N/A intake idea, OK or hokey beyond belief?

[8v-of-fury]

A Can on a Vanagon I LOVE IT!

It will look right, as opposed to on a honda or a cavalier... it will be proportionate in size at least.

That whole setup of exhaust doesn't look the least bit restrictive, it shall do well!

[RadoTD]

Sorry to derail this somewhat, although he seems to have come to his conclusion already.

Before I begin, everything below is just my thinking... no sources or data behind it, just interested to see what some of you guys think about it.


I'm thinking that a long runner intake might be a bad idea on a diesel.
On a gasser, they measure airflow and air/fuel mixture and inject the right amount of gas to use up all the air you're pumping through the engine. However, on a diesel, there is no air measurement needed; it's completely linear to your rpm; ignoring boost pins etc for now.
I made a graph to help describe what I'm thinking.

X axis - RPM
Y axis - Air pushed into each cylinder or fuel for the green line
Green - Fuel
Purple - Long Runner Intake
Black - Short Runner Intake

A long runner intake will have bigger fluxuations occurring more frequently. The fluxuations will be more severe at lower rpm's and flatten out as you increase in rpm's (something I couldn't figure out how to manipulate the graph to show).
A short runner intake will have smaller fluxuations and a lower frequency, as shown by the blue line... in theory as you approach zero, the line will become straight.

Any time the Red/Blue lines are above the Green line, you have extra oxygen you're pushing through that's not being burnt. And, when the Red/Blue lines are below the green line, you've got black smoke. If you turn the fuel up so it cuts through the tips of the waves, you'll be puffing black smoke 90% of the time, but if you turn it down to the bottom, you'll be giving up precious air.

While across the whole rev range, the long runner intake might give you more air; particularly at your desired RPM ranges, given this theory, the short runner intake is the *more efficient* design. That is obviously exaggerated and over simplified, but I'm more questioning the theory.


What do you guys think of that? I'm not a fan at all of the intake on my AAZ, but I think the key to a good intake is keeping it free flowing and getting even air to all cylinders. I've got a few ideas for the latter, but my car is a LONG way from getting a custom intake manifold made

[Vanagoner]

Hi Rado,
not done just taking a break
Is your AAZ a turbo? If so, you are right and this doesn't apply to you.  As you said, you just want something free flowing that will distribute air to all cyls evenly. 
This thread ponders the most effective way to create harmonic or acoustic supercharging on an N/A by tuning the pipes.  I agree, long pipes would be a waste of time on a TD. 
P.S. Sorry Caveman, I missed my window for getting pics up this weekend

[the caveman]

That's okay NO PRESSURE ! . I was trying to find photos on the Club 80-90 forums but with no luck, just so you can see what it looks like and how tight it is. My contention of using a 1Y intake is that we think we know better, but VW did pay engineers money to figure this all out .