matt7184

Are our stock mufflers baffle type or a straight through type design? When I looked at them visually with a flashlight, it looked like a straight through type design. Anyone know for sure?

For the people with their cats removed, did you feel any performance benefit?

XX400

I removed the cats and replaced it with a tru dual exhaust with an xpipe joined to the factory resonators and muffler. The top end difinitely feels stronger however I would recomend replaceing the rear section also as it seems pretty restrictive. The factory mufflers are straight thru design but sound like crap once you remove the cats IMO.

matt7184

I heard an SC4 around my area and it had stock mufflers and it sounded different from mine (a nice deeper tone with a little more burbling), I thought he might have had just the cats out. I cant find sounds for just the cats out

SCV8

I'm pretty sure the rear mufflers are the straight-thru type,someone else here on the forum was wondering why bother with expensive exhausts when you only get 7hp from $600 set of mufflers,and was noticing that the stock cans were straight-thru.
The 195hp Acuras have about a 2" pipe,similar muffler.

UZZ32

The Japan spec mufflers are not straight through, they are reflection type. You can see straight through a double off-set straight through muffler - looking down the standard muffler (from Japan) you can see the bend at the end where the exhaust gases go 180 degrees.
There was an enourmous difference in pressure loss between the standard rear mufflers on my car and a 2.5 inch stainless straight through type muffler.
I have some pics and V8 sounds on my web page. I also measured the pressure loss through different parts of the exhaust - the front section isn't bad and the cats were ok too. The rear four mufflers were the worst bits.
Another site for great V8 sounds is
www.hsv.com.au
They have an entire track made from V8 samples - and a cool video too match. We need someone to shoot some Soarer V8 footage - now that would be cool...

matt7184

The JDM Soarers have the baffle type, so I dont think we will see as good gains as them from just mufflers. Im thinking of just taking out my cats, reworking the piping for an X-Pipe with my own personal design and having this local shop make it with my help, should cost me about $150, but that is with pipes and access to a mandrel bender. From visually looking at the exhaust, the oval cats, and the first resonator seem like the main problems to me.

rboorgu

I have started doing some of this testing myself.

Mine is an American spec SC400

Stock RWHP =173-177

With center resonator cut out : 193-197

With full mandrel bent 2.25 from front convertors back, with x-pipe and rear bosal mufflers:: 195 rwhp.


Conclusions: the main restriction in the stock system after the convertors seems to be in the center resonator. Changing the full system did not yield much benefit. However, the x-pipe did significantly increase torque from 1800-3000 rpm. I have not done 0-60, or 1/4 mile yet. The next step is to remove the front convertors and add a center 2.5 or 3in resonator in place of the x-pipe. Currently, the system sounds good, but has a lot of boominess in the low rpm range

Raj

matt7184

When you say the center resonator was cut out, do you mean you replaced it with an X-Pipe? Just curious, but how was your gas mileage affected when you did this. 20RWHP seems pretty good since I can get the pipes made for less than $200.

The Ikon

Q: What method did you use to get your figures?

Your RWHP seems kind of low for an SC4. The stock hp is 250/260 for example in 92' - 97', the car is only supposed to lose around 20% at the wheels thru the automatic transmission. Which would make the dyno at 200/205 rwhp.

The rwhp you quoted is for the SC3 NOT the SC4... DirectQL recently dynoed his SC3 and his rwhp where around the 175rwhp mark after he got his car tune up.

At 173 rwhp your SC4 has "LOST" of 77 - 82HP at the WHEELS!:eek: Which in term = 31% rwhp lose thru the trans.

20% at the wheels is 50hp! Which is 200 rwhp.

There must be a problem with your car{hi mileage, old worn engine, weak tranny, tune-up, *****. Or the way you arrived at your figures (person dynoed, G-tech, or etc) is inaccurate!


The Ikon

rboorgu

Ikon,

I disagree. Many have tested the 92 SC400 and the usual rwhp is around 175, with some even reporting lower. I used a Gtech with estimated rolling weight of 3900, including me and half tank of gas. There is an tremendous amount of powertrain loss in these cars which is unfortunate. However, the increase in performance with the exhaust mods does seem reliable. In my first change, I simply had the center resonator replaced with two pipes making it a true dual system. Instead, I would reccomend replaceing the resonator with a x-pipe. This is the cheapest way to increase performance and maintain sound quality. The tips of the mufflers can also be replaced inexpensively. My next step is to remove the front convertors, and see what effect that has on performance. Maybe the mandrel bent system will open up once I do this.

MadMaxSC400

It's either my upgrades or my luck, but I've driven an IS that's dyno'ed at 182 whp. Let me tell you, my SC400 will smoke that IS. However, I also installed a crossover setup manipulating a larger cat and a max flow cold air intake. We shall see, my car's getting dyno'ed on thursday.
One performance gain you'll get from ditching the stock mufflers is weight savings, those things are huge and heavy
I used a pair of $80 a piece Magnaflow straight throughs, they sound deep and powerful.. everyone comments on the exhaust sound. No need to remove the resonators, those actually help flow a little and it'll make the car noisy.
One note here, I've pulled the stock half-moon shaped exhaust inlets to the cat, replaced it with a much larger cat and made a coupling into which the round ends of the pipe flow unmolested.

black sc

The X-pipe, mufflers, and bigger piping (2.5") are good ideas that I am considering. The only problem is that the mandrel bent pipes are not stainless like, the stock system. How long have you guys have had these setups? I want to know b/c, don't want to replace the pipes in a year or two.

banking

What the ^&$$ happened?
I had just posted my reply and somehow my reply did not come out correctly.
Anyway, stick with the two inch exhaust and 2 1/4" rear section w/good mufflers.
I have two extra X-pipes 2" and 2 1/4" made professionally by an NASCAR affiliate. Still in box with receipt and name, address and number and contact person.
If interested email or call.

van
8009573385 x 671

007lexus

This question is for all the folks which have dropped their cats on their cars:
Has anyone been hassled by cops or highpatrol?
Sometimes here in calif, i've seen a emission setup which is placed on on-ramps of freeways which takes readings coming from your exhaust as you accelerate onto the freeway, won't this catch those with out cats?
What about the noise factor?
How much more louder will the car sound?
Would the sound be noticable that will lead a cop to think that u dont have cats on your car?
How about the horsepower increase? How much w/o cats?


thanks,
007

The Ikon

Maybe they needed a tune up as well. Or their car where not in tip top shape... Feul filters, injectors not flowing properly, etc... to lose that much hp seems beyond the norm... Anything is possible, but not the norm... How many miles does your car have, compression, tranny condition makes a big difference...

***[Quote by: DirectQL] All and all I got my tune-up today and my car was restored to greatness again. The sparkplugs I used do seem to work great and I am happy I got the ones I got. The rotor was almost all gone and I didn't look at the cap, so I bet it didn't look too good. Sparkplug wires were also replaced alone with the fuel filter. My car dynoed peak 177 rwhp (highter than stock???) and before the tune up I was getting 147.2 rwhp. Compared the dyno to the one when my car wasn't running right, this one is such a nice smooth curve. Very great Improvement. I don't have a dyno of peak rwhp after adjusting the AFC, but I am more than sure I have gained atleast 15 rwhp. When I do replacement of the belts I will also do the cam geards and I will adjust the timeing which should work great with the AFC improving the rwhp majorly. Heheh. I recommend the place to anyone in the Chicago area. The place is called APG Performance. These guys know what they're doing and I feel much better in the quality of their work and most other shops. Also thanks to Tom Chow for keeping me company and teaching me few things about cars. Thanks Tom.

-Chris

PS. Recommend the Denso Iridiums to anyone, they're great. The stock sparkplugs were Denso Platinum.[Quote end]***

Conditioning makes a big difference.. His car picked up 30 HORSE POWER with his tune up!!! I talked to him after his 1st dyno and he said he was told to get a tune up by his mechanic... The results are plain as day... Maybe it will help out your SC4 too..

I'm very interested in seeing Max dyno in a week or two... My goal is a mere 250 rwhp... Intake w/filter, exhaust, S-AFC or ECU upgrade is what I'm thinking will get me there.... I know the best mod for $$$ is the torque converter. I'm just unsure of the day to day driving aspect yet...

Once I get some hard data I may try more mods. Not just some internet info without some data to back it up... Let's keep the brain juices flowing, but let's provide some data too...

The Ikon