Quote:
Originally Posted by Ryland
A cold air intake only helps you get more air into your engine at wide open throttle, at cruising speed it is going to give the engine more air then it needs and thus the engine is going to dump in more gas then it needs.
Your exhaust pipe and muffler are not a duct to get the exhaust to the back of the car, larger is not better, people who say it's best to go a step bigger are bad at math as the exhaust flow in your exhaust system is coming out of the engine in pulses, there for the exhaust system needs to be tuned for those pulses, again if you are running wide open all the time that is going to shift to a larger pipe but at normal driving speeds to large of an exhaust pipe is going to de-tune your engine and make it work harder.
For your long drives you might look in to smoothing out the underside of your car.
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Ah, so what you're telling me is that the car will add more fuel to the air ratio to even it out and consume more gas? I don't think the amount would be significant enough to cause a drop in fuel-efficiency. Plus, I mentioned pumping losses as an explanation for the alleged increase in MPG's that performance companies claim from their products. "Work is work," so if the engine has to "work" to get the air in, it's going to have to rev higher to do so. Don't you want to make it easier for it to do it's job?
Since you're calling me out on my math by saying that, I'm gonna call you out on your spelling. (And logic.) An engine is literally an air pump, so your first line is completely wrong.
The exhaust is the medium through which gasses flow out into the atmosphere, unless of course you have an open-header setup, which is very polluting and illegal. These "pulses" are an expression of the lapses between the release of gasses from the exhaust valves. A slightly larger diameter pipe will create a more free-flowing outlet for the exhaust charge that helps scavange those gasses after each "pulse." (The opening of the exhaust valves) While the valves are closed, a vacuum of sorts is created, keeping the stream steady and constant. So to "tune" your exhaust system, that would mean
upsizing the piping. The stock pipes are made restrictive for several reasons, but as it pertains to this discussion, their design is done with cost-effectiveness and mass production first, rather than top engine performance. As I said in my previous post, a restrictive exhaust system forces the engine to do extra work. High backpressure can cause recirculation of freshly released gasses, which is not a good thing. As mentioned above, (Not my post) the velocity will be higher in a smaller pipe, but it's a constant battle to keep the charge continually flowing through because it's such a small outlet. Bump the pipe sizing up liberally and the exhaust will flow freer in both the open and closing cycles of the valves more efficiently. For the record, I make WOT runs with a stylish factory exhaust all the time and know dudes with aftermarket exhausts that aim for top MPGs. "Detuning" the engine is only possible through a standalone engine management system which could potentially cause that, if you make a mistake. I guess what you're referring to is the guys with exhausts too big for their cars. That's also a bad thing, because there's simply too much room to create a significant charge in the exhaust stream, leading to less flow. If only they knew.
That's a novel idea, but what can you use that'll go under there?
BTW, this is off-topic, I'm sorry, but that's a really cool profile pic you've got there.