Blevinator

On my last ride, you could really smell gas. Car had longtubes with no cats.
Shop told me that it was because cats werent present. The smell was very STRONG.Would burn your eyes with the garage door closed! In speaking with one of the forum vendors, I find that the tune was too rich, and you shouldnt smell gas if tuned right, even with no cats.
Someone with headers and no cats please chime in!
Thanks

DaytonaFIC6

your car may be running rich but you will have some smell without having cats. I would not describe it as gas though, more of a 60's muscle car smell un catalyzed exhaust smell. It is hard to tell without smelling it for myself.

Blevinator

This smelled like gas out of a lawnmower can...definitely gas

cell6ida

Did you get a dyno tune to make sure your gas/air ratio is correct? If not you definelty need to. This will also give you more power.

One thing might also want to consider is using a hi-flow cat. convertor. This should block some of the exhaust fumes, but not all. Kinda of like a halfway step between stock cats and no cats.

I have cam, Lt headers, and hi-flow cats...and the smell is definetly richer than when it was stock....but more like a metallic/gas smell rather than straight gas (if there is such a thing as a metallic smell...that's the best way I know how to describe it...comming from a NON-MECHANIC) .

BSSN

Yes.

02magred

Yes you will smell fumes without cats you also smell some fumes with High flow cats.

That the nature of the beast.
and yes with a tune you may have a little less smell.

Like the other member wrote thats the muscle car smell.

Mike V.

Sorry but it's one of the big set backs to goin' w/o. For a very unscientific explaination, one of the things Cats do is burn off unignited fuel (that's one of the reasons they get so hot). So buy removing them there ya go. The thing is, w/ the new hi-flow cats on the mkt unless your racing the car (all the time) for the street there's just not enough gain to run w/o.

tomiboy

NOSZ06

I find some fuels have less odor..... I mix VP MS109 with pump fuel 50/50 ratio resulting less gas odor.

The more VP the less the odor.

BP , Shell, Chevron are my choices to mix.

NO CATS = FUEL SMELL

Mike V.

I know this has nothing to do the OP but ARE YOU ACTUALLY RECOMMENDING THE USE OF BP PRODUCT? 1ST ON THE LIST NO LESS, WOW!

BETWEEN NO CATS AND RECOMMENDING BP YOU GUYS ARE TRUE ENVIRONMENTALISTS!

I'm hardly a tree hugger, but sometimes a little thought may be worth while.

Streetk14

Yeah, and from the testing I've seen a set of good high-flow cats doesn't hurt power at all or a very minimal amount. I still get some race car fumes when my car is cold (cammed LS3 w/LG super-pros and metal matrix cats), but after the cats get a chance to warm up they do their job.

I'm in no way an environmentalist hippie, in fact, I want to run every Prius I see off the road . But I see no reason not to run cats on a street car. With a decent size cam, the fumes without cats cam get pretty bad. Almost like driving my '68 Camaro with it's 242/248 roller cam. My girlfriend could always tell when I had been driving it.

Oh, and it is not normal to smell raw fuel out the exhaust without cats. Non-catalyzed exhaust odor and fuel are 2 different things. If you are smelling fuel, it is not running right.

Andy

FloydSummerOf68

Not all cars will have a gas smell without cats.

Some do, some don't. I have ridden in 5-6 cars without cats and none had a smell of gas, while at the same time I have ridden in several that did.

My car has absolutely no smell of gas from behind the car or inside the cabin after tuning.

NormWild

You should not have a raw gas smell IMO, a stale gas smell is normal and I get it mostly under compression. I have F/I as well so I am running a lot of fuel. I would get a tune and see where your A/F is at.

3 Z06ZR1

Nice post! No cats is not for me or the street.

0Anthony @ LGMotorsports

Depends on the engine setup. The GrandAm car has to run a pretty much stock LS6 crate engine, and it does not have cats on it. I can stand by it in the shop and yes you smell it but it isn't burning your eyes bad.

Now take a big cam with a lot of overlap, at a low idle and they can be very bad. Even with cats on the car you might still smell it. Good tune or not.

Of course with any car...depends on the tune.

wbear

Correct. If you consider less heat in the tunnel, no rear O2 sensors or wires to mess with, $60 saved on not having to buy the rear wire extensions and $500 to $600 saved on not buying the cats to be no gain.

Bill Dearborn

Remembering when cars did not have cats if you had a gas smell and it seemed like you could light a match and set the air on fire the car was running too rich. I see a lot of old muscle cars at car meets that are obviously not tuned correctly. They didn't smell that way when they were new unless some dork screwed them up. If you had an acrid nose/eye burning stinging smell the car was running way lean or you had a vacuum leak (lean).

Bill

ltrz

I took the 98 vert out for a spin today and put it back into the garage. A few hours later the garage smells like raw gas? I checked under the hood and under the car, and seen no signs of gasoline. There was no odor inside the car, as it was closed up. This same problem happend one other time but not all the time I use it. I have not filled the tank in over a week. Any ideas??

gtmotor

Sounds like a faulty evap system.

You should get a check engine light reporting (approximately) where it's leaking from...

To the original post: Yes... cars without cats STINK!

zoomz

I deleted the factory cats on my 99 c5 and picked up 25hp on the dyno but one of the last times i drove the car before selling it i got stuck in stop and go traffic on the way to meet a client for lunch .

The car started getting hot so i turned the AC off in 98 degree Florida heat and every traffic light i hit , the wind was blowing the wrong way and filling the cabin with "that smell" .

By the time i got to the meeting i stunk so bad i offended everyone at the table including myself and had to explain it away and deal with my clothes stinking for the rest of the meeting .

I will never take the cats off a Daily Driver car ever again .