What's the difference between gutting out the cats and running straight pipes. Also, if I decide to just gut out the cats because they're clogged, will I lose or gain power. But what I've been told is that I will lose power because I will lose a lot of back pressure the 5th and 6th ports no opening? Can anyone please shine some light on the subject. Everytime I searched for it, everyone always went off the subject. Please help?!?!

 

1st, if you have a s5 than you dont have to worry about 5&6th ports. s4's you do, so you have to wire them open, but chances are if you just get the cat you will have enough back pressure to open them. also racing beat sells pre silenser that make the 5 and 6th ports open.

A strait pipe flows better has a bigger diamater and so on cuase it would be more of a strait line where as gutting the cats would leave you with a smaller exhuast.. but anyway.. you would get more power in the long run especially if the cat is clogged.

 

So let me get this straight, if I gut the cat I'll still have enough back pressure to open the 5th 'n 6th ports? How do I wire open the 5th 'n 6th ports? Please people, submit more information, I'm trying to be a sponge a soak up as much as possible. =)

 

since you've got an 86, it's hit or miss if you'll have the back pressure to open up your 5/6th ports...assuming they're working. it's not uncommon to hear that people's ports are stuck closed.

personally, i'm against wiring them open. you'll lose a bit of low end power. if you do a search on "auxillary ports" (maybe if you spell it correctly, that will help too ;-) ) you'll find plenty of info on this.

john

 

Having working 5th and 6th ports is great! You can wire them open if you're willing to lose the lowend power, but mine were working just fine when I was running a straight pipe in place of the cats.

 

so even though i lose back pressure from running the hollow cats i'll still have enough back pressure so the ports open?

 

If you have a stock catback, there should be enough backpressure to open the ports.

 

even if they are completely gutted out?

 

How do you "gut" the catback?

 

I think Aaron Cake was referring to the catback, (exhaust system aft of the cats) and not the cats themselves. I can assure you that the 5th and 6th ports worked just fine on my 86 GXL with NO cats and the stock catback.
BTW, I still have the race pipe that replaces the cats altogether. Should make a bit more power than gutting the cats if you're interested. (I've picked up a header and hi-flow cat and won't need it any more)
PM me if interested.

 

I see, so it's okay to run a gutted cat as long as I keep my stock cat back. Sounds good, does it really hurt my low-end though and alot of people say they gain top-end but can you give me maybe some generalized numbers on power losses and gains? Also, aaron cake, is your website aaroncake.net or org...I've seen the site but I forgot to save it.

 

My 5th and 6th sleeves still had enough back-pressue to open up when I had gutted cats and a 2.5in straight pipe cat back. The stock cat is a very restrictive thing even once it's been 'high-flowed' (read: gutted).

I've since removed my 5th and 6th sleeves completly and I can say that the engine seems more torquey even down low.(2,000-3,000rpm)

 

you removed your sleeves? how did that make your car toquey and did it affect your high- end?

 

oh yeah another thing, when i'm talking about gutting the cats, would it be just the all the cats or just the pre cats?

 

Are you sure the animal rights activists know you guys like to gut cats? All the ones in the neighborhood. Do you have emmisions in your area? You will not pass without at least one cat in place and functioning.

 

LOL yeah I do have emission's in my area but I just smogged it so I have 2 years to become completely illegal! But seriously, would be all the cats or just the pre-cats?

 

Generally, its the main cat.

Speaking of which, I can even seem to make the bolts on my budge....hmm. I'll have to figure out another way of doing it.

 

get to making my cat's "free flow" first thing tomorrow after smog =). then i'll keep a post of what progress and problems i may have or will encounter. thanks for all the info guys

 

NoPistons4Chris, yes I removed my 5th & 6th sleevs and to me at least it's made it feel alot more responsive, I guess you could say torquey down low(~3krpm) and quite noticibly increased the topend..

 

hmm, how'd you remove your sleeves? it sounds appealing. anyone else do this and have the same kind of gain?

 

Umm... how'd I do it? I dunno how to explain it...
[1]remove the inlet manifold
[2]remove the sleeves
[3]plug up a few holes
and that was about it..

If after step 1 and before step 2 you find yourself wondering where/what the sleeves are I suggest you don't attempt this mod yourself.

There is a really good write up somewhere on this forum about it... probably in the 'Archive' section of this 2nd gen catagory I think.

 

Removing the 5th and 6th port sleeves does NOT give you torque down low. That is insane and completly un-true. I will try and find the thread on this that had a dyno sheet in it. They may give you some HP(probably 1-2 hp) in the top end but I would higly doubt it. Unless you have dyno proof or 1/4 mile slips(more than one run with each setup) before and after.


Santiago

 

if you've got to worry about emissions, why not just get a race pipe...you'll need your cat in 2 years when you've gotta pass again.

john

 

hmm if you find the thread on removing your sleeves please post it up. well regarding my emissions, i'll put a race pipe when i get paid, the hollowed cats are going to temp. because i recently just started my new job last week. so it's just going to be there to get me by. besides, they are clogged as hell right now so I'd like to gut the hell out of them anyway. I know i'll need the cats in 2 years but by then i'll have the motor i'm having built so by then passing emissions will be nearly impossible.

 

Er, ok dude... you obviously have alot more experience with doing this than me.
Just to clarify, by 'down low' I was referring to ~3krpm, which to me is 'down low' in respect to our redline. How many times would you really go WOT below ~3krpm's anyway.
hehe and by the way, it gives alot more than '1-2 hp' up in the top end... I dunno if when you did this mod (if you even have?) you stuffed something else up along the way, but on my car at least it was a noticable increase.(which would indicate to me more than just a 1-2hp increase)

Anyway, if thats what you believe, i'm happy for you.


Re: the links to the threads about it, I said in my last post i'm pretty sure they are somewhere around The 2nd Gen Archive.... have fun.