exhaust knowledge

[owequitit]

Ferrari, Lamborghini, Porsche (some aftermarket exhausts) and a few other high end cars have been using the valve technology for quite a while also just to add to the list.

Yes, those were the ones that came to mind. Some of GT-One's NSX aftermarket exhausts have them as well.

[blaxemj]

Great write-ups guys thank you for sharing your knowledge with us.

[Pandemic]

So will a wider 2.25" header decrease low end power and raise high end power? What are the figures on F22a1 vs F22a4? thoes are 2 different types of headers (I'm pretty sure).

[SteveB]

So will a wider 2.25" header decrease low end power and raise high end power?

Yes...on this. Engine breathing enough for 2.25" primaries

[deevergote]

I'm not claiming to be an expert either, but to the best of my understanding, an exhaust can reach a point where it is so high-flowing that it will begin to draw unspent air/fuel mixture out the exhaust valve during overlap, resulting in reduced fuel mileage. Then again, at the level where that is likely to occur, fuel mileage isn't very likely to be at the top of the builder's list of priorities.

In terms of performance, this isn't a bad thing. It ensures that the air/fuel mixture in the cylinder is totally fresh, and not combined with any spent exhaust gas. It's a waste in terms of fuel (and cash), but the engine has no issue with it



As for a gutted cat, I don't understand why people insist that it is a good idea. Aside from destroying the environment, it doesn't help. At all. All it does is create an area in the exhaust system (close to the engine, even) that causes turbulence. A free flowing cat works. A straight pipe works. A gutted cat is idiotic. It won't harm the engine, true... but it won't help performance. If it DOES help performance, it's only because the cat that was gutted was probably clogged and useless.

[verderacer]

Gawd I love Italian and German car development !

Ferrari, Lamborghini, Porsche (some aftermarket exhausts) and a few other high end cars have been using the valve technology for quite a while also just to add to the list.

[Father Time]

Last Activity: 01-09-2008 08:09 PM Offline

I wonder where he went? I was really curious as to his schooling/ research. Not that I claim to know anything about exhaust.

Just wanted to hear his side of reason.

[victork]

first post was good stuff. i didnt know some of the facts. =) good job!

[Camurai]

So will a wider 2.25" header decrease low end power and raise high end power? What are the figures on F22a1 vs F22a4? thoes are 2 different types of headers (I'm pretty sure).

The F22A1 and F22A4 have very different headers. The F22A1 header is a cast iron 4-1 design. The F22A4 uses a tubular steel 4-2-1 design that is much more efficient. When the F22A6 was introduced, they went with a combination of the two: a cast iron 4-2-1 design that is about as efficient as the F22A4 header, but weighs considerably more.

F22A1 header:


F22A4 header:


F22A6 header:

[71_307]

for the love of god.. dont gut your cat/ take it off/light it on fire.. keep that little sucker on there.. You get the joy of driving the least you can do is save the planet a little at no horse power cost..


also wouldnt a 2" exhuast setup be way better for an accord anything larger seems way to big for a stock to mild.. 2' is good for what 200hp??

[71_307]

The F22A1 and F22A4 have very different headers. The F22A1 header is a cast iron 4-1 design. The F22A4 uses a tubular steel 4-2-1 design that is much more efficient. When the F22A6 was introduced, they went with a combination of the two: a cast iron 4-2-1 design that is about as efficient as the F22A4 header, but weighs considerably more.

F22A1 header:


F22A4 header:


F22A6 header:

Exhuast manifolds are a give to be cast.. but honda was that cheap not to even make the 4-2-1 in stainless?? i had an saturn sl2 and it even had a ss stock header lol

[d112crzy]

for the love of god.. dont gut your cat/ take it off/light it on fire.. keep that little sucker on there.. You get the joy of driving the least you can do is save the planet a little at no horse power cost..


also wouldnt a 2" exhuast setup be way better for an accord anything larger seems way to big for a stock to mild.. 2' is good for what 200hp??

2" is too small.

2.25" is what people basic bolt ons go with. My personal preference is 2.5" with a 2.5" collector.

Too big? No way. I saw gains all across the board when I put mine on.

[owequitit]

Exhuast manifolds are a give to be cast.. but honda was that cheap not to even make the 4-2-1 in stainless?? i had an saturn sl2 and it even had a ss stock header lol

Wow, that's great. I would rather have a car that isn't a plastic peice of shit as opposed to a SS exhaust manifold.

The metal on them is so thick, that it would take DECADES for them to rust through. The exhaust system will rust through long before these do. Of course I bet there is a good chance your full SL2 exhaust wasn't stainless...

[93 CB7 SE]

so a 2.5 cat-back would be good for a h23 with 50-100 shot nos and 272 cams?

[owequitit]

so a 2.5 cat-back would be good for a h23 with 50-100 shot nos and 272 cams?

Oh yeah.

Honestly, an H23 with that kind of nitrous on it would probably benefit from 3". But I don't know that I would want that much exhaust off the bottle.