Exhaust Backpressure
#1
Driver School Candidate
Thread Starter
Join Date: May 2002
Location: Georgia
Posts: 6
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
Where is it on the SC400? Trying to decide if its worth going with a cat-back exhaust system, or just the muffler from RMM. Most bang for the buck assesment. Any feedback would be appreciated. Thx.
#2
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
I did the cat back oin my sc4. Not sure about performance because I have not gone back to the track yet, but it is louder. It sounds like im driving a boat now. There may be some power gained somewhere because I can chirp my tires off the line after installing the cat back. Its the do luck one. pics posted in the forum.
check out peter scotts bigpond diehard soarer page. He has some graphs of power gains after headers and exhaust mods.
check out peter scotts bigpond diehard soarer page. He has some graphs of power gains after headers and exhaust mods.
#4
Lexus Fanatic
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
Has anyone here tried a custom true dual exhaust system here? I'm talkin' about dual cats with an X or H-pipe instead of two Y-pipes and a single cat. I'm particularly interested in anyone that has done so and passed smog in California. That's a move I'm about to make...
Here's Peter Scott's exhaust article, BTW...
http://www.users.bigpond.com/pgscott...asurements.htm
Here's Peter Scott's exhaust article, BTW...
http://www.users.bigpond.com/pgscott...asurements.htm
#5
Racer
iTrader: (3)
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
I'm designing one right now with a company called Magic Touch Designs (they deal w/ exotics, mainly the plymouth Prowler), but I live in FL and the emisions are different here. All the testing should be done by the end of November, and I should have the final system tweaked by Christmas.
Keith
Keith
Trending Topics
#8
Lexus Test Driver
Join Date: Jul 2002
Location: Florida
Posts: 861
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
Hey keith were in orlando? I'm going to UCF right now. Are you or that company anywhere close to UCF? I'm thinking we should REALLY get a SC meet in orlando. I've seen A LOT of SC owners in orlando or close to orlando. It would be nice to get together for a lil bit.
#9
Pole Position
Join Date: May 2001
Location: International
Posts: 316
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
Japanese spec exhaust is very quiet compared to the US spec exhaust - your standard rear mufflers would outflow my standard mufflers by miles.
Best bang for you buck would have be to leave the rear mufflers alone , leave the front section alone , and replace the middle mufflers and centre cat/resonator with custom straight through pipe and some sort of balance pipe - be that Nascar style x-pipe or the longer type as seen on V8 Supercars.
I went for the x-pipe in the end.
My current V8 exhaust
Best bang for you buck would have be to leave the rear mufflers alone , leave the front section alone , and replace the middle mufflers and centre cat/resonator with custom straight through pipe and some sort of balance pipe - be that Nascar style x-pipe or the longer type as seen on V8 Supercars.
I went for the x-pipe in the end.
My current V8 exhaust
#10
Racer
iTrader: (3)
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
Originally posted by jimmit
Hey keith were in orlando? I'm going to UCF right now. Are you or that company anywhere close to UCF? I'm thinking we should REALLY get a SC meet in orlando. I've seen A LOT of SC owners in orlando or close to orlando. It would be nice to get together for a lil bit.
Hey keith were in orlando? I'm going to UCF right now. Are you or that company anywhere close to UCF? I'm thinking we should REALLY get a SC meet in orlando. I've seen A LOT of SC owners in orlando or close to orlando. It would be nice to get together for a lil bit.
One of these days......
#11
Lexus Test Driver
Join Date: Jul 2002
Location: Florida
Posts: 861
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
yo keith I'm ike a mile from you. I'm right off 50 and econ. I'm right down the street from valencia comm. college. I'm tellin you we HAVE to get a orlando SC meet. It would be so awesome. We really need to race our SCs. I'd be in last place but it still would be fun as hell. I live in a house right now so we can probably meet here for awhile and hit the tracks. We should get something started. It would really be awesome.
#12
Lexus Champion
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
Originally posted by UZZ32
Japanese spec exhaust is very quiet compared to the US spec exhaust - your standard rear mufflers would outflow my standard mufflers by miles.
Best bang for you buck would have be to leave the rear mufflers alone , leave the front section alone , and replace the middle mufflers and centre cat/resonator with custom straight through pipe and some sort of balance pipe - be that Nascar style x-pipe or the longer type as seen on V8 Supercars.
I went for the x-pipe in the end.
My current V8 exhaust
Japanese spec exhaust is very quiet compared to the US spec exhaust - your standard rear mufflers would outflow my standard mufflers by miles.
Best bang for you buck would have be to leave the rear mufflers alone , leave the front section alone , and replace the middle mufflers and centre cat/resonator with custom straight through pipe and some sort of balance pipe - be that Nascar style x-pipe or the longer type as seen on V8 Supercars.
I went for the x-pipe in the end.
My current V8 exhaust
The exhaust diagram you show in on your website is from an 95-2000 LS400. The mid muffler/resonators on a SC have the cans perpendicular to the road and the LS has them parallel. Each has the unique side entry and end exit. The LS also has the short 2.5" (60mm) cut and spliced outlets from the cats. I will post pics of mine when I get the chance.
You may also note that I am currently running without rear mufflers and although the center mufflers still keep things very quiet there was a 1 mph increase in trap speed in the 1/4 mile. I agree with you that the stock cats flow well and the center section of the exhaust is the most restrictive but I doubt the USA rear mufflers would flow well enough to allow an upgraded center section to make its full potential.
#13
Lexus Champion
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
Originally posted by lex400sc
Well technically there are three cats, but the two on the down pipes don't do much so I'm not that concerned with them.
Well technically there are three cats, but the two on the down pipes don't do much so I'm not that concerned with them.
One of the biggest problems of emission control is the levels at cold start. The engine is running rich and the cats are not up to operating temperature. If you move the cats they will take longer to heat and therefore catalyze the gasses. The larger a cat is the longer it takes to heat. The stock cats flow well. The stock manifolds suck. Very few good options exist for replacing the stock manifolds requires. Peter show a very nice system but even though it would pass a sniffer when heated it is not technically emissions legal and would fail a visual inspection. Short of replacing the stock manifolds your best bet is to leave the cats as they are and build a high flow system from there.
#14
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
Have you ever heard a USA spec SC400 or LS400? Whisper quiet. The mufflers on the 1990-1994 LS400s and the SC300-400s look identical to each other. I realize looks are not definitive but the USA cars are VERY quiet.
#15
Lexus Fanatic
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
My SC400 wasn't whisper quiet when I got on it. It was about as loud as a stock Z28 actually.
JBrady, so you're saying the third cat is not legally considered a cat at all? So if I had it removed and smogged, then my car would pass inspection? I had the outlet of the "third cat" cut off and saw an intricate layer of honeycomb mesh inside. To the best of my knowledge, that's what a catalytic convertor has inside as well.
JBrady, so you're saying the third cat is not legally considered a cat at all? So if I had it removed and smogged, then my car would pass inspection? I had the outlet of the "third cat" cut off and saw an intricate layer of honeycomb mesh inside. To the best of my knowledge, that's what a catalytic convertor has inside as well.