My new custom exhaust for my 98 SC430
07-07-11, 04:15 PM
#16
I'd like to make a few points
The first V in VVT stands for variable that is always on or always changing. It does not "kick in" like Honda's VTEC.
The factory exhaust uses a Y-pipe because California spec vehicles use a third sub catalytic convertor. For Federal spec vehicles there is a resonator in it's place. Clearly the y-pipe is for ease of manufacturing but it makes no sense in a car with a v-bank engine and dual exhausts.
Are you positive the factory piping is in fact 2.25"? I believe it's actually 2". The factory y-pipe and cat or resonator is 2.5" and about 28" long. By my math the total volume of the factory pipe should be around 137 ci while a true dual would increase that to 176 ci. A 40 ci difference is less than the volume of two 12oz soda cans.
You never stated what mufflers you have.
I believe the key mistakes you made were piping that was too large and removing the factory catalytic converter.
My personal opinion of the perfect exhaust would be headers with the factory cats into an x-pipe with non high flow mufflers such as offset/offset rectangular mufflers like the factory ones all with 2" piping.
The first V in VVT stands for variable that is always on or always changing. It does not "kick in" like Honda's VTEC.
The factory exhaust uses a Y-pipe because California spec vehicles use a third sub catalytic convertor. For Federal spec vehicles there is a resonator in it's place. Clearly the y-pipe is for ease of manufacturing but it makes no sense in a car with a v-bank engine and dual exhausts.
Are you positive the factory piping is in fact 2.25"? I believe it's actually 2". The factory y-pipe and cat or resonator is 2.5" and about 28" long. By my math the total volume of the factory pipe should be around 137 ci while a true dual would increase that to 176 ci. A 40 ci difference is less than the volume of two 12oz soda cans.
You never stated what mufflers you have.
I believe the key mistakes you made were piping that was too large and removing the factory catalytic converter.
My personal opinion of the perfect exhaust would be headers with the factory cats into an x-pipe with non high flow mufflers such as offset/offset rectangular mufflers like the factory ones all with 2" piping.
2nd do you have a VVT-i 400
3rd Did you REALLY read what you quoted me.
4th How many 400's have you owned & modified.
5th Have you ever seen the inside of the stock Y pipe.
No where in my post did I ever mention that stock pipping was 2.25. No where in my post did I ever mention having deleated my cats.
Your quote unquote "opinionated" perfect exhaust, is exactly what I have now, other than the stock style mufflers & the 2" piping.
If you want to try to use the stock style mufflers for some kind of back preassure, you sure aint gonna get it 10" before it exit's the entire exhaust system.
I used 2.25 piping & 2 straight through top speed muffler.
Please bring the real "facts" & proof of them, before you try to make me look like I dont know what im talking about.
Last edited by spdrcr771; 07-07-11 at 04:54 PM.
07-07-11, 10:16 PM
#18
1. SC400 for the moment.
2. Worked on one and some GS400s
3. Yes. You made a few false points like VVT-i working as VTEC "kicking in"
4. A few
5. It's a y-pipe?
You are correct you never said the car has 2.25" piping but that makes your point about the car being designed for a y-pipe even more weird. The exhaust piping has a far larger role in exhaust scavenging than a y, h or x pipe.
2. Worked on one and some GS400s
3. Yes. You made a few false points like VVT-i working as VTEC "kicking in"
4. A few
5. It's a y-pipe?
You are correct you never said the car has 2.25" piping but that makes your point about the car being designed for a y-pipe even more weird. The exhaust piping has a far larger role in exhaust scavenging than a y, h or x pipe.
07-08-11, 09:51 AM
#19
Lexus Champion
Ok guys, let's keep things respectful.
The stock pipe sizes are dual 50mm (1.97") into a single 60mm (2.36")
VVTi is variable and there is no on/off type function but it does have settings depending on load and RPM. The intake manifold does have dual length runners a the shorter (high rpm) runners "kick in" at 4000rpm. 1998-2000California GS400s and LS400s do not have a third or center cat at the Y pipe junction and I don't believe the same years SC400s do either. This changes again for 2001+ and pre 1998 CA spec did use the center cat. The factory did not build the Y pipe for simplification of manufacture it is an engineered functional component that is important for low RPM torque production.
Many things happen in an exhaust system and a good way to consider them is like a slide trombone where changing length, size and shape of tubes and transitions changes the sound/power.
To SIMPLIFY a very complex system: what the factory Y section does is merge the two banks flow into one to accelerate the flow. This reduces the energy that can rebound back towards the engine and reduces the resistance at the exhaust valves.
There is negligent restriction to flow until the flow capacity of the 60mm pipe is reached which is above 300hp/235rwhp.
There are MANY different designs of X and Y pipes and they perform differently. The factory Y pipe works very well... better than other designs I have seen tested FOR THE APPLICATION which is preserving low-mid RPM torque while allowing good peak power.
Cutting off the factory Y pipe and replacing with another merge or simply duals will reduce the low-mid RPM torque... UNLESS you replace it with a CAREFULLY engineered Y pipe and for most there is NO NEED to do this. If you no longer have your stock Y pipe find another one.
spdrcr and bcsc400 have gone to a large effort to create a proper replacement Y pipe per my recommendations. Both of them had removed the stock Y pipe and wanted to return the lost torque. I have not made the design public knowledge for a number of reasons so please do not expect me to tell more than I already have here. Unless you are doing MAJOR power increases the stock part will serve you more than fine.
The stock pipe sizes are dual 50mm (1.97") into a single 60mm (2.36")
VVTi is variable and there is no on/off type function but it does have settings depending on load and RPM. The intake manifold does have dual length runners a the shorter (high rpm) runners "kick in" at 4000rpm. 1998-2000California GS400s and LS400s do not have a third or center cat at the Y pipe junction and I don't believe the same years SC400s do either. This changes again for 2001+ and pre 1998 CA spec did use the center cat. The factory did not build the Y pipe for simplification of manufacture it is an engineered functional component that is important for low RPM torque production.
Many things happen in an exhaust system and a good way to consider them is like a slide trombone where changing length, size and shape of tubes and transitions changes the sound/power.
To SIMPLIFY a very complex system: what the factory Y section does is merge the two banks flow into one to accelerate the flow. This reduces the energy that can rebound back towards the engine and reduces the resistance at the exhaust valves.
There is negligent restriction to flow until the flow capacity of the 60mm pipe is reached which is above 300hp/235rwhp.
There are MANY different designs of X and Y pipes and they perform differently. The factory Y pipe works very well... better than other designs I have seen tested FOR THE APPLICATION which is preserving low-mid RPM torque while allowing good peak power.
Cutting off the factory Y pipe and replacing with another merge or simply duals will reduce the low-mid RPM torque... UNLESS you replace it with a CAREFULLY engineered Y pipe and for most there is NO NEED to do this. If you no longer have your stock Y pipe find another one.
spdrcr and bcsc400 have gone to a large effort to create a proper replacement Y pipe per my recommendations. Both of them had removed the stock Y pipe and wanted to return the lost torque. I have not made the design public knowledge for a number of reasons so please do not expect me to tell more than I already have here. Unless you are doing MAJOR power increases the stock part will serve you more than fine.
07-08-11, 10:16 AM
#20
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Ok guys, let's keep things respectful.
The stock pipe sizes are dual 50mm (1.97") into a single 60mm (2.36")
VVTi is variable and there is no on/off type function but it does have settings depending on load and RPM. The intake manifold does have dual length runners a the shorter (high rpm) runners "kick in" at 4000rpm. 1998-2000California GS400s and LS400s do not have a third or center cat at the Y pipe junction and I don't believe the same years SC400s do either. This changes again for 2001+ and pre 1998 CA spec did use the center cat. The factory did not build the Y pipe for simplification of manufacture it is an engineered functional component that is important for low RPM torque production.
Many things happen in an exhaust system and a good way to consider them is like a slide trombone where changing length, size and shape of tubes and transitions changes the sound/power.
To SIMPLIFY a very complex system: what the factory Y section does is merge the two banks flow into one to accelerate the flow. This reduces the energy that can rebound back towards the engine and reduces the resistance at the exhaust valves.
There is negligent restriction to flow until the flow capacity of the 60mm pipe is reached which is above 300hp/235rwhp.
There are MANY different designs of X and Y pipes and they perform differently. The factory Y pipe works very well... better than other designs I have seen tested FOR THE APPLICATION which is preserving low-mid RPM torque while allowing good peak power.
Cutting off the factory Y pipe and replacing with another merge or simply duals will reduce the low-mid RPM torque... UNLESS you replace it with a CAREFULLY engineered Y pipe and for most there is NO NEED to do this. If you no longer have your stock Y pipe find another one.
spdrcr and bcsc400 have gone to a large effort to create a proper replacement Y pipe per my recommendations. Both of them had removed the stock Y pipe and wanted to return the lost torque. I have not made the design public knowledge for a number of reasons so please do not expect me to tell more than I already have here. Unless you are doing MAJOR power increases the stock part will serve you more than fine.
The stock pipe sizes are dual 50mm (1.97") into a single 60mm (2.36")
VVTi is variable and there is no on/off type function but it does have settings depending on load and RPM. The intake manifold does have dual length runners a the shorter (high rpm) runners "kick in" at 4000rpm. 1998-2000California GS400s and LS400s do not have a third or center cat at the Y pipe junction and I don't believe the same years SC400s do either. This changes again for 2001+ and pre 1998 CA spec did use the center cat. The factory did not build the Y pipe for simplification of manufacture it is an engineered functional component that is important for low RPM torque production.
Many things happen in an exhaust system and a good way to consider them is like a slide trombone where changing length, size and shape of tubes and transitions changes the sound/power.
To SIMPLIFY a very complex system: what the factory Y section does is merge the two banks flow into one to accelerate the flow. This reduces the energy that can rebound back towards the engine and reduces the resistance at the exhaust valves.
There is negligent restriction to flow until the flow capacity of the 60mm pipe is reached which is above 300hp/235rwhp.
There are MANY different designs of X and Y pipes and they perform differently. The factory Y pipe works very well... better than other designs I have seen tested FOR THE APPLICATION which is preserving low-mid RPM torque while allowing good peak power.
Cutting off the factory Y pipe and replacing with another merge or simply duals will reduce the low-mid RPM torque... UNLESS you replace it with a CAREFULLY engineered Y pipe and for most there is NO NEED to do this. If you no longer have your stock Y pipe find another one.
spdrcr and bcsc400 have gone to a large effort to create a proper replacement Y pipe per my recommendations. Both of them had removed the stock Y pipe and wanted to return the lost torque. I have not made the design public knowledge for a number of reasons so please do not expect me to tell more than I already have here. Unless you are doing MAJOR power increases the stock part will serve you more than fine.
07-08-11, 05:51 PM
#21
Ok guys, let's keep things respectful.
The stock pipe sizes are dual 50mm (1.97") into a single 60mm (2.36")
VVTi is variable and there is no on/off type function but it does have settings depending on load and RPM. The intake manifold does have dual length runners a the shorter (high rpm) runners "kick in" at 4000rpm. 1998-2000California GS400s and LS400s do not have a third or center cat at the Y pipe junction and I don't believe the same years SC400s do either. This changes again for 2001+ and pre 1998 CA spec did use the center cat. The factory did not build the Y pipe for simplification of manufacture it is an engineered functional component that is important for low RPM torque production.
Many things happen in an exhaust system and a good way to consider them is like a slide trombone where changing length, size and shape of tubes and transitions changes the sound/power.
To SIMPLIFY a very complex system: what the factory Y section does is merge the two banks flow into one to accelerate the flow. This reduces the energy that can rebound back towards the engine and reduces the resistance at the exhaust valves.
There is negligent restriction to flow until the flow capacity of the 60mm pipe is reached which is above 300hp/235rwhp.
There are MANY different designs of X and Y pipes and they perform differently. The factory Y pipe works very well... better than other designs I have seen tested FOR THE APPLICATION which is preserving low-mid RPM torque while allowing good peak power.
Cutting off the factory Y pipe and replacing with another merge or simply duals will reduce the low-mid RPM torque... UNLESS you replace it with a CAREFULLY engineered Y pipe and for most there is NO NEED to do this. If you no longer have your stock Y pipe find another one.
spdrcr and bcsc400 have gone to a large effort to create a proper replacement Y pipe per my recommendations. Both of them had removed the stock Y pipe and wanted to return the lost torque. I have not made the design public knowledge for a number of reasons so please do not expect me to tell more than I already have here. Unless you are doing MAJOR power increases the stock part will serve you more than fine.
The stock pipe sizes are dual 50mm (1.97") into a single 60mm (2.36")
VVTi is variable and there is no on/off type function but it does have settings depending on load and RPM. The intake manifold does have dual length runners a the shorter (high rpm) runners "kick in" at 4000rpm. 1998-2000California GS400s and LS400s do not have a third or center cat at the Y pipe junction and I don't believe the same years SC400s do either. This changes again for 2001+ and pre 1998 CA spec did use the center cat. The factory did not build the Y pipe for simplification of manufacture it is an engineered functional component that is important for low RPM torque production.
Many things happen in an exhaust system and a good way to consider them is like a slide trombone where changing length, size and shape of tubes and transitions changes the sound/power.
To SIMPLIFY a very complex system: what the factory Y section does is merge the two banks flow into one to accelerate the flow. This reduces the energy that can rebound back towards the engine and reduces the resistance at the exhaust valves.
There is negligent restriction to flow until the flow capacity of the 60mm pipe is reached which is above 300hp/235rwhp.
There are MANY different designs of X and Y pipes and they perform differently. The factory Y pipe works very well... better than other designs I have seen tested FOR THE APPLICATION which is preserving low-mid RPM torque while allowing good peak power.
Cutting off the factory Y pipe and replacing with another merge or simply duals will reduce the low-mid RPM torque... UNLESS you replace it with a CAREFULLY engineered Y pipe and for most there is NO NEED to do this. If you no longer have your stock Y pipe find another one.
spdrcr and bcsc400 have gone to a large effort to create a proper replacement Y pipe per my recommendations. Both of them had removed the stock Y pipe and wanted to return the lost torque. I have not made the design public knowledge for a number of reasons so please do not expect me to tell more than I already have here. Unless you are doing MAJOR power increases the stock part will serve you more than fine.
07-11-11, 05:41 PM
#23
Ok exhaust is done, ran into a couple of snag's but got it done.
So 1st major problem was that the driver's side header, wouldnt fit due to it hitting the steering shaft. This was not a issue with the S&S. So just removed it & cool where in. Then got it in & saw that the freekin O2 sensor bung was on the damn top. Which wasnt gonna work at all. So we had to drill a hole in my brand new header & weld in a new bung. This had to be a manufacturing fail, & no one caught it. Not very happy, but its done. Then the header flang was hitting the tranny dipstick tube. So got the big pry bar out & relieved its symptoms. Passenger side zero issues. These were harder to bolt down, meaning harder to get to the nut without having to use a 14 wrench manually, well at least the bottom anyway. So far I feel Ive got more bottom end torque, but wont know how much till I dyno it. Driving in 100 degree temp with the a/c kickin full blast, kinda hard to tell where she at just yet. But im happy, no more exhaust leak sound & a little quiet'r
So 1st major problem was that the driver's side header, wouldnt fit due to it hitting the steering shaft. This was not a issue with the S&S. So just removed it & cool where in. Then got it in & saw that the freekin O2 sensor bung was on the damn top. Which wasnt gonna work at all. So we had to drill a hole in my brand new header & weld in a new bung. This had to be a manufacturing fail, & no one caught it. Not very happy, but its done. Then the header flang was hitting the tranny dipstick tube. So got the big pry bar out & relieved its symptoms. Passenger side zero issues. These were harder to bolt down, meaning harder to get to the nut without having to use a 14 wrench manually, well at least the bottom anyway. So far I feel Ive got more bottom end torque, but wont know how much till I dyno it. Driving in 100 degree temp with the a/c kickin full blast, kinda hard to tell where she at just yet. But im happy, no more exhaust leak sound & a little quiet'r
Last edited by spdrcr771; 07-13-11 at 01:13 AM.
07-12-11, 11:39 AM
#25
Sorry we were kinda in a hurry when we left the exhaust shop, & didnt have time to get more pics. Ill post some other's as, the rear section is the same as before. The rear Y forward is all new.
Last edited by spdrcr771; 07-13-11 at 01:13 AM.
07-13-11, 08:12 AM
#26
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Ok exhaust is done, ran into a couple of snag's but got it done.
So 1st major problem was that the driver's side header, wouldnt fit due to it hitting the steering shaft. This was not a issue with the S&S. So just removed it & cool where in. Then got it in & saw that the freekin O2 sensor bung was on the damn top. Which wasnt gonna work at all. So we had to drill a hole in my brand new header & weld in a new bung. This had to be a manufacturing fail, & no one caught it. Not very happy, but its done. Then the header flang was hitting the tranny dipstick tube. So got the big pry bar out & relieved its symptoms. Passenger side zero issues. These were harder to bolt down, meaning harder to get to the nut without having to use a 14 wrench manually, well at least the bottom anyway. So far I feel Ive got more bottom end torque, but wont know how much till I dyno it. Driving in 100 degree temp with the a/c kickin full blast, kinda hard to tell where she at just yet. But im happy, no more exhaust leak sound & a little quiet'r
So 1st major problem was that the driver's side header, wouldnt fit due to it hitting the steering shaft. This was not a issue with the S&S. So just removed it & cool where in. Then got it in & saw that the freekin O2 sensor bung was on the damn top. Which wasnt gonna work at all. So we had to drill a hole in my brand new header & weld in a new bung. This had to be a manufacturing fail, & no one caught it. Not very happy, but its done. Then the header flang was hitting the tranny dipstick tube. So got the big pry bar out & relieved its symptoms. Passenger side zero issues. These were harder to bolt down, meaning harder to get to the nut without having to use a 14 wrench manually, well at least the bottom anyway. So far I feel Ive got more bottom end torque, but wont know how much till I dyno it. Driving in 100 degree temp with the a/c kickin full blast, kinda hard to tell where she at just yet. But im happy, no more exhaust leak sound & a little quiet'r
I returned them and they built me a new set with the correct bung locations.
Get your beast to the dyno.
07-13-11, 11:01 AM
#27
Yea is wish I had that option at the time, but didn't. Anyway I'll try to get to the dyno asap, but I got a track day coming up on the 30-31st. I also bent one of my wheels the other night so now. Im gonna have it fixed and all the lips polished out. Yea custom F-Sport wheels. Then buy break pads and have a alignment done all before my track day.
07-14-11, 01:17 AM
#30
Man guys, now that Ive got to drive the car a few days, & tonight I had to help a friend with a flat on his SC on the side of the highway. I got to play a little not in 105 temp with the A/C kickin. Wow this new exhaust is MONEY. Man ive got so much more bottom torque & hell it feels like it just pulls harder all the way to redline. Dyno will not lie, but its probably gonna be at least a month, before I can get that done. It was well worth the money & time I spent.