Why does everbody think that i will loose power if i remove the cats. Does anybody have a before and after test to prove this, and what year truck was it on? I know the 01 have a little better intake so i was thinking that it would flow more air hence the need to remove the cats for more flow. I put on JBA headers and the assometer felt it. Very suttle but i still felt it. I am also going to use N2O so the more flow the better i would think. Thanks

 

The only reason removing cats would affect your truck negatively would be the following reasons:

1. Your computer is OBDII, and as such needs O2's aft cats to be in the "performance mode" this should be easily defeatable through O2 sims.

2. You probably wont pass inspection/emissions without a special chip.

If someone tells you that the motor needs back pressure, then they are FOS. In fact, let me make a quote out of GM high tech, september, 2001:

In an interview with Judson Massengill

"...anybody that tells you an engine requires backpressure from the muffler to make power is probably trying to pedal an inefficient muffler. There is no such thing as too much muffler flow but there sure is a problem with too little."

Now, this statement is about mufflers, but the backpressure effect remains the same with cats. Less flow.

 

Well let me state this from my personnel experience's with my truck.

I first had a complete bassani kit on the truck, I ran a 12.7 the one weekend.

the following week I took off my cats and replace with dynomax bullet race mufflers (allot more flow over the cats). My truck went 12.9's all day. Now the temps where almost the same, the Humidity was about the same, and the BP was about the same as the 12.7 runs. So what was different on the truck. I have no cats now. Well that would make me think that I lost some power from running with out cats huh!

 

I wonder if that statement is meant for N/A vs. Blower?

 

That statement was for Gen 2 lightnings 99svt. Do you have cats on your truck 99?

 

I took the cats of my 99. The best I ever ran was a 13.51 with the cats.
I cut them off and the slowest I ever ran was a 13.44 with the same mods at the same track. the best was a 13.33.
My mods have all changed but the cats are still off.

 

If someone tells you that the motor needs back pressure, then they are FOS. In fact, let me make a quote out of GM high tech, september, 2001: In an interview with Judson Massengill

"...anybody that tells you an engine requires backpressure from the muffler to make power is probably trying to pedal an inefficient muffler. There is no such thing as too much muffler flow but there sure is a problem with too little."

well, no offense, but I couldn't give a rats *** what somebody from GM high tech thinks about anything, much less my Ford truck.

Secondly, if this is true, they why even bother with an exhaust system at all? just rip it all off and let the exhaust dump right out of your cylinder head exhaust ports, don't even bother with manifolds (or headers). aside from the fact that it is noisey of course, you will loose gobs of power. try even with open headers, you will loose torque, try it if you think I'm wrong and let us know what you find out.

P.S. my 01 runs consistant 13.25-13.30 with everything bone stock except for a superchip from JDM. yes my air filter is stock too.

P.S.S. honestly, though, if you like the sound and you won't have law problems then go for it, but don't expect HP (and especially Torque) gains from losing your cats.

later,
chris

 

Go ahead, remove them. You WILL lose torque.

 

Tried removing the cats last year and seemed to lose about half a 10th,but the jury is still out on straight pipes.

 

Terrific attitude....Besides what do GM engineers know? GM only hires engineers from "University of GM"...they'd be lucky to get a graduate from the University of Ford (think they'll win the NCAA tournament this year? ). Besides they're not familiar w/ that "special" kind of engine design the Ford uses...you know the "internal combustion" engine.

Exhaust manifolds are designed as "Vacuum" cleaner of sorts. They literally help vacuum spent gases from the exhaust chamber, with the use of high pressure/low pressure and Temperature physics. They scavenge off the exhaust. So your exhaust system does more than "quiet" the engine.

They also help prevent damage to the valve train. Ever drop a cold marbel in boiling water....it'll crack. The same will happen to your valves. That's why exhaust leaks around the manifold can be extremely harmful (if severe enuff). Cold air will rush in due to the high vacuum pressures between cylinder pulses and crack the valves due to the extreme temp. variations.

Your headers/Catback act as a linear cooling device. As the exhaust travels down the length of the header it slowly cools. This prevents a sudden and immediate temp change. A sudden air temp change will form a Cork...(ie. Backpressure) in your exhaust system (cold air high pressure/Warm air: low pressure).

I don't know enuff about Fords Catalytics to comment on their efficiency.....however I wonder if Top fuel dragsters use cats? Based on the logic from this thread.....they're obviously loosing gobs of torque by omitting them.

Have a nice day, everyone.

 

Now that was funny.

 

I'm not an engineer by any degree but I will tell you that based on my personal experience, that statement is false in most cases. There is no doubt that running a stock exhaust say on an older fox Mustang with aluminum heads and other goddies is going to be a restriction and would benefit from a free flowing muffler but run that car open header and watch your torque go out the pipes. A small amount of backpressure allows for more scavenging and produces more torque. Of course we are talking about a supercharged Lightning so the rules are slightly different since the air is forced in the engine and doesn't rely on filling the cylinder naturally. Same with any turbocharged vehicle, you need the least restrictive exhaust possible.

As for the question at hand, in my opinion, it would not be worth the hassle removing the cats. Many have seen minimal gains (from what I have been reading) by changing exhaust parts. Save the $$ and get another mod. That is one of the great things about message boards, you get to aquire knowledge from people who have been there and done that. I have spent thousands of dollars on parts (Mustang) that supposedly gave me so much hp against the advise of others to see that I gained nothing and probably lost power. Stupid me, but it's all part of the game, some stuff works, some doesn't.

sorry for the ramble, I'm bored