>do my own cams, headers, tranny swaps you name it >still

>>14848834
All I know is that when a Cat goes bad your gas mileage goes to shit. Or when you blow an O2 sensor, your gas mileage goes to shit and then you burn out your cat.

>>14848834
Feeds your exhaust through a filter that converts the chemicals in it to less harmful ones without getting used up.

It also throttles your exhaust like a motherfucker and if you actually have them intact on a performance car you're a faggot.

>>14848855
I know high flow cat or decatting helps make turbo cars produce more power, but does it also do the same for NA?

Is it a solid performance gain?

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>>14848834
Basically, your cat platinum alloy-clad mesh, or honeycomb structure.

What happens is the platinum metal is a surface that lowers the activation energy needed for the reactions that turn some of what CO and NOx are in the exhaust into water, CO2, and N2 gas. Essentially, the temperature of the exhaust gas isn't high enough for these reactions to happen spontaneously. When the gas passes over the platinum, though, the surface of the platinum allows for the processes needed for the alteration to take place at a lower temperature.

>>14848918
An engine is an air pump, N/A or F/I. Get a high-flow.

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ITT: if typing your post into Google instead of 4chinz produces an answer, you suck your boyfriend's cock twice instead of once.

>>14849074
Thanks. How much can i expect a high flow cat to give?

Basically the honeycomb structures get super heated by exhaust gases and evaporate most of the unburnt fuel.

Contrary to popular bullshit deleting cats actually has fuck all gain on hp because most high flow cats dont restrict the exhaust system anymore.

They should be a mandatory requirement for every car even pre cat cars should run them.

Catalytic converters make your car less powerful and less fuel efficient to make liberals feel good about shitting up your life.

>>14849101

No, they catalyse exhaust gases.

If fuel is getting into the converter, the temperature will climb and the exhaust will smell like rotten egg sewer ass.

>>14849118
>What is a modern diesel
Lewl

>>14849118
>>14849101
Wait, so cat converter deletes are what makes that popping sound from the exhaust whenever a performance car is slowing down? Like backfire

>>14849087
Not a lot, but it can be a bit of a bottleneck. If you're working over your exhaust system you owe yourself a high flow cat or cats.

>>14849127
Will still do it with cats, the muffler design makes a bigger difference, and exhaust length.

>>14849127
no just makes your car loud as shit not backfires backfires in performance vehicles are 9.9/10 times anti lag systems for turbos

>>14849153
Everything in this post is wrong

>>14849127
No the popping sound is unburnt fuel hitting the exaughst manifold usually.

Most EFI engines do it to cool the engine down by spraying fuel into the cylinder chamber during the exhaust phase
>>14849147
Ding ding.

Short headers love to backfire

>>14849153
Jesus fucking christ, at least take a second to google shit before you go full retard and hit post when you've typed something that stupid.

>>14849165
would you like to back that up with some facts or you just going to shit post

>>14849101
This.

A model high flow cat of the correct size for your exhaust is not taking any power because it acts like a muffler, letting you run less muffler behind it. If you take the cat out and don't want your car to be fucking horrible on the freeway, you'll need bigger resonators therefore producing the same restriction in the first place.

>>14849174
>call a fucking idiot a fucking idiot
>somehow shitposting
Learn what it actually means fucking retard.

Also, yes, N/A cars backfire. Mine loves to every time I downshift from a higher than 1500 RPM.

>>14849193
>model
modern

>>14849174
>guy asks honest question
>you make up some ridiculous nonsense for some reason
>I'm the shitposter

>>14849194
I never said they didn't. they just asked if this was the case for performance vehicles which I replied no due to the majority of them running anti-lag systems which due cause back-fire/after-fire or due to special combustion settings set in the ecu. So it is you that may need to hit the google search before you post.

>>14849194
>>14849215
samefag

>>14849232
>me
>ever wanting to be associated with heartbreaker apart from some technical stuff

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>>14849227
>performance vehicles
>99% of which are road-legal sports cars
>99% of that 99% are running fucking anti-lag on a street car

>>14849087
If you're doing engine upgrades without upgrading your exhaust be aware that your cat is taking away about 30% of the gain. You can also expect a decent gain from any kind of true dual exhaust pipe. exhaust brands don't matter, have a machine shop make you one for the best fit and cheapest price.

>>14849247
True duals are only worth it it's a dual-head engine like a V or boxer though.

>>14849247
Yes faggot, because a dual system will really improve the flow from my single turbo

>>14849153

For one, it's not a backfire. A backfire, as the prefix back would imply, is ignition before the intake valve. A backfire damages fuel injection equipment and throttle bodies. Anyone with experience on blowers will have opened a backfire plate getting a little keen on going down in jet size, or damaging power valves in the metering circuit of a Holley style carb.

Overrun is unburnt fuel combusting aft of the exhaust valve. If there is sufficient oxygen the mixture will ignite in the exhaust manifold. If there is not, it will ignite further in the exhaust tract where there is sufficient oxygen a-la RX7 belching flames from the muffler.

Overrun occurs when the intake and exhaust valve are open during overlap and unatomised liquid fuel can pass through the combustion chamber and into the exhaust tract. An open exhaust tract amplifies the effects. Many modern cars should not overrun as the ECM activates fuel cut during decel.

Anti-lag is not a backfire, as there is no ignition forward of the intake valve. Anti-lag sequentially disables spark in alternating cylinders to dump raw fuel and oxygen into the exhaust manifold in a grossly exaggerated overrun to build heat, pressure and volume (enthalpy) required to drive the turbine.

Naturally aspirated engines benefit from sequentially disabling spark as a spark-cut rev limiter. This is used for launch control. Fuel cut rev limiters have up to a 300ms sag as the injector duty cycle resumes, and this can cause bogging off the tree.

>>14849137
This 100%.
I gained close to a good 5% engine power with a high flow cat. So a 200HP rated GM 90° V6 with 200,000 miles went from 180ish BHP back up to about 195BHP with a MF high-flow cat, a 10% larger exhaust pipe after the manifold, and a shot of gumout. Probably ended up right back at 200-205ish BHP after spark plugs, intake cleaning, 93 tune, and switching to synthetic oil. Also shot flames out the exhaust and backfires sounded like close range shotgun blasts

>>14849275
>Overrun occurs when the intake and exhaust valve are open during overlap and unatomised liquid fuel can pass through the combustion chamber and into the exhaust tract. An open exhaust tract amplifies the effects. Many modern cars should not overrun as the ECM activates fuel cut during decel.

How do I make my Mustang overrun? Shit sounds cool as fuck when it happens

>>14849289

Is your Mustang a carburetted or fuel injected engine?

>>14849299
Depends on the year, my 89 overruns and it's F/I.

>>14849299
06 GT so fuel injected

>>14849308

Most likely this ECM does not utilise fuel cut on decel. This was a selling point of Nippon Denso fuel injection systems in 1992 and is now commonplace but it was not for quite some time.

>>14849309

Unless you can access the ECM fuel cut table your best bet is an un-obstructed exhaust tract without baffles in the exhaust stream, perforated glasspack mufflers should help there.

>>14849299
Cam(s) with overlap

>>14849284
You didn't gain anything from the high flow cat, you gained it from replacing a shit old cat.
A modern one (2005+) will gain you essentially nothing if you remove it, outside of making more noise and flames. Downside is your car now stinks like shit and can kill you more easily.

>>14849275
Jesus Christ how can you idiots have this little knowledge about automobiles.

I only read the first paragraph an already know you have no idea what you are talking about.

Backfires are combustion of unburned hydrocarbons and oxygen in the exhaust system. Usually they occur when the throttle is suddenly shut from WOT and there is suddenly a large amount of residual fuel in the exhaust manifold/exhaust. When this hot unburned gas comes in contact with enough oxygen in the exhaust system it combusts (oxidies) and a pop is heard.

Typically catalytic converters are oxygen rich due to their chemical process and the fuel is combusted in the cat in a gradual fashion preventing the popping sounds.

Backfires are NOT pre-detonation (aka detonation or "pinging"). Predetonation is an entirely unrelated process by which the air:fuel charge detonates and presurizes the cylinder before the piston reaches TDC, this causes the rotating assembly to begin compressing the rapidly expanding combusted air:fuel charge. Needless to say this is bad for making power, bad for efficiency, and bad for the engine's durability/longevity.

tl;dr the guy above and most of the people in this thread are fucking idiots.

>>14849275
OK and thank you for the information.
but I wasn't saying that anti-lag is back-fire(or at least not trying too) but that it can cause back fire or after fire in the case of most vehicles its implemented.

>>14849327

Perhaps you should have read past the first line.

Nowhere are we talking about pre-ignition, which is ignition within the combustion chamber before the intended ignition event.

The catalytic converter does not produce oxygen, you fool. Nowhere is the reaction balanced with oxygen.

A backfire is a combustion event before the intake valve. Doesn't bother me that you do not know this and think otherwise. I think you need to brush up on your nomenclature.

>>14849327
He didn't say anything about pinging you retarded fuck

>>14849327
here you go new friend.
https://www.youtube.com/watch?v=XVDXLW3P7q8

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>>14849327

> This is not a backfire.
> - Your post

>>14849351
how much damage can that do even with specialized headers/manifold or really anything else.

Anyone can explain why my oil gauge is jumping sporadically. like when ever I turn over its off and I get oil lights but every so often or if I hit a bump it pops back on for like a couple seconds.
I think its sending unit or fuel pump
>car needs oil change badly as well which is getting done soon.
any help?

>>14849394
Check your oil level.

>>14849398
full sorry I didn't included this.

>>14849380

A lot, actually. The easiest thing to damage is the injector tip, if the engine is fuel injected. If carburetted the power valve in a Holley style carb will often blow out. Damage to the throttle body can also occur by shearing the retainer grub screws and dislodging the plate or displacing the shaft or bushings. Nitrous backfires like that image are very nasty and will often split the seams of a fully fabricated aluminium plenum.

>>14849394
Yea if you are full check the sender or gauge, if those check out check your grounds for that circuit

>>14849431
awesome thanks I been seeing others with the same problem say it was due to metal savings gunking up the fuel pump and getting under and removing the oil pan from a early 2000 ford f150 super-cab is a bitch

>>14849272
why are you putting any exhaust pipe on your lawnmower?

>>14849481
Lawnmowers have turbos now?

>>14849488
why not fuck rocks

>>14849272

It will if the original single pipe is restricting the flow of spent exhaust gasses. Always remember that cross sectional area of the pipe is king for reduction of pressure in the exhaust tract. A single 4" pipe will have a CSA of 12.57 square inches versus 14.14 square inches for two 3" pipes. Where that comes unstuck is you now must fit more pipework of smaller dimensions than a single 4" pipe which may or may not be feasible.

If you had a long and convoluted exhaust tract with mufflers and emission controls then you may in fact develop more power with a dual exhaust system with your single turbocharger than a single pipe.

>>14849488
yes actually most of them do

Using this thread

Recently bought a 30y/o car. It spews out a black liquid and has crazy amouts of white smoke. New fuel system so thats not it. Any hints?

>>14849652
sounds like she's buggered.
Go to your local car dealer and trader her in for $200 on a Honda.

>>14849652
Head gasket and/or bent head

>>14849442
regardless do an oil change ASAP as oil breaks down and could cause the metal shavings issue you describe

>>14849652

Black liquid emits from where, the exhaust outlet? And is it white smoke or a tinge of blue? Is the engine turbocharged, is it a diesel? Give a few extra details, but it does not sound good at all.

>>14849729
N/a gas engine, completely white smoke, puddle of black liquid forms in the exhaust tip and drips/spews from there

>>14849757

White smoke in a petrol engine is an indicator of moisture. When the black liquid drips, rub it between two fingers. I am thinking that it will not have the consistency of lube oil and instead will be moisture and carbon black from the exhaust. What is happening with the cooling system, is there a loss of fluid?

>>14849782
Coolant leak near the radiator

Appreciate the help

>>14849798

How rapidly are you losing coolant? When the engine is started, is there a steady stream of bubbles visible when the radiator cap is removed?

This leak near the radiator, what is the cause? Perforated pipe, perforated radiator core, crack in the end tank?

If you are losing coolant, white smoke is evident and moisture is emitted from the exhaust I would be looking at either a significant head gasket failure or cylinder head failure between exhaust valves or a crack in the exhaust runner allowing coolant to enter the exhaust tract.

What does the lube oil look like, is there a creamy textured buildup underneath the oil filler cap or on the dipstick? When the engine is run without the oil filler cap, how bad is the blowby? A gentle force when the cap is removed is quite normal but there should not be pulsing 'puffs' of blowby gasses.

What engine is this?

>>14849829
Coolant only drips when engine is turned off after a drive. No idea about bubbles, the leak is coming from the radiator itself.

Oil is normal, just replaced some leaky fuel injectors so i havent seen if there was still some gas getting in there yet

>Engine
Porsche 2.5L i4

>>14849853

Open the radiator cap (when cold) and start the engine, observe for bubbling. This may be exhaust gasses in the cooling systems from the compromised seal.

Is there an EGR system on this engine that is water cooled? This may also be an ingress point.

I am not familiar with Porsche engines, but is the throttle body heated by water? Has this been compromised?

The most likely cause is as other posters mentioned above, failure of the head gasket or cylinder head. I think you may have a serious issue with this engine.

>>14849924
Fukkkkkk, thanks for your help, ill look into this tomorrow

>>14849936

Good luck, and take your time. Write down everything you find as this will help you keep on track of your thoughts when diagnosing the fault. Check the cooling system and observe for these bubbles and start logging your coolant loss in a notepad. You need to repair that external coolant leak as well, it is important that the cooling system is able to be pressurised to one Bar without the presence of air in the cooling loop.

>>14849936
Hey 944 owner here, are you sure it's not just your radiator? The have plastic sides that are prone to fail.

And yes the white smoke is moisture, don't worry unless it starts to smell sweet.