Sorry, first, I should have been clearer that pipe length is A factor .... there are others ......

Books have been written on this ... but engineers have figured out some clever things to do with both intake and exhaust systems.

First, both systems are trying to flow gases as efficiently as possible .... and in both systems you aren't dealing with a totally smooth flow .... both on the intake and exhaust systems you are dealing with "pulses" of gas flow. You can use these pulses to improve the filling of the cylinder with it intake charge .....

A simple example .... you know the idea of valve overlap ... that period where the intake and exhaust valves are open at the same time ..... and during that time the "momentum" of both the intake gases and the exhaust gases will help pull the intake charge through the cylinder often so much so that some intake charge flows through into the exhaust .... in fact a well designed cam and intake can allow the intake charge to continue to flow into the cylinder while the piston is starting the compression stroke. Suppose the exhaust valve was also still open ... and a "pulse" of exhaust pressure from another cylinder exhausting at that moment is used to push intake gases that had been pulled through into the exhaust back into the cylinder through the exhaust valve ...... I'm "pushing" intake gases into the cylinders through BOTH valves !!! Neat trick ... huh ???

In the NASCAR example, think of that exhaust pipe as being a series of high and then low pressure "pulses" travelling down the pipe .... when a pulse leaves the end of the pipe, it actually "pulls" or "affects" the pulses behind it ..... think of it as a "vibration" that affects the gases all the way back to the exhaust valve, and engineers can use that vibration to better purge and fill the cylinder, just as they use the "vibration" of the intake gases (see the "runners" in your intake manifold ... they have a "tuned" length also) to assist in getting the most charge possible into a cylinder.

Bottom line .... an exhaust system is not just a bunch of pipes and mufflers/cats to "dump" the exhaust gases out the back of the car .... it has a dirrect effect on your engines performance, just as changing the intake manifold can affect your engines performance.

You want to look for a "system" that has been engineered to improve performance. The folks that do the "I'll get headers from A, an X pipe from B and mufflers from C" aren't doing themselves any favors ... it is probably luck if they haven't hurt the performance of the car or ended up even with the stock system. Take a look at the claims of the vendors, but the stock system isn't bad. Chevy spent a lot of engineering time on it ... not to mention the money invested in the Z06 titanium system ..... I wonder how many third party vendors have done the same.

 

Ummmm, doesn't the STS rear mount turbo system have turbos after the cats? So couldn't the internals of the cats damage the turbos if they fell apart?

 

Yes.

That was the point nickolbag was making.
It had nothing to do with exhaust backpressure, tuned mufflers, valve overlap,etc.
Maybe not directly related to the topic, but that was his point.
Thank goodness someone else understood this.

 

It was mostly directed to somebody calling anybody that takes the cats off their cars an idiot. Probably should have quoted post 19 instead of the other 2 posts I quoted. Ooops. I waas just stating that some people have real resons for doing it so I wouldn't call them an idiot. My reason.........just for sound.

 

Gotcha.
I'd be afraid of running cats too, if I had a rear mount setup.

 

 

Sure, you'd probably damage the turbo if the cats fell apart ... but you'd also damage the turbo if the oil lines that have to run from the engine to the turbo and back to the engine sprung a leak ... and you'd probably destroy the engine too in that scenario .....

The Squires system is non-OEM .... but also has virtually no effect on the exhaust ... it is one of the few turbo systems that has a CARB E.O. issued for it ... (D-593-1) I kinda doubt it is "hurting" the cats if it has an E.O. .....

Smog legal turbo ... see ... it can be done ......

 

Look dammit. I'm not trying to argue with arrogant fools who believe everything their computer tuners tell them. I know I can use an offroad pipe W/O cats and TUNE out the O2s. Maybe I will do that eventually. This is my first time using a fuel injected setup with an OBD system and all that BTW. Everything I have previously built has been carbed. This car will be carbed one day too I would imagine, I have already looked into the conversion manifold. My original question was where to find MIL ELIMINATORS. I can't BELIEVE how many people have attacked me and think that it is their way or the highway. This is outrageous. I guess everyone is supposed to mod their cars the SAME way huh? Way to take the fun out of it guys! I didn't ask where to tune my car on a dyno. I didn't ask if it was illegal. I didn't ask your opinion on what I was doing. I didn't ask if you think I'm too young to know what I was talking about. I know what I know and who I am. Don't worry about what I'm doing. If anyone has a set of MILs please PM me.

Thank you,
Will Cochrane

 

Well if you are going to take a major step back and put carbs on because that is what you know then you are really in for an education!

 

Go back to post #7 ..... I already showed you that the "MIL eliminators" don't exist anymore .... here's the link again .......

http://www.usdoj.gov/opa/pr/2007/July/07_enrd_490.html

This isn't my opinion ... it is the answer to your question ..... other people have tried to explain to you that the ONLY answer today is to "tune out" the rear HO2S ......

The fact you don't like the answers is your problem .... when you have matured enough to understand that just because you aren't getting the answer you seem to expect doesn't make everyone here a jerk.

Since you know that you can find a "MIL eliminator" and that you can build a better engine with a carb instead of a computer .... you tell us the answers ..... apparently you don't like ours.

 

Dude, you are feeding the "beasts" here. Corvette owners in general (and the newer the generation / model year the more applicable this is) are typically more mature (mentally) and educated (i.e. not everyone has a job allowing them to afford these cars).

No, that doesn't mean everyone on this forum is the 75 year old guy in the fast lane doing 45MPH that doesn't understand perfomance; we have 8 second street leagal cars rolling around on this forum. What is DOES mean however is the majority of folks on the CF are not particularly interested in assisting you in an illegal, (not really an issue for most of us - we aren't hall room monitors) very bad for the environment modification that yields little (if any) performance gains.

There is a wide margin between "growing daisies out of your exhaust" and intentionally adding to the already poor air quality found in most parts of this country. Think of it this way; it's like a smoker barging into your home and stinking up the place (no offence to all those smokers out there :0 ) and you can't do anything about it. In your particular case, I would be careful about posting your real first and last name; you never know who you might **** off, and the next thing you know you have some government agency hassling you about your car.

On your comments about fuel injected, computer controlled cars; that is THE reason to buy a vehicle like the C5. You can literally get away with murder, have your cake and eat it too. Definitely going backwards in a big way by dumping the technology you have for a carbureted car. No contest. Hell, the issue you are posting about is a prime example; with tuning SW that you can own it takes less than 5 mins to edit out the rear 02 codes and BAM, you are back to being "legal" as far as the government is concerned. All from the comfort of your laptop - it doesn't get any better than this.

My suggestion; surf on over to LS1Tech.com - lot's of knowledgeable folks over there, the motors are for the most part identical between Camaro's and C5's. If you can't get the feedback you are looking for on LS1Tech it doesn't exist.

 

Another point to consider. In NJ, when the state inspection is done on OBD II cars, the machine plugs into the diagnostic port and sends the info directly to Trenton. Without cats on your car, I seriously doubt you will find someone to inspect it when the time comes. A friend of mine does state inspections at his shop and won't touch any car that is blatantly illegal. He doesn't want to lose his license and be fined for your tampering. Also, you might not be aware but NJ has random road side emission testing vehicles that use road side sniffers. If you should be lucky enough to get caught by one, they will impound your car on the spot. Good luck!

And all this for 3 hp? Go on a diet (you or your car) and you can make up the difference.

 

I think that kinda stuff is in north jersey, I have never seen such a thing down here. And I weigh 150 soaking wet lol.

Listen people. I am not trying to stir up trouble. I didn't think I would meet this kind of resistance. Not among american car owners. Maybe a BMW forum or something, but come on. What happened to the MUSCLE CAR guys? Just not the crowd I expected... And I understand now that MILs are not sold anymore. OK. Maybe someone has a set around not being used. And for the record, it's not your answers I don't like, its the way you are giving them. Not all of you, but some. It's rude and not very welcoming to this forum...

 

take them off and get a tune. and u are good to go.

i had mine off for 3-4 years. had 02 sims for a while but then my tuner tuned it out.

do what u want to do.. dont not do it cause of some tree huggers on here. there is a smell. its a FUEL smell its nothing bad. if u have ever been around fast cars you know the smell well.. i bet its more then 3hp on the big cube and fi setups...

 

Don't cry.

 

THANK YOU

 

I am a muscle car guy,,I only get 1 corvette magazine,,spend more time in Car Craft and Chevy High Performance Mags! That IS where I learned about the futility of going cat-less.They are the ones who have printed dyno results showing no appreciable gain with out cats! The guys here (for the most part) try to pass along information from experience. You kind of lit your own fire when you shot back some rather smart *** reply s.When that happens here on the forum it usually results in just what you got here! It's a fact of life now that with the fed and state smog police out there you are sooner or later have to wise up if you want to run your car on the street.I've had to work like hell to keep my 69 bb on the street but you do what you have to do. Your car ,,your choice,,But if you ask questions,,don't take shots at the answers unless you can take the heat it creates!

 

I sliced my cats open, gutted them and then TIG welded them back shut. Didnt do anything else. Car runs better with out the restrictive POS's on there. The earth recovered from the volcano eruptions its had, i doubt our catless cars are going to do anything..

 

Dude, a couple of the guys can be a little caustic, but they are giving you great info. Taking the cats off is more work and money than its worth. The reality is the idea of "cats = bad" should have died out a long time ago, they are not really a big deal now. You can get more HP by taking your muffler off, which I wouldn't do but thats my opinion. A lot more if you get a good tune, or a LT header system, CAI intake and the list goes on.

The MUSCLE CAR guys are making mods that make real HP, not just taking stuff off their cars and thinking they did something good. The reality is these engines make more hp per ci than the muscle cars of old, and it takes more knowledge to add hp to them than it did back in the day. They are also tuning the the @#%! out of their cars, if you don't know what you can do with a computer tune, then you are missing out on a LOT of power. What these things can do is so far a head of carbs its not funny.

If you love sound, one of the best mods that I've done is getting ported heads with larger exhaust valves. It makes the exhaust sound so much deeper, its great. I almost hated the way the LTs changed the sound, loud but had a sharp tinny sound with the stock heads Now with the new heads it sounds just plain mean.
Now thats MUSCLE CAR.

Not sure why your clinging to the idea of taking the cats off and O2 sims, or even carbs

Good luck with the idea you know better than everyone else...

 

Absolutely in my plans. I am currently searching for a set of used LS1 heads. My buddy's cfm numbers are pretty amazing with LS1 heads he's ported. I'd like to buy a used set to save me the down time. Does anyone know offhand how big of an intake valve we can get away with without block work??