back pressure?

[oktogo]

ok back to the subject no fightin. does any one know if the thermal coated ones are as good as the ciramic

 

[Rons beast]

ok back to the subject no fightin. does any one know if the thermal coated ones are as good as the ciramic

What I'm hearing is, it's a question of timeframe.

If you just want more power and swap parts and combinations on the vehicle all the time, or plan to sell it in a couple of years, go cheep.

If you plan to keep it spend the money on ceramic. It seems to out last anything on a vehicle that's used.

While I haven't used the thermal ones, the flap I'm hearing at shows and among friends is go ceramic.

 

[Rons beast]

A coating doesn't make one better than another. Coatings are purely cosmetic. If you want to keep the heat inside the pipes, put heat shields around them. If you want them to last, buy the ones made of the thickest material. If you want the best performance for the money, keep the stock manifolds.

Coatings are NOT purely cosmetic. (you can believe that, but that would be belief in a fallacy)

Heat shields are usually not asthetically pleasing, (and asthetics are sometimes desired)

The thickest material will not always last the longest. (or look the best , depending on the purpose intended)

The best performance will NOT always come from stock manifolds. (REALLY??!!)

are you sure you're from Earth?

 

[Krafty]

I don't know if that bush bar and winch on your bronco there is up to regulation, you better pull it off and go back to a rusty bumper that doesn't protect your front end.

oh and better not put those e3 spark plugs in there either, thats not what came from the factory.

So when it comes to increasing HP don't ask Steve83 cause he doesn't know what increased HP feels like. or how to do it. /emoticons/[email protected] 2x" width="20" height="20" />

 

[Rons beast]

Xxxxx:

I've gone back over this thread, and I did not see that quote. Maybe you were the only recipient.
Point is when someone adds their .02...YOU don't need to "debunk" (your words) their opinion. We are sharing OPINIONS here and everyone has the right to theirs. Heaven knows you have yours. Heck, in another thread you criticized another member for suggesting the use of WD-40! OMG! man, come on!!

If I get suspended for posting this, I'm very OK with that. I don't think I'm in the minority, because this is not the , " KEEP IT STOCK AND LISTEN ONLY TO x." Zone.

 

[50joe]

Found the following on the internet, but From what I have heard from engine builders and machine shops, the amount of back pressure needed totally depends on the engine. Taking a bone stock engine, and running 4" true duals not only is useless, but it actually lowers the amount of power the engine can produce. But running too small of a system on a worked up engine will restrict it, and slow it down. As far as burning valves, although not enough backpressure can contribute to this, it is mostly caused by another problem in the system forcing the mixture too lean. Lack of backpressure can contribute to a lean condition, causing valve burning, but mostly on carburated engines. EFI uses the O2 sensor to determine the required fuel trim, and has the ability to adjust the trim as needed, TO A POINT. Usually going a lil bigger wont hurt anything, provided its done correctly. I personally run a 3" system off one cat through a flowmaster. If I wanted duals, I wouldn't go any bigger than 2 1/2 unless I was over 400 HP. Your best bet is to consult with any reputable performance exhaust installers. If they know what they are doing, they can tell you if you are doing more harm than good.

Destroying a myth.

Some say that "an engine needs backpressure to work correctly." Is this true?

No. It would be more correct to say, "a perfectly stock engine that cannot adjust its fuel delivery needs backpressure to work correctly." This idea is a myth. As with all myths, however, there is a hint of fact with this one. Particularly, some people equate backpressure with torque, and others fear that too little backpressure will lead to valve burning.

The first reason why people say "backpressure is good" is because they believe that increased backpressure by itself will increase torque, particularly with a stock exhaust manifold. Granted, some stock manifolds act somewhat like performance headers at low RPM, but these manifolds will exhibit poor performance at higher RPM. This, however does not automatically lead to the conclusion that backpressure produces more torque. The increase in torque is not due to backpressure, but to the effects of changes in fuel/air mixture, which will be described in more detail below.

The other reason why people say "backpressure is good" is because they hear that cars (or motorcycles) that have had performance exhaust work done to them would then go on to burn exhaust valves. Now, it is true that such valve burning has occurred as a result of the exhaust mods, but it isn't due merely to a lack of backpressure.

The internal combustion engine is a complex, dynamic collection of different systems working together to convert the stored power in gasoline into mechanical energy to push a car down the road. Anytime one of these systems are modified, that mod will also indirectly affect the other systems, as well.

Now, valve burning occurs as a result of a very lean-burning engine. In order to achieve a theoretical optimal combustion, an engine needs 14.7 parts of oxygen by mass to 1 part of gasoline (again, by mass). This is referred to as a stochiometric (chemically correct) mixture, and is commonly referred to as a 14.7:1 mix. If an engine burns with less oxygen present (13:1, 12:1, etc...), it is said to run rich. Conversely, if the engine runs with more oxygen present (16:1, 17:1, etc...), it is said to run lean. Today's engines are designed to run at 14.7:1 for normally cruising, with rich mixtures on acceleration or warm-up, and lean mixtures while decelerating.

Getting back to the discussion, the reason that exhaust valves burn is because the engine is burning lean. Normal engines will tolerate lean burning for a little bit, but not for sustained periods of time. The reason why the engine is burning lean to begin with is that the reduction in backpressure is causing more air to be drawn into the combustion chamber than before. Earlier cars (and motorcycles) with carburetion often could not adjust because of the way that backpressure caused air to flow backwards through the carburetor after the air already got loaded down with fuel, and caused the air to receive a second load of fuel. While a bad design, it was nonetheless used in a lot of vehicles. Once these vehicles received performance mods that reduced backpressure, they no longer had that double-loading effect, and then tended to burn valves because of the resulting over-lean condition. This, incidentally, also provides a basis for the "torque increase" seen if backpressure is maintained. As the fuel/air mixture becomes leaner, the resultant combustion will produce progressively less and less of the force needed to produce torque.

 

[Rons beast]

Great explaination Joe, Thanks.

Following your explaination, would it be fair to say that headers installed on an engine would help produce more power as long as the corresponding changes are made to assure the proper mixture is maintained?

These changes to the exhaust system should be coordinated with the fuel delivery system, and ignition systems.

There are many aftermarket products to help someone do this. The important thing is to be sure to coordinate systems.

 

[50joe]

Great explaination Joe, Thanks.Following your explaination, would it be fair to say that headers installed on an engine would help produce more power as long as the corresponding changes are made to assure the proper mixture is maintained?

These changes to the exhaust system should be coordinated with the fuel delivery system, and ignition systems.

I would have to agree with that not only from what I have heard, but also from personal experience. Going a little bit over stock will not hurt a thing. As a matter of fact, FORD has been know to not only under rate their horsepower/torque ratings to keep the EPA happy, they are also famouse for "tuning down" their motors to do the same. Simple mods like a mild exhaust, in my opinion, not only sound better, but will increase performance. The trick is not to go overboard, know what you have built, and what will work with it. A mild cam and a few mild mods on a Ford small block will benifit from a increase in the flow, just as long as you dont go crazy. Oversized exhaust on a motor will cause nothing but grief. Hope this helps someone......

 

[oktogo]

I would have to agree with that not only from what I have heard, but also from personal experience. Going a little bit over stock will not hurt a thing. As a matter of fact, FORD has been know to not only under rate their horsepower/torque ratings to keep the EPA happy, they are also famouse for "tuning down" their motors to do the same. Simple mods like a mild exhaust, in my opinion, not only sound better, but will increase performance. The trick is not to go overboard, know what you have built, and what will work with it. A mild cam and a few mild mods on a Ford small block will benifit from a increase in the flow, just as long as you dont go crazy. Oversized exhaust on a motor will cause nothing but grief. Hope this helps someone......

it rly has help thankyou but all thight fight was very funny tho. and i guss im goint with the thermal coasted ones there 280 and will hopely last.

 

[muddrivermike]

Hey Ive talked with a few people and they all say to go with the coated headers.They said it stops them from rusting from the outside and able to withstand the outside elements better than the painted black ones,which as anybody who has them know that once you start the painted ones up it just burns off and starts to rust up within a couple weeks.Put the money out for the good ones,Thats what Im doing after I build the 460 for mine.