Full Custom Stainless Steel Exhaust
2.25" would give you a nice even distribution of increased low and high end power. 2.5" and you will lose a bit of low end power. We are talking about dual exhausts here, not single. A 2.5" piping will work well with a sc300 i6, which is sufficient enough for a mild turbo setup as well. 3" on a sc3 would be nice if you are running a t60 setup. 2.5" on a sc400 would be nice while supercharged. I wouldn't go more than a 2.25" if it's a na V8 sc400. My custom exhaust setup is 2.25 "x" pipe setup, and it's great so far!
Exhaust wrap is generally used to wrap the exhaust manifold/headers. This is to keep the exhaust gases warm, so that they exit the system quickly. I dont need to bother about rust as the headers are stainless steel 
Aalso the high temperature of the headers would keep the wrap bone dry!
Aalso the high temperature of the headers would keep the wrap bone dry!
Thread Starter
Driver
iTrader: (2)
Joined: Aug 2009
Posts: 159
Likes: 2
From: Bridgeport,CT/Scotland,UK
Hello scfou, you are right about this and I explained this below.
Sorry mate I dont agree with you on this.
Basically the exhaust gases coming out of the engine are extremely hot and at high pressure. Once they come out into the headers, they obviously expand and loose the heat resulting in the gas molecules slowing down with reduced kinetic energy. So when the next set of cylinders fires and the gases exit into the headers and you still have some of the previous exhaust gases sitting in the system offering resistance to the flow of gases. This obviously results in you losing some of the power. So you have to opt for the least possible resistance in the system. This can be achieve in the following ways:
1) All the performance exhausts are straight through and offers least resistance to the out going gases. This increases horse power.
2) In a V6 or V8 configuration you have exit from either sides of the engine. So adding a balance pipe makes the gases go out of the system even faster. This is because when you add a balance pipe in a V system, the gases coming out of one side is used to create a negative pressure(vacuum sort) on the other side. When the next set of gases comes out of the second side they exit with higher speed due to this negative pressure and inturn causing a negative pressure in the first side. This is one of the reasons to have a balance pipe either a H pipe, X pipe or a Prochamber.
3) Also you can make the gases exit the system even faster by keeping the gases hot. This can be achieved by wrapping the headers in a wrap which generally is made of materials that insulate heat. This keeps the gases hot and they exit the system quickly and produce more power. Also this results in the exhaust gases not dissipating heat under the hood and keeping the temp low under the hood (you can choose to use the easier option of a heat shield to keep the temp low under the hood but this will not result in hot exhaust gases as the heat would be dissipated into the air not resulting in added power).
Ceramic coating is the best option than wrapping but unfortuantely I never managed to find a ceramic coating company in here and gave up on this idea and stuck to wrapping.
Basically the exhaust gases coming out of the engine are extremely hot and at high pressure. Once they come out into the headers, they obviously expand and loose the heat resulting in the gas molecules slowing down with reduced kinetic energy. So when the next set of cylinders fires and the gases exit into the headers and you still have some of the previous exhaust gases sitting in the system offering resistance to the flow of gases. This obviously results in you losing some of the power. So you have to opt for the least possible resistance in the system. This can be achieve in the following ways:
1) All the performance exhausts are straight through and offers least resistance to the out going gases. This increases horse power.
2) In a V6 or V8 configuration you have exit from either sides of the engine. So adding a balance pipe makes the gases go out of the system even faster. This is because when you add a balance pipe in a V system, the gases coming out of one side is used to create a negative pressure(vacuum sort) on the other side. When the next set of gases comes out of the second side they exit with higher speed due to this negative pressure and inturn causing a negative pressure in the first side. This is one of the reasons to have a balance pipe either a H pipe, X pipe or a Prochamber.
3) Also you can make the gases exit the system even faster by keeping the gases hot. This can be achieved by wrapping the headers in a wrap which generally is made of materials that insulate heat. This keeps the gases hot and they exit the system quickly and produce more power. Also this results in the exhaust gases not dissipating heat under the hood and keeping the temp low under the hood (you can choose to use the easier option of a heat shield to keep the temp low under the hood but this will not result in hot exhaust gases as the heat would be dissipated into the air not resulting in added power).
Ceramic coating is the best option than wrapping but unfortuantely I never managed to find a ceramic coating company in here and gave up on this idea and stuck to wrapping.
Thread Starter
Driver
iTrader: (2)
Joined: Aug 2009
Posts: 159
Likes: 2
From: Bridgeport,CT/Scotland,UK
2.25" would give you a nice even distribution of increased low and high end power. 2.5" and you will lose a bit of low end power. We are talking about dual exhausts here, not single. A 2.5" piping will work well with a sc300 i6, which is sufficient enough for a mild turbo setup as well. 3" on a sc3 would be nice if you are running a t60 setup. 2.5" on a sc400 would be nice while supercharged. I wouldn't go more than a 2.25" if it's a na V8 sc400. My custom exhaust setup is 2.25 "x" pipe setup, and it's great so far!
You can check this thread out for more info about the size of the piping for an SC400 in which Scott clearly mentions the power gains he got with 2.5" exhaust.
https://www.clublexus.com/forums/per...t-guide-2.html
Last edited by edinlexv8; Dec 23, 2009 at 05:30 PM.
i just mentioned the exhaust wrap stuff to give you a heads up and for you to keep an eye on it.if it's all good for you then all is well.good luck.i'm going to be putting headers and a new exhaust on myself.the last part i was waiting on showed up on my porch today.mufflers yeeeeeeeeeeeeeeeeeeeeeeeeahhhhhhhhhhhhhhhhhhhh
Lexus Champion
Joined: Feb 2001
Posts: 3,124
Likes: 32
From: Texas
If you are not a Lextreme member it is a great performace site for these engines. Here is a long thread and my post in that long thread for detail.
http://www.lextreme.com/forums/showp...9&postcount=56
http://www.lextreme.com/forums/showt...?t=6955&page=6
Heck, for that matter do a google search on jbrady lexus headers
Thread Starter
Driver
iTrader: (2)
Joined: Aug 2009
Posts: 159
Likes: 2
From: Bridgeport,CT/Scotland,UK
Well, if you do a search on my name and exhaust both on Club Lexus and Lextreme you will find a great deal of the reasons behind my statements.
If you are not a Lextreme member it is a great performace site for these engines. Here is a long thread and my post in that long thread for detail.
http://www.lextreme.com/forums/showp...9&postcount=56
http://www.lextreme.com/forums/showt...?t=6955&page=6
Heck, for that matter do a google search on jbrady lexus headers
If you are not a Lextreme member it is a great performace site for these engines. Here is a long thread and my post in that long thread for detail.
http://www.lextreme.com/forums/showp...9&postcount=56
http://www.lextreme.com/forums/showt...?t=6955&page=6
Heck, for that matter do a google search on jbrady lexus headers
I recommend All Muffler and Auto Services, my boy Peter does nice exhaust work. He's in San Francisco, CA. If you guys are nearby just pm me for their info. One thing though, no mandrel machine.
