Gixer 1000

Sup fellas ...

I just bought a 93 sc300 (5 spd) with 100k on it. The check engine light was on when i bought the car. (paid 7600)
My friends scanner says its 2 o2 sensors. The guy i bought the car from said the lexus dealer just replaced them 3 months ago, and the light came back on. My friend belives its the cat. causing the sensors to go bad again. So now im going to hollow out my cat and get a cat back exhaust. In a year or so im going to have a turbo kit put on and know ill need a custom exhaust for the turbo. So im waiting on the full system.

Also my cam seals are leaking. Its not a bad leak, not puddles or dripping, but i want to wait and have the whole motor done at the same time. Do u think its ok to let them go if i check the oil and look for drips?

So my questions are ...
1. Whats a great cat back exhaust for the $ ?

2. Besides cold air intake and elec. fan, what else is a great power upgrade for under 2k ?

3. Can i get bigger injectors without upgrading anything else in the fuel system ?

Thanks alot for any posts or advice...
Go Bucs !!! Super Bowl Champs to B !!!

pcmw

Gixer,

Welcome to ClubLexus. You should become aquainted with the search function. All of your concerns are not new to the forum and have been addressed in detail. If after searching you read the threads, and have specific questions, it is better to add on to those threads so that others coming later can find one thread with all the information.

Here is a great place for you to start. http://www.intellexual.net/faqframes.html

Best of Luck,

MW

Gixer 1000

Thx for the link, lots of info.
Ive read alot of threads and posts, just figured id ask ...

pcmw

Fair enough.

#1. Not really a great aftermarket exhaust, so most people order a pair of magnaflows and straight pipe them. Greddy does have a kit at ~$1000

#2. Cold air setup doesn't do much for the SC over the stock. Elec fan and unorthodox pulley are pretty nice upgrades. The S-AFC is supposed to help also.

#3. Bigger injectors with no other upgrade will not help. You need a controller to tune them, etc.

Gixer 1000

Thx alot pcwm. Ive learned alot today

pcmw

no problem and welcome again.

MW

Bean

iTrader: (1)

#1 the JIC Magic system is nice but its expensive... much cheaper to get two straight-thru mufflers and a resonator and get it custom built at an exhaust shop

#2 the cold air intake things don't do much more than having a K&N cone filter replacement (pick up the setup at importtoys.com)
stay away from pulley upgrades; the unorthodox especially; it'll end up killing your engine because it has no harmonic balancer

#3 no point in getting bigger injectors, don't worry about it

my input? get intake, exhaust, and put a 100 wet shot on it (prolly need upgraded rims and tires too)
with this you'll have the power (provided the grip is there) to run mid-high 13s

Gixer 1000

Thx guys. Im going to do the elec. fan and k&n filter right away. About the exhaust, im not going to have the money for a turbo kit for at least a year or so. So if i go 3" from the cat back wont i loose to much back pressure ? My friend suggested that i put a
2 1/2" y pipe after the cat, and then go back to 3" from there back, and two straight-thru mufflers.

Think that will be enough back pressure ?
and then i can just replace that piece with a 3" one when i get a turbo kit.

Also im looking for the plug-in device for my o2 sensor (correct me if im wrong, but thers one in front of the cat and one behind it)
when i hollow out the cat, ill need this device to keep the check engine light from coming back on.

And any advice on the cam seals leaking ?

Thx alot

GO BUCS !!!!!!!!!

pcmw

Gixer,

If you have a 2.5" Y-Pipe. Then why put 3" pipe after it? Just run 2.5" the length of the system.

MW

Gixer 1000

Hi MW, because ill want the 3" when i go turbo, and that way all i need is the one part and not all the way back.

Thx

Bean

iTrader: (1)

if you're going to have a dual where there's a split; going 2.5 on both pipes is plenty of breathing room...

a basic turbo kit won't benefit much (if at all) from a 2.5" dual to a 3" dual...

3" dual IMO is def too little backpressure on a stock car, unless you're running nitrous; and even then 2.5" is perfectly fine

wmulli

Why do you guys think back pressure is a good thing? Check out this link:

Turbo Exhaust Discussion

Bean

iTrader: (1)

back pressure on an N/A motor is required to some degree (less and less is needed the more air the engine pumps at lower rpms)

hence why you don't want much at all with a turbo

what i'm calling backpressure is a tad different i guess...

if you have too large of a diameter of piping anywhere in the exhaust system, the air being pushed out of the engine will slow down and create more backpressure against the air being pumped out of the engine...

but low-end grunt is very important to a lot of people; this is why domestic engines have a different head profile (also pertains to trucks)...
the smaller exhaust ports, valves, exhaust system, whatever it is; the more low-end power you will make... of course this approaches a point of sanity
the bigger the exhaust ports, valves, exhaust system, whatever it is; the less low-end power you will make, but the more top-end power you will make...


whatever tho... still goes that dual 3" is too big for a N/A motor; you won't have much more top-end; and you'll die until 4000rpms when the motor finally pushes out enough air to utilize (to a small fraction) the large size of the exhaust system

Gixer 1000

Thx for the peplys ...

Im going with 2.5 from the cat back.
can someone tell me if there is 2 cat. converters in the stock exhaust system, or is the "cat looking" thing thats in the middle a resinator ???

also im told if i hollow out my cat, ill need a plug in piece for my o2 sensor behind the cat, or else the check engine light will come on.
anyone know where i can get one of these ???
ive searched the forums and the net with no luck.

and last, if the check engine light is on, does the car run in a different mode ??? someone told me its in limp mode if the check engione light is on . i dont think so, but it dosent hurt to ask ...

Bean

iTrader: (1)

a precat right after the exhaust manifold; and full main cat in the middle of the exhaust system right before the main cat...

and a resonator before each muffler...

negatory on the O2 sensor thing; thats only for OBDII cars; you have a 93; an OBDI car...

your two O2 sensors are in the exhaust manifold; it'd be impossible for them to sense any changes
don't hollow out your cat; just get a test pipe; it flows better... but if your gonna do that; you'd better get another muffler into the mix; because its gonna be LOUD LOUD LOUD...

i have a single 3" with the stock cat on there with no resonator and its pretty loud at WOT

i also think putting a testpipe on the car will hurt you bad on low-end power... REAL bad... you may not even gain any at the top either... prolly wanna leave it in for now; unless youre getting a turbokit

some people will say the car DOESN'T run in limp mode; but i got a check engine light from my ECU wiring getting jostled around and i KNOW i lost power... it was obviously ignition timing which is ECU controlled; so i feel that it DOES make a difference... i unplugged my battery to clear the code; and then drove it around for a day and took 3 tenths off of my 1/8th mile time with the same 60'