Removed my rear mufflers this afternoon.
10-18-02, 03:46 AM
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Removed my rear mufflers this afternoon.
The rear muffler sections were very easy to remove... just a little liquid wrench and they came right out. As far as intial impressions go...
1. My idle is higher. In drive the idle has gone up about 100RPM and when I parked the vehicle after driving it for the first 10 mi the idle was fluctaing. I haven't noticed it agian..so I guess it was just an ECM learning issue.
2. The sound is great....no drone....at any speed....the exhaust seems to be getting less and less noticeable the more I drive...agian...could be ECM changes...could be me getting used to it. Above 65 you really can't tell unless you have the hammer down. IMHO..just the right level of sound.
3. As far as power gains go.... seems like there has definetly been a tq increase 0-60 seems to come much quciker...throttle response feels improved quite a bit. The engine definetly revs faster. But the downside so far is that the top end seems to have been hurt. When I punch it at 60,65,70 the engine revs faster, but I don't feel the same pull that I used to. Guess there's always a trade off. Maybe Jbrady's intake mod will balance things out....either way as far as sound,weight reduction and 0-60 performance(where I do 90% of my driving) go.....well worth it. I guess I really wont know until I get on the dyno. As soon as I finish the intake mod...flush all my fluids, and throw in some new NGK's I will make a few runs.
1. My idle is higher. In drive the idle has gone up about 100RPM and when I parked the vehicle after driving it for the first 10 mi the idle was fluctaing. I haven't noticed it agian..so I guess it was just an ECM learning issue.
2. The sound is great....no drone....at any speed....the exhaust seems to be getting less and less noticeable the more I drive...agian...could be ECM changes...could be me getting used to it. Above 65 you really can't tell unless you have the hammer down. IMHO..just the right level of sound.
3. As far as power gains go.... seems like there has definetly been a tq increase 0-60 seems to come much quciker...throttle response feels improved quite a bit. The engine definetly revs faster. But the downside so far is that the top end seems to have been hurt. When I punch it at 60,65,70 the engine revs faster, but I don't feel the same pull that I used to. Guess there's always a trade off. Maybe Jbrady's intake mod will balance things out....either way as far as sound,weight reduction and 0-60 performance(where I do 90% of my driving) go.....well worth it. I guess I really wont know until I get on the dyno. As soon as I finish the intake mod...flush all my fluids, and throw in some new NGK's I will make a few runs.
Last edited by Japanimal; 10-18-02 at 03:48 AM.
10-20-02, 07:39 PM
#2
Lexus Champion
Sounds great 
This is bare NONE the easiest mod and can be reversed just as easy.
1. I never noticed an idle fluctuation. Not too worried as long as everthing is smooth and within reason.
2. I hear a drone during deceleration whenever the RPMs are under 2000rpm. Not bad but there. Car is louder at idle and under acceleration to 2000rpm then pretty much as before until high RPM and full throttle and only slightly louder... probably not noticing due to air intake sound during same time.
3. I agree that low end power is better but feel the top end is improved as well. I agree that the diverging Y-section is definitely restrictive as is the 2" ID resonator before it. If you search my posts you will see that I am thinking about how I want to build replacement plumbing from the cats back.
This is bare NONE the easiest mod and can be reversed just as easy.
1. I never noticed an idle fluctuation. Not too worried as long as everthing is smooth and within reason.
2. I hear a drone during deceleration whenever the RPMs are under 2000rpm. Not bad but there. Car is louder at idle and under acceleration to 2000rpm then pretty much as before until high RPM and full throttle and only slightly louder... probably not noticing due to air intake sound during same time.
3. I agree that low end power is better but feel the top end is improved as well. I agree that the diverging Y-section is definitely restrictive as is the 2" ID resonator before it. If you search my posts you will see that I am thinking about how I want to build replacement plumbing from the cats back.
10-20-02, 07:42 PM
#3
Lexus Champion
Idle has gone back to normal...now I am feeling a power gain all the way across the board. The y that splits into the middle muffler section( the mufflers after the resonator...before the rear mufflers) looks pretty restrictive....anyone have any thoughts on that one?
10-22-02, 12:22 PM
#4
Lexus Champion
In the interest of combining several posts on Japanimals mods with the exhaust... I am copying and pasting some posts below.
_____________
Japanimal
Exhaust drone
I have noticed what you described as drone....when the car is downshifting.....(highway offramp for instace....but I feel it...don't actually have any bothersome noises inside the interior...or that is just the way I percieve it. I get the same thing at idle in park on cold starts...just more of it. Still not near enought to bother me. I put the tubing from the rear section back on the car sans mufflers. Now the exhaust exits onto the rear muffler heat shields...instead of the rear diff. Haven't driven the car yet... but I am gonna guess sound should be even quieter as there is less for the exhaust gasses to bounce off of under the car. I am thinking that I might just go the whole way and do a setup similar to the one on Peter's soarer...only I would keep the X pipe closer to the stock cats and use 4 mufflers instead of two...like he suggested. Do you know of anyone who has done a setup like his on a 98-00 1UZFE? I am not sure what year his Soarer/SC is but I am wondering if the OBDII systems will adapt as well as a pre 96 4.0L setup would??
____________
JBrady
Well, it doesn't look like you want to put those stock mufflers back on... Once that hacksaw comes out going back requires at LEAST a welder
Anyway, I am in agreement that the whole system can be much improved. You may want to read through my earlier exhaust post:
https://www.clublexus.com/forums/sho...threadid=55774
Since that time I have been thinking about many options. Honestly, I would love to try a few different combinations... X-pipe, Y-pipe, single and dual path resonators, various final stage mufflers, different pipe diameters, different headers and cat locations... there are so many theories and it is fun to build and test things. But, at present do not have my own shop so my "testing" has been confined to simple removal of parts and mental gymnastics.
One of the things I think would be interesting would be to replace the LS cat-to-rear mufflers with the GS400 parts. The GS has the same 2" primaries with a larger ID center resonator. The divergent Y after the center res is much better than the LS and then it has twin straight through resonators vs. the LS having twin funky pre-mufflers with side inlets. My guess is the 10hp difference between these 2 factory engines is all found here. So, if you could locate this setup from a GS owner removing his parts in favor of a true cat back as talked about in the GS engine forum... could be an easy/cheap way to upgrade.
Now, if you want to build your own... my hat is off to you. I look forward to your posts and if you are ever in Houston we should get together and "test" these cars against each other
_____________
Japanimal
With the tubing that was between the rear mufflers and the center resonators put back in there is no drone.....whatsoever...as I expected. That sporty sounds is there..just less of it, and no drone. At idle you cannot tell the exhaust is modified. I cut the tubing 5 inches away from the muffler inlet so that the exaust exits just underneath the sway bar. As far as what it did to power....it cannot be all that bad...b/c I broke the tires loose at 40mph today on dry pavement. It was overcast and a little humid today here in Dallas but there was no moisture on the ground. I wasn't even giving it full throttle maybe like 80-90% of full throttle. I have only had VSC come on once and that happened when I gave it way too much throttle from a dead stop while it was raining. Never had any probs on dry pavement until today. I was unaware that the GS4's center resonators are straight through.....instead of the less than ideal setup we have. In light of this new info I am gonna try and get my hands on the front section of the GS Exhaust (Section between Cats and rear mufflers). There has to be a lot of restriction in the center resonators b/c the y joint that spits into the sides of them is the only part of my factory exhaust that has any corrosion on it. The y joint that is right after both Cat's might have some corrosion, but I can't tell b/c of the heat shielding. Anyway thanks for paving the way on the exhaust mod!
_________
Japanimal
In all fairness breaking the tires loose at 40MPH may not be such a big deal. There is no: spare tire, no jack, no toolkit, no med kit underneath the front seat, no center console, no ash trays,no owners manual, no engine cover ...etc. I myself tip the scales at only 160 or so. I did have a full tank of gas, but the muffers took about 20-25lbs off the car. So..for all I know the weight reduction may be the cause.
___________
JBrady
Actually, it is impressive. The car is very near peak power in 1st gear at 40mph. If there was ANY traction reduction, dust, oil, sand, etc... there is no doubt that the car would break traction. When I lived in Dallas I had a TBird turbo 2.3ltr 4 cyl that I had modified. It ran a best of 14.65 @ 93mph and there was one stretch of Royal Lane near Las Colinas that I could break'em loose on in dry weather at 50-55mph... and that car had positraction.
Anyway, very interesting on the drop in drone from extending the outlets. Makes sense, I just didn't consider cutting my parts and didn't want to have any made as I am planning on different parts alltogether.
Keep it up.
I would suggest combining this entire exhaust story under 1 thread to make it easier at a later date to locate these details... trust me, I do it all the time when someone asks about cold air or exhaust mods.
Hey, what about the intake mod?
_____________
Japanimal
Exhaust drone
I have noticed what you described as drone....when the car is downshifting.....(highway offramp for instace....but I feel it...don't actually have any bothersome noises inside the interior...or that is just the way I percieve it. I get the same thing at idle in park on cold starts...just more of it. Still not near enought to bother me. I put the tubing from the rear section back on the car sans mufflers. Now the exhaust exits onto the rear muffler heat shields...instead of the rear diff. Haven't driven the car yet... but I am gonna guess sound should be even quieter as there is less for the exhaust gasses to bounce off of under the car. I am thinking that I might just go the whole way and do a setup similar to the one on Peter's soarer...only I would keep the X pipe closer to the stock cats and use 4 mufflers instead of two...like he suggested. Do you know of anyone who has done a setup like his on a 98-00 1UZFE? I am not sure what year his Soarer/SC is but I am wondering if the OBDII systems will adapt as well as a pre 96 4.0L setup would??
____________
JBrady
Well, it doesn't look like you want to put those stock mufflers back on... Once that hacksaw comes out going back requires at LEAST a welder
Anyway, I am in agreement that the whole system can be much improved. You may want to read through my earlier exhaust post:
https://www.clublexus.com/forums/sho...threadid=55774
Since that time I have been thinking about many options. Honestly, I would love to try a few different combinations... X-pipe, Y-pipe, single and dual path resonators, various final stage mufflers, different pipe diameters, different headers and cat locations... there are so many theories and it is fun to build and test things. But, at present do not have my own shop so my "testing" has been confined to simple removal of parts and mental gymnastics.
One of the things I think would be interesting would be to replace the LS cat-to-rear mufflers with the GS400 parts. The GS has the same 2" primaries with a larger ID center resonator. The divergent Y after the center res is much better than the LS and then it has twin straight through resonators vs. the LS having twin funky pre-mufflers with side inlets. My guess is the 10hp difference between these 2 factory engines is all found here. So, if you could locate this setup from a GS owner removing his parts in favor of a true cat back as talked about in the GS engine forum... could be an easy/cheap way to upgrade.
Now, if you want to build your own... my hat is off to you. I look forward to your posts and if you are ever in Houston we should get together and "test" these cars against each other
_____________
Japanimal
With the tubing that was between the rear mufflers and the center resonators put back in there is no drone.....whatsoever...as I expected. That sporty sounds is there..just less of it, and no drone. At idle you cannot tell the exhaust is modified. I cut the tubing 5 inches away from the muffler inlet so that the exaust exits just underneath the sway bar. As far as what it did to power....it cannot be all that bad...b/c I broke the tires loose at 40mph today on dry pavement. It was overcast and a little humid today here in Dallas but there was no moisture on the ground. I wasn't even giving it full throttle maybe like 80-90% of full throttle. I have only had VSC come on once and that happened when I gave it way too much throttle from a dead stop while it was raining. Never had any probs on dry pavement until today. I was unaware that the GS4's center resonators are straight through.....instead of the less than ideal setup we have. In light of this new info I am gonna try and get my hands on the front section of the GS Exhaust (Section between Cats and rear mufflers). There has to be a lot of restriction in the center resonators b/c the y joint that spits into the sides of them is the only part of my factory exhaust that has any corrosion on it. The y joint that is right after both Cat's might have some corrosion, but I can't tell b/c of the heat shielding. Anyway thanks for paving the way on the exhaust mod!
_________
Japanimal
In all fairness breaking the tires loose at 40MPH may not be such a big deal. There is no: spare tire, no jack, no toolkit, no med kit underneath the front seat, no center console, no ash trays,no owners manual, no engine cover ...etc. I myself tip the scales at only 160 or so. I did have a full tank of gas, but the muffers took about 20-25lbs off the car. So..for all I know the weight reduction may be the cause.
___________
JBrady
Actually, it is impressive. The car is very near peak power in 1st gear at 40mph. If there was ANY traction reduction, dust, oil, sand, etc... there is no doubt that the car would break traction. When I lived in Dallas I had a TBird turbo 2.3ltr 4 cyl that I had modified. It ran a best of 14.65 @ 93mph and there was one stretch of Royal Lane near Las Colinas that I could break'em loose on in dry weather at 50-55mph... and that car had positraction.
Anyway, very interesting on the drop in drone from extending the outlets. Makes sense, I just didn't consider cutting my parts and didn't want to have any made as I am planning on different parts alltogether.
Keep it up.
I would suggest combining this entire exhaust story under 1 thread to make it easier at a later date to locate these details... trust me, I do it all the time when someone asks about cold air or exhaust mods.
Hey, what about the intake mod?
10-22-02, 12:31 PM
#5
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Posts: n/a
Hmmm, these performance discussions are exciting and interesting.
After my experience with the K&N filter, I wonder if ANY kind of modification to the stock airbox or filter can yield any performance results. I'd like to lean towards Jbrady's idea with the cut hole and bet it has SOME kind of performance increase.
The intake thing makes me really wonder about any of the Lex vehicles gaining any performance (in light of creating problems too) with some kind of intake/airbox mod. At this point the ONLY thing that can convince me is to see dyno numbers, but then again, even if you do get 10HP, what about the stuttering engine, and the carbon buildup (which may cause the stuttering.) It seems there's too many problems coming out of "pandoras airbox" to get good gains. ;-)
After my experience with the K&N filter, I wonder if ANY kind of modification to the stock airbox or filter can yield any performance results. I'd like to lean towards Jbrady's idea with the cut hole and bet it has SOME kind of performance increase.
The intake thing makes me really wonder about any of the Lex vehicles gaining any performance (in light of creating problems too) with some kind of intake/airbox mod. At this point the ONLY thing that can convince me is to see dyno numbers, but then again, even if you do get 10HP, what about the stuttering engine, and the carbon buildup (which may cause the stuttering.) It seems there's too many problems coming out of "pandoras airbox" to get good gains. ;-)
Last edited by Lvangundy; 10-22-02 at 12:32 PM.
10-22-02, 01:01 PM
#6
Lexus Champion
Originally posted by Lvangundy
Hmmm, these performance discussions are exciting and interesting.
After my experience with the K&N filter, I wonder if ANY kind of modification to the stock airbox or filter can yield any performance results. I'd like to lean towards Jbrady's idea with the cut hole and bet it has SOME kind of performance increase.
The intake thing makes me really wonder about any of the Lex vehicles gaining any performance (in light of creating problems too) with some kind of intake/airbox mod. At this point the ONLY thing that can convince me is to see dyno numbers, but then again, even if you do get 10HP, what about the stuttering engine, and the carbon buildup (which may cause the stuttering.) It seems there's too many problems coming out of "pandoras airbox" to get good gains. ;-)
Hmmm, these performance discussions are exciting and interesting.
After my experience with the K&N filter, I wonder if ANY kind of modification to the stock airbox or filter can yield any performance results. I'd like to lean towards Jbrady's idea with the cut hole and bet it has SOME kind of performance increase.
The intake thing makes me really wonder about any of the Lex vehicles gaining any performance (in light of creating problems too) with some kind of intake/airbox mod. At this point the ONLY thing that can convince me is to see dyno numbers, but then again, even if you do get 10HP, what about the stuttering engine, and the carbon buildup (which may cause the stuttering.) It seems there's too many problems coming out of "pandoras airbox" to get good gains. ;-)
When someone uses a MAF adapter to fit a cone filter they loose the factories carefully engineered part (the air horn and shape of the inside of the air filter box). That is why I haven't experienced any problems NOR has Peter Scott with his 1st gen SC400 and his BFI mod which I relied upon to make my LS mod. I have posted his site MANY times and again encourage anyone considering this type of mod to thoroughly read his lengthy site.
http://www.users.bigpond.com/pgscott/
10-22-02, 03:55 PM
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Carbon Buildup????
When you say carbon buildup...do you mean oil build up on the MAF that accumulates after a K&N or similar oiled cotton guaze filter is installed. Keep your stock filter and that won't be a problem. As far as JBrady's mod goes....you are not actually changine the maf location, airbox location, tubing...all you are doing is shielding off a small section of the engine compartment, removing a headlight seal and cutting the front off of the box. Worste case scenario you end up changing your filter more often or you end up with a warmer intake charge.....which will result in a loss of power. And the only time that would happen would be at low speeds if you didn't shield it correctly. In terms of mods to these LS400's, I will go as far to say that anything more than JBrady's muffler and intake mode, along with changing the tubing in the exhaust system so that it more closely matches that of a GS400/430 would be a waste of time for most people. Without changes to the ECM there is only so much you can do in my opinion...an yes there is always a trade off weather it be noise or whatever...otherwise Lexus would have done it from the factory. Lexus engineers are after all "Lexus engineers".
Last edited by Japanimal; 10-22-02 at 03:57 PM.
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10-23-02, 04:42 PM
#8
Lexus Champion
continuing the discussion on exhaust mods, Japanimal sent me a private message. As I was answering I felt it was worth sharing with the board... so...
Well, it is all a question of how much you want to spend???
Optimally, I would replace EVERYTHING. Real headers with a REAL collector http://www.burnsstainless.com/TechAr...ry/theory.html
merge the 2 sides with a proper X or Y pipe
http://www.burnsstainless.com/Crosso...rossovers.html
high flow resonators and mandrel bent stainless lines.
and to make it super trick... use a diverter valve that sends all the flow through a stock muffler on one side at low speed and throttle an opens to a high flow side when power is wanted.
Back to reality (the above system would cost a couple grand or more)
Stage 1: starting at the 2.4" center pipe after the resonator, 2.5" to 3" transition, Y-pipe diverge from 3" to twin 2.25", pipes, into twin 2.25" Walker Dynomax turbomufflers or Ultraflows depending on preference.
Stage 2: replace existing 2" Y-pipe/2" resonator assembly with a new dual 2.5" into 3" Y-pipe and 3" resonator, mating up with the 3" section of stage 1.
Stage 2s Y-pipe would actually merge at about 2.5" then transition up to 3" similar to as seen in these pictures
http://www.burnsstainless.com/Crossovers/y-pipe3.gif
Japanimal wrote on 10-20-02 14:58:
What do you think the next logical step for upgrading the exhaust would be? You mentioned something about changing the center resonator piping....2.0 Vs 2.5in ....and redoing the restrictive y joint before the straight through resonators? Thanks
BTW....big improvement without the rear mufflers.
What do you think the next logical step for upgrading the exhaust would be? You mentioned something about changing the center resonator piping....2.0 Vs 2.5in ....and redoing the restrictive y joint before the straight through resonators? Thanks
BTW....big improvement without the rear mufflers.
Optimally, I would replace EVERYTHING. Real headers with a REAL collector http://www.burnsstainless.com/TechAr...ry/theory.html
merge the 2 sides with a proper X or Y pipe
http://www.burnsstainless.com/Crosso...rossovers.html
high flow resonators and mandrel bent stainless lines.
and to make it super trick... use a diverter valve that sends all the flow through a stock muffler on one side at low speed and throttle an opens to a high flow side when power is wanted.
Back to reality (the above system would cost a couple grand or more)
Stage 1: starting at the 2.4" center pipe after the resonator, 2.5" to 3" transition, Y-pipe diverge from 3" to twin 2.25", pipes, into twin 2.25" Walker Dynomax turbomufflers or Ultraflows depending on preference.
Stage 2: replace existing 2" Y-pipe/2" resonator assembly with a new dual 2.5" into 3" Y-pipe and 3" resonator, mating up with the 3" section of stage 1.
Stage 2s Y-pipe would actually merge at about 2.5" then transition up to 3" similar to as seen in these pictures
http://www.burnsstainless.com/Crossovers/y-pipe3.gif
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