Free-flowing Intake and Exhaust for Fuel Economy

[SVOboy]

Oh my goodness, here it is again...

But really, I just read a bunch of sites saying performance intakes and exhaust are good for fuel economy and blah blah blah. It makes sense to me, it really does, but 400 on an exhaust and having the result suck would really really suck.

And it just doesn't make sense, because from a honda perspective, the cars with the best gas mileage has the smallest intake manifolds. And that's not just the cheap cars, it's the cars like the VX that had an *** load of engineering put into them to get great gas mileage, so honda wouldn't have just gotten cheap on that part.

Has anyone tried this? I might just get some really huge tubing and a cone filter and try it. Or else, mehbe I'll block off half my intake opening for a tank or two and see how it feels. I just dunno.

[kickflipjr]

I think free flowing exause is bad for city milage (not enough backpressure for low rpms). I am not sure about
the highway. I also think low backpressure makes warm up time longer because all the heat is going out the pipe.


The usually ricer cat back is 2.5" piping. I think that is too big for most fuel efficient 4 bangers.

The performance exaust people all claim more hp/mpg/tq. It WILL help mpg if your driving a 6,000 rpm all day copared to a stock setup driving at 6,000 rpm all day.

[Compaq888]

for a 4 banger I think 2.00-2.25 is the max for both power and economy. For my car I've been told to go a max of 2.5 because I had nitrous. My exaust is still stock cause I took the nitrous off.

What ricers don't understand is that you can put an electric cutout right after the header that opens and closes at any rpm you want. You don't even have to press a button. They can keep their stock exaust system and have power when they mash on the gas.

Like if I were to get it for my car I would program it to open 3000-6200rpm. So until 3000 rpm it's closed. Not only it would give a unbeliavable top end but at smog nobody is going to say anything because your exaust system is fully stock. It's also cheaper than getting a header and a complete catback.

[SVOboy]

What ricers don't understand is that you can put an electric cutout right after the header that opens and closes at any rpm you want. You don't even have to press a button. They can keep their stock exaust system and have power when they mash on the gas.

They do actually understand this but most opt out of it because they know the importance of running a cat for legal or nice person reasons.

The people that I've seen run like this generally have the switches for only when they see the track.

[Compaq888]

Originally Posted by SVOboy

They do actually understand this but most opt out of it because they know the importance of running a cat for legal or nice person reasons.

The people that I've seen run like this generally have the switches for only when they see the track.

If I had this system I would not drive over 3000rpm on the street. Going in that rpm burns a lot of fuel and gets you in trouble with the cops. For a honda I'd set it at 4000rpm.

[SVOboy]

It does burn a lot of fuel, haha. And if you try to launch that high you get crazy wheel hop (or at least I did on my mom's camry, I was freakin scared).

When I take my car to the track it'll be the same condition as street but mehbe with a different tune on it.

[rh77]

Originally Posted by SVOboy

Oh my goodness, here it is again...

Crap - it's back. The exhaust thread. Honestly, I wish there were some real answers out there, especially for the Honda design -- because I really need to replace mine. I think only a Honda engineer can answer the questions we have. Otherwise, we're going to need an experiment to get the answers we want.

RH77

[SVOboy]

Me too, I'm planning on interning at honda in the shop for a while but I'm doubting they'll know anything about it either.

[rh77]

Originally Posted by SVOboy

Me too, I'm planning on interning at honda in the shop for a while but I'm doubting they'll know anything about it either.

That's cool; but yeah, I think the exhaust diameter, backpressure, exhaust flow, and header style vs. fuel economy are advanced design issues, that someone high-up in the ranks knows every detail. The team that designed the exhaust system for the VX for example. The thing is, at Honda, the whole team works together as one unit instead of divisions that have their own responsibilities and meet once in a while to put the pieces together (but still, each system has an expert and apprentices). Unfortunately, I don't speak Japanese. Maybe we should write to them, I don't know. They're pretty cool with the advancement of environmental causes and their brands. My folks live pretty close to where they make the Civics and Accords in Ohio -- drove by the plant once -- very clean looking.

RH77

[SVOboy]

If we wanted to write a letter as a site I have a friend that could translate it into japanese for us, or at least clean up my sloppy japanese. Mehbe I'll talk to her father since he used to be head of jamsat and he can call honda for us.