Is there any danger in removing the smog control set-up on a TBI car? I know that this thing isn't great for car performance and I have a friend that said that they are easy to remove and it won't mess with the way the car runs. Any suggestions as to how to go about the removale or even if I should. Thanks.

 

Leave it unless you have a reason too. No point in going through all that work, to gain MAYBE 2 hp. I removed mine because I'm getting headers, and didn't wanna buy brand new headers only to remove the air tubes. I had the air pump removed anyways to get better access to the water pump, so I just scrapped it all.

 

Oh, ok. I was thinking about headers, but not sure now. May sell. Thanks for the info.

 

I guess you should better keep it. You might find it handy when the right time comes. It was installed there for a purpose & not just for some crappy aesthetic purposes

 

personally, im of the mind that the smog controllers dont do a whole lot. if you look at the dynamics of the A.I.R. system, it only dilutes the mixture of gases by inserting a larger volume of fresh air. they say it helped to reburn un-combusted gases, i think it was crap. i took mine off, and found that most of the hoses went to dead ends. could have been from the previous owner, i dont know. all i know is, the system is in the way, and its nearly impossible for it to do what it says under the circumstances and engine perameters.

if you wanna make power, ditch it. if you need to be smog compliant, keep it or take your chances with building the engine with C.A.R.B. parts.

 

smog doesn't help with horsepower it makes the engine run cleaner.
and sacrifices a few ponies in the process, think about it like this...
the smog recirculates exhaust(burnt gas and air) back into the engine so your burning smoke basically, which makes the air marginally cleaner coming out the tailpipe amongst the cat and what not. if you had to run fast and be performing at your best would you rather be breathing clean fresh air or smokey dirty air? clean air = more horsepower, tho with tbi you will need a computer tune if you remove your smog because it relays information to the ecm.

 

Do you have any proof of your opinions that emissions control devices do nothing, or is it just an opinion?

The catalytic converter does the most good in cleaning up a car's exhaust. The EGR valve is second and the AIR system is third. Only the cat affects your wide open throttle power, and with an aftermarket "high-flow" cat the decrease is less than 5 horsepower. This has been proven repeatedly on a dyno, and is not just my opinion.

By removing your emissions control devices on a street car in the United States (a violation of federal law regardless of if your state does emissions checks or not) you have shown that we hot rodders are irresponsible and cannot be trusted, so there must be more laws made to stop us.

Edit: I forgot, the charcoal cannister helps control bad emissions too, as well as the PCV system.

 

I started this thread over a year and a half ago. Still have the smog, despite the bad bearings making lovely noises at idle. My car came without at a cat (bought it at 103,xxx miles). I plan to swap in a LS1 and I plan to run cats with the exhaust when I do. The main reason I wanted to take the AIR off was because of the noises make the car sound like a clunker and the room it'd free up in the engine bay more than the 2 or 3 horsepower I'd gain.

 

it seems like gm had a bunch of morons engineering the smog control setup in the 80s.
the egr only pulls exhaust from 2 cylinders and is then injected back into the same two worthless.
and then there are people that will tell you that running with out egr will blow up the engine because the cly temps get to high that may or may not be true but apparently gm thought that only 2 out of the 8 cly got to hot lol.
cause the other 6 have no routing to the egr so apparently only 2 of the 8 need exhaust recirculation?

just looking at an intake manifold shows you egr is is plumbed from only 2 exhaust ports and then is put back in on the same 2 intake ports .

then the air injection pump only functions for 5 min on startup the rest of the time its just wasting hp .

gm learned from there mistakes and used a electric smog pump on lt-1s but its illegal to use the newer pump on earlier cars for some reason.

gm also learned that they didn't have to use 8 separate air tubes freeing up a mild restriction on the exhaust manifolds .
also the lt1s egr works better as it is hooked into its plenum area to send exhaust to all cylinders instead of 2

the only issue i had when i removed the smog pump and air injection from my car was after 3 years the cat clogged up but that could also be from the car have 140k miles on it and being the factory cat.

i have since replaced the cat with one that doesn't use Air injection ,
had gm did better design on the smog control parts maybe less people would remove them .
i know if they used a setup more like the lt1's use i would never had removed it , nothing is lost by having them on an lt1.

you would think aftermarket electric smog pumps would be all the rage
aswell aftermarket egr setups to cool combustion chamber temps
but then you see the lt4 didnt use an egr so then you get people wondering why keep them on there car if "high performance" engine didint need them.

but none are for some reason but yet off road pipes do sell and egr delete kits sell .

overall removeing all the smog components will not hurt the how the engine runs .
removeing the cat you can pick up a little power but really its not worth it for how the car's exhaust stinks at a stop light and it pollutes like crazy a high flow cat is a better option.

removeing pcv is pointless as you gain nothing from removeing it .

also removeing charcoal cannister is worthless as once again you gain nothing but annoying gas vaper smell .

removeing the egr really changes nothing .

but removeing the Air injection you can free up some power and makes the engine bay look much cleaner and you can do tune ups alot easier.

the only thing i removed from my car was the air injection but i also put a high flow cat on that didnt use air injection and it can fast pass e-check with lower amounts of every thing they test for then a factory car .

 

I have had my car for fifteen years now and have played around with just about all of this crap. Removing and/or plugging the PCV valve, did nothing. Doing the same with the EGR valve, samething. Removing the smog pump and the AIR injection in my opinion helped the most and it was a noticeable difference....again in my opinion. However, adding headers was the big ticket item. I had headers with straight pipes and with cherrybombs in between going out the sides.

The straight pipes were too loud and stunk. With the cherrybombs they were a little quieter and stunk a little less. I since put a mandrel bent y-pipe on the headers with a a high-flow magnaflow cat' and a mandrel bent pipe out to a straight through stainless SINGLE outlet muffler. The car doesn't stink at all now and honestly, it doesn't feel any different then when it had the straight pipes with or without the cherrybombs.

The moral to the story is if you are going to do it, do it RIGHT! Don't be a cheap b@stard and cookie cut. By stuff that is "custom" fit and that will also save you alot of time and grief. Also, depending on what your plans are hobby wise and/or money wise, you may find better satisfaction with your car working on the suspension and weight reduction then splurging on bolt-ons, engine mods, and/or engine swaps. I speak from experience so my $.02.

 

I've just left the engine alone except for a open element breather and a JET II chip (got it cheap, figured why not?). The open element really did help the car after 3500 RPM. The SS hood I have is functional, so it gets more cool air that it would with a solid hood.
As you can see from my sig, I've went the suspension mod route with my car til this point. I do plan on a LS1 (or 2)/ T56 swap when I get out of school. Til then, the 305 is doing fine.

 

Wait, but if you have a 5.7, you have a 350, not a 305.

Did you replace the PCV valve with a breather? Does it foul up the engine bay at all?

I did the samething and noticed a remarkable difference with the car. After changing out shocks and springs, going to a fiberglass hood, tossing the back seats and getting aluminum drum rotors for the rear, the car feels alot better performance wise all around. I still want to replace the driveshaft with an aluminum one, replace all the pulleys with aluminum ones and if I can score a lexan rear glass for cheap.........WOOOOOO!!!!!!!!

 

No, I have the TBI 305. I chose that screen name before I got my current car. Was looking at a 91 Z28 with the L98, but ended up with the RS lol. I'm still running the stock PCV (stock as in original design, not original part)

 

So, you did chuck the PCV valve for a breather filter then? Here, you may want to read this in regards to your TBI 305: http://www.goingfaster.com/spo/modthel03.html

 

Look at it again. The EGR system gets its exhaust gasses from one exhaust cylinder, passes the gas thru the EGR valve, and into the intake manifold. However, the intake manifold has passages that dump the gas into the incoming air in the plenum. It mixes with the air and goes to all 8 cylinders.

The air pump runs all the time, either dumping air into the cat or into the exhaust manifolds. On deceleration, its dumping the air out the curved pipe on the "black box" because its not needed on decel. And the horsepower required to turn it might be 2 at the most. Its not as bad as the A/C or the water pump are, for sure.

I forget the reason, but you should keep the PCV system on fuel injected, computer-controlled cars (other than the smog-legality reason). On non-computer carb cars, you can get away with a breather.

That goingfaster.com site is a joke, its all theory and nothing he wrote has been proven to work in the real world. Ignore it.

 

REALLY! What theory is it based off of? None is the answer!!!!

Everything is backed by data that was taken from different individuals that have done different make-ups of different engines (and I'm referring to the sections based on modding the 305 engine only and not the other parts to the site). All the data is backed by dyno results for every different configuration. None of this is done by the author personally. I have always noticed that people that knock all the info have never actually read it. If you bother to read every individual link you might realize that but since you didn't, you simply p!ss on it. The info provided is no different then that that you find on CHP magazine.

I mean seriously, how can you "theorize" dyno results for different stages of bolt-ons?! You can't. There is lots of garbage on goingfaster.com but not the section pertaining to the build-ups of 305 engines. It's stuff you can do a Google search for and find elsewhere (which I have done) but why when all this info is on there from the get-go.