PPE V8 Headers GS, LS, SC
01-04-11 | 07:57 AM
#137
01-04-11 | 08:12 AM
#138
What similar design and what vehicle?
Gain in power is not the same as a gain in response. First S&S header install member used a racing 2.25-to-2.5" merge I donated and had a 2.25" Y pipe made. Loss of low end response was very obvious. Felt "mushy". It gained 1rwhp. Removed and went back to stock and car felt snappy again. An SC400 had a custom 2.5"-to-3" Y pipe built using a quality merge pipe from Dr.Gas. Lousy midrange at best. Replaced with 2-to-2.5" Y pipe and car woke way up.
Stock Y has an excellent merge section. Looks restrictive but it is not. Pipes are 50mm (1.97") into a 60mm (2.36") resonator and center pipe. You do not have a center resonator you have a center third catalyst. The GS above tested stock 400 Y-pipe (resonator) against stock 430 Y-pipe (catalyst) and found no power or performance difference. For now, I would not recommend changing your Y pipe.
Gain in power is not the same as a gain in response. First S&S header install member used a racing 2.25-to-2.5" merge I donated and had a 2.25" Y pipe made. Loss of low end response was very obvious. Felt "mushy". It gained 1rwhp. Removed and went back to stock and car felt snappy again. An SC400 had a custom 2.5"-to-3" Y pipe built using a quality merge pipe from Dr.Gas. Lousy midrange at best. Replaced with 2-to-2.5" Y pipe and car woke way up.
Stock Y has an excellent merge section. Looks restrictive but it is not. Pipes are 50mm (1.97") into a 60mm (2.36") resonator and center pipe. You do not have a center resonator you have a center third catalyst. The GS above tested stock 400 Y-pipe (resonator) against stock 430 Y-pipe (catalyst) and found no power or performance difference. For now, I would not recommend changing your Y pipe.
Last edited by airbender; 01-04-11 at 08:36 AM.
01-04-11 | 08:24 AM
#139
After they added the Y-pipe, it looks like power actually went down beneath 4-4.25k RPM. Probably not something I would want if I wanted to retain low end power. The stock y-pipe is capable enough to support our engines, until you're boosted.
01-04-11 | 08:38 AM
#140
01-04-11 | 09:56 AM
#141
Yeah...I guess so. Basically after my headers, everything is stock on my exhaust system. My Borlas are only rear section mufflers, so they don't do much. I may find that I have to re-vamp my entire exhaust system once I get the SC installed as this is new territory for me.
01-04-11 | 10:34 AM
#142
Yeah...I guess so. Basically after my headers, everything is stock on my exhaust system. My Borlas are only rear section mufflers, so they don't do much. I may find that I have to re-vamp my entire exhaust system once I get the SC installed as this is new territory for me.
01-04-11 | 10:58 AM
#143
Lexus Champion
Joined: Feb 2001
Posts: 3,124
Likes: 31
From: Texas
That said all the aftermarket systems I have seen use substantially larger tube diameters than stock. The larger the tube the lower the velocity for any given flow. The physics get complicated but the simplified answer is to use the smallest possible tube size that will not restrict power. This can become a tradeoff as it is better to give up say 5rwhp at 6200rpm than to loose 10rwtq at 3000-4000rpm.
Do you have any pictures of the system? Tubing sizes? Links?
01-04-11 | 11:00 AM
#144
Lexus Champion
Joined: Feb 2001
Posts: 3,124
Likes: 31
From: Texas
Yeah...I guess so. Basically after my headers, everything is stock on my exhaust system. My Borlas are only rear section mufflers, so they don't do much. I may find that I have to re-vamp my entire exhaust system once I get the SC installed as this is new territory for me.
01-04-11 | 11:17 AM
#145
I would need more information and pictures on your system before making an educated guess.
That said all the aftermarket systems I have seen use substantially larger tube diameters than stock. The larger the tube the lower the velocity for any given flow. The physics get complicated but the simplified answer is to use the smallest possible tube size that will not restrict power. This can become a tradeoff as it is better to give up say 5rwhp at 6200rpm than to loose 10rwtq at 3000-4000rpm.
Do you have any pictures of the system? Tubing sizes? Links?
That said all the aftermarket systems I have seen use substantially larger tube diameters than stock. The larger the tube the lower the velocity for any given flow. The physics get complicated but the simplified answer is to use the smallest possible tube size that will not restrict power. This can become a tradeoff as it is better to give up say 5rwhp at 6200rpm than to loose 10rwtq at 3000-4000rpm.
Do you have any pictures of the system? Tubing sizes? Links?
some pics in here
https://www.clublexus.com/forums/gs-...2-problem.html
its the same as this one but he cut his off and made a custom Y-pipe
https://www.clublexus.com/forums/2ge...st-norcal.html
here are the only pics i have off them.i found out when getting it someone cut and extended the tips (Op I bought it from says it wasnt him but who knows) since they stick out to far and the welds looked awful i decided temporarily to paint the welds black and polish the cans up so when they were installed it wasnt really noticeable
ok i finally found some pics......post # 6/7
https://www.clublexus.com/forums/per...alled-wow.html
01-04-11 | 11:38 AM
#146
Oh so the Greddy is only replacing the second y-pipe and not the first one. You shouldn't see to much negative lost since the first y pipe after the headers is key. But who knows. But hey, Happy 1000th post to me. 
01-04-11 | 11:52 AM
#147
Lexus Champion
Joined: Feb 2001
Posts: 3,124
Likes: 31
From: Texas
The system shown is a "Y pipe back" system so the stock Y pipe is used. IMO it will not change the way the PPE headers function for you.
That said the system may cause some low end response.
What was your impression after the install of the exhaust?
On my LS400 I pulled off everything after the stock Y pipe an it was LOUD. I took it for a quick drive and I believe it was slightly slower. It is easy to get impressed by sound and most are HOPING for more power when moddifying the exhaust... so... many will "think" they have gained power when sometimes power is lost. Power is of course relative to the RPM range.
The PPE headers should not increase sound much if any. Maybe a slight change in "note".
That said the system may cause some low end response.
What was your impression after the install of the exhaust?
On my LS400 I pulled off everything after the stock Y pipe an it was LOUD. I took it for a quick drive and I believe it was slightly slower. It is easy to get impressed by sound and most are HOPING for more power when moddifying the exhaust... so... many will "think" they have gained power when sometimes power is lost. Power is of course relative to the RPM range.
The PPE headers should not increase sound much if any. Maybe a slight change in "note".
01-04-11 | 11:56 AM
#148
Well I dnt disagree with u cause u definately seem to know more than me when it comes to this as I was looking at the dyno sheet here is the link tell me what u think I wish there was a way to get a lower end dyno on these cars http://www.importtuner.com/powerpage.../photo_08.html and this dyno was done on a car with 200,000 on the dash
01-04-11 | 12:06 PM
#149
01-04-11 | 12:32 PM
#150
Im thinking about going back to a Y pipe. So John, would you say 2" mandrel bent from the cats to a "as close as possible" Y design as stock. To a 2.5" center piece then to my exsisting 2.25 mandrel axle backs would be ideal.