Catted vs Catless Headers Power Gains differences

[gtengr]

Originally Posted by Jyn

I do not recommend an aftermarket header with a catalytic converter. Besides the power issues, the increased flow (and heat) will wear the converter away much faster. Not sure about the high flow cats manufacturers are using for their parts on the 86 platform, but I've seen them wear away in as little as 2 years on another platform.

True. If I was changing to an aftermarket cat it would have to be an HJS.

[mav1178]

Some misconceptions in this thread...

Same brand same design, catted headers will make slightly less power than stock.

One big thing against catted headers in terms of power gain is packaging. If you want to run a cat in the header, you MUST have it after the pipes merge. This means either very short primary/secondary runners (usually 4 to 1 design) or something that is absurd in terms of piping layout (which inflates cost).

Catless headers don't have this design limitation, so the design can be more focused on longer/smoother tubes with better layout.

[churchx]

Well, even catless headers on twins have difficulties to get THE optimal piping length. Think of designs of longtube headers like Ace's or Nameless'. Former had to tuck extra length in overpipe potion, later - add extra piping bends in front of engine. Underbonnet space clearance SO suck in modern cars. It was much more pleasant to work with older cars (and probably design aftermarket parts for without resorting to different hacks), where there is small engine within spaceous empty space around it, without "wonders" of "lift car to take off wheel and bumper to change light bulb" of modern cars, where engineers played tetris filling all the space.

[vagthomas]

Originally Posted by nikitopo

Yes. This is pretty much what you can expect. You should also use a better air filter. The factory one is pretty restrictive.


It is fine, not many put much faith on the new exhaust manifold because "older is better..." :b

Here is the reference: http://www.ft86club.com/forums/showp...65&postcount=1

Have you installed catted headers?

[nikitopo]

Originally Posted by Jyn

I do not recommend an aftermarket header with a catalytic converter. Besides the power issues, the increased flow (and heat) will wear the converter away much faster. Not sure about the high flow cats manufacturers are using for their parts on the 86 platform, but I've seen them wear away in as little as 2 years on another platform.

This is not valid only for a catted aftermarket header. An aftermarket high quality coilover with have a much smaller life too. Same for other parts. You are paying for performance and you need to have a trade off somewhere else ...

In my opinion, any street legal car should have a catted header. We are not allowed to have a catless header here, but it is not about of what we are allowed or not. It should be about common sense and about not to pollute the atmosphere with poisons. At least not on a city with heavy traffic and people walking around. On a race track and if we are building a dedicated race car is another story. Personally, I am getting very sad when someone installs a catless header and then questions how to cheat the emission controls and pass the car. Finally, the 10-15hp difference between a catted and a catless header is just nonsense.

[steve99]

Car has two cats standard. One in header second larger higher capacity cat in front pipe.


If you leave cat in front pipe or install high flow cat front pipe you still have cat in system.


The primary purpose of the cat in header appears to be to pass an emissions test soon after start-up. Hence the crazy rich mixtures and retarded timing to heat primary cat , during the cold start phase programmed into ecu.


once warmed up the secondary cat is likely the one doing the bulk of the work during normal running.

[vagthomas]

Originally Posted by churchx

StraightOuttaCanadaEh: but most of those 10-15 will come from tune. And catted aftermarket headers are not guaranteed to not get CEL with stock tune, just lessened chances, and also not exactly legal if anything done to stock cats including relocation/replacement with non-stock (which is the case) too. And it costs more then catless. That all makes catted aftermarket headers way less desirable, more expensive, less gains, and not legal too if inspection checks.
Imho better install aftermarket air filter + ecu tune OR go for catless header + ecu tune (with which disable cat readiness checks too for no CELs) leaving 2ndary cat in frontpipe stock. Cheaper/more power/as "legal" as catted aftermarket header. And you get also gains that aftermarket catted one brings, like change to sound (if UEL) with catted one too. About the only thing one has to remember with catless, that it's one of things that rise exhaust loudness, so some louder catbacks may result in too loud result if combined with catless header.

These sound logical.

So, I would summarise proposed set ups as follows:

1) After Market Filter + Stock Headers + ECU Tuning for a gain arnd 10-15 whp

2) After market filter + Catless Headers + ECU Tuning + Stock Front Pipe for a gain of arnd 20-25 whp (even 30 whp if E85)

3) In case of After market filter + Stock header + ECU Tuning + Catless Front Pipe would there be any significant power gains compared to case No1?

Final Question: Which header brand and which catless front pipe brand would you recommend?

[guybo]

It's against federal emissions law to change the position of cats. That's why even on aftermarket catted headers they have the cat in the stock position. It's also illegal to remove cats. These laws are for road-going cars of course. Well technically it's for any cars but that's for a different discussion.

There's a huge difference between OFT tuned stage 1 (with cats, stock exhaust) and OFT stage 2 catless. The car was night and day different on my.... *ahem* "track" car. I don't know if Ecutek does the stage 1 better but with OFT IMHO it's not worth the money unless you are going catless and stage 2.

[churchx]

gyubo: you forgot also bit, that cats can be replaced only with stock cats if one fails. That strikes out legality-wise aftermarket catted exhaust bits too, even if they still have cats in somewhat old place.
------------
vagthomas:
3) there would be gains. But less then from catless header, as primary cat in header is in "worst" place, hurting flow most and dictating worse/less efficient header design.
Main pro of catless front pipe is ability to run with stock ecu tune without throwing CELs, as sensors are upstream prior it.
But then again imho it makes little sense to pay a lot in aftermarket exhaust bolt-on parts and NOT to get tune, getting just part of possible gains from upgrades, so that "gain" is of less importance.

From catless frontpipes these seemed interesting to me:
Fujitsubo one with dual resonators. LOL, it even makes impression like having cat, has extra port for sensors, and resonators may help with enhancing sound/dealing with drone.
Or Nameless one with integrated overpipe.
But if i'd be willing to do anything to any of stock cats, my primary choice would be catless header + stock frontpipe.

From headers i'd consider these:
Ace Type A/350 (CS400 if RHD country/car) with DT tune for supposedly best gains
OFT+OFH for nice package
Groupe-S for budget catless header
JDL or Tomei for a bit more expensive ones
For track-only car Ace anaconda or /150/250 or PTuning

Catted header, JDL or FT86SF

[nikitopo]

Originally Posted by steve99

Car has two cats standard. One in header second larger higher capacity cat in front pipe.

Where did you find that the second has larger capacity? I think that the first one in header has 500 cells and aftermarket catted headers have usually 200 or 100 cells (?)

[Jyn]

Originally Posted by nikitopo

It should be about common sense and about not to pollute the atmosphere with poisons.

So then go complain at all of the forced induction section of this thread.

Complain at people that run aftermarket tunes that increase gas consumption, and similarly, CO2 emissions.

Why are people not all driving Teslas and hybrid cars?


A HFC in the front pipe and removing the very-restrictive header cat. converter is a much preferable compromise than just running straight piped from the header-back.

[Jyn]

I can't believe I'm reading concerns about "modifying your exhaust system is illegal" on a forum dedicated to a sports car in a section about modifying components of your car... I'm so confused.

[Summerwolf]

Originally Posted by Jyn

I can't believe I'm reading concerns about "modifying your exhaust system is illegal" on a forum dedicated to a sports car in a section about modifying components of your car... I'm so confused.

Same reason a topic on HID install goes into the ethical ramifications of doing an HID install.

[Detroiter]

Originally Posted by Jyn

I can't believe I'm reading concerns about "modifying your exhaust system is illegal" on a forum dedicated to a sports car in a section about modifying components of your car... I'm so confused.

I've always felt the same way when people bring up emissions on a sports car forum. It just doesn't really make any sense. I get the whole wanting to not pollute the environment and am actually somewhat of a "tree hugger" in that sense.

But I don't think people realize that if you combine every single sports car enthusiast on the planet and take into account that MAYBE half of them run a catless car the amount of emissions comparable to the rest of the world's cars, semi trucks, trains, freight ships, power plants, military equipment, ect... is so small that it would be hardly noticeable to change it to everyone running a full catted setup.

http://www.enfos.com/blog/2015/06/23...-million-cars/
There are plenty of articles about this and completely proves that sports cars are in no way the problem.

So i say to all the car enthusiasts out there, if your area does not do emissions testing, don't worry about running catless