Second Drive With Sport Cats Installed . . . .
09-12-2014, 09:37 PM
#1
Rennlist Member
Thread Starter
Second Drive With Sport Cats Installed . . . .
I am posting this to hopefully help anyone who may be sitting on the fence as to whether or not to install them.
First, some background is needed.
Back in March I purchased a 3.8 build by Blackforest in San Diego. The former owner had spent almost $20k on the rebuild using Mahle components, RS cam grind,heads flowed, chip, etc. He also had B&B headers and B&B performance mufflers installed.
When I got the car I could sense the slightly fatter mid-range, but didn't really notice much of any improvement above 4k revs compared to my early '95. It just really didn't seem to breathe as well above 4k as my '95. Like the flywheel was too heavy if that makes sense.
The former owner had passed away in June the previous year so I could not ask him any questions, but Mark the motor builder remembered the customer and motor well. I told him that it just didn't seem to breathe right.
At his suggestion, reading threads here, and realizing the original cat had near 80k miles on it, I started to think about a set of sport cats. (The car has 79k miles now, the 3.8 build was at 53k miles)
I have FD II's on my early '95 coupe ( OBD 1, Bischoff) and absolutely love the sound, but what about these B&B's? Everyone says they drone, mine are from a later batch so they did a little, but not bad. Darrin told me he could rework them to be almost III's. So I got to thinking, if he could rework them to be like III's, then the B&B's must be more like MotorSound, because they sure are not like my II's.
Trying to decide what muffler to use delayed my ordering. When I finally pulled the trigger, the sport cats were on back order.
Because I wasn't sure how this would all play out (whether to use sport cats or straight X pipe) I decided on the Fabspeed product. That way if I wanted to change, it was an easy swap from cat to straight X. I didn't want to deal with CEL possibilities from an X pipe and I had also read in some cases ( I don't remember where, don't know how true it is) where burnt exhaust valves were more common with a cat-less system. Definitely did not want to deal with that.
I have seen Honda motorcycles and others where the joining of the exhaust banks was done. It seemed like a good idea. Maybe I'm just gullible here, I don't know. The idea of ditching the OEM cat for one that breathed better seemed like what was needed.
This concept of joining the pipes had me curious as to how large the hole was. 1", 2"? so I've taken a pic if you are curious as well.
So I decided to try the B&B muffs first and go from there.
It took my indy about an hour and a half to install with me helping. Fortunately since it is/was a CA car, and the motor had been out 25k miles ago, everything came apart and went together smoothly. O2 sensors can sometimes fail after removal and my indy mentally prepared me for that, but we had no issues.
I was impressed with the quality of the plumbing, very heavy tubing, not thin walled. (I had to laugh as it sort of looked like a kitchen sink drain). Fasteners and clamps are all first rate. There was one thing that we found, two of the copper nuts supplied, were 12mm, the rest 13mm. We laughed at the next guy who might remove it, a WTF moment for him. The gaskets supplied weren't awful, but we reused the ones Blackforest had installed as they were of better quality.
On initial start-up it sounded much better at idle, a fatter, richer ($1,400 richer), fuller sound. The B&B had kind of a tinny sound before. I needed to get out of the populated area to give it a good test.
Although the old cat looked fine, it had been impeding flow. With the sport cat installed the hold back sensation was gone, it now revs freely and easily up to the redline.
The motor is now happy, it seems to breathe like it should.
Downshifting from 4th to 3rd and stepping on it is awesome. A sophisticated nasty, the way a Porsche should be.
So many thanks to Ilko for the push, Martin S. for the data and huge shove, and Nam for the patience to deal with my numerous texts . . .
Best Regards,
.
First, some background is needed.
Back in March I purchased a 3.8 build by Blackforest in San Diego. The former owner had spent almost $20k on the rebuild using Mahle components, RS cam grind,heads flowed, chip, etc. He also had B&B headers and B&B performance mufflers installed.
When I got the car I could sense the slightly fatter mid-range, but didn't really notice much of any improvement above 4k revs compared to my early '95. It just really didn't seem to breathe as well above 4k as my '95. Like the flywheel was too heavy if that makes sense.
The former owner had passed away in June the previous year so I could not ask him any questions, but Mark the motor builder remembered the customer and motor well. I told him that it just didn't seem to breathe right.
At his suggestion, reading threads here, and realizing the original cat had near 80k miles on it, I started to think about a set of sport cats. (The car has 79k miles now, the 3.8 build was at 53k miles)
I have FD II's on my early '95 coupe ( OBD 1, Bischoff) and absolutely love the sound, but what about these B&B's? Everyone says they drone, mine are from a later batch so they did a little, but not bad. Darrin told me he could rework them to be almost III's. So I got to thinking, if he could rework them to be like III's, then the B&B's must be more like MotorSound, because they sure are not like my II's.
Trying to decide what muffler to use delayed my ordering. When I finally pulled the trigger, the sport cats were on back order.
Because I wasn't sure how this would all play out (whether to use sport cats or straight X pipe) I decided on the Fabspeed product. That way if I wanted to change, it was an easy swap from cat to straight X. I didn't want to deal with CEL possibilities from an X pipe and I had also read in some cases ( I don't remember where, don't know how true it is) where burnt exhaust valves were more common with a cat-less system. Definitely did not want to deal with that.
I have seen Honda motorcycles and others where the joining of the exhaust banks was done. It seemed like a good idea. Maybe I'm just gullible here, I don't know. The idea of ditching the OEM cat for one that breathed better seemed like what was needed.
This concept of joining the pipes had me curious as to how large the hole was. 1", 2"? so I've taken a pic if you are curious as well.
So I decided to try the B&B muffs first and go from there.
It took my indy about an hour and a half to install with me helping. Fortunately since it is/was a CA car, and the motor had been out 25k miles ago, everything came apart and went together smoothly. O2 sensors can sometimes fail after removal and my indy mentally prepared me for that, but we had no issues.
I was impressed with the quality of the plumbing, very heavy tubing, not thin walled. (I had to laugh as it sort of looked like a kitchen sink drain). Fasteners and clamps are all first rate. There was one thing that we found, two of the copper nuts supplied, were 12mm, the rest 13mm. We laughed at the next guy who might remove it, a WTF moment for him. The gaskets supplied weren't awful, but we reused the ones Blackforest had installed as they were of better quality.
On initial start-up it sounded much better at idle, a fatter, richer ($1,400 richer), fuller sound. The B&B had kind of a tinny sound before. I needed to get out of the populated area to give it a good test.
Although the old cat looked fine, it had been impeding flow. With the sport cat installed the hold back sensation was gone, it now revs freely and easily up to the redline.
The motor is now happy, it seems to breathe like it should.
Downshifting from 4th to 3rd and stepping on it is awesome. A sophisticated nasty, the way a Porsche should be.
So many thanks to Ilko for the push, Martin S. for the data and huge shove, and Nam for the patience to deal with my numerous texts . . .
Best Regards,
.
09-12-2014, 10:58 PM
#3
Rennlist Member
Nice review for those who may be thinking about sport cats, Al. That Xpipe is a thing of beauty. Glad you pulled the trigger, and now your 3.8 is breathing like it's never breathe before. I'm sure the extra decibel is music to the ears 
09-13-2014, 12:32 AM
#4
I've got the FD 200 Cell Cats with Motorsound on my car...I think it sounds fantastic...a lot less heat being generated back there and about 25lbs lighter...the car breathes easier and revs more freely
09-13-2014, 01:58 AM
#5
Nordschleife Master
09-13-2014, 04:42 PM
#6
Instructor
Thank you. This is an awesome read for me, as I am going back and forth between Fabspeed sport cats and Fister Stage II (no motorsound pkg). Rennlist, any idea which mod would be a better performance upgrade? If you feel this question isn't relevant to the thread, I'll go elsewhere.
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09-13-2014, 06:54 PM
#8
Rennlist Member
I took my X pipe and Cat Bypass off....
...to drop the HP, to run in a weight to HP class. Well drop it it did, in a big way. The car went from 262 to the rear wheels (Unofficially, I have a had a 268 HP Dyno...the same dyno that did the 262...an outlier???)...down to 239.
239 just sucks...so much so that I am putting the X pipe and cat delete pipes back on....if I have to I'll add weight to the passenger floorboard, or some restrictor plates to get the HP to about 255.
The Fabspeed X pipes rule!!!!! They're addictive too.
239 just sucks...so much so that I am putting the X pipe and cat delete pipes back on....if I have to I'll add weight to the passenger floorboard, or some restrictor plates to get the HP to about 255.
The Fabspeed X pipes rule!!!!! They're addictive too.
09-13-2014, 07:04 PM
#9
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Fister mufflers are not a performance mod. Sound only. There are significant differences between Fister sport cats and Fabspeed X Pipe cats. The Fisters do not merge cylinder banks which arguably are better than a merged system. Has something to do with scavenging. Bill Verburg explained it very well in one of his posts I recall reading, although I'm sure each design has advantages/disadvantages depending on RPM.
09-13-2014, 07:26 PM
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To better answer my assertion that separate pipes are better than an X-Pipe here is the post I previously referred to:
"There is a diffusion chamber on entry to the cat. It is not an X pipe.
If you understand how an exhaust works you will understand why an X works on an odd fire engine like a US V8 but not on an even fire engine like a Porsche 6 or a Ferrrari V8.
The exception can be seen in Ford GT40 where the 90 deg V8 w/ 90 deg crank instead uses a 180 deg(bundle of snakes) to conect the offending left bank cylinder to the right collector and the corresponding right bank cylder to the left collector.
It all boils down to the fact that a 90deg V8 w/ a 90deg crank(always odd fire) always fires 2 pulses consecutively into a single bank on one side then later)this is where the distinctive US V8 ruble comes from) on the other side, this tends to overload the collector, you could use lager pipes and collsector but this is inefficient because it slows gas velocity in the pipes at low revs, the X relieves this overload and allows smaller pipes and collectors that help at low speed.
On an even fire engine such as a Porsche flat 6 or a Ferrari V8 w/ a flat 180deg crank, this does not happen, the flat 6 keeps the pulses in a bank 120deg apart and the Ferrari 90deg apart, keeping the exhaust pulses as far separated as possible for max efficiency at all revs."
__________________
Bill Verburg
"There is a diffusion chamber on entry to the cat. It is not an X pipe.
If you understand how an exhaust works you will understand why an X works on an odd fire engine like a US V8 but not on an even fire engine like a Porsche 6 or a Ferrrari V8.
The exception can be seen in Ford GT40 where the 90 deg V8 w/ 90 deg crank instead uses a 180 deg(bundle of snakes) to conect the offending left bank cylinder to the right collector and the corresponding right bank cylder to the left collector.
It all boils down to the fact that a 90deg V8 w/ a 90deg crank(always odd fire) always fires 2 pulses consecutively into a single bank on one side then later)this is where the distinctive US V8 ruble comes from) on the other side, this tends to overload the collector, you could use lager pipes and collsector but this is inefficient because it slows gas velocity in the pipes at low revs, the X relieves this overload and allows smaller pipes and collectors that help at low speed.
On an even fire engine such as a Porsche flat 6 or a Ferrari V8 w/ a flat 180deg crank, this does not happen, the flat 6 keeps the pulses in a bank 120deg apart and the Ferrari 90deg apart, keeping the exhaust pulses as far separated as possible for max efficiency at all revs."
__________________
Bill Verburg
Last edited by 1990-964; 09-13-2014 at 08:02 PM. Reason: edit
09-13-2014, 08:08 PM
#11
Rennlist Member
Thread Starter
Whether or not one design is better than another was irrelevant to me, Martin's numbers were.
Martin's dyno numbers have merit. Same car, same dyno, different exhaust set-ups. He did all the work for me/us. Thanks again Martin.
I can see where cross-pulse might make a slight difference at idle and low revs, but at say, 3,500 RPM I would think the system is passing an awful lot of gas. Not sure it makes much of a difference at that point, but I am by no means an expert even though on occasion I have stayed at a Holiday Inn.
I'm more familiar with the rarification pulse in two-stroke design as it is important to build slight backpressure for scavenging cylinder gas as two-strokes do not have exhaust valves.
It begs the question though; does anyone have data like Martin does on the FD sport cats? I just may buy another set.
Regards,
.
Martin's dyno numbers have merit. Same car, same dyno, different exhaust set-ups. He did all the work for me/us. Thanks again Martin.
I can see where cross-pulse might make a slight difference at idle and low revs, but at say, 3,500 RPM I would think the system is passing an awful lot of gas. Not sure it makes much of a difference at that point, but I am by no means an expert even though on occasion I have stayed at a Holiday Inn.
I'm more familiar with the rarification pulse in two-stroke design as it is important to build slight backpressure for scavenging cylinder gas as two-strokes do not have exhaust valves.
It begs the question though; does anyone have data like Martin does on the FD sport cats? I just may buy another set.
Regards,
.
09-14-2014, 01:45 AM
#15
Rennlist Member
X Pipes Don't work?
Let's say the X pipe doesn't work, well then how could it be possible that going to two (2) cat delete pipes in place of the stock cat and sport mufflers could produce 23 HP? Note my car went from 262 down to 239, or was it 238, whose counting?
As I mentioned above......the HP loss could be even more. When I did the first dyno soon after installing the X pipe and the cat delete pipes, I thought 262 was too high. So a few weeks later, on a mild, cool rainy day, I went back to the same dyno...pulled 268 HP...I was looking for 255. I needed lower HP running in a weight to HP class. So if the second dyno of 268 were accurate, my re-installing the stock cat, taking off the the cat bypass pipes could have cost me close to 30 HP.
I have all the dynos....scanner is on the fritz, so I'll have to FAX them to any non-believers.
As I mentioned above......the HP loss could be even more. When I did the first dyno soon after installing the X pipe and the cat delete pipes, I thought 262 was too high. So a few weeks later, on a mild, cool rainy day, I went back to the same dyno...pulled 268 HP...I was looking for 255. I needed lower HP running in a weight to HP class. So if the second dyno of 268 were accurate, my re-installing the stock cat, taking off the the cat bypass pipes could have cost me close to 30 HP.
I have all the dynos....scanner is on the fritz, so I'll have to FAX them to any non-believers.