power difference--single vs. dual exhaust???
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From: Tucson, AZ. L98-85 AUTO COUPE: 120k MILES: daily driver. SOUND OFF IF YOU'VE BEEN THERE. Ex-Jumpin' Junky-82nd Airborne-2/505 PIR: 1st ID-1/16th Inf: Recon Marine Retread. GOD BLESS GRUNTS.
power difference--single vs. dual exhaust???
i might be getting some cash soon, and i'm thinking of a new exhaust.
is there much of a power difference between running a dual cat, dual pipe exhaust--versus a single cat, y pipe set-up both with long tube headers?
thanks, frog.
btw, i'm still working on my tranny problem. when i feel well enough, i'll be back on it trying to beat off the governor cover to see if the gear is fried. twenty years has made the damn thing resistant to jack-stand in the car removal.
is there much of a power difference between running a dual cat, dual pipe exhaust--versus a single cat, y pipe set-up both with long tube headers?
thanks, frog.
btw, i'm still working on my tranny problem. when i feel well enough, i'll be back on it trying to beat off the governor cover to see if the gear is fried. twenty years has made the damn thing resistant to jack-stand in the car removal.
Last edited by parafrog; May 10, 2005 at 10:31 PM.
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St. Jude Donor '04-'05-'06-'07
I don't have any numbers but it only stands to reason if you're going to install headers a well designed dual system would also be an asset.
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Not anything you would notice, besides, the 2-in-1 system kills alot of resonance with the cat being there.
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From: Tucson, AZ. L98-85 AUTO COUPE: 120k MILES: daily driver. SOUND OFF IF YOU'VE BEEN THERE. Ex-Jumpin' Junky-82nd Airborne-2/505 PIR: 1st ID-1/16th Inf: Recon Marine Retread. GOD BLESS GRUNTS.
Originally Posted by vader86
Not anything you would notice, besides, the 2-in-1 system kills alot of resonance with the cat being there.
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St. Jude Donor '04-'05-'06-'07
Do what I did, after finally getting the entire exhaust system I wanted from headers on back. My Power Effects system had no crossover or X pipe. I measured the temperature of the entire system from the header collectors to the mufflers and found one area, about 3" long, that was about 100 degrees hotter than anywhere else. I installed a crossover precisely there and the difference in the smoothness of sound, low end response and torque was VERY noticeable. Resonance is not bad on this system when turned to it's lowest setting (but is present in a limited RPM range) and was not noticeably changed around town. But on the highway, from about 68 MPH on the exhaust from inside the car is now nearly as quiet as stock.
Last edited by Corvette Kid; May 10, 2005 at 10:37 PM.
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Originally Posted by parafrog
i don't understand. i will be using cats on both options. will the single eliminate more resonance?
The single cat is huge, and will kill resonance better; its presence is effective as an H or X-pipe crossover, slightly helping low-end torque and killing resonance.
So yes, the single one will kill resonance a little better.
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From: Tucson, AZ. L98-85 AUTO COUPE: 120k MILES: daily driver. SOUND OFF IF YOU'VE BEEN THERE. Ex-Jumpin' Junky-82nd Airborne-2/505 PIR: 1st ID-1/16th Inf: Recon Marine Retread. GOD BLESS GRUNTS.
Originally Posted by Corvette Kid NC
Do what I did, after finally getting the entire exhaust system I wanted from headers on back. My Power Effects system had no crossover or X pipe. I measured the temperature of the entire system from the header collectors to the mufflers and found one area, about 3" long, that was about 100 degrees hotter than anywhere else. I installed a crossover precisely there and the difference in the smoothness of sound, low end response and torque was VERY noticeable. Resonance is not bad on this system when turned to it's lowest setting (but is present in a limited RPM range) and was not noticeably changed around town. But on the highway, from about 68 MPH on the exhaust from inside the car is now nearly as quiet as stock.
that sounds like a very good technique. according to my past reading, the biggest factor in getting the maximum desired results from any dual exhaust balancing (either x or straight pipe), is the exact location of the crossover. results can vary if the precise location isn't found. obviously, the primary objective is to use the opposite side's strong exhaust pulse to help scavenge its opposite when its pulse weakens. using a higher temp analysis probably shows the lag point where the pulse weakens and leaves the exhaust gasses slowed if not sitting increasing the pipe temperature. logically, i would think that this lag point would be the source of much of the interior resonance. the fresh pulse may hit the lagging pulse and cause vibration. although; as per your observations, the location of the lag is probably dependent on rpm, but there is, no doubt, a point or area which will offer a happy median. a reading taken at idle may offer the best results for off the line torque.
anyway, just thinking. i took some extra meds so my brain is actually working--maybe too much.
kid, what did you use to take the temp readings? and please don't say a thermometer. also, did you take your readings at idle.
thanks, froggy
Last edited by parafrog; May 10, 2005 at 11:32 PM.
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St. Jude Donor '04-'05-'06-'07
Originally Posted by parafrog
that sounds like a very good technique. according to my past reading, the biggest factor in getting the maximum desired results from any dual exhaust balancing (either x or straight pipe), is the exact location of the crossover. results can vary if the precise location isn't found. obviously, the primary objective is to use the opposite side's strong exhaust pulse to help scavenge its opposite when its pulse weakens. using a higher temp analysis probably shows the lag point where the pulse weakens and leaves the exhaust gasses slowed if not sitting. logically, i would think that this lag point would be the source of much of the interior resonance. the fresh pulse may hit the lagging pulse and cause vibration. although; as per your observations, the location of the lag is probably dependent on rpm, but there is, no doubt, a point or area which will offer a happy median. a reading taken at idle may offer the best results for off the line torque.
anyway, just thinking. i took some extra meds so my brain is actually working--maybe too much.
kid, what did you use to take the temp readings? and please don't say a thermometer. also, did you take your readings at idle.
thanks, froggy
anyway, just thinking. i took some extra meds so my brain is actually working--maybe too much.
kid, what did you use to take the temp readings? and please don't say a thermometer. also, did you take your readings at idle.
thanks, froggy
I used one of those thermometers that you point at a heat source and it gives you a digital readout. Always do the test w/ these several times to verify a consistent reading. I took it at idle but immediately after a drive into town (and back) and so everything was up to temp.You know? You bring up a good point. I wonder if this location would vary by RPM and load? It would be interesting to do this on a dyno. It makes sense that it COULD make a difference as many other exhaust variations can affect torque curve, etc. Oh thanks, now you've given me something ELSE to obsess about!
Last edited by Corvette Kid; May 10, 2005 at 11:38 PM.
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Just curious, how far behind the headers did the hotspot end up being?
I always thought that getting it as close to the headers as possible was the best, as it would be hottest closer to the headers. The hotter the gasses are, the faster the velocity, thus making for the best scavenging.....
It's what I thought/think. what do you think?
I always thought that getting it as close to the headers as possible was the best, as it would be hottest closer to the headers. The hotter the gasses are, the faster the velocity, thus making for the best scavenging.....
It's what I thought/think. what do you think?
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St. Jude Donor '04-'05-'06-'07
Originally Posted by 4bblC4
Just curious, how far behind the headers did the hotspot end up being?
I always thought that getting it as close to the headers as possible was the best, as it would be hottest closer to the headers. The hotter the gasses are, the faster the velocity, thus making for the best scavenging.....
It's what I thought/think. what do you think?
I always thought that getting it as close to the headers as possible was the best, as it would be hottest closer to the headers. The hotter the gasses are, the faster the velocity, thus making for the best scavenging.....
It's what I thought/think. what do you think?
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St. Jude Donor '05
I personally like duals, but a single 3" exhaust is fine. Late model SS Camaros use it, make a lot more power than most of our L98's. Getting some thicker walled tubing can make a difference in interior noise.
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St. Jude Donor '07 thru '25
Originally Posted by vader86
Not anything you would notice, besides, the 2-in-1 system kills alot of resonance with the cat being there.
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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Originally Posted by Corvette Kid NC
Not even close. The collectors were actually very cool compared to this spot.
Apples and oranges.
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An engine needs about 2.2cfm per CHP before back pressure starts to cost significant power. So on a 240chp L98 you need to flow at least 530cfm; on a 350chp L98 would need 770cfm of flow.
Though this is not a problem for a single 3" mandrel bent pipe it is tough to find a cat that will flow that number. So, if you have a lightly-heavily modified L98 you would benefit from true duals with dual cats.
Though this is not a problem for a single 3" mandrel bent pipe it is tough to find a cat that will flow that number. So, if you have a lightly-heavily modified L98 you would benefit from true duals with dual cats.
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Originally Posted by CTYANK2
Today I had my gutted cat replaced with a new Catco cat and the resonance increased significantly.
However the total exhaust needs to be considered.
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St. Jude Donor '04-'05-'06-'07
Originally Posted by CentralCoaster
If your headers are coated, or thicker guage, or stainless, then you'll get lower surface temperatures even if the gasses are hotter.
Apples and oranges.
Apples and oranges.
