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15

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 ...


8

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 ...


7

Under normal use (non-performance type use), the valves, both intake and exhaust, should last the life of the engine. If and when they do leak, it will not take long for the valve to become a burnt valve. In your case, I doubt they were leaking prior to pulling everything apart. If the exhaust valves had leaked, they would have been fried. If valves do not ...


7

This NIH (National Institutes of Health) Study monitoring CO inside the cabin of a vehicle during commutes over an extended period has some pretty interesting data. From the study the mean CO concentration was 9.8 ppm, with a standard deviation of 5.8 ppm Here is another study Here is another study that reflects older data ('80's and '90's) sampled ...


7

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 ...


7

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 ...


7

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 ...


6

Generally when an engine runs, if it is running lean, it will run hotter. If an engine is running rich, it will run cooler. Each individual cylinder is no different. After an engine is completely warmed up, if one measures each cylinder at the same basic place on the exhaust manifold, you can get an idea of which cylinder is running lean and which is running ...


6

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 ...


5

The bottom line is yes, if you drag your exhaust over the speed bumps, it will cause damage to your car. It will be mainly localized to the exhaust on the vehicle. Besides flattening out the exhaust pipes, you also put stress on the joints and the hangers for the different mounting points. If you hit the exhaust hard enough, you can cause further damage to ...


5

If you don't want to weld, you can use a joint like this: NOTE: The above image is for demonstration purposes only. I couldn't readily find one which was 2" on each side. The only difference is, the inside diameter on both ends would be 2". Your outside diameter 2" pipes would fit inside. Use two muffler clamps to attach. You'll need to match the outside ...


5

You shouldn't need to use sealant on the gaskets. Most exhaust manifold gaskets either come with their own sealant (like Fel-Pro's do with the silver looking stuff), or they are metal and don't require it either. I believe sealants (such as high temp Permatex Copper) will just burn off anyway, because the heat at the head/header interface is far beyond what ...


5

Just to add to the other answer as I ran into this same issue, what kind of emissions do I have on my mitsubishi galant? I had this code: P0421 and I had to replace my O2 Sensor & the catalytic converter but I wasn't sure if I needed the CARB (California Air Resource Board) compliant ones or not. There is a label that identifies what type you have. I ...


5

The dollar bill test is quite simply using a dollar bill (any denomination ... doesn't have to be American currency, even) and placing it against the exhaust tip while the vehicle is idling. You are looking/listening to what the bill does while against the exhaust tip. If it just flutters there without making much noise, you have healthy exhaust valves. If ...


5

A few things to consider if you end up doing this: A longer shaft will reduce the speed that you can safely spin the turbos up to It's got to do with something engineers call rotordynamics, although I highly doubt you would need to spin something up to 125,000 RPM for a turbojet application :) You may also find that the existing journal bearings are not ...


4

Q1: Is that a reason to worry or replace them, provided that they don't actually malfunction? The only reason you'd want to replace stock manifolds is if they are cracked (or broken) or if you want to do a performance upgrade. Q2: Do exhaust manifolds have a propensity to rust faster than other parts and why? Yes. The reason is because of the ...


4

According to this website from the University of Washington: Manifolds and/or exhaust pipes on some vehicles can reach 1200 degrees F. It is rare to find temperatures this high in normal operation. If your laser thermometer can read up to at least that high, you should not have any issues. EDIT: As pointed out by @Zaid below: ... if a cylinder ...


4

You should be fine. Though I would recommend unplugging the connector to fuel injector #7 to minimize the amount of unburnt fuel that makes its way to the catalytic converter.


4

It's possible to cause valve damage if the engine is hot and cold air is sucked up into the exhaust (by backpressure when the throttle is closed). However, you'd have to basically disconnect the exhaust right after the exhaust header, or have a cracked exhaust header, for that to happen. So it's extremely unlikely you caused any engine damage. A more real ...


4

If an exhaust restriction is suspected a pressure gauge pre-catatlyst works just fine. My maximum cutoff pressure is 1.25 psi but most good systems will be well below that. The intake manifold vacuum is also a good clue. If it is not close to the idle reading at 3000 rpm suspect an exhaust restriction. In the case of a restriction the vacuum reading will be ...


4

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 ...


3

I would never ignore a worn tie rod; you could be driving down the road, hit a serious bump, and suddenly lose your ability to steer in a straight line, or worse. If you have the the tie rod replaced, I doubt that any reputable mechanic would tackle that without also repairing the power steering rack. I personally would never ignore any kind of steering ...


3

Exhausts inside the car is not healthy at all. As someone said, perhaps another mechanic should be considered. As to the problem, it sounds like the exhaust pipe is leaking before the catalytic converter. The engine light would likely light up because of this, since the Lambda (Oxygen) sensor in the converter would be receiving less exhausts (and more ...


3

If the catalytic convertor is truly plugged, you wouldn't be able to drive the vehicle, so this makes me wonder about the voracity of your statement. With a plugged cat, the back pressure created behind it will only let you rev the engine to around 1500-2000 rpm. I had to replace a set of heads on a pick-up truck for a guy because he continued to run the ...


3

Also, remember that MAF is a reading of the amount of air entering the engine. If you have a backflow issues (high backpressure) or even a timing issue where the valves are not opening and closing at the correct time (slack chains, jumped timing), your MAF sensor readings will reflect this as well. I know this post is late, but any who are looking into this ...


3

Ferrari V8's have flat-plane crankshafts, which should already give yours a very distinctive exhaust note that I believe is what you're referring to as "rasp". As such, I don't think a cross-pipe is necessary to improve sound quality. If your concern pertains to the lack of volume, it can be remedied with use of mufflers that don't suppress sound as much ...


3

Background The 2009 Aprilia Tuono has a writeable ECU but you need the appropriate equipment from Aprilia in order to perform the task. AFAIK there are no aftermarket tools to replace the ECU programming equipment provided only to Aprilia dealerships. As well, Aprilia recommends that you DO NOT put a piggyback ECU on it. It is one of the few manufacturers ...


3

There are currently two kinds of narrowband sensors used these days: titania sensors (NTK) and zirconia (Bosch). This answer only addresses the zirconia sensors which are the most common type. Referring to the diagram (which was created by Michael Handrich and shared under a Creative Commons license), the sensor is a galvanic cell that generates what's ...


2

Depending on the colour of the smoke that is produced from the exhaust it could be different sources, have you had a valve cover replacement done on the car? I've worked on some cars that have leaking valve covers where the spark plugs are located and this causes issues with oil seeping into the cylinders, which could be a source of smoke, and oil loss. ...


2

These are the exact jets and shims that you will need for your 1984 Honda Gold Wing GL1200 four Main jets size 118 four Pilot jets size 38 and 8 shims for each Slide Needle, 2 shims per needle You will also need to the following 1 D-Adjuster for fuel screw adjustment Legend D-Adjuster for air/fuel on idle circuit Pilot Jet Main Jet



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