Hot answers tagged

52

Safety, comfort, noise and space are the things that come to mind. Safety Exhaust gasses are hot as hell. Hot enough that we put heat shields all over the exhaust line. In engines, we are actively trying to remove heat. Adding more from the exhaust goes completely against that and would increase overheating. Also, would you want a hot exhaust pipe near ...


45

Well, we can have a pipe going out the front of a car as in this design here: or its heavier predecessor: Arguably, the aerodynamic properties are not optimal in both, but here is a similar approach where aerodynamics have been considered for sure: other designs (like trucks) do account for aerodynamics by putting the exhaust tubing behind the relevant ...


37

It signifies that the car is running absolutely correct. Here is the reason why: A gasoline (petrol) molecule is made up as such: C8H18 (or 8 Carbon atoms and 18 Hydrogen atoms) Energy is obtained from the combustion of it by the conversion of a hydrocarbon to carbon dioxide and water. The combustion of octane follows this reaction: 2 C8H18 + 25 O2 → ...


29

My general rule for exhaust bolts/nuts is to order new ones with the part you are replacing, knowing full well that there is a good chance you'll destroy the ones you are removing. Better to be prepared ahead of time than to be stuck waiting for new parts from another country after you've disassembled everything. Personally, I have a rule of ordering every ...


20

This is a term used to describe the shapes of the pieces of tubing used to create exhaust pieces with very hard turns. Imagine an apple pie. Now cut it in 8 individual pieces (triangles). You can now make complex shapes by arranging the pieces in different ways. In the image below, you can see how each weld marks off each piece of tubing. If you pay ...


18

Briefly: The exhaust pipes are shaped to suck gasses out of the combustion chamber over a range of RPMs. Somewhat longer: Imagine a 2 stroke engine without an exhaust*1. When the exhaust valve opens, burned gasses leave the cylinder. Leave the valve open for a long enough time and the cylinder will be at ambient air pressure. Now run the engine at a ...


14

Yes, at least half of the exhaust is coming straight out of that gap without passing through the muffler. As you've noted, this leads to an increase in noise (or music, depending on your taste). To my eye, that looks like a hassle to fix on your own. There appears to be the rusted remnants of two bolts holding the Y-pipe to the passenger side muffler and ...


14

Sounds like a lean condition Here's something to chew on regarding identifying a lean or rich condition on a motorcycle. Symptoms of Lean or Rich carb settings on a motorcycle What I believe you are hearing is backfiring. It isn't loud because the baffling systems on modern motorcycles are so effective. If you have a lean condition that suddenly ...


14

Several things; Exhaust coming out the front is dangerous. If the fumes are ingested into the cab the driver may be harmed. Normally a car is driven forward. If the exhaust is coming out the back this gives the least chance of the fumes making it inside the cab. Mufflers are large components. Often there is not enough room inside the engine compartment to ...


13

My first concern is that you have an exhaust leak. The exhaust is designed to exit at the rear and or side of the car, far away from your fresh air intake of the ventilation system in the cowl area. I would check for an exhaust leak starting at the front as you stated that it's coming in from through the ventilation system. This can be dangerous and should ...


12

Pressure drop is to flow as voltage drop is to current With all else equal, removing the resonator or muffler will reduce the restrictions in the exhaust pipe. This means that the ability of the exhaust headers to flow gases will increase, not decrease. However, this does not necessarily mean that the engine will produce more power, since that is the ...


12

A catalyst is a chemical that contributes in a chemical reaction but remains unchanged after the whole reaction is complete. In a catalytic converter platinum is the catalyst that converts unburned hydrocarbons into H2O and CO2. If there is too much unburned hydrocarbons going into the catalytic converter, it greatly increases the temperature inside the ...


11

Basically you have an exhaust leak, it's dangerous (to you in the form of carbon monoxide) and should not be ignored. An easy way to check for the leak is to pull a vacuum line off the intake and suck a small amount (1 - 2oz) of transmission fluid into the intake via that vacuum line. Make sure the vehicle is outside, because it's going to smoke a lot. The ...


11

Human Error I have firm belief that the cause of burned valves with short pipes is due completely to human error, lack of understanding and poor judgement. I believe this myth has been perpetuated by actual 'evidence' of having burned valves but the attribution of the cause is incorrect. Guy with burned valves story He has a hot rod he builds. He ...


10

They Exist I was unable to find any manufacturers that have rolled out this technology into production vehicles but there are several manufacturers that have the baseline technology in R&D Formula 1 Formula 1 has always been a playground for engineers and with the new rules implemented in 2012 the current platforms are running this technology and ...


10

There is this nice animation of a 2-stroke engine with an expansion chamber Source It works like this: While moving downwards after ignition, the piston exposes the exhaust opening, and the burned gas streams into the exhaust pipe like a (high pressure) shock wave. Due to the inertia, this gas will create a slight vacuum wave behind it, which helps to ...


10

I certainly don't claim to have any special inside knowledge as to why Porsche engineers decided to route the exhaust that way, but I think that we can analyze the possibilities and trade-offs from an engineering view and perhaps see how one might come to such a conclusion. The possible options I think we can safely eliminate any front-facing exhaust ...


10

A muffler is a harmonically tuned chamber that is designed to reduce the noise created by the combustion process. Mufflers are usually designed with specific sound frequencies in mind. When a vehicle is being designed, the engineers will measure the sound frequencies emitted by the engine, and using harmonic tuning, create mufflers that specifically cancel ...


10

Is your Check Engine Light on? That's a rhetorical question, what I mean to say is that if your ’04 Forester is in good tune, it really should not produce that much carbon monoxide. Also, there are really no long-term health hazzards of non-chronic carbon monoxide exposure, other than death. (It binds with red blood cells in a way that prevents transport ...


9

I have typically replaced my stock exhaust systems with aftermarket race systems. Many stock exhaust systems have dual-wall designs so you never see the pipe that the exhaust is actually flowing into. All of my exhaust pipes glow orange/red when I ride them hard. It's fine and completely normal. Yamaha dirt bike with exhaust glowing red. Here's a bonus ...


9

Exhaust inside a car is bad. It can come in through your vents, through the floor, or through the firewall. No matter where it's coming from, you should get it fixed because you can pass out from carbon monoxide, and if the engine keeps running after the crash it could kill you. It probably won't take too much to fix -- the hard part is finding the air leak....


9

Looks like part of the muffler to me. You should have it replaced it could end up obstructing the exhaust.


9

Cats can stop functioning in a couple of ways: physical deformation due to high temperatures According to this article, the catalyst melts at temperatures above 2100 °F (1200 °C). In the event of a meltdown, the catalyst gets permanently damaged, at which point it doesn't scrub the nastiness out of the exhaust gases and serves as a major exhaust ...


9

Cabin filters on modern cars use something called activated carbon (or at least some of them do) which is basically two paper / cotton sheets either side of a fine layer of carbon particles. It looks to me as though your cabin filter has a hole in it and therefore is blowing carbon all over the inside of the cabin. I'd take it back to wherever installed ...


9

The exhaust also creates a pressure differential, which can help scavenge exhaust gases from the chamber. So a properly tuned exhaust will therefore increase the fuel efficiency of the engine. Whilst an engine without an exhaust would make more power, it would also consume more fuel.


8

The cat back is just that the exhaust pipe including the muffler from the catalytic converter to the end of the tail pipe. Seems odd to me, not impossible just odd that you would need to replace the entire exhaust system from the cat back to pass inspection. I see from your profile that you are from PA and road salt can deteriorate an exhaust in that time-...


8

What does it do? (better performance [and how so?]? better mileage? cooler sounds?) It depends. One of the goals of a performance exhaust is usually to create a tuned system: A tuned exhaust system is an exhaust system for an internal combustion engine which improves its efficiency by using precise geometry to reflect the pressure waves from the ...


8

You will likely be annoyingly loud but otherwise fine. As always, you are liable for your own compliance with local noise ordinances. I would recommend that you drive with the windows up until you give the car to the shop in order to avoid any risk of carbon monoxide poisoning. For example, don't drive with the trunk propped open: the low pressure behind ...


8

I used these kits occasionally when I was young and broke, so my knowledge isn't that current. Back then, they were good for a couple of months, maybe a little longer depending on how bad and where the hole is. If the exhaust pipe is so rusted it'll break in a few months, that kit is not going to last very long as the movement of the breaking pipe will ...


8

Even before a cat plugs, you can test your cat using a laser thermometer. You are looking to compare the inlet and outlet temps on your cat. Do the following: Run the engine up to operating temperature (at least ten minutes so the cat should be fully warm) Check and record the inlet temperature. You're looking to measure the temperature right where the ...



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