Cats or no Cats

[oxwhite03vert]

I'm sure that this subject has been beaten to death, but a search didn't turn up much. I've got an '87 GT with stock headers, off-road H and old, old, OLD Flowmasters on the stock piping. I've been looking at other members cars only to notice that almost nobody has cats on their exhaust setup. How do you guys get away with it? I have been told by one of our city's finest that it's a $1000 fine for the first time you are caught without cats. After that you will not be able to register your car until it is fixed.

I want my car to be legal, but I don't want to put that old crappy H back on the car. Should I go with a Catted X or H? I want longtubes and I plan on using GT tailpipes with the turndowns at the end.

Any help is greatly appreciated.

 

[Fishhawk]

I'm sure that this subject has been beaten to death, but a search didn't turn up much. I've got an '87 GT with stock headers, off-road H and old, old, OLD Flowmasters on the stock piping. I've been looking at other members cars only to notice that almost nobody has cats on their exhaust setup. How do you guys get away with it? I have been told by one of our city's finest that it's a $1000 fine for the first time you are caught without cats. After that you will not be able to register your car until it is fixed.

I want my car to be legal, but I don't want to put that old crappy H back on the car. Should I go with a Catted X or H? I want longtubes and I plan on using GT tailpipes with the turndowns at the end.

Any help is greatly appreciated.

It all depends on if you have to have a smog test every year. When I lived in Chicago I needed the cats, I moved to a county in N/W Indiana that does not test and I am pulling them in favor of an off road X-pipe. It also depends on if the police in your area are tight a$$ed. If your car is loud it may give them a reason to pull you over and take a look at your exhaust to see if you have Cats, otherwise I think they have better things to do then check peoples exhaust systems.

 

[crazypete]

Cut the heatshields off your old pipe and have someone weld them to the new pipe. Instant fake cats for hardass cops to see. But honestly, in smogachussetts with longtubes, mac prochamber and flowmasters, nobody has bothered me or even asked. One cop even gave me a smile and a nod. ????

I think the key is to act responsibly. If you do stuff that makes them want to kick your @ss then they will look under the car to find a reason. If you are not barreling at 45 mph down your 25 mph street then chances are they wont bother you. Big gigantic hood scoops, cowl hoods , rally stickers, keep em spinnings, smurf headlights and bling will greatly increase your chance of getting harassed. Keep it clean, drive responsibly, nobody will ever bother you.

When inspection time comes, go around a few shops, find someone open minded. Have them do some work for you, couple hundred bucks to establish yourself as a good customer (alignment, oilchange, whatever) then take it there for inspection. Amazing how often they will forget to look underneath.

 

[oxwhite03vert]

don't your cars stink though? I hate to sit very long at a redlight for fear that I may kill an innocent bystander with some 93 octane perfume.

 

[crazypete]

Yeah it does....

A big fat ignition system and indexed plugs will help burn more before it leaves the chamber.

Why do you run 93? Do you have detonation or pinging? 87 is the way to go (if you can take it). Better power and cheaper. Burns easier. Just a side note.

Longtubes make the best numbers but boy oh boy are they a pain to install. I recommend the mac prochamber midpipe if you do go the longtubes route. Wonderful BB sound. GGGGGGGGGGGROOOOAR!

 

[Fishhawk]

Yeah it does....

A big fat ignition system and indexed plugs will help burn more before it leaves the chamber.

Why do you run 93? Do you have detonation or pinging? 87 is the way to go (if you can take it). Better power and cheaper. Burns easier. Just a side note.

Longtubes make the best numbers but boy oh boy are they a pain to install. I recommend the mac prochamber midpipe if you do go the longtubes route. Wonderful BB sound. GGGGGGGGGGGROOOOAR!

Better power with less octane? Thats news to me.

 

[Fishhawk]

don't your cars stink though? I hate to sit very long at a redlight for fear that I may kill an innocent bystander with some 93 octane perfume.

Very smelly. I have a Magnaflow X-pipe W/Cats and it smells like a combination of gun powder and rotten eggs. Hopefully I'll get rid of that with the off-road X I'm putting on next week.

 

[TheUser]

Better power with less octane? Thats news to me.

There was a post a couple weeks/months ago about this. Michael Yount went into details about it, so you might try to look that up. Basically, the lower the octane, the easier the gas is to burn, which is why you get higher octane gas if you have detonation/preignition or high compression

You should get the best performance with the lowest octane fuel that you can run without experiencing detonation because it's easier to burn...another benefit is it's cheaper

I'm going through this issue w/ my LX 5.0 right now. I need to replace the mid-pipe, but I'm not sure if I want to go w/ an off-road H or a catted version. I don't mind the cats (high flow cats only lose a 2-5 hp generally), but I have to get all of the smog tubing back, which is my main thing. Also, you could buy a hi-flow h/x pipe used and save some $$$.

 

[MrKwik]

Most cops arent going to get on their hands and knees to look under your car unless their donut rolled under there so I wouldnt worry about it too much. I also think that that in most states they can only fine you if they can prove you REMOVED them, not just that you dont have them. Could be wrong on that but I think thats how it is in Kansas anyway. Of course if you live in an inspection state, thats something else altogether.

 

[Fishhawk]

 

[Fishhawk]

There was a post a couple weeks/months ago about this. Michael Yount went into details about it, so you might try to look that up. Basically, the lower the octane, the easier the gas is to burn, which is why you get higher octane gas if you have detonation/preignition or high compression

You should get the best performance with the lowest octane fuel that you can run without experiencing detonation because it's easier to burn...another benefit is it's cheaper

I'm going through this issue w/ my LX 5.0 right now. I need to replace the mid-pipe, but I'm not sure if I want to go w/ an off-road H or a catted version. I don't mind the cats (high flow cats only lose a 2-5 hp generally), but I have to get all of the smog tubing back, which is my main thing. Also, you could buy a hi-flow h/x pipe used and save some $$$.

If thats the case then why is there 105 racing fuel?

 

[dstanggt50]

If you can afford it, I would get cats anyway, I used to live in TX where I knew someone to pass me, now that I've moved, I don't know anyone, and probably going to have to buy a shortie catted x or h pipe for my longtubes.

 

[Foxfan88]

for higher output motors, that have really high compression pistons, they need that octane fuel.

 

[Fishhawk]

for higher output motors, that have really high compression pistons, they need that octane fuel.

But street cars (without cats) make more power with racing fuel also. It also is my experience that you will get better gas mileage with 93 octane then with 87. I've proven this time and time again with all my street cars and trucks that I've owned throughout the years. The 460ci. F-350 I currently own being the most obvious. If I run 87 I can't get anything better then 11 MPG. I run 93 and I will get 13. That only means one thing. Higher octane, better power.

 

[crazypete]

Higher octane fuel is necessary if you have really high compression in your motor. A lower compression fuel will ignite on its own without sparkplug input from the increased heat of sudden compression of the mixture. A slower burning fuel will make it to the spark point and follow your engine's timing.

 

[crazypete]

So by burning less fuel and ejecting more in the exhaust, you get better milage? Maybe it's the computer's knock sensing advancing the timing to a high advance due to the higher octane getting the extra milage. I heard EEC's do that.

But the extra cost of 93 vs 87 outweighs the extra milage gained.

 

[89CopCoupe]

The fuel rating (87,93 etc) is a rating given fuel based on that particular grade of fuels tendency to combust/ignite when compressed .... a lower grade (number) will combust more easily than higher grades when compressed ...

When you up the static compression in an engine, you must use a higher grade to keep the fuel from detonating prior to the desired time.

Advancing the timing too far gives this same effect.

Like Pete said, run the lowest grade you can get away with

 

[TheUser]

If thats the case then why is there 105 racing fuel?

the same reason there's JET fuel...it's for Jets. Racing fuel is for race motors, which typically have higher compression and/or advanced timing. You do what you think is best for you; just trying to relay some information.

 

[super302]

Most cops arent going to get on their hands and knees to look under your car unless their donut rolled under there