More power!

[deevergote]

This one?



But yeah, the F22A4 is identical to the F22A1 aside from the exhaust manifold, which adds 5hp. It has yet to be determined whether or not the A4 manifold would add 5hp to an A6 or not... so maybe subtract 5hp from my estimates. Regardless, you'll see a noticeable gain!

[2winRB25]

Somethings look different but that is the car. It was a whole lot lower today when I seen it. And yeah he is a very nice guy. I only had a $100 bill and a $50 bill (because I wasn't thinking) and he was asking $125. He insisted that $100 would be fine.

And yeah, Im hoping to feel a gain with the butt dyno. Maybe an increase in mpg as well but Im not holding my breath on that one.

[deevergote]

MPG may decrease a little with the H23 manifold. It shouldn't be significant, though.

[2winRB25]

MPG may decrease a little with the H23 manifold. It shouldn't be significant, though.

Kind of what I thought based on my S14 but I have heard other possibilities. Thank you for all you input.

[deevergote]

Increasing intake airflow will increase the oxygen in the mixture. When the o2 sensor sees more oxygen, the ECU sends more fuel. You can increase MPG with a good ECU tune (I saw a 5mpg increase on my H22A with a tune), but a stock ECU will probably cause it to decrease a little the more you increase airflow.

[RyanD]

I don't know a name, all I have is a phone number. He drives a slammed goldish silver 92 or 93 with black painted OEM wheels. Young but walks with a cane. Thats about all I remember.

I forgot to mention I have the F22A4. But still my goal is equal to or slightly greater than that of an F22A6. So 10hp. The guy I bought the parts from said the A4 exhaust manifold I have will work fine with the parts I bought so I have everything and I'm ready to get started on it.

he walks with a cane now??? imma have a word with him on that

Josh is a very good buddy of mine

[RyanD]

Somethings look different but that is the car. It was a whole lot lower today when I seen it. And yeah he is a very nice guy. I only had a $100 bill and a $50 bill (because I wasn't thinking) and he was asking $125. He insisted that $100 would be fine. .

its slammed now. super cup kit and its all the way down he can hit a skunk in that thing and it would tear the exhaust off

[wagon-r]

But yeah, the F22A4 is identical to the F22A1 aside from the exhaust manifold, which adds 5hp. It has yet to be determined whether or not the A4 manifold would add 5hp to an A6 or not... so maybe subtract 5hp from my estimates. Regardless, you'll see a noticeable gain!

The F22A6 is pumping more air through the engine, which means that the stock exhaust manifold is going to be even more restrictive on the F22A6 than on the F22A1. If the A4 manifold adds 5 hp to the F22A1, its hard to believe that it will be less with the F22A6 engine.

[deevergote]

The F22A6 cast manifold is a different design than the F22A1's cast manifold. The A1 is a 4-1 design, whereas the A4 and A6 both have a 4-2-1 design. It's entirely possible that the A4 and A6 manifolds flow equally well. It's also possible that the A6 manifold flows better. People assume the A4 manifold is better because it's welded steel, not cast iron... but that's not necessarily true. Cast iron has flow potential.

[wildBill83]

A cast iron 4-2-1 exhaust flows better than the welded steel 4-2-1. The weld seams create turbulance. It make no logical sense that they would upgrade the intake and cam but place a more restrictive exhaust on their "sportier" motor.

[deevergote]

That's my thinking. The texture of the cast iron also causes the gasses flowing near it to slow down. That thin layer of slower exhaust gas acts as a lubricant for the rest of the exhaust.

[Accrdwgnguy]

Even with the tiny primaries on the A6 manifold? I can't see how a header with 25% to 50% larger primaries flows less than a stock manifold.

[GhostAccord]

Larger doesn't always mean more flow. If he exhaust isn't restricted by the stock manifold then opening it up would only serve to slow down the exhaust velocity. In that case you would actually be loosing any sort of suction/ or difference in pressure at the merge collectors.

Might as well just have 4 straight pipes and say they work better..... However they don't. You completely loose the benefits of having wave pulse/pressure differences pulling the exhaust out through.

There is a happy medium when designing headers and the OEM usually tune theirs for optimum efficiency with the stock engine. As you make changes to the engine then undoubtedly the exhaust must also undergo some changes. However, you want to maintain velocity and laminar flow. These two walk a tight line, too much velocity (small pipe) and the flow becomes turbulent. Going too larger won't help ether. As with lower velocity comes higher pressures. the more we can keep pressure out of the equation the better.

[deevergote]

The comparison was being made between the tubular A4 manifold and the cast A6 manifold. But yes, flow velocity is the important factor. The header/manifold that allows for the most efficient exhaust flow is the best part for the job. Too small, and it's a bottleneck. Too large, and the lack of velocity will create turbulence, which will be a restriction, which could make larger pipes more restrictive than smaller pipes when it matters most.

[GhostAccord]

Larger pipes also equal more surface area, therefore cooling the exhaust gases quicker. This also contributes to the slowing of the gases as well.

On another note, the cast manifold will most times maintain those temps longer than a thin walled tube header.