How Much Do S4 Cats Affect Power?
10-03-2003, 08:16 AM
#16
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Say it isn't so, the Wisconsin crew now talking about how much HP an aftermarket exhaust can add! Funny, when I mentioned this a few weeks back, nobody seemed to pick up on it?
Oh My!
I'm sure glad my setup already has that high flowing mandrel bent system, though it could stand to be ceramic coated...
Oh My!
I'm sure glad my setup already has that high flowing mandrel bent system, though it could stand to be ceramic coated...
10-03-2003, 09:18 AM
#17
Three Wheelin'
By Z:
Don't forget about the stock pump running out of capacity issue. If the fuel supply system isn't getting enough fuel to the engine to make more power, you're not going to make any more no matter how free flowing your exhaust system is.
Don't forget about the stock pump running out of capacity issue. If the fuel supply system isn't getting enough fuel to the engine to make more power, you're not going to make any more no matter how free flowing your exhaust system is.
By Old & New:
I'll bet you a beer that it is closer to 545.
I'll bet you a beer that it is closer to 545.
By Z:
I wouldn't be at all surprised if you did more than 535rwhp IF you have enough fuel.
I wouldn't be at all surprised if you did more than 535rwhp IF you have enough fuel.
By Andy K:
I don't think Lagavulin's newest hp gain from enhanced exhaust will require much extra fuel if any.
I don't think Lagavulin's newest hp gain from enhanced exhaust will require much extra fuel if any.
By Z:
More freely flowing exhausts also tend to lean out the mixture. Easier exhaust flow allows for better cylinder scavenging, meaning more fresh air charge can get into the cylinder. You're going to need some additional fuel to maintain the proper air/fuel ratio if you've got that increase in fresh air going into the cylinders.
More freely flowing exhausts also tend to lean out the mixture. Easier exhaust flow allows for better cylinder scavenging, meaning more fresh air charge can get into the cylinder. You're going to need some additional fuel to maintain the proper air/fuel ratio if you've got that increase in fresh air going into the cylinders.
By Andy K:
I have read reports of installing freeer flowing exhausts yeilding lower psi yet increades HP.
I have read reports of installing freeer flowing exhausts yeilding lower psi yet increades HP.
So at my 492 rwhp dyno run, my fuel pressure started falling off at 6000 RPM. More horsepower will exacerbate the problem since I need more fuel to go along with the additional air flow through the engine courtesy of the new exhaust.
By the way Andy, if you haven’t already, go pick up the Nov 2003 issue of ‘Muscle Mustangs and Fast Fords’ as there is a great, huge article on roots and whipple’s. I bought it myself since it’s such a great read.
By John:
Say it isn't so, the Wisconsin crew now talking about how much HP an aftermarket exhaust can add! Funny, when I mentioned this a few weeks back, nobody seemed to pick up on it?
Oh My!
Say it isn't so, the Wisconsin crew now talking about how much HP an aftermarket exhaust can add! Funny, when I mentioned this a few weeks back, nobody seemed to pick up on it?
Oh My!
Last edited by Lagavulin; 10-03-2003 at 12:55 PM.
10-03-2003, 02:28 PM
#19
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What about a couple of small resonators and a crossover in place of the stock S4 cats? I have an RMB (not installed yet) and am curious about removing the cats but I don;t want my car to be too loud. I've heard an 87 with RMB and Ott X pipe and it was too loud for my taste.
-Joel.
-Joel.
10-03-2003, 03:03 PM
#20
What are you doing with Fuel delivery Lag? Bigger pump? Bigger lines?
Please do tell. I am planning on finding two different entry points for teh rail when I put everything together.
Please do tell. I am planning on finding two different entry points for teh rail when I put everything together.
10-03-2003, 03:04 PM
#21
Burning Brakes
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Joel,
A couple of short straight-thru mufflers after an X-over might give you the sound you desire.
I haven't done a 928 exactly like that before, but I did a similar setup on a 5L MBZ years ago and it worked out nicely - from a dB and HP perspective.
Greg
A couple of short straight-thru mufflers after an X-over might give you the sound you desire.
I haven't done a 928 exactly like that before, but I did a similar setup on a 5L MBZ years ago and it worked out nicely - from a dB and HP perspective.
Greg
10-03-2003, 04:21 PM
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I've got an "X" pipe, two straight through style mufflers in the center muffler location, and two resonators in the stock rear muffler location. It's a 2.5" mandrel bend and all ceramic coated system that's been on the car for 3-4 years now. Sound is definitely a matter of personal opinion, but I don't think mine is too loud at all during part throttle. Full throttle isn't obnoxiously loud or anything, but the sound will get peoples attention.
10-03-2003, 05:50 PM
#23
Three Wheelin'
By John:
Nice touch on editing out the "Briggs and Stratton" comment from your last post Lag...they do make a good engine.
Nice touch on editing out the "Briggs and Stratton" comment from your last post Lag...they do make a good engine.
10-03-2003, 06:18 PM
#24
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Lag,
You should have felt as such, since it looks like the car already makes over 300 to the road, and I haven't even installed the new cooler or turned the screw past 8 lbs. yet...
Must be those "Briggs and Stratton" manifolds...?
You should have felt as such, since it looks like the car already makes over 300 to the road, and I haven't even installed the new cooler or turned the screw past 8 lbs. yet...
Must be those "Briggs and Stratton" manifolds...?
10-03-2003, 11:38 PM
#25
Three Wheelin'
By John:
...since it looks like the car already makes over 300 to the road..
...since it looks like the car already makes over 300 to the road..
Did you dyno the car? No?
Put the car on a dyno and POST THE RESULTS!
I hope for your sake that your buddy PeteS doesn't see this since as usual, you've painted a red and white bulls-eye on your forehead, and hung a neon colored 'Kick Me!' sign on your back. Evidently, you haven't learned a thing.
10-04-2003, 02:44 AM
#26
I have them off my 89 sterling. I will be doing something different when everything goes back together.
10-04-2003, 03:09 AM
#27
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I don't know how much S4 cats can hurt performance.
My ***, narrow as it is, is only so sensitive.
Proprioceptive sense aside, I suspect less than 10 horsepower in a naturally aspirated car. However, when you start adding boost....the detriment probably increases geometrically...which means that the more power you make, the greater the PERCENTAGE loss occurs. This is a fact of aerodynamics, in relation to how drag increases with the square of speed. This lets me believe that Lagavulin and his fanged cheese-head friends are probably on the right track.
I removed what looked like a sewer pipe from the underside of my '85 S2. It was aluminum, about 4 inches wide, and had a huge resonator where the cats normally should be. At the back, a cheap turbo muffler had been installed. Oval in section, it was mounted vertically! The result was lots of noise, and a very odd look!
Well, I had this exhaust removed and installed a pair of S4 cats and a Borla cat back. The sound was a tiny bit subdued after this change, but the car didn't stink like an old school bus at stop lights, and it looked way better. And I couldn't feel any difference in performance. With the cats, my car turned a 13.8 @ 106 quarter mile one day at the drag strip in Bithlo, Florida.
I suspect, after talking to Connie Kalitta's mechanics, that I might have a bad cat or two. The car seems to be running rich, and when warm, has a high throttle miss that has baffled me for years. I think cats are important, since I run every day that I can and appreciate clean air, but I've noted that several people on this forum have passed emissions tests without their cats! Perhaps Louis Ott's croxover isn't such a bad idea-
Normy!
'85 S2 5 Speed
My ***, narrow as it is, is only so sensitive.
Proprioceptive sense aside, I suspect less than 10 horsepower in a naturally aspirated car. However, when you start adding boost....the detriment probably increases geometrically...which means that the more power you make, the greater the PERCENTAGE loss occurs. This is a fact of aerodynamics, in relation to how drag increases with the square of speed. This lets me believe that Lagavulin and his fanged cheese-head friends are probably on the right track.
I removed what looked like a sewer pipe from the underside of my '85 S2. It was aluminum, about 4 inches wide, and had a huge resonator where the cats normally should be. At the back, a cheap turbo muffler had been installed. Oval in section, it was mounted vertically! The result was lots of noise, and a very odd look!
Well, I had this exhaust removed and installed a pair of S4 cats and a Borla cat back. The sound was a tiny bit subdued after this change, but the car didn't stink like an old school bus at stop lights, and it looked way better. And I couldn't feel any difference in performance. With the cats, my car turned a 13.8 @ 106 quarter mile one day at the drag strip in Bithlo, Florida.
I suspect, after talking to Connie Kalitta's mechanics, that I might have a bad cat or two. The car seems to be running rich, and when warm, has a high throttle miss that has baffled me for years. I think cats are important, since I run every day that I can and appreciate clean air, but I've noted that several people on this forum have passed emissions tests without their cats! Perhaps Louis Ott's croxover isn't such a bad idea-
Normy!
'85 S2 5 Speed
10-04-2003, 03:21 AM
#28
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Speaking of Louis Ott's crossover......I noticed that his website seems to be out of commision. So, can anyone supply me with a new site, an email address or by what means do you go about ordering from him now.
Thanks,
Thanks,
10-04-2003, 09:14 AM
#29
Three Wheelin'
By Brenadan:
What are you doing with Fuel delivery Lag? Bigger pump? Bigger lines?
What are you doing with Fuel delivery Lag? Bigger pump? Bigger lines?
That is just one scenario though; we'll keep you posted.
10-04-2003, 12:08 PM
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Originally posted by SharkFan
Speaking of Louis Ott's crossover......I noticed that his website seems to be out of commision. So, can anyone supply me with a new site, an email address or by what means do you go about ordering from him now.
Speaking of Louis Ott's crossover......I noticed that his website seems to be out of commision. So, can anyone supply me with a new site, an email address or by what means do you go about ordering from him now.