Changed my air box

[Paul Workman]

Looks nicely done!

I had one of those (SLP?) "Claw" intakes on my 95 LT1 car. Intuitively speaking, it looked to have some potential over stock, but never dyno'ed it to actually see if function = form.

The stock intake on the LT5s is an area worth exploring, far as improvements go. Case in point: The vacuum is so great that often the accorion tube will collapse at WOT, in spite of an open lid box (I discovered).

1) The collapsing screams "impedance" at the opening of the tube; enough so that there is a pressure drop within the snorkel sufficient for outside air pressure to collapse the unsupported tube. And, when applying principles of "laminar flow", it would be difficult to find a surface with greater impedance than that accordion style tube bridging between the filter and the intake horn. (This was addressed on the C5 and C6 with the smooth carbon fiber bridge instead.) Installing hoops keeps the tube from collapsing, but does nothing for (theoretical**) surface impedance/internal pressure drop.

2) The "Coplan" sleeve insert does provide a bridge over the accordion surface, which has to be an improvement to flow (I'd bet a ham sandwich on it!).

**Note: I have to leave it at "theoretical" based on observation and basic flow principles. But, w/o actual quanitative measurements of air pressure or velocity to prove it, quantification is stll "at large".

So, from a flow dynamics point of view, the "Claw" appeals to my sense of flow, compared to stock. Sure would be interesting to see some "before and after and back again" dyno comparison of that system and stock.

I'm just sayin. This is a topic I'm studyin' up on at present, in conjunction with increases in TB area, is why all the elaboration. (Don't mean to steel the thread)

P.

[XfireZ51]

One indicator of inlet performance would be how close to 100kPa you get at WOT.

[Paul Workman]

Originally Posted by XfireZ51

One indicator of inlet performance would be how close to 100kPa you get at WOT.

No agruement, but a simple vacuum gauge in the intake horn, as in a "before and after" test, would be easily done as cheap test...methinks. No?

P.

[vilant]

Thanks, guys, I don't know if it looks good, lol, but it will when I have it painted.
Paul, the claw was still connected to the air horn via the accordian. Are you saying the accordian would collapse at WOT w/ the original air box but not the claw? Or either, because of the accordian? How did you find out it was collapsing? And where do you find the insert your talking about? It would be interesting to see what the difference is between the two on a dyno. I have both, but it costs $150 for 3 runs on a dyno at the shop near me. Not sure I want to spend that to quell my curiousity though, lol.

[Paul Workman]

Originally Posted by vilant

Thanks, guys, I don't know if it looks good, lol, but it will when I have it painted.
Paul, the claw was still connected to the air horn via the accordian. Are you saying the accordian would collapse at WOT w/ the original air box but not the claw? Or either, because of the accordian? How did you find out it was collapsing? And where do you find the insert your talking about? It would be interesting to see what the difference is between the two on a dyno. I have both, but it costs $150 for 3 runs on a dyno at the shop near me. Not sure I want to spend that to quell my curiousity though, lol.

I didn't realize the "Claw" retained use of the accordion tube. Too bad - a missed opportunity, methinks.

Yes, the accordion, otherwise unsupported, will likely collapse at WOT even if attached (in my case) to an open K&N filter box.

I learned on this site that collapsing was an issue with the hose, and it occured at around 5500 rpm or so. That too was my case: fell flat on it's nose at 5500 rpm.

Killing two birds w/ one rock, or sleeve, as it were, I used a strip of 16ga aluminum cut approx. as wide as the tube is long and approx a foot or a little more long and shaped it into an oval to fit snuggly on the inside of the hose. I trimmed the lenght to overlap enough so I could pop-rivit the seam. Works like a dream, and I knew it the first time I went WOT and it pulled hard to 7000+ rpm.

Not wishing to beat a dead horse, but some go to all the trouble of routing out the inside of the air horn at the same time the TB is opened up to 63mm or so and not address the accordion hose seems counter productive (to me). Certainly the TB effort works - well known fact, and maybe porting the air horn helps too. But, I have an idea that to go to that extent and NOT address the flow across that accordion bridge piece can't be as affective as it would be if it was smoothed out. And, when I look at the C5 and C6 filtered air intake tubes - i.e., smooth - it seems like that issue was finally taken into account.

Dyno time is expensive, no question. And, dyno time is further increased when there is any significant increase in output resulting from a physical change, as the tune may need to be tweaked to be keep everything in balance after the change. However, it would be interesting to test this and other ideas to see what is valid and if so by how much. It gives me an idea for possibly a funded dyno session setup for the purpose of exploring this and other power adder ideas. After all, the Registry helps sponsor certain social events, why not a a "tech" event that consists of a specific, formal set of experiments in order to quantify validity? Just a though.

P.

[vilant]

Originally Posted by Paul Workman

But, I have an idea that to go to that extent and NOT address the flow across that accordion bridge piece can't be as affective as it would be if it was smoothed out. And, when I look at the C5 and C6 filtered air intake tubes - i.e., smooth - it seems like that issue was finally taken into account.

Dyno time is expensive, no question. And, dyno time is further increased when there is any significant increase in output resulting from a physical change, as the tune may need to be tweaked to be keep everything in balance after the change. However, it would be interesting to test this and other ideas to see what is valid and if so by how much. It gives me an idea for possibly a funded dyno session setup for the purpose of exploring this and other power adder ideas. After all, the Registry helps sponsor certain social events, why not a a "tech" event that consists of a specific, formal set of experiments in order to quantify validity? Just a though.
P.

I don't doubt a smooth duct = smoother air flow. The question is: Is there any noticeable change in engine operation or performance between the ribbed vs. smooth duct? Not so sure you could really acurately prove it. Maybe a "tech " event is the way to find out. We need to get a list of things to test, then find a shop to rent for the day, and get enough people to split costs and test different theories. I would be into doing that, I would test air boxes, ducts, and coil packs. I'm looking into Marc's hoops to prevent the collapsing issue (even though this hasn't happened yet).