Headers for V8 cars, Please read
08-01-05, 11:20 AM
#796
Lexus Champion
Originally Posted by SC & RX
Hi,
Thanks again jbrady for all of you have done; I was #5 on the header order by the way!
Based on what you have written, I can tell you posses an extraordinary knowledge of exhaust system construction. I think I have read through all of the exhaust posts so I hope that I am not asking questions that have already been addressed but that I missed. I know you have recommended 2.25" tubing for the system with a "Y" pipe having 45 degree inlets. Do you recommend the same degree for the outlet "Y"? Also, what diameter tube do you recommend for the center-pipe? Finally, what type of mufflers do you recommend?
Thanks again jbrady for all of you have done; I was #5 on the header order by the way!
Based on what you have written, I can tell you posses an extraordinary knowledge of exhaust system construction. I think I have read through all of the exhaust posts so I hope that I am not asking questions that have already been addressed but that I missed. I know you have recommended 2.25" tubing for the system with a "Y" pipe having 45 degree inlets. Do you recommend the same degree for the outlet "Y"? Also, what diameter tube do you recommend for the center-pipe? Finally, what type of mufflers do you recommend?
Thank you for taking the time to research and read what I have already written. Some will PM or post a repetitive question and actually say "too much to read, please answer my question". Although I generally do answer the request is basically saying "I am too busy too read but you should take the time to answer me". Truth is, I could read almost all of the posts I have made here in less time than it took me to put together a couple of the more complex posts I have written.
Now, to your question, you want the primary pipes to join together forming a TOTAL angle between them of 30 to 45 degrees. Do not slash cut each pipe at 45 degrees as that would yield a total angle of 90 degrees (much to wide). The tighter the angle the better in some ways. The outlet pipe is the center pipe and 2.50 is a reasonable choice although I intend to experiment with 2.125 primary and 2.50, 2.75 and 3.00" center pipes and also step centers and alternate merge configurations. For now 2.25 into 2.50 should be OK. Create at least 10 inches of center pipe before you split it back into the dual muffler section.
08-01-05, 03:39 PM
#797
Originally Posted by Hollywood
I'm also getting a 3.92 rear too. Might be in before the headers not sure.
I am going to do 2x 2.25 ypipe, running as separate pipes as far as possible till I get to near thae cat back which ill have the 2x 2.25's run into a 2.5" tapering into a 3" then I'll taper to the 2.5" cat back flange IIRC. No Cats. If it's too loud I'll add a free flow 3" periforated race resonator instead of the 3" expansion area.
I will be dynoing on a mustang dyno w/ 94 octane gas.
I am going to do 2x 2.25 ypipe, running as separate pipes as far as possible till I get to near thae cat back which ill have the 2x 2.25's run into a 2.5" tapering into a 3" then I'll taper to the 2.5" cat back flange IIRC. No Cats. If it's too loud I'll add a free flow 3" periforated race resonator instead of the 3" expansion area.
I will be dynoing on a mustang dyno w/ 94 octane gas.
PS: the O2 sensor will code Check Engine from experience. Trust me.
Guys Read this : http://www.popularhotrodding.com/eng...re/0505em_exh/
Last edited by jgscott; 08-02-05 at 01:12 AM.
08-01-05, 11:28 PM
#798
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Originally Posted by jbrady
The SRT addresses the fact that the factory MAF is restrictive. They do it by placing the MAF element in a larger diameter housing. The increased flow relative to the factory MAF calibration makes the car run VERY lean. This requires a correction to the signal to the ECU. SRT calls this part their Race ECU. If you tune the ECU to run a slightly leaner mixture than the factory setting under full power you will gain power. However, each application tends to be slightly different as the factory OBDII programing is dynamic and even resetting it tends to produce a variable in the relearn. gawd ran a baseline dyno on his 3.77 LSD and SRT intake equiped 99 GS400 prior to the header install. His torque was good at 260 but the power was on the low side at 230rwhp. A/F ratios were too rich at 11.5-to-1. His ECU needed a leaning to closer to 12.5 or 13 to 1 for best power.
So, to answer your question, IMO the SRT is currently the best aftermarket peak power intake for the GS400. There are some other tuning considerations including tapered pipe and resonator chambers that could improve the intakes performance and possibly regain any lost low RPM power. Since no one is making this theoretical part YET... the SRT is the best choice for PEAK performance but not low end performance. When in comes to confrontations such as the one gawd had in the street stories section of CL... the SRT was definitely helpful.
So, to answer your question, IMO the SRT is currently the best aftermarket peak power intake for the GS400. There are some other tuning considerations including tapered pipe and resonator chambers that could improve the intakes performance and possibly regain any lost low RPM power. Since no one is making this theoretical part YET... the SRT is the best choice for PEAK performance but not low end performance. When in comes to confrontations such as the one gawd had in the street stories section of CL... the SRT was definitely helpful.
08-02-05, 04:06 PM
#799
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Originally Posted by jgscott
I think you are going to make a system that is going to have a strange powerband with little or no increase in HP. If you use a Race resonator as your expansion chamber you will really slow the Velosity down getting to the back of the system.
PS: the O2 sensor will code Check Engine from experience. Trust me.
Guys Read this : http://www.popularhotrodding.com/eng...re/0505em_exh/
PS: the O2 sensor will code Check Engine from experience. Trust me.
Guys Read this : http://www.popularhotrodding.com/eng...re/0505em_exh/
.........
08-02-05, 09:05 PM
#802
Lexus Champion
Originally Posted by 49IS300
Anyone hear the dyno results from Monday? Did it take place? Im pretty anxious to hear the results. 
https://www.clublexus.com/forums/sho...d.php?t=172937
08-02-05, 09:52 PM
#803
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Originally Posted by jbrady
Yes, the dyno was ran, power is up. Before I comment further check out this post from gawd.
https://www.clublexus.com/forums/sho...d.php?t=172937
https://www.clublexus.com/forums/sho...d.php?t=172937
Cant wait for my headers to come in.
08-02-05, 10:37 PM
#804
Originally Posted by jbrady
Yes, the dyno was ran, power is up. Before I comment further check out this post from gawd.
https://www.clublexus.com/forums/sho...d.php?t=172937
https://www.clublexus.com/forums/sho...d.php?t=172937
What was the news from the dyno?
Jonny
08-02-05, 11:16 PM
#805
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Originally Posted by Dx3
OK, but still don't have any numbers or feedback from it
What was the news from the dyno?
Jonny
What was the news from the dyno?
Jonny
08-03-05, 05:22 AM
#807
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Originally Posted by 49IS300
Anyone hear the dyno results from Monday? Did it take place? Im pretty anxious to hear the results.
Throw us a bone gawd...BTW, nice kill on the S4.
08-03-05, 08:40 AM
#808
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Well, I want everyone to see the dyno charts, but I don't have a scanner so I faxed them to John. HE might have a time decifering them, since the printer couldn't print out the legends for each curve. He should have them up in the next day or so.
08-03-05, 09:16 AM
#809
Originally Posted by gawd
Well, I want everyone to see the dyno charts, but I don't have a scanner so I faxed them to John. HE might have a time decifering them, since the printer couldn't print out the legends for each curve. He should have them up in the next day or so.
08-03-05, 10:31 AM
#810
Lexus Fanatic
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Originally Posted by gawd
Well, I want everyone to see the dyno charts, but I don't have a scanner so I faxed them to John. HE might have a time decifering them, since the printer couldn't print out the legends for each curve. He should have them up in the next day or so.