Headers
- Thread starter ihiryu
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The 1UZFE EGR Delete Kit is available for sale here.
Are you saying that you would prefer the S&S headers over the Rush headers?
Without cutting through your header, could you perhaps give some more detailed analysis of their weaknesses?
Also, if you have a spare pair of their headers lying around, I would rather have to ship them to me at my expense then cut them up for science.
Any insight would be great.
The above is a pretty good description of what to expect. Let me add a bit.
The stock twin pipes off the catalysts is 50mm which is 1.97" which is obviously right at 2" pipes. They are mandrel bent and are stainless. Lexus uses the SAME size pipes on the GS400 and the GS430. I often say the 1990-1994 1UZFE was overrated and actually is more like 230hp/250tq. The GS400 is accurated rated at 300hp/310tq. The GS430 is accurately rated at 300hp/325tq. So, IMO, until you add at LEAST 70hp and 75tq the stock dual 50mm pipes are sufficient.
Dynomax rates most of their mufflers by David Vizards formula for free loss exhaust flow. His formula states that you need 2.2cfm of flow per horsepower for a zero loss exhaust system. Dynomax rates there UltraFLO SS 2" mufflers pt# 17279 (effectively straight 2" pipes) at a zero loss power of 636cfm = 318hp EACH. Now, this is not the end of the discussion but a single 2" pipe will have NO problem flowing enough for 150-200hp and if you believe the above over 300hp for a SINGLE 2" PIPE.
The IMPORTANT considerations will be the TRANSITION areas and other obstructions to flow as well as ANYTHING that induces turbulence as that will dramatically reduce flow potential.
REAL WORLD:
Club Lexus member Pearlpower has installed the S&S headers on his 2002 SC430 (300hp/325tq) and gained 14rwhp and 22rwtq
http://www.clublexus.com/forums/showthread.php?t=197918&highlight=headers&page=5
and was VERY PLEASED with the increase in responsiveness and seat of the pants power feeling. Keep in mind the stock SC430 has a catalyst at the merge of the twin 50mm pipes.
Club Lexus member jp430 gain 28rwhp and 16rwtq on his SUPERCHARGED GS430 and this is with a LOSS of 1/2psi of boost (higher flowing post supercharger parts will reduce boost).
Both of the above examples are WITHOUT TUNING.
Now, on the supercharged example if you really compare the before header and after header runs you will find MUCH more of a gain with as much as 43rwhp and 34rwtq. Again, this is WITH the stock 50mm twins and the center catalyst in place.
http://www.clublexus.com/forums/showthread.php?t=184071&highlight=supercharger+headers&page=3
Now, Jibbby is stating a small loss in low rpm torque. Keep in mind that he DELETED his catalysts (not recommended) and built 2.5" downpipes off his headers (please correct me if this is wrong) and he has no other direct experience with S&S headers (please correct me if this is wrong) so I HOPE that he will STOP making statements without having experience or data to support his GUESSING.
The FACT of the matter is that when installed as recommend the S&S headers increase power and torque from idle to redline and will support and substantially increase the power on even a supercharged 4.3 liter GS430.
Bottom line: exhaust is so MUCH MORE than peak flow capacity of any individual or group of parts. Peak flow is ONLY needed at peak power. Peak torque occurs at a lower RPM than peak power so flow at peak torque is LESS than peak power. Any system that supports peak power will be MORE than enough for EVERY OTHER RPM POINT.
Comparing the 1990-1994 1UZFE cars that dyno around 175rwhp and 185rwtq you will notice that a combination of S&S headers and the stock Y pipe will support a gain of at LEAST 85rwhp and 90rwtq over your stock parts. (Pearlpower making 261rwhp and 278rwtq). This is not how much you will gain but rather how much you COULD gain without a serious restriction.
So, why would you want larger parts that will reduce your low and mid range power?
I have no experience with major exhaust modifications on my SC400; but, I do trust conventional exhaust equations to be a very good guide as to what is a proper and an improper exhaust decision any motor. While the 1UZ may deviate slightly from the theoretical averages for this or that reason (DOHC, over-square bore, etc), it has to be close enough to follow the conventions. If the variance motor-to-motor was indeed significant, these conventions would not be as well accepted as they are among exhaust gurus.
If someone wanted to use S&S Headers to bolster their low end -even though shorty headers bias the power band to the top end by nature- it could absolutely be done with the appropriate decisions made from the headers back. If someone wanted to bias power to the top end at the expense of low end, that could be done as well.
The headers simply supply an efficient framework to build the remainder of the exhaust around: different pipe decisions from the headers back will have different implications on the same headers.
JBrady
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Jake Breyck
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jibbby
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EKtuning.com
Texheaders
S&S Headers for the GS400's not such a good fit for the SC's...
Headers will give the 1uz-fe motors good highend power and some mid range... You may loose a little lowend power so becareful if you'r still running the stock torque converter on the automatics... Something to consider..
Texheaders
S&S Headers for the GS400's not such a good fit for the SC's...
Headers will give the 1uz-fe motors good highend power and some mid range... You may loose a little lowend power so becareful if you'r still running the stock torque converter on the automatics... Something to consider..
Blizzy
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S&S makes shorty headers with the smallest and most appropriately sized primary headers (among all headers available) for the stock motor. They require modification to the factory exhaust to fit, but headers are best accompanied by a full exhaust overhaul to begin with.
Mandrel bent 2" duals should maintain a strong power band from idle to the redline. If mandrel bending is not available, 2.25" duals might be a better selection to help compensate for the inefficiencies at the crush bends. Although, 2" crush bent piping would not be the end of the world, since a 2" pipe is capable of providing unobstructed flow for ~150hp of exhaust fumes.
The Rush Headers run $825 after international shipping. The long tube design will bias the power band toward the low end, while the 1.675" primaries (as compared the S&S at 1.5") is slightly oversized for an otherwise sotck motor.
EK Tuning headers alledgedly bolt right up to the stock exhaust, but their company is extremely difficult to get in touch with. Their turnover time on the Lextreme group buy is currectly far exceeding their original estimates.
I would favor the S&S headers on the stock motor, but I would favor the Aussie Rush headers in the event that supercharging is in your future: 1.675" primaries for a mild set up and 1.75" primaries for a high boost application.
Mandrel bent 2" duals should maintain a strong power band from idle to the redline. If mandrel bending is not available, 2.25" duals might be a better selection to help compensate for the inefficiencies at the crush bends. Although, 2" crush bent piping would not be the end of the world, since a 2" pipe is capable of providing unobstructed flow for ~150hp of exhaust fumes.
The Rush Headers run $825 after international shipping. The long tube design will bias the power band toward the low end, while the 1.675" primaries (as compared the S&S at 1.5") is slightly oversized for an otherwise sotck motor.
EK Tuning headers alledgedly bolt right up to the stock exhaust, but their company is extremely difficult to get in touch with. Their turnover time on the Lextreme group buy is currectly far exceeding their original estimates.
I would favor the S&S headers on the stock motor, but I would favor the Aussie Rush headers in the event that supercharging is in your future: 1.675" primaries for a mild set up and 1.75" primaries for a high boost application.
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I'm not knocking Rush headers but I believe they are made by Liverpool Exhaust who trade as Tex's Headers.
The quality of the joints leaves a lot to be desired.
If I get the time I will slice up a header and post some photos.
The quality of the joints leaves a lot to be desired.
If I get the time I will slice up a header and post some photos.
Blizzy
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Are you saying that you would prefer the S&S headers over the Rush headers?
Without cutting through your header, could you perhaps give some more detailed analysis of their weaknesses?
Also, if you have a spare pair of their headers lying around, I would rather have to ship them to me at my expense then cut them up for science.
Any insight would be great.
jibbby
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- Santa Monica, California
When installing the S&S Headers on my SC400 a few years back, the two down cats needed to be deleted as well as 2 custom made down pipes with end flanges needed to be created to accomadate the connection between the S&S headers and the rest of my entire exhaust system...
It was a pain in the arse to install, but the results were rewarding...Noticed nice top end gains, and some mid range... I did loose a little lowend power which was fine by me because of my aggressive torque converter stall rate and the torque my car is currently putting out...
It was a pain in the arse to install, but the results were rewarding...Noticed nice top end gains, and some mid range... I did loose a little lowend power which was fine by me because of my aggressive torque converter stall rate and the torque my car is currently putting out...
JBrady
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The above is a pretty good description of what to expect. Let me add a bit.
The stock twin pipes off the catalysts is 50mm which is 1.97" which is obviously right at 2" pipes. They are mandrel bent and are stainless. Lexus uses the SAME size pipes on the GS400 and the GS430. I often say the 1990-1994 1UZFE was overrated and actually is more like 230hp/250tq. The GS400 is accurated rated at 300hp/310tq. The GS430 is accurately rated at 300hp/325tq. So, IMO, until you add at LEAST 70hp and 75tq the stock dual 50mm pipes are sufficient.
Dynomax rates most of their mufflers by David Vizards formula for free loss exhaust flow. His formula states that you need 2.2cfm of flow per horsepower for a zero loss exhaust system. Dynomax rates there UltraFLO SS 2" mufflers pt# 17279 (effectively straight 2" pipes) at a zero loss power of 636cfm = 318hp EACH. Now, this is not the end of the discussion but a single 2" pipe will have NO problem flowing enough for 150-200hp and if you believe the above over 300hp for a SINGLE 2" PIPE.
The IMPORTANT considerations will be the TRANSITION areas and other obstructions to flow as well as ANYTHING that induces turbulence as that will dramatically reduce flow potential.
REAL WORLD:
Club Lexus member Pearlpower has installed the S&S headers on his 2002 SC430 (300hp/325tq) and gained 14rwhp and 22rwtq
http://www.clublexus.com/forums/showthread.php?t=197918&highlight=headers&page=5
and was VERY PLEASED with the increase in responsiveness and seat of the pants power feeling. Keep in mind the stock SC430 has a catalyst at the merge of the twin 50mm pipes.
Club Lexus member jp430 gain 28rwhp and 16rwtq on his SUPERCHARGED GS430 and this is with a LOSS of 1/2psi of boost (higher flowing post supercharger parts will reduce boost).
Both of the above examples are WITHOUT TUNING.
Now, on the supercharged example if you really compare the before header and after header runs you will find MUCH more of a gain with as much as 43rwhp and 34rwtq. Again, this is WITH the stock 50mm twins and the center catalyst in place.
http://www.clublexus.com/forums/showthread.php?t=184071&highlight=supercharger+headers&page=3
Now, Jibbby is stating a small loss in low rpm torque. Keep in mind that he DELETED his catalysts (not recommended) and built 2.5" downpipes off his headers (please correct me if this is wrong) and he has no other direct experience with S&S headers (please correct me if this is wrong) so I HOPE that he will STOP making statements without having experience or data to support his GUESSING.
The FACT of the matter is that when installed as recommend the S&S headers increase power and torque from idle to redline and will support and substantially increase the power on even a supercharged 4.3 liter GS430.
Bottom line: exhaust is so MUCH MORE than peak flow capacity of any individual or group of parts. Peak flow is ONLY needed at peak power. Peak torque occurs at a lower RPM than peak power so flow at peak torque is LESS than peak power. Any system that supports peak power will be MORE than enough for EVERY OTHER RPM POINT.
Comparing the 1990-1994 1UZFE cars that dyno around 175rwhp and 185rwtq you will notice that a combination of S&S headers and the stock Y pipe will support a gain of at LEAST 85rwhp and 90rwtq over your stock parts. (Pearlpower making 261rwhp and 278rwtq). This is not how much you will gain but rather how much you COULD gain without a serious restriction.
So, why would you want larger parts that will reduce your low and mid range power?
jibbby
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Blizzy
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Here is what I have observed:
(1) Zuffen has made me aware of the design inefficiencies in the Tex's Header collectors (20mm of pipe protruding into the collector, inhibiting and not encouraging flow). This drops the Aussie headers down on my wish list, that's for sure.
(2) S&S Headers are appropriately designed for a 4L motor. Using general equations to give an idea of where peak torque would be made on a 4L motor with 1.5" primary exhaust pipes, the result is 4569rpm. This number is very close to stock peak torque rpm numbers from the factory, which means the S&S Headers should result in a similarly shaped -albeit stronger- power band upon install (Understanding Header Design - Car Craft Magazine).
(3) A 2.5" exhaust like Jibby has installed is rather oversized, even for a 1UZ on nitrous. Based on the standard exhaust conventions of 115CFM/sq.in of pipe cross sectional area and 2.2CFM/hp, a 2.5" pipe should capacitate unobstructed flow for 530 CFM, or 240hp. This means 2.5" duals are sufficient for a 480hp engine, which clearly the 1UZ is not. (Auto Exhaust Science)
An oversized exhaust will present exhaust gases too much room to "get lost" on their way out on the low end when exhaust gas velocity is not swift. An undersized exhaust will present exhaust gases an overly efficient scenario on the low end, resulting in more low to midrange power while choking the motor on the top end.
Put a ready-to-race 1000whp TT 1UZ on 2.5" duals, and it may not make its full power potential, but it will certainly make more than the 480hp which the exhaust piping would supply flow for unobstructed. Additional power would be being made in spite of -and at the expense of- exhaust backpressure from choke, but big power will still be made, and that motor would have a wicked low end to boot.
Put this same motor on 4" duals, and the motor would dyno the full 1000whp, but the turbo would take longer to spool, the low end would be underwhelming, and the car would be much less useful in nearly every automotive scenario save the dyno itself.
(4) In my opinion, the stock motor probably deserves 2" duals or a 2.5" single, mandrel-bent or not. Based on the exhaust assumptions above, 2" duals would flow 150hp unobstructed in each pipe, and a 2.5" single exhaust would flow 240hp before experiencing any choke. To me, these numbers are most appropriate for the stock motor.
For my intended mild FI set up (~375whp) via centrifugal suupercharging, I think 2.25" duals should be appropriate (425CFM/pipe or 193hp/pipe). Although, for a street car, I think I would be more well served to put 2" duals from the headers back rather than 2.5" duals on such a supercharged set up.
(1) Zuffen has made me aware of the design inefficiencies in the Tex's Header collectors (20mm of pipe protruding into the collector, inhibiting and not encouraging flow). This drops the Aussie headers down on my wish list, that's for sure.
(2) S&S Headers are appropriately designed for a 4L motor. Using general equations to give an idea of where peak torque would be made on a 4L motor with 1.5" primary exhaust pipes, the result is 4569rpm. This number is very close to stock peak torque rpm numbers from the factory, which means the S&S Headers should result in a similarly shaped -albeit stronger- power band upon install (Understanding Header Design - Car Craft Magazine).
(3) A 2.5" exhaust like Jibby has installed is rather oversized, even for a 1UZ on nitrous. Based on the standard exhaust conventions of 115CFM/sq.in of pipe cross sectional area and 2.2CFM/hp, a 2.5" pipe should capacitate unobstructed flow for 530 CFM, or 240hp. This means 2.5" duals are sufficient for a 480hp engine, which clearly the 1UZ is not. (Auto Exhaust Science)
An oversized exhaust will present exhaust gases too much room to "get lost" on their way out on the low end when exhaust gas velocity is not swift. An undersized exhaust will present exhaust gases an overly efficient scenario on the low end, resulting in more low to midrange power while choking the motor on the top end.
Put a ready-to-race 1000whp TT 1UZ on 2.5" duals, and it may not make its full power potential, but it will certainly make more than the 480hp which the exhaust piping would supply flow for unobstructed. Additional power would be being made in spite of -and at the expense of- exhaust backpressure from choke, but big power will still be made, and that motor would have a wicked low end to boot.
Put this same motor on 4" duals, and the motor would dyno the full 1000whp, but the turbo would take longer to spool, the low end would be underwhelming, and the car would be much less useful in nearly every automotive scenario save the dyno itself.
(4) In my opinion, the stock motor probably deserves 2" duals or a 2.5" single, mandrel-bent or not. Based on the exhaust assumptions above, 2" duals would flow 150hp unobstructed in each pipe, and a 2.5" single exhaust would flow 240hp before experiencing any choke. To me, these numbers are most appropriate for the stock motor.
For my intended mild FI set up (~375whp) via centrifugal suupercharging, I think 2.25" duals should be appropriate (425CFM/pipe or 193hp/pipe). Although, for a street car, I think I would be more well served to put 2" duals from the headers back rather than 2.5" duals on such a supercharged set up.
Thermactor
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A good cheap/easy upgrade for the early 1UZ guys is the exhaust manifolds off a 95-97 LS400, they flow a lot better than the early manifolds.
jibbby
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It is well known that 2.25" madrell piping on the 1uz-fe N/A motors flow the best...
This is what I have on my SC400 now...The funny thing is when I changed out my rear section 2.50" non mendrel bent piping to the 2.25" mandrell bent piping I notice no change in performance what so ever...I almost kicked my self for doing the change in the first place...
So I would like to mention you most likely will not notice a difference between 2.25" mandell and 2.50 bent non mendrell piping on the early model 1uz-fe motors N/A.. That is following the stock exhaust design..X
Again, I base my statements and assumptions on actual changes done to my SC400 before and after..
This is what I have on my SC400 now...The funny thing is when I changed out my rear section 2.50" non mendrel bent piping to the 2.25" mandrell bent piping I notice no change in performance what so ever...I almost kicked my self for doing the change in the first place...
So I would like to mention you most likely will not notice a difference between 2.25" mandell and 2.50 bent non mendrell piping on the early model 1uz-fe motors N/A.. That is following the stock exhaust design..X
Again, I base my statements and assumptions on actual changes done to my SC400 before and after..
Blizzy
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I have no experience with major exhaust modifications on my SC400; but, I do trust conventional exhaust equations to be a very good guide as to what is a proper and an improper exhaust decision any motor. While the 1UZ may deviate slightly from the theoretical averages for this or that reason (DOHC, over-square bore, etc), it has to be close enough to follow the conventions. If the variance motor-to-motor was indeed significant, these conventions would not be as well accepted as they are among exhaust gurus.
If someone wanted to use S&S Headers to bolster their low end -even though shorty headers bias the power band to the top end by nature- it could absolutely be done with the appropriate decisions made from the headers back. If someone wanted to bias power to the top end at the expense of low end, that could be done as well.
The headers simply supply an efficient framework to build the remainder of the exhaust around: different pipe decisions from the headers back will have different implications on the same headers.
Tony95sc400
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sorry for the thread jack. -jibby, im located in los angleles and i jus got a set of s&s headers. Where did you get them installed. I cant find any shops. thanks
-tony
-tony
jibbby
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Tony, I live in Santa Monica and there is a shop on Lincoln Blvd in the city of Santa Monica, called A+ Auto repair...The garage owner is Leo and he can install the S&S Headers for you, relocate the 02 sensors, create the the two down pipes with correct flange bolt patterns, and delete the two small cats all for $500... You will need to leave your car there for two days...
Leo is a nice guy but is busy, so call first and make an appointment....It's a small shop and doesn't look like much but they do outstanding work...
Leo - 310 314-3104 A+ Auto repair....
Leo is a nice guy but is busy, so call first and make an appointment....It's a small shop and doesn't look like much but they do outstanding work...
Leo - 310 314-3104 A+ Auto repair....
The Redline 03
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There's some interesting things I just read on this thread. I was wondering if instead of X piping you go with a Y and what would you recomended to keep the flow well and keeping a smooth powerband through out the rpm range? For example what size piping would suit both the pipes flowing into it to the end of the exhaust?
jibbby
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A highflowing X design is the best for flow...If you have the Y's and a single pipe where the main center cat is located that helps flow but still not as good as the X....
What are you trying to accomplish with your exhaust system? I think the powerband would remain the same whether you decide to go with the X member or the Y...
What are you trying to accomplish with your exhaust system? I think the powerband would remain the same whether you decide to go with the X member or the Y...
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The Redline 03
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Well, it'll be going into the car in my sig. The Y design is for clearance issues under the 86 more than anything really and to keep weight down to a minimum. It will also be more of a sleeper car.
