Will removing cats add noticable power

You will get increased throttle response, a little better noise, and likely some power improvment. Maybe in the 10hp range on a 308?

Check your local laws first.

 

Exactly what I have seen too.

 

Sounds about right to me. Much smoother low end.
BT

 

I have a '79 catless 308 w/ an Ansa. Exactly what the others said including great sound.

 

A "little noise?"

Your car will be loud and mean!

I noticed that the car revs much more freely. I haven't noticed a power difference, but then again I don't ever notice power increases.

 

My old headers are for sale on this message board if you want to get rid of your cat's.

http://www.ferrarichat.com/ferrariads/showproduct.php?product=614&sort=1&cat=13&page=1

I added a Stebro with my new headers.Very nice sound, very free flowing, reasonably priced. the Knock on stebro is the look, it is delivered in raw stainless. You could spend an afternoon polishing or send to jet-hot and for $90.00 they put a ceramic coating on that resembles chrome. see my ad the headers in the ad have been coated.

sound file:
http://media.putfile.com/308-ferrari-stebro

 

Sweet video.

Did the same on my 911 by putting a cat bypass pipe and saw a big difference, those older cats are marginale after 25 years...
Then went nuts and by-passed the muffler all together the neighbors love it...looks nice at night with the blue flames and all.
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One other thing to keep in mind. It will REALLY increase the smell of exhaust all around and in your car. I mean burn your eyes stink. You may or may not be able to tolerate it. Around town it can be a little much but on the highway it's fine.
It gets in your clothes too.

 

Dr. Tom, sure you don't have a gas leak? Removed the cats and added a Stebro on my 3.2QV and it's a clean set up with minimal emissions and absolutely no fuel odor. Running rich? any coughing? sputtering? that sort of thing?

 

Have the same prob with mine. Have to pull it out of the garage when it is warming up or my clothes stink of exhaust fumes for the rest of the day..

 

You are 100% correct thats what I found to be the downside with the Tubi/Hyperflow arrangement you can smell it for hours after you get out the car specialluy as its a spider.

 

I don't really notice any smell in my 348 without the cats.
BT

 

I hope not. It's done that for about 8 years now without any drivability problems. Just smells really strong. Sounds like others have had the same experience so I am probably safe from a gas leak.
The CO is spot on too.

 

Kept the stock muffler (for now), removed the cats and rejetted the extremely lean factory carbs on my '78. Feels like more than 10hp gain, but the real difference is in throttle response.

I also added the individual K&N filters, but more for the look and sound more than the power (seems to be a bit more power in cold weather, a bit less in warm)

I also have a bit of a gas smell, but I think I went just a tad too rich on the carbs. Haven't put my gas meter on it....

Bill

 

I do not notice any significant smell either. IMO the car is running leaner with the stebro over factory (still rich, but leaner)

 

GREAT video! That sounds absolutely fantastic. How many rpm's were you turning when you shifted?

 

Not sure of the effect on a carbed car. However, a few years ago when I had a QV, I removed the CAT and added a test pipe. Before and after dyno's were within 1hp and 1ft.lbs throughout the whole range. However, the burning eyeballs at a stoplight and the extra reasonance did not make it worthwhile. My exhaust stayed original so freeing that up could have potentially made more HP.

 

6200-6500 (guessing)

 

Did the ANSA sport exhaust with no cats on my Mondial QV last spring (it's a Euro, so no cats anyway), and noticed a seat of the pants feel in performance. Of course the baffles in the old exhaust had collapsed and were causing problems with the engine with back pressure, so just putting a new exhaust on may have done it anyway. Love the sound. And yes, I have to pull the car out of the garage to warm it up or it makes the house stink.

 

The exhaust of a 308 without cats should not water your eyes. If it’s that bad it’s too darn rich. A trip to the Sun exhaust analyzer and a little trial and error with the mixture adjustment got my ‘83 idling and running smooth with just a moderate smell. It may still be a bit strong for warming up in the garage, but it’s not really safe to do that anyway.

 

John,
I don't mean to sound dumb, but where/how do you adjust mixture on these injected cars?

 

Not dumb at all. My ’83 is US spec; that’s all I can speak for. From the back of the car, there’s a half-moon cutout in the left edge of the air box cover about 3 inches from the rear of the box. Directly below that cutout, about 4 inches down, is the “air mixture adjustment screw” on the FI unit. It's in the 3 o'clock position on the unit. On US cars (and maybe all) the factory covered it with a cap, but it can be pried off. In the owner’s manual it’s shown on page 69 figure 61 item A. Small increments of adjustment are necessary – you don’t want it so lean it stumbles, or even worse burns a valve.