for REAL - Group Exhaust Info From Fabricator Russ
Posted: Sat Apr 20, 2002 12:28 pm
I don't know what the S H I T is happening man....
The message wouldn't forward. This time I copy / pasted, and it's here
Here's the summary again. Full text discussion follows immediately
Two (2) simultaneous muffler options;
1) straight thru, and
2) quieter more expensive reversing style
Both mufflers with single tastefully styled outlet
Three (3) "B" pipe options;
1) straight,
2) with cat,
3) with cat and resonator
Downpipe is where it gets complicated;
Simple most economical is the 3 inch with large fishmouth type flange at
turbine outlet. Flows better than stock, and much better with no cat.
Adding a cat should be no problem if necessary for the California criminals.
O2 sensor in stock location
Best design keeps turbine and wastegate gas separated for 18-24 inches. Area
inside turbine housing must be partitioned a la MRT. Pipe section directly
after turbine should bulge using 30 degree expansion cone for 18-24 inches to
allow swirling gasses from turbine to slow and straighten smoothly.
Wastegate gas can be reintroduced with minimal performance loss. Converter
in downpipe not doable with this design, single cat would be in usual
location under shifter.
Overall system size recommended is 3 inch.
Ballpark for dump style downpipe is $325
Ballpark for dual style downpipe is $500
Transition from two cats to one probably legal in 49 but not in California
Read the full discussion below from Russ, to get all the details of this summary
Larry Witherspoon
ssspoon@aol.com
HERE'S RUSS KAPPELMAN'S FULL ON DISCUSSION OF SUMMARY ABOVE
Larry:
Wow! There really is a lot of discussion going on over this whole exhaust system thing. I have been in communication with you and Zak concerning the details of the proposed system. Let me lay out what I have in mind in a clear manner that can be appreciated by everyone; so that we can be assured that we are all on the same page. Please forward this message to the group.
First let me say that none of the pipe work that I am building will be compatible with any stock pipe sections. The fact that the stock O.D. (outside diametre) is right at 2.39 inch goes a long way to explain why the proposed 3 inch O.D. will not mate to it. My pipe work will, however, follow the stock path under the car for the best possible fit and finish.
Muffler options: I don't see any reason why two different mufflers can't be offered simultaneously. I am sure there are several straight through muffler designs available that will fit in the confines of the stock location with no clearance problems. The reversing style muffler (quieter) will be a bit more challenging. The model that I have my eye on has 3 inch passages all the way through which is difficult to find in and of itself. It is, however, an RV muffler and is very long. It will have to be shortened and possibly indexed in order to fit it under the car. This is not a big deal but it is more work (read money). This means that the reversing style option will likely cost more than the straight through design. Both of these muffler will likely have a single outlet of tasteful size and style. I am personally not a fan of the 'coffee can' look.
'B' pipe: There is really not much to say bout this pipe other than it should not be a problem to offer three options simultaneously; straight, catalytic converter, resonator. The largest driving force behind the cost of this pipe will be the chosen option, obviously.
Downpipe: Here is where we start to have fun. The simplest and most economical option is a 3 inch pipe with a large fishmouth type flange at the turbo outlet to collect all of the gasses and send them down the line. This is not the best design for a downpipe but it flows better than stock (far better without a converter) and gets the job done. Incorporating a converter into this pipe should not be a problem if you require it. The O2 sensor will be in the same location as the original. The operation of the O2 sensor in this application is dependant strictly upon location in relation to the turbo and not the converters.
[[ Misc. info: Heat energy in the exhaust is used by three things; turbine, O2 sensor, converters. The turbo consumes some of the heat energy in the exhaust to drive the compressor wheel via the turbine wheel. The O2 sensor must be hot (at least 575 F) to begin sending its signal (0-1 volt) to the computer. Because the turbo consumes some of the heat in the exhaust the O2 sensor should be directly after the turbine i.e. stock location in stead of further down the line. (Why not put it before the turbine? I don't know. Subaru did just that on the EA81T in '84. Why did they move it into position after the turbo in the EA82T and the EJ22T? I don't know.) Converters begin doing their job at 600 F and operate optimally at 1200-1400 F. At 1800 F the substrate begins to melt. ]]
The best design for a downpipe for this application is one that keeps the gasses from the turbine and the wastegate separate for 18-24 inches before merging them together again using a dual tube system. The reason for this is the gasses from the turbine should be handled vary carefully in order to realize maximum power output. First, the area inside the turbine housing where the flange bolts on must be partitioned so no cross contamination of gases occurs. The pipe section directly after the turbine should expand to some size using a 30 degree expansion cone. I have no idea exactly how large this pipe section should be. I am guessing at 4 inches in the interest of being able to fit all of this under the hood of a Legacy. This large section and its 30 degree expansion cone are there to allow the gasses that are coming out of the turbine to slow their spiraling flow path and change to a smooth straight flow. This takes about 18-24 inches. Once this is complete the pipe can be reduced smoothly to a more Overall system pipe diametre is recommended at 1.5 times exducer diametre. 3 inches is fairly close and should satisfy our needs quite nicely.
A word about cost: I told Zak that I estimate the price of the 3 inch dump downpipe to be $325. This is just an estimate, not a quote. The fact that this pipe is so similar to the pipe currently offered for the EA82T gives us an idea of the cost. The dual downpipe would be nearer the $500 price range; again not a quote. It remains to be seen what sort of complexities will reveal themselves with this level of fabrication. The cost of the rest of the pipe sections can be estimated by the obvious complexity or lack there of.
Converters: if you don't need them for inspection then consider omitting them. A few years ago I contacted Catco, a converter manufacturer, about the legalities. I was told that in 49 states it is legal to go from a two cat system to a one cat system. This would have us using no cat in the downpipe (highly recommended) but including one in the usual location: just below the shifter. In Red Communist California you must retain the two cat system no matter what. If you live in California you might be able to get by with a single cat in the usual location because most cars conform to that standard. The inspection station might not know that Subarus are supposed to have two and may let you pass because you look 'normal'. Which way to go will be entirely up to you since you will have to live with the consequences.
[[Misc. info: What is the difference between a two cat system and a one cat system? In a two cat system the first cat is the reducing converter. It contains a substrate of ceramic matrix (or possibly aluminum oxide) coated with rhodium and platinum. This converter reduces or separates oxides of nitrogen (NOx) emissions into nitrogen and oxygen. The second cat is the oxidizing converter. It is comprised of a substrate coated with platinum and palladium. Its job is to oxidize hydrocarbons (HC) and carbon monoxide (CO), converting them to water vapor and carbon dioxide. A single cat system combines all of these functions into one unit called a three way converter (three way because it handles all three pollutants: NOx, HC, CO). Sometimes air is injected into the three way converter between the two stages when there is insufficient oxygen liberated from the oxides of nitrogen to sufficiently oxidize the hydrocarbons and carbon monoxide. Why Subaru has used the two converter system (in lieu of a 3way) for so lon Hope all of this helps. Let me know if you need any more information.
Regards,
Russ
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The message wouldn't forward. This time I copy / pasted, and it's here
Here's the summary again. Full text discussion follows immediately
Two (2) simultaneous muffler options;
1) straight thru, and
2) quieter more expensive reversing style
Both mufflers with single tastefully styled outlet
Three (3) "B" pipe options;
1) straight,
2) with cat,
3) with cat and resonator
Downpipe is where it gets complicated;
Simple most economical is the 3 inch with large fishmouth type flange at
turbine outlet. Flows better than stock, and much better with no cat.
Adding a cat should be no problem if necessary for the California criminals.
O2 sensor in stock location
Best design keeps turbine and wastegate gas separated for 18-24 inches. Area
inside turbine housing must be partitioned a la MRT. Pipe section directly
after turbine should bulge using 30 degree expansion cone for 18-24 inches to
allow swirling gasses from turbine to slow and straighten smoothly.
Wastegate gas can be reintroduced with minimal performance loss. Converter
in downpipe not doable with this design, single cat would be in usual
location under shifter.
Overall system size recommended is 3 inch.
Ballpark for dump style downpipe is $325
Ballpark for dual style downpipe is $500
Transition from two cats to one probably legal in 49 but not in California
Read the full discussion below from Russ, to get all the details of this summary
Larry Witherspoon
ssspoon@aol.com
HERE'S RUSS KAPPELMAN'S FULL ON DISCUSSION OF SUMMARY ABOVE
Larry:
Wow! There really is a lot of discussion going on over this whole exhaust system thing. I have been in communication with you and Zak concerning the details of the proposed system. Let me lay out what I have in mind in a clear manner that can be appreciated by everyone; so that we can be assured that we are all on the same page. Please forward this message to the group.
First let me say that none of the pipe work that I am building will be compatible with any stock pipe sections. The fact that the stock O.D. (outside diametre) is right at 2.39 inch goes a long way to explain why the proposed 3 inch O.D. will not mate to it. My pipe work will, however, follow the stock path under the car for the best possible fit and finish.
Muffler options: I don't see any reason why two different mufflers can't be offered simultaneously. I am sure there are several straight through muffler designs available that will fit in the confines of the stock location with no clearance problems. The reversing style muffler (quieter) will be a bit more challenging. The model that I have my eye on has 3 inch passages all the way through which is difficult to find in and of itself. It is, however, an RV muffler and is very long. It will have to be shortened and possibly indexed in order to fit it under the car. This is not a big deal but it is more work (read money). This means that the reversing style option will likely cost more than the straight through design. Both of these muffler will likely have a single outlet of tasteful size and style. I am personally not a fan of the 'coffee can' look.
'B' pipe: There is really not much to say bout this pipe other than it should not be a problem to offer three options simultaneously; straight, catalytic converter, resonator. The largest driving force behind the cost of this pipe will be the chosen option, obviously.
Downpipe: Here is where we start to have fun. The simplest and most economical option is a 3 inch pipe with a large fishmouth type flange at the turbo outlet to collect all of the gasses and send them down the line. This is not the best design for a downpipe but it flows better than stock (far better without a converter) and gets the job done. Incorporating a converter into this pipe should not be a problem if you require it. The O2 sensor will be in the same location as the original. The operation of the O2 sensor in this application is dependant strictly upon location in relation to the turbo and not the converters.
[[ Misc. info: Heat energy in the exhaust is used by three things; turbine, O2 sensor, converters. The turbo consumes some of the heat energy in the exhaust to drive the compressor wheel via the turbine wheel. The O2 sensor must be hot (at least 575 F) to begin sending its signal (0-1 volt) to the computer. Because the turbo consumes some of the heat in the exhaust the O2 sensor should be directly after the turbine i.e. stock location in stead of further down the line. (Why not put it before the turbine? I don't know. Subaru did just that on the EA81T in '84. Why did they move it into position after the turbo in the EA82T and the EJ22T? I don't know.) Converters begin doing their job at 600 F and operate optimally at 1200-1400 F. At 1800 F the substrate begins to melt. ]]
The best design for a downpipe for this application is one that keeps the gasses from the turbine and the wastegate separate for 18-24 inches before merging them together again using a dual tube system. The reason for this is the gasses from the turbine should be handled vary carefully in order to realize maximum power output. First, the area inside the turbine housing where the flange bolts on must be partitioned so no cross contamination of gases occurs. The pipe section directly after the turbine should expand to some size using a 30 degree expansion cone. I have no idea exactly how large this pipe section should be. I am guessing at 4 inches in the interest of being able to fit all of this under the hood of a Legacy. This large section and its 30 degree expansion cone are there to allow the gasses that are coming out of the turbine to slow their spiraling flow path and change to a smooth straight flow. This takes about 18-24 inches. Once this is complete the pipe can be reduced smoothly to a more Overall system pipe diametre is recommended at 1.5 times exducer diametre. 3 inches is fairly close and should satisfy our needs quite nicely.
A word about cost: I told Zak that I estimate the price of the 3 inch dump downpipe to be $325. This is just an estimate, not a quote. The fact that this pipe is so similar to the pipe currently offered for the EA82T gives us an idea of the cost. The dual downpipe would be nearer the $500 price range; again not a quote. It remains to be seen what sort of complexities will reveal themselves with this level of fabrication. The cost of the rest of the pipe sections can be estimated by the obvious complexity or lack there of.
Converters: if you don't need them for inspection then consider omitting them. A few years ago I contacted Catco, a converter manufacturer, about the legalities. I was told that in 49 states it is legal to go from a two cat system to a one cat system. This would have us using no cat in the downpipe (highly recommended) but including one in the usual location: just below the shifter. In Red Communist California you must retain the two cat system no matter what. If you live in California you might be able to get by with a single cat in the usual location because most cars conform to that standard. The inspection station might not know that Subarus are supposed to have two and may let you pass because you look 'normal'. Which way to go will be entirely up to you since you will have to live with the consequences.
[[Misc. info: What is the difference between a two cat system and a one cat system? In a two cat system the first cat is the reducing converter. It contains a substrate of ceramic matrix (or possibly aluminum oxide) coated with rhodium and platinum. This converter reduces or separates oxides of nitrogen (NOx) emissions into nitrogen and oxygen. The second cat is the oxidizing converter. It is comprised of a substrate coated with platinum and palladium. Its job is to oxidize hydrocarbons (HC) and carbon monoxide (CO), converting them to water vapor and carbon dioxide. A single cat system combines all of these functions into one unit called a three way converter (three way because it handles all three pollutants: NOx, HC, CO). Sometimes air is injected into the three way converter between the two stages when there is insufficient oxygen liberated from the oxides of nitrogen to sufficiently oxidize the hydrocarbons and carbon monoxide. Why Subaru has used the two converter system (in lieu of a 3way) for so lon Hope all of this helps. Let me know if you need any more information.
Regards,
Russ
To unsubscribe from this group, please send an email to:
BC-BFLegacyWorks-unsubscribe@egroups.com
zZz <http://docs.yahoo.com/info/terms/> .