engine. So where there is no coolant, there is no leakage. The Epoxy material forms one wall of the runner, and the opening into the chamber is extended into the face of the rotor housing.
It will have similar port timing as a periphery port. Useless on the street. Very high idle speeds. No power below 6,500 RPM. Max power above 9,000 RPM.
Both require a very free flowing muffler. Very loud, just under 103 DB.
Lynn E. Hanover
Notice that the curve across the top of the port is not correct. The outer part of the closing line should be a bit taller (later closing) than the inner. This so that the side seal gradually is pulled back onto the flat surface, with the very tip end arriving last onto the flat.
The side seal runs off of the bridge at the half way point, and remains unsupported until the rotor is closing the port. Notice the inner track (the path of the trailing end of the side seal) just runs off into the port at the top of the picture.
Notice that the leading end of the side seal is supported by the bridge. This track line demarkates the inside limit of the additional port. Stay about 1/16" from that track line. The outer limit of the additional (bridge port) is the 1/8" of iron left in place to seal out the coolant. See the two triangles. This is a 12A iron and may not be exactly the same as a 13B.
The track of the outer oil scraper is used to demarkate the inner limit of the enlarged stock port. Leave a 1/16" so that you may radius all along that wall.
You should leave the bridge face about 1/4" wide (or more). And leave the thickness close to "as cast". Very thin faces tend to wear quickly and a missed shift can crack a thin bridge. The underside of the bridge will be sharp, with the edge facing into the inlet flow. This is fine for power, but sharp edges invite cracks. So I break that sharp edge with some fine wet and dry paper. There is no place for a sharp edge anywhere in the engine.
So that leaves only the closing point line to be copied from a template, or pattern you have made from a piece of iron from a good running engine. Or you can rig up a big degree wheel and lay it out yourself.
I hope that this helps out a bit.
Lynn E. Hanover
02-25-2004, 05:01 PM
#10
Senior Member
Join Date: Jan 2002
Location: CT
Posts: 1,345
this is good for racign clasees, when the class doesnt permit the peripheral port,if you are doign this on teh street a pport would be more reliable. just somethign to think about if you are not already aware of.