Top end rebuild and exaust questions

[SFK830]

So finally my intake leak got to the point where my 98 cutlass has to sit, after replacing said manifolds we where still getting air in the coolent lines so we ripped the block back apart to find some nice blown headgaskets. So my heads have been sent out to be planed and i was wondering if it would be worth my time to have them ported (this is only a 3100 sfi were talking about but i do want it to be much faster than stock basicly im wondering would the gains be worth the money).

Also i have a thrush glass pack and the car sounds great running cat-resonator-glasspack, but i have an extra glass pack and was wanting to set it up so it was glasspac-resonator-glasspack so i wouldnt be running a cat. My questions for the exaust system start there because im not shure how i can delete the post cat o2 sensor, iver heard of this being done on other cars any ideas guys?

My last question is regaurding headgasket thickness i know that by changing the thickness i can change the quench and with planed heads im already gonna have slightly highe comp can anyone recommend a higher comp thickness for me? of course i kno i will have to double check agenst how much was planed off the heads for valve clearence but im looking for opinions of people more accustomed to these motors.

[SappySE107]

You should use the 3400 heads or 2000 and newer 3100 heads. They are better than what you have. For porting, you can have them ported for sure and make more power, but if you or the person doing them don't know what they are doing, you could hurt the performance. Milling the head doesn't do much for compression. You cannot go thinner on the head gaskets either as there is already .040" quench.

Deleting the cat on a street driven car is not recommended, because I like to breathe. You won't gain much (good luck proving 2hp), and it will smell horrible. Just don't do it.

Now lets talk about stuff that is cheaper and gives more power. Get the 3400 intake manifolds, and use a 3400 throttle body. 56 vs 52mm TB and the large port manifolds are worth a considerable gain in power. 15hp all day long.

[SFK830]

Im not overly concerned with a 2hp gain, nor the smell i really just want a louder sound, now that being said im setting it up so i can bolt the cat right back in place if i think its to loud without it or find for any other reson i want the cat back in place. Ive already had my 3100 heads planed so switching to larger heads is now out of the question, i have very little time left befor the motor has to go back togeather and although i would like to swap the larger manifolds on i cant find any around here for cheap. I really wanted to get headers since im more concerned with the sound/performace than i am all out performance but couldnt find any online.

Ive never ported heads and as bad as this may sound im not sure really of the process, any links to a write up on it? I would probally have it doen by the guys at the machiene shop where my heads are at but ive heard its relitivly simple to do yourself, so if they charge more than i think its worth i could give it a port job myself.

[bob442]

its 70$ max for a magnaflow cat. if you want it louder put a aftermarket muffler on it or get rid of the resinator thats inbetween the cat and muffler.
I agree with Ben, i like to breathe too, and its not worth the ticket, the tow bill, having to go repersent your self in court, and have a licensed mechanic approve your car road worthy if you get caught with out the cat.

[SFK830]

Well i already have a 2nd glasspack so id rather not have to get a hi flow cat. Here in mid missouri cops arnt strict at all, i went through a sobriety checkppoint in my 300zx without my front bumper or driverside quarter panel and my front turn signels mount in the front bumper, and i didnt have proof of inot away with a warning im more concerned with how not having a cat would effect my performance

[mfuller]

Please for the love of God keep a catalytic converter installed.
It doesn't matter if your state does emissions testing or not; it's a federal requirement that if your car came with a cat and is used on public roads, it must keep the cat.
If you want it loud, just run a straight pipe (no muffler/resonator) after the cat.

[robert 1980]

Get a set of headers and install a dump or ''Cutout'' Before the cat then it would be loud as hell

[bob442]

you should be more concerned with how not having a catalytic converter is irresponsible and reckless. But its ok, that 1.5HP gain will dominate over any import

[SFK830]

I have 3 other people on this street running no cats, and like i said befor its gonna be able to bolt back on, one person not running a cat isnt gonna make anymore of a difference. I looked and couldnt find any headers online. So can we mover away from the subject of the cat if no one can provide me with information about how to delete my emissions o2 sensor.

As far as adding a dump valve that would allow me to only run cat-less when i want however i want sound, like i would have to run a glasspack on the cutout, plus id have to spend more money that way and this was only a 100 dollar car so im keeping money spent on it to a minimum while trying to see how much speed i can coax out of the little guy.

[pocket-rocket]

I've read that installing one of those spark plug non-foulers on the rear O2 is enough to fool the PCM without removing the O2 sensor.

Not to beat a dead horse, but be aware that not running a cat or hollowing one out will give your engine a more raspy sound and make the car louder. I hate the way my truck sounds even with a new Cherry Bomb turbo muffler...

[SFK830]

I am aware of the rasp factor however yours is worse than normal because of the turbo mufflers, i have a friend who has true duals, 2.5 inch and hi-flow cats and it rasps like a mother. my cutlass currently makes no rasp, has no bloback sound to it nothing it sounds good but its not very loud at all. Thank you someone for staying on topic and helping me out with my o2 bypass problems ill check into it.

Also i know that the 2000+ intake manifolds are higher flow, and sicne i cant find headers i was wondering if GM stepped up the bore size of there exaust manifolds aswell?

[bszopi]

Go with a cat only, and you will get a pretty decent and loud sound. Solves all the problems.

Sent from my DROID2 GLOBAL using Tapatalk

[SFK830]

Thanks for the input but i am going with my dual glasspack setup and im gonna use a spark plug non fouler to bypass my ecm throwing a code. If the sound istn right i might delete the resonator and play around with it a little more, possibly even put the cat back on.

Thanks for all the help and hopefully soon i can post an exaust clip on here and you guys can tell me what you think.

[SFK830]

Just for anyone whos curious the 3100 sounds amazing running only the downpipe and a sigle glasspack, the rest of my exaust work should be finnished tomarrow at wich point i shall make a video for you .

And thank you "pocket-rocket" for the tip on the plug non-foulers thats the method wich i have decided to use and looks like it will work i will know forsure withen the next few days or so.

[BillS]

Allow me to agree with all the 'leave the CAT in comments' You can get the sound you want and still be socially responsible.

I run a 3.4 in an old car that doesn't require any smog equipment. A simple muffler and tip resonator give excellent sound. I'm sure a similar exhaust on your car with CAT would result in good noises.

I run a single system as it is lighter and a dual wouldn't add any power.