Wastegate Exhaust System?

[2000StreetRod]

Cat catagories

In researching catalytic converters on the internet I've learned that there are multiple categories available: racing, off-road, OBDI, OBDII and CARB. Only CARB certified cats can be sold to addresses in California and are basically equivalent to the OEM unit. CARB certifcation is the strictest for emission control. Racing and off-road cats apparently have no emission control requirements. OBDI cats have no post-cat O2 sensor to monitor the effeciency of the cat. OBDII cats have a post-cat O2 sensor to determine when a cat loses it's emission effectiveness.

Ceramic substrate cats are as effective as metallic substrate cats and less expensive to manufacture. However, ceramic substrate cats are slightly more restrictive and more temperature sensitive than metallic subtrate cats. Metallic substrate cats are more desireable for high performance engines (especially forced induction) which often operate at richer air/fuel ratios resulting is higher cat temperatures.

Here in South Carolina we have no annual emission inspections and I could probably install a racing cat on my Sport if I did it myself. However, eventually there may be inspections here and I don't want to pollute the environment. Also, since I don't weld I'll have the cats installed by a shop that may require OBDII compliant units.

Eventually, if the opportunity occurs, I want to add forced induction. I want my upgraded exhaust system to be adequate for it. Therefore, I plan to install metallic core, OBDII compliant cats in the near future. Adding the requirement of small size to fit in the space available will significantly reduce the number of products to consider.

 

[CDW6212R]

That is what I found but I forgot the difference between ceramic/metallic substrates.

I would prefer the slim no shield designed cats, because they will fit in tighter spaces. Those generally are 4", round profile, and rather short. I'd like to find that one of those comes a little bigger than that, then it would flow better still, and fit in tighter spaces than a shielded cat.

I'm betting that any OBDII compliant cat is shielded and results in being smaller for a given internal brick size.

 

[2000StreetRod]

Flowmonsters?

I'm going to find out more about Flowmonsters: metallic high flow cats

 

[CDW6212R]

I'm going to find out more about Flowmonsters: metallic high flow cats

Those look very promising. I have two similar to that in 2.5" that I got from an eBay seller, a few years back. I'm likely to use them for my truck, thinking I may end up making a 2nd set of cat pipes. I usually end up doing things twice just to get them just right.

 

[2000StreetRod]

selected a local exhaust shop

I've selected a local exhaust shop that is willing to install any components I want including dual high flow cats. So far I've only talked with the manager and not the exhaust specialist. They have the capability to weld stainless steel but can't bend stainless steel pipes. As soon as I finish my engine oil thermostat and front sway bar bushings/links installation I'll drive my Sport into the shop to discuss components and confirguations with the exhaust guru. The manager is agreeable to purchasing the components I select to make a little more money and save me a little money. Or I can purchase some (or all) of the components and they'll install them.

 

[CDW6212R]

That's good, having an agreeable local shop helps a lot.

 

[2000StreetRod]

Eliminating cat brands

Below are cat brands I've eliminated with my reason:

MagnaFlow - for metallic substrate largest inlet/outlet diameter is 2.25 inches

PaceSetter - 2-way instead of 3-way, not OBD2 approved

Vibrant Performance - OBD1 not OBD2 for metal core

Davesport - only 100 cells/sq in, probably result in cat efficiency DTC, not EPA certified

Random Technology - ceramic substrate

SLP Performance - ceramic substrate

GESi - too expensive ($432), minimum inlet/outlet 3 inches

Walker - no 2.5 inch single inlet/single outlet universal

 

[toypaseo]

I was going to mention the Vibrant GESi one, since i seen one installed on a EVO in Modified Magazine. Never seen the price until now... holy crap...

 

[CDW6212R]

Below are cat brands I've eliminated with my reason:

MagnaFlow - for metallic substrate largest inlet/outlet diameter is 2.25 inches

PaceSetter - 2-way instead of 3-way, not OBD2 approved

Vibrant Performance - OBD1 not OBD2 for metal core

Davesport - only 100 cells/sq in, probably result in cat efficiency DTC, not EPA certified

Random Technology - ceramic substrate

SLP Performance - ceramic substrate

GESi - too expensive ($432), minimum inlet/outlet 3 inches

Walker - no 2.5 inch single inlet/single outlet universal

Well done, that's a good list, or a good bad list.

 

[2000StreetRod]

metal core cat candidates

Flowmonster 415 Series Metallic, $85:
415200, 2.0 inlet/outlet
415225, 2.25 inlet/outlet
415250, 2.5 inlet/outlet
415300, 3.0 inlet/outlet
300 cells/sq in
4 in diameter, 11 in long
OBD1 & OBD2 approved
5.9L max engine

Eastern Catalytic 7" Bullet, $88:
79124, 2.25 inlet/outlet
79125, 2.5 inlet/outlet
79130, 3.0 inlet/outlet
200 cells/sq in
4.25 in diameter, 11 (2.25 & 2.5), 10 (3.0) in long
OBD2 approved
3.8L max engine

Eastern Catalytic 9" Bullet, $108:
79224, 2.25 inlet/outlet
79225, 2.5 inlet/outlet
79230, 3.0 inlet/outlet
200 cells/sq in
4.25 in diameter, 13 (2.25 & 2.5), 12 (3.0) in long
OBD2 approved
5.9L max engine

MBS Performance Exhaust, $100:
HiFlCv, 2.0 inlet/outlet,
HiFlCv, 2.25 inlet/outlet
HiFlCv, 2.5 inlet/outlet, 410 cfm @ 28"
HiFlCv, 3.0 inlet/outlet, 467 cfm @ 28"
300 cells/sq in
4 in diameter, 11 in long
OBD1 & OBD2 approved
5.9L max engine

Flowmaster 200 Series, $147 (2.0 thru 2.5), $187 (3.0):
2000120, 2.0 inlet/outlet
2000124, 2.25 inlet/outlet
2000125, 2.5 inlet/outlet
2000130, 3.0 inlet/outlet
4.0 (2.0 thru 2.5), 5.0 (3.0) in diameter, 12.75 (2.0 thru 2.5), 14.0 (3.0) in long
OBD2 approved
5.7L max engine

 

[2000StreetRod]

Catalyst Efficiency

It would be interesting to determine how efficient my stock cats are after thirteen years and to compare that efficiency to the replacement cats. According to the Ford 2000 Model Year OBD Summary:

"The Catalyst Efficiency Monitor uses an oxygen sensor before and after the catalyst to infer the hydrocarbon efficiency based on oxygen storage capacity of the ceria and precious metals in the washcoat. Under normal, closed-loop fuel conditions, high efficiency catalysts have significant oxygen storage. This makes the switching frequency of the rear HO2S very slow and reduces the amplitude of those switches as compared to the switching frequency and amplitude of the front HO2S. As catalyst efficiency deteriorates due to thermal and/or chemical deterioration, its ability to store oxygen declines. The post-catalyst HO2S signal begins to switch more rapidly with increasing amplitude, approaching the switching frequency and amplitude of the pre-catalyst HO2S. The predominant failure mode for high mileage catalysts is chemical deterioration (phosphorus deposition on the front brick of the catalyst), not thermal deterioration. . .

In order to assess catalyst oxygen storage, the monitor counts front and rear HO2S switches during part-throttle, closed-loop fuel conditions after the engine is warmed-up and inferred catalyst temperature is within limits. Front switches are accumulated in up to nine different air mass regions or cells although 3 air mass regions is typical. Rear switches are counted in a single cell for all air mass regions. When the required number of front switches has accumulated in each cell (air mass region), the total number of rear switches is divided by the total number of front switches to compute a switch ratio. A switch ratio near 0.0 indicates high oxygen storage capacity, hence high HC efficiency. A switch ratio near 1.0 indicates low oxygen storage capacity, hence low HC efficiency. If the actual switch ratio exceeds the threshold switch ratio, the catalyst is considered failed. . .

TYPICAL MALFUNCTION THRESHOLDS:
Rear-to-front O2 sensor switch-ratio > 0.75 (bank monitor)
Rear-to-front O2 sensor switch-ratio > 0.60 (Y-pipe monitor)
Rear-to-front O2 sensor switch ratio > 0.50 for E10 to > 0.90 for E85 (flex fuel vehicles)"

I assume that there is a PID associated with the O2 sensor switch-ratio. My next exhaust related task will be to set up a data collection configuration file for exhaust related parameters. Then I'll drive my Sport and collect stock cat data. After the exhaust is modified I'll repeat the data collection and compare results. My stock cats probably have 400 cells/sq in and therefore a larger storage capacity. However, being old their storage may be comparable to a new cat having 200 cells/sq in.

During my cat research I learned why the air/fuel ratio is cycled between rich and lean. According to Wikipedia:

"Three-way catalysts are effective when the engine is operated within a narrow band of air-fuel ratios near stoichiometry, such that the exhaust gas oscillates between rich (excess fuel) and lean (excess oxygen) conditions. However, conversion efficiency falls very rapidly when the engine is operated outside of that band of air-fuel ratios. Under lean engine operation, there is excess oxygen and the reduction of NOx is not favored. Under rich conditions, the excess fuel consumes all of the available oxygen prior to the catalyst, thus only stored oxygen is available for the oxidation function. Closed-loop control systems are necessary because of the conflicting requirements for effective NOx reduction and HC oxidation. The control system must prevent the NOx reduction catalyst from becoming fully oxidized, yet replenish the oxygen storage material to maintain its function as an oxidation catalyst."

 

[CDW6212R]

That does not sound good. If the ideal temps for the cats matched the best A/F ratios, then it would correspond and the PCM programming would favor both.

But if the cat's ideal temperature operating range is different at all from the best A/F ratios for power and economy, which would the OEM programming favor? If they favored the cat's needs the most, that could be a reason that virtually all stock programming is less than ideal. I've never read of a stock vehicle having a new tune installed, and find that nothing was gained. I have always wondered why there would be something to gain for any stock vehicle, the OEM programming should have been perfect to begin with.

 

[2000StreetRod]

air/fuel ratios

I don't know about the cat's ideal temperature. I know that it needs heat and that is way it is located close to the exhaust manifold. A rich fuel mixture allows combustion to occur in the cat raising it's temperature.

According to my Bosch Fuel Injection & Engine Mangement book maximum power is achieved at 0.86 lambda (12.6:1) [0.9 lambda (13.2:1) in another section] and minimum fuel consumption is at 1.05 lambda (15.4:1). For engine exhaust before a cat NOx peaks at 1.03 lambda while HC and CO decrease as lambda increases. After the three-way cat NOx is very low at 1.0 lambda but steeply increases at 1.01 lambda. The stoichiometric air/fuel ratio (14.7:1) results in nearly complete combustion with minimal harmful emissions after the cat.

At moderate to wide open throttle the PCM reverts to open loop using programmed air/fuel ratios and ignores the O2 sensors. I don't know what the stock setting is but many tuners set the air/fuel ratio to 12.8:1 for WOT.

 

[CDW6212R]

I learned a while back that you can test an O2 sensor with a simple propane torch, adjusting the temperature it sees by varying the flame, color etc.

I've never done it but that's when I learned that the O2 responds by voltage change, to a narrow temperature range. Too hot and the sensor only reads one way, lean or rich, and too cold it reflects the opposite. So that temperature range is required to be near what results from typical good A/F ratios.

It is just good in the end that we can control the A/F ratios, things are better than they were for tuning, back in the early 90's Now we don't deal with FMU's or adjusting the fuel pressure etc.

 

[2000StreetRod]

O2 sensor compares

The O2 sensor compares the oxygen level in the exhaust to the oxygen level in ambient air. There's a vent to the outside in the sensor. Sometimes while off roading the sensor vent gets covered with mud resulting in erroneous readings. Sensors require at least 600 deg F for effective operation. The O2 sensor heater decreases the time before the output is reliable compared to just depending on the exhaust. That allows the PCM to enter closed loop sooner and control emissions. When a sensor is blown with a torch the voltage output is still representative of the relative oxygen content between the exhaust end and the vent. The torch acts as the heater but (if the sensor is removed from the exhaust pipe) also influences the sensor output voltage according to the oxygen content of the torch exhaust compared to ambient air. New narrow band sensors typically have an output voltage swing from more than 0.9 volts (lambda = 0.98) to less than 0.1 volts (lambda = 1.02). As the sensor ages the maximum voltage decreases to around 0.83 volts and the minimum increases to about 0.1 volts. I don't remember what my wideband air/fuel ratio sensor outputs are but the meter range is from air/fuel ratio = 10:1 to 16:1. My Bosch manual states that an ignitable mixture ranges from 10:1 to 17:1.

 

[2000StreetRod]

cat efficiency PIDs

This afternoon I started constructing a data logging configuration file to monitor the efficiency of my catalytic converters. According to the Ford MY 2000 OBD Summary the criteria to enter the once per driving cycle 900 second (15 minutes) catalyst monitor operation is:

1. HO2S response test complete
2. no DTCs (P0133/P0153) prior to calculating switch ratio
3. no evap leak check DTCs (P0442/P0456)
4. ECT, IAT, TP, VSS, CKP sensors OK
5. Time since engine start-up (70 deg F start) > 330 seconds
6. Engine Coolant Temp > 170 deg F & < 230 deg F
7. Intake Air Temp > 20 deg F & < 180 deg F
8. Engine Load > 10%
9. Throttle Position = Part Throttle
10. Time since entering closed loop fuel > 30 sec
11. Vehicle Speed > 5 mph & < 70 mph
12. Inferred Catalyst Mid-bed Temperature > 900 deg F
13. EGR flow > 1% & < 12%
14. Steady Air Mass Flow > 1.0 lb/min & < 5.0 lb/min

I selected the following PIDs:
AIR FLOW #/MIN
BANK1 TOTAL NUMBER OF SWITCHES
BANK2 TOTAL NUMBER OF SWITCHES
CAT TEST IN PROGRESS
CAT TEST IS READY TO TEST
CAT TP RATE OF CHANGE
COOLANT TEMPERATURE
EGR PERCENT ACTUAL
ENGINE SPEED
INFERRED CATALYST TEMPERATURE
INFERRED EGO TEMPERATURE
INFERRED EXHAUST VALVE TEMPERATURE
INLET AIR TEMP
LONG TERM FUEL TRIM BANK 1
LONG TERM FUEL TRIM BANK 2
SHORT TERM FUEL TRIM BANK 1
SHORT TERM FUEL TRIM BANK 2
THROTTLE POSITION ABSOLUTE
VEHICLE SPEED

I realized this evening that I need to add engine load. I performed a 5 minute data log after the engine had been idling (for another test) for at least 15 minutes. Even though the criteria was not satisfied to enter the cat monitor test I did retrieve some useful data:

The average INFERRED CATALYST TEMPERATURE WAS 677 deg F. I found an article on the internet stating that the max safe temperature is about 1650 deg F.

The average INFERRED EGO TEMPERATURE was 921 deg F.

The average INFERRED EXHAUST VALVE TEMPERATURE was 580 deg F. The max safe temperature is about 1650 deg F.

I need to learn more about "inferred EGO temperature" and "cat tp rate of change".

 

[Campoli]

I'm doing my exhaust next week on my 2000 sohc now I got a quick question when I replace my rear dual cats do I have to put 2 back? I don't want to screw with the o2 sensors. And also I've never made a custom exhaust with cats I've always eliminated them since I new a ship that would let me slide but now in on a different state and haven't found an understanding shop so how do I use cats with put any o2 sensor cut outs in them it's probly a dumb question but like I said never had to worry about that in the past

 

[2000StreetRod]

different configurations

. . . when I replace my rear dual cats do I have to put 2 back? I don't want to screw with the o2 sensors.

I think I have the original cats on my Sport. The configuration is one cat in each downpipe with an upstream O2 sensor. The pipes go into a dual inlet single outlet muffler with post cat O2 sensors just upstream of the muffler. After the muffler there is a resonator in the tailpipe just before the rear axle. I think it is a reasonable stock configuration which may only be standard on a 2WD Sport. I've heard of a Y configuration with 2 inline cats but was not aware of a 4 cat configuration. Is it possible what you're calling the rear dual cats are addtional mufflers? Talk to your exhaust specialist about the best and legal approach.

And also I've never made a custom exhaust with cats I've always eliminated them since I new a ship that would let me slide but now in on a different state and haven't found an understanding shop so how do I use cats with put any o2 sensor cut outs in them it's probly a dumb question but like I said never had to worry about that in the past

Shame on you. Cats reduce obnoxious noise as well as pollutant emissions. There is a significant potential fine to a shop that illegally modifies an exhaust system for other than off-road or racing use. The peak performance lost with good flowing cats is small. Trust your exhaust specialist if the shop has a good reputation.

 

[Campoli]

I don't have a sport it's an xls w factory Y there are two small cats passenger and driver then the Y then the dual (rear) cats then the muffler to tail pipe no res on my ex

As for the catless customs most were for chevelles camaros GTOs and two were for eclipse awd turbos ment for the track but did see some street time

 

[2000StreetRod]

Please use your own thread

I found your thread about replacing your exhaust system: Exhaust ?? . This thread is about me replacing my exhaust.