Lvangundy

OK!

Well I got bored and took my car out to a muffler shop to have the middlle resonators removed. The piping size was not changed.

Result? A quiet growl only audible from the outside rear of the car under 2000 RPM's. It feels a little smoother on the freeway, but I was told by the guys at the shop that you lose low end torque when changing the exhaust. Anyone have any input on this?

I found my camera so I'll take some pics and post them up! I'm thinking I want more growl..will changing the pipe size yeild a deeper and a tad louder output?

;-)

LOTC

I havent found any loss in low end torque, just some nice growl which you wouldnt expect from the LS. It also adds bettero flow at higher speeds.

If you change the pipe size from 2.5in to 3in it might get louder,but you will get better air flow, which means a little more power, also I have heard that the stock y-pipe takes a bit of power away from the car.

Lvangundy

Ok - maybe we'll get some tech heads in here to debate on this..

I have heard several arguments as I told people I took out part of my exhaust on why it won't do anything do increase performance.

The primary argument I got is that the early Lexo's didn't have a 'smart' ECU and couldn't recalibrate when it detected change in parts. Another thing was that a certain amount of backpressure is needed to help the car accelerate and removing the parts that help with this decreases performance.


So what's the REAL or (at least opinionated) deal??

indypwr

I OWN A GS30 (1996). MY FIRST MOD WZ THE EXHAUST. 1ST, I TOOK OUT BOTH OF MY RESONATORS AND REPLACED THEM WITH A PIPE, OF COURSE. I DID LOSE SO MUCH BOTTOM END POWER, THE CAR GOT LOUDER AND I DIDNT' LIKE IT. SO I PUT THEM BACK AND REPLACED MY STOCK MUFFLERS WITH MAGNAFLOW. I HVNT CHNGD MY PIPING YET BUT I WILL SOON.

ALTHOUGH I LOST BOTTOM END PWR, I DID GAIN TOP END PWR. BUT THE CARS OR ALL LEXUS CARS HV A LOT OF TOP END PWR SO, I WZ MORE CONCERN ON GAINING BOTTEM END PWR.

HOPE THAT HELPS.

Lvangundy

What do you mean 'so much bottom end'. I assume you mean torque?

No offense, but I'm finding it hard to believe all this chatter about intakes and exhausts taking away low end power and giving more HP at high rpms.


Are these proven numbers reported on dyno graphs? What is the extent ot all the bolt on mods at which you lose or gain performance?

I wanted to get my car dyno'd before and after that K&N filter and my exhaust but SP engineering never replied to my inquiry about getting my car on a run. Maybe I'll give them a call.

Lvangundy

I took my car back to the shop again to have a longer section of pipe installed and increased diameter. (not really worth the $ I spent)

STILL not that much more noise!! The growl is a little louder, but only at RPMs below 1.5K..Otherwise nothin!

Also..drove a 92SC for the first time..hehe bit quicker than my LS for sure.


Question..does anyone know if the center exhaust/cat? piece is a resonator or a 3rd catalyst?

JBrady

I started a thread on this and included a killer link supplying flow data, size and weight for the various parts of the system... please review.

https://www.clublexus.com/forums/sho...threadid=55774

First thing to understand (and contrary to popular myth) is you do NOT want ANY backpressure. Now, the crazy thing is changing to larger diameter piping will often result in a loss in low rpm power. People THINK they have reduced backpressure and therefore the myth. Actually, the larger diameter pipes flow WORSE at low rpm/gas speed and create MORE backpressure at low rpm. I understand this is hard to understand but it has to do with turbulent flow, atmospheric pressure, energy pulsing, enertia and more.

Anyway, the goal is maximum flow at ALL rpms. To this goal I am designing a complete cat back system for 1995-2000 LS400s and it should be easily modified to fit 1990-1994 LS400s and all year SC400s. Critical areas are bends and transitions. Choice of resonators and mufflers will affect power and sound. To debunk another myth, louder is not always more power.

I expect to use all mandrel bent tubing, replace the Y with an "X" pipe, change to a dual path resonator, change to high flow second resonators and finish with Dynomax turbo mufflers. The Dynomax parts flow extremely well, have great sound and are not loud. The X pipe add power and torque while quieting the exhaust and adding an "exotic" sound. Pipe size will be only slightly larger than stock. This will be an extensive system and will cost around $1000 installed in mild steel. For stainless add about $500.

BTW, center part is a resonator, not a cat.

LOTC

keep us posted on this project Jbrady.